ICEE2019: INTERNATIONAL CONFERENCE OF ENVIRONMENTAL ERGONOMICS
PROGRAM FOR FRIDAY, JULY 12TH
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08:30-10:00 Session 18: Drowning
08:30
The physiological pathways to drowning

ABSTRACT. Immersion in cold water represents one of the greatest environmental stresses to which the body can be exposed, and immersion is the second most common cause of accidental death in many countries of the world. However, it is a relatively “hidden” killer with many of the 1,000+ immersion-related deaths that occur each day worldwide going unnoticed. Drowning is also a “disease of youth”, 64% of deaths are < 30 years old; 25% are < 5years old.

In this presentation the physiological responses to cold water immersion, particularly those hazardous responses that can be a precursor to pathophysiological consequences such as drowning and sudden cardiac arrest will be briefly reviewed. The importance of understanding these physiological responses lies in the insight it gives to “the cause of the cause of death”; this can help target and promote interventions such as training, equipment and treatment protocols that reduce immersion deaths. These will be explored in the rest of the symposium.

08:45
Immersion suits for arctic waters

ABSTRACT. The harsh arctic environment with low sea and air temperatures, strong winds and waves represent a challenge to protection and survival in emergency situations. The aim of this study was to evaluate whether a helicopter transportation immersion suit provided sufficient protection in accordance with the thermal and functional requirements described in ISO 15027, and identify possible weaknesses during exposure to ambient conditions as expected in the Barent Sea. Methods: The immersion suit was tested in a controlled laboratory study at SINTEF SeaLab in Trondheim, Norway. Six subjects were exposed to cold air (-11.3°C) and seawater (-0.1 °C) wind (5 m · s-1) and 40-50 cm waves. Every 10th minute the subjects were overflowed with water. Test subjects were recruited in accordance with the criteria described in ISO 15027-3. The subjects were fitted with equipment for measuring core and skin temperatures, heart rate and heat flux, which were measured continuously during the test. Oxygen uptake was measured every 20 minutes through the test period and the subject’s perceived thermal sensation and comfort were assessed. Results: Only one of five subjects was able to complete the defined three-hour test period. For four of the subjects, the tests were stopped because they reached one of the termination criteria: skin temperatures fell to 10°C at one of the transducers for more than 15 minutes or one of the temperatures fell to 8°C. Core temperature fell 0.5 ± 0.3°C and none of the subjects reached the termination criterion for core temperature. The requirements for the temperature in the neck and the back (that it should not fall below 25°C) were satisfied. The temperatures of the fingers and toes reached the termination criteria for four of the five subjects. The subjects voted the temperature of their body, feet and hands as “cold” at the end of the test. Ice clotted on the splash hood and buddy line. This reduced visibility and made it difficult to take hold of, pull out, attach and release these items when wearing gloves. Heat flux increased up to seven times when the test subjects were exposed to cold air and water. Metabolic heat production increased 1.5-3 times due to increased heat production by shivering. Conclusion: In this study, which simulated more extreme weather conditions with cold air (-11°C), water (0°C), wind (5 m·s-1) and waves (40-50 cm) than those described in existing international standard ISO 15027. The mean exposure time of the volunteer subjects was 120 minutes (ranging between 65 and 180 minutes) and the mean drop in core temperature was 0.5° C. The hands and feet were most vulnerable to cooling, and the temperatures of the fingers and toes reached the termination criteria in four of the five subjects. It is recommended that standards for immersion suits that is to be used in Arctic waters should be revised to meet the requirements for a more harsh environment.

09:05
Initial responses to cold water immersion in men and women

ABSTRACT. Introduction: Sudden immersion into cold water evokes an inspiratory gasp followed by uncontrollable hyperventilation and tachycardia. Given the large individual variation in the response, it was hypothesised that the difference between men and women would be minimal. Data collected over the last 20 years have been reanalysed to examine this.

Method: 15 women (mean [SD]: 21 [4] years; 163 [6] cm; 65 [11] kg) and 66 men (22 [2] years; 179 [6] cm; 80 [13] kg) undertook a head-out seated immersion into stirred water at 15.6 (0.5) °C wearing swimwear. Inspiratory minute volume (VI), respiratory frequency (fR), tidal volume (VT) and heart rate (HR) were recorded at rest in 23.2 (6.2) °C air and during the first 30 seconds of immersion. The inspiratory gasp (largest breath within the first 10 seconds of immersion) was also recorded.

Results: fR, VT, VI and HR were all increased on immersion (P<0.0001). fR and HR increased similarly in men and women (from 15 [4] to 35 [13] breaths.min-1 and 90 [17] to 113 [20] bpm). VT and the gasp were greater in men than women (Rest: 1.08 [0.40] L v 0.77 [0.21] L; P=0.0032. Immersion: 1.78 [0.55] L v 1.41 [0.29] L; P=0.0104; Gasp: 2.48 [0.58] v 1.84 [0.45] L; P=0.0004). VI was also greater in men, but only during immersion (58.3 [22.7] L.min-1 v 43.3 [15.4] L.min-1; P=0.0049). In both men and women, fR increased more than VT on immersion (142 [102] % v 80 [56] %; P=0.001). VT and gasp were correlated with stature (P<0.05).

Conclusions: Although men had a greater VT than women, the increase from resting was similar and probably related to larger lung volumes rather than sensitivity to cold water. fR appears to be a better indicator of ventilatory drive on immersion than VT in both men and women.

09:20
Resuscitation in drowning: theoretical aspects

ABSTRACT. Introduction: The majority of resuscitations take place after a primarily cardiac arrest. Public training programs are aimed at this situation. Resuscitation of drowning represents a minority of all resuscitations that take place around the world. Resuscitation after drowning includes several physiological, technical and practical elements that do not occur under common circumstances, but are typical for the environments near by water or on the water. Method: Narrative review Results: A cardiac arrest after drowning is the result of cardiac hypoxia. The sequence of events under water is: tachycardia; bradycardia; pulseless electrical activity; asystole. Ventricular fibrillation is rare in a drowned person. At the same time, most of the drowning victims are young, which means that the hypoxic heart has the opportunity to regenerate and to function as a healthy heart after resuscitation. At the same time, hypoxic brain damage can remain, resulting in survivors with long-term severe brain damage. Many drowning victims have aspirated a volume of water sufficient to cause lung damage and an acute respiratory distress syndrome. Another element of drowning is hypothermia caused by rapid cooling of the deep body tissues by the aspiration of water. This hypothermia can prolong hypoxic survival time and thereby protect the brain under extreme circumstances. Not only is the physiology of drowning complex and poorly understood. Also resuscitation measures in drowning are complex and differ to what is commonly taught for other scenarios. In drowning, the emphasis is on ventilation, while the AED should not interfere in such a way that any hypoxic period is prolonged. Ventilation can be extremely different as result of pulmonary oedema. Often resuscitations of drowning victims have to occur under extreme circumstances including noise, cold, rain and waves. Protective clothing and the limited space to perform the resuscitations are other problems that will influence the efficacy of resuscitation. Conclusions: The common way that people are trained to resuscitate does not take into account the physiological and ergonomic challenges that are typical for drowned victims.

09:40
“Should I stay or should I go?” Evidenced based triage for pre-hospital resuscitation and extracorporeal life support in a profoundly hypothermic patient post drowning.

ABSTRACT. Pre-hospital decision making for victims with profound hypothermia following a drowning event is complex and idiosyncratic, with resulting limited relevant guidance in the literature. This case presentation, of a successful resuscitation of a profoundly hypothermic victim following a drowning event, examines the evidence-base for pre-hospital triaging of such victims. This includes the commencement, or withholding, of resuscitation and extracorporeal life support (ECLS). Little specific guidance exists for pre-hospital triage of profoundly hypothermic patients following a drowning event. Key factors extrapolated from the clinical and physiological literature that may aid decision making include: immersion versus submersion; requirement for CPR; and initial core temperature. The suggested default position is to delay the decision to cease resuscitation attempts until further diagnostic tests can be performed e.g. in hospital

10:30-12:06 Session 19: Cold and hypoxia
10:30
An Artificial Neural Network to predict Divers’ Sensation of Cold Based on Survey Data

ABSTRACT. Introduction: Cold sensation leading to thermal discomfort is a major issue while practicing scuba diving. EN 14 225 standard classifies diving suits in regards of their foam thickness and proposes water temperatures ranges. But, some important parameters are not taken into account, especially duration, depth and local body discomfort. Decathlon’s Thermal Laboratory decided to build a model predicting whereas divers are cold or not, according to several diving scenarii and features. A large customer campaign was organized to get thermal sensations after a multitude of diving sessions. The resulting database was used to develop this predictive model using machine learning.

Method: After cleaning, our data set consists of 709 examples with 211 positives (cold) and 498 negatives (not cold) split into training, cross-validation and test set with a ratio of 0.6 / 0.2 / 0.2. We optimized a feedforward neural network with 100 units embedded within one hidden layer. The negative log-likelihood cost function has been used as a cost function -logP(y|x), where (x,y) is the (features, target class) pair.

Results: Evaluating our model on test set, we obtained an accuracy of 75.52% and a precision of 80,26% which is a good result given the amount of data. In our knowledge no such model with this accuracy is publically available for this specific application.

Conclusions: This work is a first attempt on the use of Artificial neural network to predict divers’ cold sensation. The precision reached is encouraging for further studies such as local cold sensations. However, we are aware that a larger data set would be of great help to enrich our experimental database and hopefully improve the accuracy.

10:42
The effect of shivering on whole-body glucose tolerance and insulin sensitivity
PRESENTER: Adam Sellers

ABSTRACT. Introduction: Impaired glucose tolerance is predominately the result of skeletal muscle insulin resistance. Exercise is one method of increasing skeletal muscle insulin sensitivity and glucose tolerance. Additionally, we previously showed for the first time that mild cold exposure also increased insulin sensitivity. During more intense cold exposure, with evident shivering, plasma glucose turnover and carbohydrate oxidation are increased. Specifically, during cold stress, muscle glycogen is utilised at lower metabolic rates than compared to exercising, which may prove beneficial for inducing lasting improvements to glucose metabolism. Therefore, the aim of this study is to determine the effects of shivering on oral glucose tolerance and insulin sensitivity.

Method: Eight healthy, non-cold acclimated males completed two test days, one with cold exposure (CE, 10°C) to induce ~1 h of shivering and the other test day resting at a thermoneutral temperature (TN, 32°C). Both conditions utilised a water-perfused suit, which was removed after CE/TN and then participants passively rewarmed/rested on a bed for 90 min. Energy expenditure (EE), core temperature (Tcore) and mean skin temperature (Tmeanskin) were measured during 1 h CE/TN. Next, participants consumed 75 g of glucose for an oral glucose tolerance test (OGTT). After the glucose load, blood was frequently sampled for 3 h to determine glucose tolerance and estimate insulin sensitivity.

Results: Preliminary results show that EE during 1 h of shivering was greater than during 1 h at thermoneutral (11±1 kJ/min versus 5.5±0.5 kJ/min). Tmeanskin decreased from 33.8±0.2°C at the start of CE to 27.2±0.3°C at the end. Prior to CE, Tcore was 36.9±0.1°C and remained stable during CE (36.8±0.1°C).

Conclusions: The cold exposure was sufficient to approximately double energy expenditure. Moreover, during the cold exposure Tmeanskin decreased notably whereas Tcore remained stable. The complete dataset, along with data from the OGTT, will be presented during the conference.

10:54
Mental fatigue independent of boredom and sleepiness does not impact self-paced physical or cognitive performance in normoxia or hypoxia.

ABSTRACT. Introduction: Altitude exposes humans to stressors including hypobaric hypoxia, cold, solar radiation and prolonged cognitive effort. This study aimed to explore the individual and combined effects of mental fatigue and hypoxia on physical and cognitive performance. Method: Following ethical approval from Loughborough University, 15 healthy males (mean ± SD; 24.2 ± 3.27 years) completed one familiarisation session and six experimental trials, including: 1) normoxia (0.209 FiO2) and no mental fatigue; 2) normoxia (0.209 FiO2) with mental fatigue; 3) low normobaric hypoxia (0.13 FiO2) and no mental fatigue; 4) low normobaric hypoxia (0.13 FiO2) with mental fatigue; 5) high normobaric hypoxia (0.10 FiO2) and no mental fatigue; 6) high normobaric hypoxia (0.10 FiO2) with mental fatigue. All conditions were completed at 21°C with 50% relative humidity. Mental fatigue was induced using a 16-min individualised cognitive test. Each condition included a 15-min self-paced time trial on an arm bike, followed by a 60-s isometric maximal voluntary contraction (MVC) of the biceps brachii. Supramaximal nerve stimulation was used to quantify central and peripheral fatigue with voluntary activation (VA%) calculated using the twitch interpolation method. Following each time trial, participants performed the Tower of Hanoi (TOH) cognitive test. Subjective measures of mental fatigue (VASF) and mood (BRUMS) were assessed. Results: A main effect of hypoxia was observed on average power output, oxygen consumption and muscle oxygenation (P ≤ 0.004), with no effect of mental fatigue, (P ≥ 0.599). VA% of the biceps brachii was reduced in hypoxia, (68.42 ± 5.64%, P = 0.039). Time to completion in the TOH was significantly increased in all conditions (+14.74 ± 6.99-s, P ≤ 0.041) however no effect of mental fatigue or hypoxia was observed on cognitive performance, (P ≥ 0.138). Conclusions: Hypoxia impacted physical performance whilst mental fatigue had no effect on physical or cognitive performance.

11:06
The roles of arterial CO2 pressure on cardiovascular responses to apnea during dynamic two-legged knee extension exercise
PRESENTER: Ryoko Matsutake

ABSTRACT. Introduction: During aquatic exercise, breathing can be restricted (apnea). Apnea during exercise can cause reductions in heart rate (HR) and active muscle blood flow with concomitant elevations in blood pressure and cerebral blood flow, though mechanisms underpinning these cardiovascular responses remain to be elucidated. Apnea leads to elevations in arterial CO2 pressure (i.e., hypercapnia). Hypercapnia is known to modulate HR, blood pressures, and muscle and cerebral blood flows. Thus hypercapnia may in part or in whole mediate the apnea induced modulation of cardiovascular responses during exercise. In this study, we assessed the roles of arterial CO2 pressure on cardiovascular responses to apnea during dynamic exercise. Method: Ten young adults (nine men and one women) performed maximum apnea during a dynamic two-legged knee extension exercise at a workload that elicits a HR of approximately 100 beats min-1. This apneic exercise was preceded by 3-min voluntary hyperventilation that reduced end-tidal CO2 pressure to 23.0 ± 1.6 (SD) mmHg (pre-apnea hypocapnia trial). As a control trial, the above protocol was performed while keeping end-tidal CO2 pressure at normocapnic level, which was achieved by CO2 inhalation. Results: Pre-apnea hypocapnia resulted in longer apnea duration relative to the control trial. In parallel, end-apnea arterial O2 saturation was reduced by pre-apnea hypocapnia in comparison to the control trial. At the time point wherein apnea ended in the control trial, mean arterial pressure and middle cerebral artery mean blood velocity were lower, whereas HR and leg blood flow were higher in pre-apnea hypocapnia than the control trial. Conclusions: Our results suggest that hypercapnia contributes to apnea mediated modulation of cardiovascular responses including elevations in blood pressures and active muscle and cerebral blood flows and a reduction in HR during dynamic exercise.

11:18
Cognitive performance is associated with cerebral oxygenation and peripheral oxygen saturation, but not plasma catecholamines, during graded normobaric hypoxia

ABSTRACT. Introduction: The physiological mechanisms responsible for cognitive decline following exposure to hypoxia have received little attention. This study examined the effects of graded reductions in fraction of inspired oxygen (FiO2) on oxygen saturation (SpO2), cerebral oxygenation, cardiorespiratory variables, activity of the sympathoadrenal system (adrenaline, noradrenaline) and hypothalamic-pituitary-adrenal axis (cortisol, copeptin), and cognitive performance. Method: Twelve healthy males (mean [SD], age: 22 [4] yrs, height: 178 [5] cm, mass: 75 [9] kg, FEV1/FVC ratio: 85 [5] %) completed a 4-task battery of cognitive tests to examine inhibition, selective attention (Eriksen Flanker), working memory (n-back) and simple and choice reaction time (Deary-Liewald). Tests were completed before and following 60 minutes of exposure to FiO2 0.2093, 0.17, 0.145, and 0.12. Results: Following 60 minutes of exposure response accuracy in the n-back task was significantly reduced in FiO2 0.12 compared to baseline (82 [9] vs. 93 [5] %; p < 0.001) and compared to all other conditions at the same time point (FiO2 0.2093: 92 [3] %, FiO2 0.17: 91 [6] %, FiO2 0.145: 85 [10] %, FiO2 12: 82 [9] %; all p < 0.05). The performance of the other tasks was maintained. Δ accuracy and Δ reaction time of the n-back task was correlated with both Δ SpO2 (r (9) = 0.66; p < 0.001 and r (9) = - 0.36; p = 0.037 respectively) and Δ cerebral oxygenation (r (7) = 0.55; p < 0.001 and r (7) = - 0.38; p = 0.045 respectively). Plasma biomarkers were not elevated in any condition or correlated with cognitive performance. Conclusions: These findings suggest that reductions in peripheral oxygen saturation and cerebral oxygenation, and not increased activity of the sympathoadrenal system and hypothalamic-pituitary-adrenal axis, as previously speculated, are responsible for a decrease in cognitive performance during normobaric hypoxia.

11:30
Human brown adipose tissue and skeletal muscle contribution for resting, non-shivering and shivering thermogenesis during gradual cold exposure

ABSTRACT. Introduction: Human brown adipose tissue (BAT) has been reconfirmed as a major organ for non-shivering thermogenesis (NST). Based on the previous studies, Asians showed less active BAT compared to Europeans. The skeletal muscle (SM), which is the major effector for resting and shivering thermogenesis, might contribute to NST. We hypothesized that human with less BAT would have more contribution of SM to NST, and/or induce earlier shivering onset for compensating the less thermogenesis.

Method: Nineteen males participated in this study. Their percentages of body fat and SM mass were estimated by electrical impedance method. The BAT activity and detectable volume was investigated using fluorodeoxyglucose (FDG)-PET/CT. They conducted cold exposure test in a climatic chamber. After baseline measurement in thermoneutral condition, ambient temperature was gradually decreased in 20 min and maintained at 18°C for 90 min for inducing NST. Then, ambient temperature was decreased to 12°C in 30 min for initiating minimal shivering. Oxygen uptake (VO2), rectal and skin temperature were measured.

Results: BAT volume was significantly correlated with change in VO2 relative to baseline (∆VO2 NST) during the final 10 min of mild cold exposure (r=0.60, P<0.01). The SM mass was correlated with baseline VO2 (r=0.82, P<0.01) but not with ∆VO2 NST. The BAT volume was not correlated with ∆VO2 at the final 10 min of minimal shivering (∆VO2 Shiv+NST) nor shivering component (∆VO2 Shiv = ∆VO2 Shiv+NST - ∆VO2 NST). The ∆VO2 Shiv+NST was negatively correlated with SM mass and VO2 base (r=-0.46, P<0.05; r=-0.46, P<0.05).

Conclusions: The hypothesis of metabolic compensation between BAT and SM was rejected. It was confirmed there was a significant correlation between BAT and NST, with no direct association of SM. Participants with less resting metabolism induced greater cold-induced thermogenesis. This could be a reason for the negative correlation between SM and ∆VO2 Shiv+NST.

11:42
Thermal variety and health
PRESENTER: Harry Kennard

ABSTRACT. Introduction: As with many upper latitude countries, the UK experiences a higher rate of deaths in winter than in summer months. The consensus is that dangerous cold exposure contributes to these excess winter deaths. However, determining when, where and for whom this dangerous exposure occurs is challenging. Rather than using static domestic measures of ambient temperature or local weather stations, this paper reports a novel method which makes use of the experienced temperature – that is, a characterisation of the immediate thermal environment of a participant. Using data from the UK Biobank - a large longitudinal observational health study of over 100,000 participants - we report the demographic, housing and health covariates of experienced temperature.

Method: The experienced temperature was derived from a wrist worn monitor worn by each participant for a week in everyday life. Following an extensive data processing exercise, the temperature time-series were summarised in a variety of measures, such as minimum, mean and the standard deviation. The standard deviation is used as a characterisation of participants ‘thermal variety’.

Results: The thermal variety experienced by participants increases with increasing health satisfaction and separately with activity levels. It decreases with age, body mass index and the external temperature.

Conclusions: While no causal claims can be made, the results suggest that increased thermal diversity correlates with health and activity levels. These results complicate the picture that mild cold exposure is necessarily linked with ill-health.

11:54
Protection of face against cooling while using powered respirators in the cold environment
PRESENTER: Kirsi Jussila

ABSTRACT. Introduction: Respiratory protective equipment (RPE) is required in several outdoor professions in the cold, e.g. mining, steel and construction work. Powered air purifying respirators (PAPRs) decrease breathing resistance and thus psychophysiological strain, but facial cooling occurs in the cold. The aim was to prevent facial cooling while using PARP in the cold and determine the influence of the cold protection on protective efficiency of the PARPs.

Method: Thermal insulation (Icl) of two PARPs with and without air flow and with and without thin (1.0 mm) and thick (3.0 mm) balaclavas were measured by using thermal head model in climatic chamber at air temperature (Tair) of +10°C. Also two half face masks and one full face mask were tested. Facial cooling was measured (N=7) wearing two PARPs at -20°C. Experimental protocol (40 min) included standing, stepping (20-cm high step), lifting a dumbbel and standing. Face skin temperatures (Tfs) and Tair inside the facemask were measured and thermal sensation on face was asked.

Results: Half and full face masks without air flow are protecting face against cooling, but when PARPs with air flow was used Icl dropped on an average 62%. Thin balaclava increased the Icl on the face by 29 and 81% without and with air flow, respectively. Whereas thick balaclava increased the Icl on the face by 73 and 144% without and with air flow, respectively. Tfs was 5.4±2.4°C higher with thin balaclava and 7.7±2.6°C with the thick balaclava under PARPs. Thermal sensation was experienced warm with the balaclavas. The balaclavas didn’t have any influence on protective efficiency of the PARPs.

Conclusions: Cold protection of the face is recommended when PAPRs are used in the cold (<-10°C). Skin cooling can be prevented by using even a thin balaclava under PARP.

This study was supported by The Finnish Work Environment Fund.

13:00-14:36 Session 20: Perception
13:00
Characteristic of human behavioural thermoregulation of clothing removal during and after exercise: effect of thermal perceptions and autonomic function
PRESENTER: Tze-Huan Lei

ABSTRACT. Introduction: The effect of unventilated clothing can significantly impair our thermoregulatory function (Core temperature (Tcore), skin temperature (Tskin), Local sweat rate (LSR) and skin blood flow (SKBF)) and thermal perceptions (thermal discomfort (TD), sensation (TS) and skin wettedness (SW)) during and following exercise recovery in temperate environment. Therefore, the ability to perceive and to select appropriate thermoregulatory behaviour by removing some part of the clothing is necessary to attenuate both thermoregulatory and perceptual strains. However, limited studies are available and therefore we examined whether partial clothing removal is an effective thermoregulatory behaviour to attenuate both thermoregulatory and perceptual strains in thermal neutral environment during and after the recovery of exercise. Method: Ten healthy males (age: 21.9 (0.3) years; height: 173.9 (2.0) cm; mass: 62.3(2.6) kg; VO2max: 51.8 (4.2) mL.kg-1.min-1) wore long sleeve T shirt and performed two cycling trials for 40 minutes and with 20 minutes on recovery at 40% VO2max in 23∘C, 65% RH environment. In one trial, they were permitted to roll up their sleeve at any time they want (Roll) whereas in the other trial they were instructed to remain in long sleeve (Long) until the end of the recovery. Thermal perceptions were measured at every 10 minutes whereas thermoregulatory variables were measured continuously throughout the trial. Result: All subjects behaved by rolling up their sleeve (Roll up time: 21.4 ± 1.3 minutes) and Tskin ,LSR, local SW, TD, TS and whole body SW were all lower in Roll than in Long (all p < 0.05) whilst Tcore and SKBF remained similar throughout the entire trail Conclusions: We conclude that partial clothing removal is an effective thermoregulatory behaviour to modulate local thermal perceptions, whole body skin wetness and sudomotor function during exercise and may persist after the recovery of exercise in temperate environment.

13:12
The influence of ethnicity on thermal sensation responses in British and Chinese individuals

ABSTRACT. Introduction: Thermal comfort models have largely been developed using data acquired from studies conducted using participants of Western European and North American ancestry. Consequently, these models have been used to inform the design of indoor climate systems installed worldwide. Little is known of the impact of other factors such as ethnicity (encompassing geographical, social and cultural issues), on a person’s level of thermal comfort and sensation. Some data suggest a warmer preference temperature in Asians. It is unclear whether this would be due to a sensitivity difference.

Method: This study aimed to investigate whether ethnicity influences cutaneous thermal sensation responses in British and Chinese individuals. Thirty-two participants, (16 British [age 25.4±3.45] and 16 Chinese [26.3±1.75 years; mean ± SD) were body-matched to within ±1kg/m2 of Body Mass Index. Local thermal sensation responses across thirty-three body locations were examined using a conductive thermal probe set to a warm (40 ⁰C) and a cool (20 ⁰C) stimulus in a thermoneutral environment (25°C air temperature, 50% relative humidity). Thermal sensation ratings were obtained immediately prior to the stimulus being applied, on initial contact with the skin and after 10-seconds of contact. Perceptual ratings of whole-body thermal sensation, thermal comfort and thermal preference were measured at 5-minute intervals to monitor overall thermal state.

Results: Chinese individuals reported slightly greater thermal sensation responses to the warm stimulus though this was only statistically significant for some areas on the front torso. No significant differences were observed for the cool stimulus between the ethnic groups (p = 0.11).

Conclusions: The thermal sensitivity maps obtained in the present study are consistent with earlier observations. However, the data indicate that there is only a minor difference in the thermal sensation responses to a warm stimulus between the tested British and Chinese groups.

13:24
Whole-body thermal sensation is independently modulated by local changes in foot skin temperature

ABSTRACT. Introduction: Skin temperature is an important physiological parameter in thermal comfort evaluation. Variations in skin temperature are often greatest at the feet, thus it is suggested that the feet modulate and dominate whole-body thermal sensation and perceptions of comfort, especially in the cold. However, the thermal state of the whole-body and feet tend to change together. This study investigated whole-body and foot thermal sensations and comfort by independently changing the thermal state of the feet from that of the whole-body.

Method: Trials were performed in a climatic chamber at 23°C, 50% relative humidity. 10 females, on three separate occasions rested seated on a medical bed, positioning their feet at hip level within a custom-built climate system. Three environmental conditions (neutral-23°C, heating-38°C and cooling-15°C) were applied to both feet for 30-minutes. Mean skin temperature (Tsk_body) was estimated from five sites. Mean (left) foot skin temperature (Tsk_foot) was determined from seven sites. Thermal sensation and thermal comfort were recorded every 5-minutes for the whole-body and left foot.

Results: While Tsk_body remained stable, Tsk_foot significantly changed during 30-minutes of foot conditioning (heating +1.9°C, neutral -0.3°C, cooling -4.5°C, p<0.01). Foot thermal sensation remained neutral with neutral conditioning (p=0.92) but increased from neutral to warm with heating (p=0.01) and decreased from neutral to cold with cooling (p=0.01).

Discussion: The literature indicates that typically a ±1.0-1.5°C increase respectively decrease in Tsk_body from neutral is required to elicit slightly warm or slightly cool whole-body thermal sensations. In our data, regression analysis indicated a +0.9°C and -0.2°C change in Tsk_body, mainly caused by the foot, was enough to elicit slightly warm, respectively slightly cool, whole-body thermal sensations. This apparent increased sensitivity to Tsk_body with local cold exposure, indicates a larger role of the feet in modulating whole-body sensations compared to the rest of the body.

13:36
The effects of low-intensity exercise on local and whole-body thermal sensations in hypothermic resting humans

ABSTRACT. Introduction: Thermal sensation is modulated by both skin and core temperatures, and is an important controller of the thermoregulatory behaviour. Previous studies suggested that thermal sensation to locally-applied cold stimulus is blunted during exercise compared to rest. However, whether exercise also modulates thermal sensation to whole-body cold stress has not been investigated. Furthermore, the effects of hypothermia on local thermal sensation at rest and during exercise need to be established. We investigated therefore the effects of low-intensity exercise on local and whole-body thermal sensations in hypothermic humans during cold water immersion. Method: Nine healthy young males (24 ± 2 years) were cooled thorough cold water immersion (18°C) up to their abdomen while resting (rest trial) or during low-intensity cycling (30-60 W, 30 rpm) (exercise trial). Esophageal and skin temperatures, oxygen uptake, heart rate, mean arterial pressure, and skin and whole body thermal sensations were measured at normothermic baseline, during cold water immersion with 0.5 and 1.0°C decrements in esophageal temperature from baseline. Skin thermal sensations to thermal stimuli were measured by applying Peltier element thermode to the chest. Results: Esophageal and mean skin temperatures did not differ between the trials. Oxygen uptake and heart rate were higher in the exercise than rest trials throughout cold water immersion. Whole-body thermal sensation tended to be higher in the exercise than rest trial at esophageal temperatures of -0.5 and -1.0°C from baseline (P=0.051 and 0.092, respectively). On the other hand, thermal sensations to locally-applied cool (29.5 ± 1.0°C) and warm (33.8 ± 0.6°C) stimuli did not differ between the trials throughout cold water immersion. Conclusions: These results suggest that whole-body but not local thermal sensation is blunted by low-intensity exercise during cold water immersion resulting in < 1.0°C decrease in core temperature.

13:48
Connected Helmets: piloting the big data era using continuous field evaluation of Thermal Comfort
PRESENTER: Alizée Navarro

ABSTRACT. Introduction: The area of thermal comfort in helmets has mainly been investigated using either laboratory testing or modelling. Subjective ratings are often used with a limited number of participants, rarely in the field. The aim of this exploration is to create a complete approach starting from large scale field data collection with newly designed embedded systems towards a big data analysis for a better understanding of thermal comfort changes associated with helmet design parameters.

Method: The first phase of the study was dedicated to finding the optimal solution for the measurements of both physical and subjective data regarding thermal comfort in helmets. The second phase will correspond to a pilot test in real life situations (skiing and cycling) to evaluate the robustness of the solution. The third phase will take place on a larger scale with around 200 users.

Results: The challenge of the first phase was to find the right sensors (locations, technical specifications) for the measurements of thermal parameters (temperature and relative humidity) and the ability to integrate them in different types of helmets. Hygrocron (Maxim) were tested but ruled out due to their size, sampling frequency and response time. STH35 (Sensirion) represented the right compromise with fine wires connected to a small acquisition pad attached to the helmet, transmitting data via Low Energy Bluetooth to a mobile application. The system can dynamically track physical changes within the helmets. A watch (Geonaute onMove500) is currently modified in order to track subjective ratings.

Conclusions: This ongoing study will deliver a large dataset in a wide range of situations which will enhance our understanding of thermal comfort in real life contexts. Big data analysis will help in the prediction of discomfort and therefore suggest product adaptations in connection with personal parameters (e.g: exercise intensity) and environmental parameters (e.g wind speed).

14:00
Thermal Comfort Assessment of an Automotive Cabin Environment in a Transient Cooldown Scenario
PRESENTER: Mark Hepokoski

ABSTRACT. Introduction: Objective assessment of automobile cabin thermal environments can be challenging since evaluators must rely on subjective reports. Consequently, test devices that incorporate human thermal models are being used more often to improve consistency and reduce time and effort in vehicle testing.

Methods: A test protocol was developed to investigate the effectiveness of a test device to predict the thermal comfort reported by humans in an automobile undergoing a transient cool down. A vehicle was exposed to a 40°C a hot soak, after which a human entered and reported subjective responses as the climate system was manipulated from the control room. The climate system set points were 22°C for the first 40 minutes, 18°C for the next 10 minutes, and 26°C for the final 10 minutes. This protocol was repeated 9 times: Once for each of the 7 participants, who were wearing light summer clothing (0.34 CLO); and, twice for a Thermetrics HVAC (passive sensor) Manikin, which measured environmental conditions for processing by the TAITherm human thermal model. The manikin-model results were compared quantitatively (using RMSD and bias) to the average of the human subjects.

Results: The mean skin temperature, overall thermal sensation, and overall thermal comfort obtained from the manikin-model were generally within one standard deviation of the human subjects.

Conclusions: Despite the good agreement between the manikin-model and the human averages, the relatively large standard deviations in the human subjective responses indicate that variability among human subjects should be more fully considered. In the future, the manikin-model should perform multiple simulations that vary individual characteristics (e.g., clothing insulation/fit, sex, physical fitness, activity) to obtain a range of potential comfort states. More broadly, this study demonstrates the unsuitability of a “one-size-fits-all” vehicle climate control system, and consequently, that some level of personalization should always be considered in product design.

14:12
Thermal comfort range of Perceived Temperature based on Thermal Sensation Votes in Korea

ABSTRACT. Introduction: The Perceived Temperature (PT) is an equivalent temperature based on Klima-Michel Model which considers the complete heat budget of the human body. The PT is based on Predicted Mean Vote (PMV). Actual Thermal Sensation Votes (TSV) reflects subjective deviations from the regional climate, culture, socioeconomics, and recent experiences of outdoor conditions. Thermal assessment for the equivalent temperatures may be replaced using surveyed TSV for the local climate. In this study, we optimized the thermal comfort range of PT for Korean climate based on TSV. Method: The TSV was obtained from heat-stress experiments in a climate chamber (chamber study) conducted in the summer of 2017 and 2018. The number of subjects participating in the 2017 and 2018 was 11 and 9, respectively. The chamber environment was set to 30℃ and 35℃ in 2017, and 28℃, 33℃, and 38℃ in 2018. As for exercise, walking by 4 km h-1 speed was chosen. The experimental protocol consists of two periods; 10 minutes resting and 60 minutes for exercise. Thermal sensations differ among individuals even when they are exposed to the same environment. To reduce these differences, Mean TSV (MTSV) was used. The PT was calculated using environmental conditions and anthropometric characteristics of subjects. Results: The fitted linear regression for the relationship between MTSV and PT is MTSV=0.13PT-2.66. The obtained PT range from MTSV "slightly warm (1)", "warm (2)", "hot (3)", and "very hot (4)" are increased by 8℃. The comparison of the two PT thermal scales shows that the PT range of Koreans is larger than that of Germans for each thermal sensation level. It means that the Koreans have higher thermal tolerance than PMV. Conclusions: This chamber study was conducted only for the high-temperature condition to improve information about heat waves in Korea. This method can be applied for any other climate regions where the PT range is unknown by modifying experimental conditions.

14:24
Thermosensory mapping of skin wetness sensitivity across the body of young males and females at rest and following maximal incremental running

ABSTRACT. Introduction: Humans lack skin hygroreceptors and we rely on integrating cold and tactile inputs from A-type skin nerve fibres to sense skin wetness. Yet, it is unknown whether sex and exercise independently modulate skin wetness sensitivity across the body. The aim of this study was to map regional sensitivity to cold, neutral and warm wetness at rest and post maximal incremental running in young males and females. Method: 10 males (27.8±2.7y; BSA: 1.92±0.1m2) and 10 females (25.4±3.9y; BSA 1.68 ± 0.1m2) underwent a quantitative sensory test where they reported the magnitude of thermal and wetness perceptions (Visual Analogue Scales) resulting from the application of a cold (5°C below skin temperature) wet (0.8ml water), neutral wet, and warm wet (5°C above skin temperature) thermal probe (1.32cm2) to the forehead, neck, underarm, lower back, and dorsal foot, at rest and following a maximal incremental running test. Results: We found that: 1) females were ~14 to ~17% more sensitive to cold-wetness than males (p=0.029), yet both sexes were as sensitive to neutral- and warm-wetness (p>0.05); 2) regional differences were present for cold-wetness only, and these followed a cranio-caudal increase that was more pronounced in males (i.e. the foot was ~31% more sensitive than the forehead; p=0.002); 3) maximal exercise reduced cold-wetness sensitivity over specific regions in males (i.e. ~40% decrease in foot sensitivity; p=0.003), and it also induced a generalised reduction in warm-wetness sensitivity in both sexes (i.e. ~4 to ~6% ; p=0.015). Conclusions: For the first time, we show that females are more sensitive to cold wetness than males, and that maximal exercise induce a reduction in local skin wetness sensitivity, i.e. hygro-hypoesthesia. These novel findings expand our fundamental and applied knowledge on sex differences in thermoregulatory physiology.

14:36-15:00 Session 21: Posters Friday
Location: Marble hall
14:36
Hand sweating magnitude during Alpine skiing in sub-zero ambient conditions

ABSTRACT. Introduction The aim of the present study was to assess the magnitude of sweating in gloved hands during Alpine skiing in sub-zero conditions.

Methods The field study was carried out at the Nassfeld Ski Resort. Male (N=31) and female (N=27) participants took part in this study: age (male 32(13); female 27(7) yrs), weight (male 80(8); female 60(7) kg) and height (male 181(6); female 167(4) cm). The subjects participated in two trials, each repeated and conducted over 4 consecutive days: 1) (Impermeable) ski gloves worn with a water-impermeable membrane; 2: (Permeable) ski gloves worn without a water-impermeable membrane. Glove weight was recorded before and after skiing. The difference in the gloves’ mass in the Permeable and Impermeable conditions provided an index of the amount of sweat that was evaporated.

Results Ambient temperature varied from -5.1 to -1.5 C throughout each day. The average (SD) daily distance skied was 54 (5) km, with no significant difference in the distance skied between the 4 days of skiing. The sweat production was greater for males (32.2 g) than females (24.5 g) and with greater sweating noted in the morning compared to afternoon skiing.

Conclusions Substantial sweating of gloved hands may be anticipated during downhill skiing in sub-zero ambient temperatures. Increased moisture in the glove may affect the thermal insulation characteristics and contribute to thermal discomfort.

Acknowledgements We are indebted to Miro Vrhovec, Tadej Debevec, Daniela Z. Pavlinic, Shawnda Morrison, Jana Stanič and Matjaž Likeb for their assistance. The study was supported by W.L. Gore & Associates

14:36
Compensable and non-compensable cold exposure: Effects of body morphology and body composition

ABSTRACT. Introduction: Cold exposure (CE) in humans can be categorized as compensable (C-CE) or non-compensable (NC-CE), leading to preserved or decreased core temperature (Tcore), respectively. Responses to a decrease in skin temperature (Tskin) or Tcore have been seen to be quantitatively different among individuals with varying body morphology and body composition. The purpose of this study was to examine the relationship between body morphology and composition on changes in Tskin and Tcore in men during C-CE and NC-CE.

Methods: Five males (27.7±4 y) participated in the C-CE and five males (26.5±5.3 y) participated in the NC-CE. Height and weight were taken and body composition was measured using DEXA. Skeletal muscle mass (SM), body surface area (BSA), body fat (BF) and body volume (BV) were calculated. Participants were either exposed to CE for 60 min using a liquid conditioned suit (LCS; 5℃) or NC-CE for 60 min using cold-water immersion (CWI; 20℃). Tskin was measured using 12 site thermocouples during LCS and Tcore using a telemetric pill during CWI.

Results: For C-CE, a relationship was found between final Tskin and BF (r2=-0.937, p=0.019), but not with BSA (r2=-0.672, p>0.05), BV (r2=-0.863, p>0.05) and SM (r2=-0.655, p>0.05). In contrast, during NC-CE, changes in Tcore were correlated to BSA (r2=0.994, p=0.001), BV (r2=0.943, p=0.016) and BF (r2=0.91, p=0.032), but not to SM (r2=0.643, p=0.242).

Conclusion: This preliminary study indicates that while changes in Tcore are related to interindividual differences in BSA and BV during NC-CE, these individual body characteristics are not linked to changes in Tskin during C-CE. Even though this finding was expected for NC-CE, it remains that this assumption is not confirmed during compensable CE as it relates to changes in Tskin. Consequently, more research is needed to establish the exact parameters that dictate cold response during compensable cold exposure.

14:36
Iron deficiency anemia impairs cardiovascular responses after graded exercise to exhaustion in the cold

ABSTRACT. Introduction. Blood pressure recovery after incremental exercise is considered as a prognostic tool for various cardiovascular diseases (McHam et al., 1999). Iron deficiency anemia (IDA) forces the heart to work harder in order to provide tissues with oxygen, thus causing serious heart problems, such as arrhythmias and an enlarged heart. Moreover, exposure to a cold environment can augment vasoconstriction, even more so in an anemic population, since cold exposure potentiates the catecholamine response (Dillman et al., 1979). Thus, the aim of this study was to examine the cardiovascular responses following incremental exercise to exhaustion in thermoneutral and cold conditions across a wide range of hematocrit values. Methods. Eight normotensive young males, four diagnosed with chronic mild IDA and four healthy individuals (Hct: 38.4±0.91% and 46.0±0.82%, respectively, range: 37.1-47.0%) were tested on two separate occasions, in neutral (22.5oC, 45%rh) and cold (11oC, 45%rh) conditions, in a randomized order. In both environments, following a 20-min rest, the participants performed a graded test to exhaustion on a cycle ergometer followed by a 5-min recovery. Systolic pressure (SP), diastolic pressure (SP), mean arterial pressure (MAP), and heart rate (HR) were monitored with finger plethysmography. Pearson r correlation was used to investigate the relationship between baseline Hct and Δ values of cardiovascular parameters (peak exercise–5min recovery). Results. In the thermoneutral condition, a non-significant correlation between Hct and ΔSP, ΔDP, ΔMAP (r=0.60, 0.43, 0.48, p>0.05) and ΔHR (r=-0.15, p>0.05) was observed. However, in the cold condition, Hct was highly correlated with ΔSP and ΔMAP (r=0.85, p=0.01) as well as with ΔDP (r=0.76, p=0.05) and slightly correlated with ΔHR (r=0.66, p=0.07). Conclusion. In summary, IDA impaired blood pressure recovery after maximal exercise in the cold. This may be attributed to an exacerbated catecholamine response, which could pose a health concern in an anemic population.

14:36
Reduced post-exercise vasodilatory response after combined acclimation to hypoxia and heat

ABSTRACT. Introduction: Baroreflex sensitivity seems attenuated in acute hypoxia and exacerbated in chronic hypoxia (Bourdillon et al., 2018). Arterial blood pressure (MAP) drop below pre-exercise values after a single exercise bout appears accentuated with acute hypoxia due to a pronounced increase in peripheral vasodilation (Rowell & Blackmon, 1989). The elevated sympathetic response in chronic hypoxia attenuates vasodilatory response and augments MAP in healthy humans at rest and during exercise (Calbet et al., 2003,2014), whereas no synergistic effect of heat and hypoxia has been shown. No study has examined the adaptive post-exercise blood pressure responses after hypoxic confinement in humans. Methods: Seven young normotensive males underwent a 10-day normobaric hypoxic confinement (FiO2:13.5%) interspersed with daily 90-min normoxic controlled-hyperthermia (target Tre:38.5°C) exercise sessions in warm conditions (35°C,50%RH). Prior to and after confinement, the participants were tested under normoxia (FiO2:20.9%) and hypoxia (FiO2:13.5%) in a randomized and counterbalanced order. The initial workload was set at 40% of normoxic PPO for 30min and was immediately followed by 20W/min increments until exhaustion. During the 30-min seated recovery cardiovascular parameters were recorded by finger plethysmography. Data were analysed using one- and two-way ANOVA for repeated measures with Tukey post-hoc tests pre and post confinement. For technical reasons 6 subjects were included in the post-confinement analysis. Results: After hypoxic confinement, post-exercise total peripheral resistance (TPR) and cardiac output were not different between normoxia and hypoxia (p=0.20 and p=0.37, respectively) and no TPR drop from resting values was observed in any condition. The profound post-exercise hypotension manifested in hypoxia pre-acclimation was not evident post-acclimation, since MAP was not reduced compared to rest in either normoxia or hypoxia. Conclusion: A 10-day combined acclimation to hypoxia and heat attenuated the vasodilatory response during recovery in normoxia and hypoxia and abolished the profound post-exercise hypotension observed after cycling in acute hypoxic conditions.

14:36
Greater vasodilation in hypoxia compared to normoxia following dynamic exercise

ABSTRACT. Introduction: After a single bout of exercise, mean arterial pressure (MAP) drops below pre-exercise values. This phenomenon, called post-exercise hypotension (PEH), is commonly observed following long bouts (30–60 min) of moderate intensity (50–60%VO2peak) dynamic exercise (Halliwill, 2001). Hypoxia affects blood pressure homeostasis in humans, since hypoxemia induces vasodilation and therefore hypotension (Rowell et al., 1989). However, studies examining hypotension following dynamic exercise in hypoxia are scarce (Horiuchi et al., 2016). Therefore, the aim of the present study was to compare normoxic with hypoxic post-cycling hemodynamic responses. Methods: Seven young healthy normotensive male subjects were tested in thermoneutral conditions (23oC, 50%rh) on two occasions, under hypoxia (FiO2:13.5%) and normoxia (FiO2:20.9%), in a randomized order. After a 2-min resting period, the participants exercised on a cycle ergometer at 40% of their normoxic peak power output for 30 min immediately followed by an incremental test to exhaustion; thereafter, they were monitored during a 30-min seated recovery period. Blood pressure, cardiac output (CO), total peripheral resistance (TPR), heart rate and stroke volume were recorded by finger plethysmography (Finometer). Data analysis was conducted using one- and two-way ANOVA for repeated measures with Tukey post-hoc tests. Results: During recovery, TPR was lower (p=0.002) and CO tended to be higher (p=0.075) in hypoxia than in normoxia. Post-exercise TPR dropped below resting values in both conditions (p<0.01). Post-exercise MAP values were consistently, although non-significantly, lower in hypoxia compared to normoxia across the recovery period (91.7±1.8 vs. 95.7±3.1 mmHg; p>0.05). At the 30th min of recovery there was a strong tendency for PEH in normoxia (p=0.057), whereas PEH was profoundly exhibited in hypoxia (p=0.001). Conclusions: These findings suggest an enhanced peripheral vasodilation which offsets the slightly higher cardiac output after cycling in hypoxia. As a result, PEH seems to be further augmented in hypoxia compared to normoxia.

14:36
Effects of a 1-week cold-water acclimation protocol on oxygen consumption during moderate aerobic bike exercise in normothermia after 48-h recovery period.

ABSTRACT. It has recently been observed an increase in muscular UCP-3 content, an uncoupling protein linked to mitochondrial expression, after cold-acclimation period. Whether or not these observations are sustained once back in warm conditions and impact oxygen consumption at exercise has never been investigated. Therefore, the present study aimed to investigate if a 1-week cold acclimation protocol led to modification of cycling VO2 after 48-h recovery period that could be explained from a rise in UCP-3 content.

Six (6) participants underwent the protocol consisting of two 30 minutes standardized bike tests (Neo Smart, TACX) sustained at 50% maximal aerobic power (MAP) at room temperature before and after a cold-acclimation week (1-h daily cold bath at 16°C). Oxygen consumption at exercise (VO2), at rest before (VO2before) and after (VO2after), heart rate (HR), heart rate recovery (HRr) mean skin temperature (TSK), thermal comfort (TCex) and rating of perceived exertion (RPE) were measured during the two tests. Core temperature (Tcore) and thermal comfort (TCacc) were measured to control the intervention.

Initials results demonstrated a trend for VO2 to increase post vs pre-acclimation (0.13±0.08 LO2.min-1 p=.173) parallel to a significant increase of RPE (0.43±0.13 p=.043), while others parameters did not change (VO2before: 0.01±0.02 L.min-1 p=.833; VO2after: 0.00±0.02 L.min-1 p=.599; HR: 1.29±1.01 bpm p=.249; HRr: -1.15±2.18 bpm p=.600; TSK: -0.18±0.27°C p=.345; TCex: 0.24±0.16 p=.225). Significant decrease in Tcore (-1.08±0.19 °C p=.028) and TCacc (-3.75±0.25 p=.020) alongside no changes in power (-0.52±1.01 W, p=.753) and cadence (0.09±0.45 rpm, p=.753) demonstrate the control we exerted. Data expressed as average difference Post – Pre ± SE.

These observations suggest changes in mitochondrial complex that could be UCP-3 related, explaining why no changes were observed in VO2 at rest before and after exercise, while an increase can be observed when cycling at 50 % MAP in normothermia after 48-h recovery period.

14:36
Human Thermal Comfort Model in Electric Vehicle with Infrared Warmers

ABSTRACT. Introduction: There is significant interest in electric vehicles (EVs) due to their capability to reduce CO2 emissions compared with internal combustion engine vehicles. There is demand for a new technology that can provide low energy consumption and reasonable thermal comfort for passengers in electric vehicles (EVs). We aim to develop human thermal comfort model for local radiant heating in EV and verify its effectiveness. Method: Experiments were conducted in an environmental chamber containing a real operable vehicle. The temperatures inside the environmental chamber were kept at 20°C and 7°C. The infrared (IR) warmer control component was installed separately outside the dashboard. The EV in the environmental chamber was soaked for 1.5 hrs. The subjects first spent 2030 min inside the EV without heating. Subsequently, heating (IR warmer, HVAC or heating wire for vehicle seat) was applied according to the experimental conditions and subjects recorded their thermal sensation every 2 min for 0.5 hrs. Results: Radiant heaters placed on the wall of the vehicle cabin interior may offer a solution to reduce heating energy consumption. Partial heating allows the energy consumption to be reduced while the passengers can feel an increased heating effect due to radiation heat transfer characteristics. The combination of low HVAC and IR warmer was more energy efficient than using only strong HVAC. Local thermal sensation increases after IR warmer surface temperature reaches the steady state, indicating that the IR warmer is not effective until it reaches the target temperature after which it affects the local thermal sensation of the lower body. Conclusions: The effect of a new energy saving heating method called local radiant heating was investigated using real EV experiments. It was confirmed that using the IR warmer and HVAC together to attain the same level of overall thermal sensation (in equivalent time) is more energy efficient than with a conventional HVAC. Good thermal environment with less energy can be achieved by interworking with the simulations of internal environment and human body temperature.

14:36
Experimental study of the thermal comfort in car cabin

ABSTRACT. Introduction: Standard ISO 14505-2 describes thermal comfort evaluation based on the Equivalent temperature (Teq) and Comfort Zone Diagram (CZD). The standard describes principles, measurement procedure and examples of measurement equipment. The aim of the contribution is to show how the method (Teq + CZD) was applied in testing of air distribution system for ventilation of middle-class car cabin.

Method: The tests for comparison of thermal sensation of test subjects and thermal manikin prediction were performed. The middle-class car with HVAC unit set to AUTO 22 °C was used and three different environments were tested: +10 °C no sun, +25 °C with 900 W/m2 and +32 °C with 900 W/m2 all in climatic chamber with wind simulator set to 80 km/h. The group of 10 test subjects acted as driver and the thermal manikin (Newton type) was the co-driver. Newton’s control mode was set to constant surface temperature mode 34 °C, the test subjects were stabilized 1 hour before test in thermal neutral environment. The thermal sensation votes from ten main body parts and overall thermal comfort were collected via questionnaire and compared with data from the thermal manikin.

Results: The results of test subjects thermal sensation and thermal manikin prediction were compared. The lowest discrepancy was reached in the seat contact parts and in legs and feet; the highest discrepancy was found in the arms. But the accuracy of prediction was within one standard deviation. The discrepancy in measurements in arms region can be explained by different position of manikin's and test subject's arms because manikin is rigid but test subject can adjust the position based on his/her driving habits.

Conclusions: The evaluation of local thermal sensation prediction based on Teq and Comfort zone diagram method versus test subject data was made. The accuracy of prediction was sufficient and discrepancy was within one standard deviation. We can conclude based on authors experiences that method is sufficient for scoring of HVAC technologies in the early stages of their development.

14:36
Individual and combined impact of hypoxia and acute inorganic nitrate ingestion on autonomic thermoregulatory responses to the cold

ABSTRACT. Introduction: This study assessed the impact of normobaric hypoxia and dietary nitrate (NO3) ingestion on shivering thermogenesis and vascular control in response to acute whole-body cooling.

 

Method: Ten male volunteers underwent supine passive cooling at 10°C air temperature across four conditions; NORM_PLAC: 20.9% fraction of inspired oxygen (FiO2) with ~0.003 mmol NO3- ingestion, NORM_NTR: 20.9% FiO2 with ~13 mmol NO3- ingestion, HYP_PLAC: 12.6% FiO2 with ~0.003 mmol NO3- ingestion, HYP_NTR: 12.6% FiO2 with ~13 mmol NO3- ingestion. Shivering thermogenesis via mechanomyography (MMG) and pulmonary oxygen uptake (O2) were continuously assessed to determine shivering onset. Vascular activity, via laser doppler flowmetry (LDF) at the forearm and mean arterial pressure (MAP), in addition to rectal and skin temperature (Tre and Tsk), were continuously assessed and analysed across a 30 min time window during passive cooling. Preliminary data from 7 participants is presented.

 

Results: Hypoxia significantly reduced (earlier) shivering onset time assessed via MMG and O2 (mean of NORM condition minus HYP conditions; MMG, 500 ± 140 s, P=0.02; O2, 337 ± 158 s, P=0.04) and increased microvascular perfusion (NORM minus HYP; LDF, -18 ± 7 PU, P=0.03). Hypoxia reduced MAP, reduced Tre and increased Tsk (NORM minus HYP; MAP, 3 ± 2 mmHg, P=0.2; Tre, 0.06 ± 0.06 °C, P=0.3; Tsk, -0.24 ± 0.19 °C, P=0.3), though these differences were not significant. No significant main effects were found for nitrate ingestion (mean of PLAC conditions minus NTR conditions; MMG, -430 ± 220 s,O2, -532 ± 326 s; LDF, 21 ± 16 PU; MAP, 4 ± 2 mmHg; Tre, -0.06 ± 0.07 °C; Tsk, -0.21 ± 0.29 °C).

 

Conclusions: Initial findings suggest increased heat loss with hypoxic exposure, leading to earlier onset of shivering thermogenesis. No differences were seen with nitrate ingestion. Interactions between hypoxia and nitrate ingestion requires further investigation. 

14:36
HYPOBARIC NORMOXIC EXERCISE
PRESENTER: Joshua T. Royal

ABSTRACT. Introduction: Continuous habitation at altitude reduces the ability to conduct exercise at an effective intensity and duration, and may lead to cardiovascular deconditioning. As a prelude to a study investigating the potential of providing personnel at the Concordia Antarctic Research Station with the possibility of conducting normoxic exercise in a hypobaric environment, we conducted a pilot study at an altitude of 3,883 m, using a portable oxygen concentrator to establish normoxia during hypobaric exercise. The aim of the ongoing study is to evaluate the effects of hypobaria and hypoxia upon exercise tolerance and perception of exercise intensity.

Method: Eight subjects conducted 3 different experimental trials (Normobaric-Normoxic (NN), Hypobaric-Hypoxic (HH) and Hypobaric-Normoxic (HN)). NN was performed at the Jozef Stefan Institute (Slovenia: 295 m); both hypobaric conditions were performed in hypobaric conditions mimicking the conditions at Concordia (3,883 m altitude), with an oxygen concentrator utilised to provide supplemental oxygen for HN (3,883 m with + O2). Each trial consisted of a 5-min rest phase, a 15-min exercise period (100 steps.min-1; 30 cm step) and a 5-min recovery stage. HR, VE, VO2, SaO2 and RPE were measured throughout all stages of the test.

Results: Preliminary results confirm that hypobaric hypoxia can be reduced with an oxygen concentrator.

Conclusion: The provision of a system providing altitude dwellers with the ability to conduct normoxic exercise may mitigate the known hypoxia-induced cardiovascular deconditioning and loss of appetite.

Acknowledgement: This study is supported, in part, by the Slovene Research Agency and the European Space Agency.

14:36
Exercise Ice Maiden: Physiological responses to incremental exercise in normoxia and hypoxia before and after an Antarctic expedition
PRESENTER: C.Douglas Thake

ABSTRACT. Introduction: The purpose of this study was to characterise the physiological adaptation to chronic prolonged arduous exercise under Antarctic conditions in females (http://exicemaiden.com/). Submaximal and peak physiological responses to exercise were measured in normoxic and hypoxic conditions before and after the expedition.

Method: Within three weeks of expedition departure (Pre) and return (Post) all six members team members (aged 33(3) years) undertook incremental exercise tests to volitional exhaustion on a treadmill in normoxia (N) and hypoxia (H) equivalent to 3000m. After an initial 3 min at 5.0 km•hr-1 at a 1% gradient speed was increased to 7.5 km•hr-1. Thereafter, speed was increased by 1 km•hr-1 every 3 min until an RER of 1 was exceeded. Subsequently speed remained constant, and the gradient was increased by 1% every 1 min until volitional exhaustion. Data are expressed as median and interquartile range. When Friedman’s test returned significance at P<0.1 post hoc Wilcoxon signed rank tests identified differences between trials.

Results: Peak oxygen consumption (L•min-1) declined pre to post expedition in both N -7(9)% and H -9(3)% (P<0.05). However when changes in body mass (Pre 73.6(5.0) vs. Post 65.6(5.3) kg) were accounted for no difference was observed (Pre 44(1) and 36(3), Post 45(4) and 35(4) ml•kg-1•min-1for N and H respectively). Post expedition participants reached volitional exhaustion at a steeper gradient in both N and H trials. Although not affected in N maximal fat oxidation (MFO) was seemingly reduced in H post compared to pre expedition (0.24(0.10) versus 0.34(0.09) g•min-1; P<0.05), however running economy (ml•kg-1•km-1)at MFO did not vary.

Conclusions: The reduced fat oxidation in H at a given level of work alongside the participant’s ability to exercise at higher gradients post expedition is indicative of greater dependency on carbohydrate metabolism and improved anaerobic capacity.

14:36
Effect of hypoxia on thermal sensation and thermoregulatory response during exercise
PRESENTER: Bun Tsuji

ABSTRACT. Introduction: Hypoxia reduces sweating and cutaneous vasodilatory responses during exercise as reflected by reduced sensitivity of the responses in response to increased core temperature (Kolka et al. 1987; Miyagawa et al. 2010). In addition, hypoxia at rest reportedly decreases cold sensation of the toes but not warmth (Golja et al. 2004). However, it remains unclear whether hypoxia decreases thermal sensation during and after exercise, and whether the effect of hypoxia varies at different body sites. We therefore examined the effect of hypoxia on thermal sensation and thermoregulatory response during exercise. Method: Thirteen healthy subjects (three men and ten women) performed cycle exercise at 30% of peak oxygen uptake in normoxia for 35 min under hypoxic (12%O2) and normoxic (20.9%O2) conditions. During resting, exercise and post-exercise, cutaneous thresholds for warm and cold sensation on three regions (forehead, chest and forearm) were measured by the method of limits (±0.3 °C/s). Esophageal temperature (n=9), skin temperature at seven sites, heart rate, arterial blood pressure, respiratory gases, forearm sweat rate and forearm skin blood flow were continuously measured. Results: Cutaneous threshold for warmth at forehead was significantly increased during exercise (3.2±2.1 vs. 2.3±1.5°C, P=0.013) and post-exercise (3.2±2.4 vs. 2.3±1.7°C, P=0.045) in hypoxia than in normoxia. The threshold for cold at forehead was significantly decreased during post-exercise resting (-2.3±1.6 vs. -1.6±0.8°C, P=0.025) and tended to be lower during pre-exercise (-2.0±1.3 vs. -1.5±0.8°C, P=0.061) in hypoxia than in normoxia. The thresholds for warmth and cold at chest and forearm did not differ between conditions. Esophageal temperature thresholds for sweating and cutaneous vasodilation were increased in hypoxia than in normoxia (n=9, both P<0.05). Conclusions: Present results suggest that exercise in hypoxia diminishes the sensation of warm and cold at forehead, but not at chest and forearm.

14:36
Protective workwear for hot conditions: an index for thermal management attributes

ABSTRACT. Introduction: Personal protective clothing (PPC) is important from both a protection and thermal management perspective, particularly as PPC frequently covers more than 80% of the wearer’s body. PPC selection is often based on standard ranges without knowledge of thermal comfort attributes. There are numerous attributes that are important when evaluating PPC suitability for workplace conditions. This study investigated thermal management attributes of a selection of 8 workwear ensembles worn in hot outdoor conditions. To contextualize findings and provide a new tool for selection of PPC, a novel Total Performance Ranking Index (TPRI) was developed.

Method: A sweating thermal manikin was used to determine garment thermal management attributes. Several manikin groups were created to enable specific evaluation of each garment type- e.g. shirt; as well as entire ensemble. Material attributes were also determined. The TPRI prioritised attributes deemed important for effective performance in hot conditions with weighting assigned to attributes important for these conditions; e.g. garment total mass and thermal water vapour resistance; and permeability index; material air permeability and surface properties. Each of these characteristics was weighted according to importance for the application and environment.

Results: The results show that garments/materials exhibited significant differences in numerous cases over all attributes evaluated. Garments that demonstrated effective attributes with vapour and moisture related tests performed well in overall results and ranking. Results demonstrate clear and easily ranked differences between garments and materials based on TPRI ranking.

Conclusions: The TPRI provides a novel approach to evaluating garments and weighting of attributes to rank PPC and other functional materials and clothing for other applications for use in a range of different environmental conditions. The TPRI is a new tool for designers, manufacturers and purchasers to use as a straightforward approach to development and selection of industrial PPC suitable for hot outdoor conditions.

14:36
Investigation into the risk of injury in workers setting cables in place during construction in cold conditions

ABSTRACT. Introduction: Present research investigated the risk of work-related musculoskeletal injury in work crews setting cables in place along the rail corridor for new signalling equipment in cold conditions. This work involved feeding cables from large, vehicle-mounted reels through underground conduits on a point-to-point basis. Method: Applied experimental design was combined with using wearable sensors to capture objective measurement of body movement patterns (that is, joint motion and posture) and muscle activity. Trunk and lumbar forward flexion and the muscle activity of the back musculature were measured during two methods of cable pulling: using a conventional method and using a specially constructed trestle to elevate the cable above ground level. Results: The trunk inclination and lumbar flexion demonstrates that cable pullers use high levels of trunk inclination and lumbar flexion, as demonstrated by the mean and peak values. Higher levels of trunk inclination and lumbar flexion occur at the start of a rope or cable pulling cycle where the worker reaches to a position slightly higher than ground level to obtain their grasp. In addition to adopting these high levels of back movement, force exertion for cable pulling is most likely highest at this point of the cycle. This was demonstrated with analysis of EMG data. Force exertion to pull the rope or cable along, once the participant was upright, was also identified as problematic. Conclusions: The investigation demonstrated and quantified trunk inclination, lumbar flexion (L5/S1) movement and EMG values for the usual method of cable pulling in cold conditions. It also provided preliminary evidence on the likely impact of a novel trestle device to raise the cable when pulling it close to a pit, thus improving operator back postures and movements in these conditions.

14:36
Music enhances self-paced maximal exertion in normoxia and hypoxia.

ABSTRACT. Introduction: High altitude is characteristic of a combination of environmental stressors which inhibit performance. Music has ergogenic effects through enhancing psychological factors such as mood and cognition. This study aimed to explore the impact of music as a tool for mitigating the performance decrements observed at altitude. Method: Following ethical approval from Loughborough University, 13 healthy males (mean ± SD; 23.9 ± 4.01 years) completed one familiarisation session and four experimental trials: 1) normoxia (0.209 FiO2) and no music; 2) normoxia (0.209 FiO2) with music; 3) normobaric hypoxia (0.13 FiO2) and no music; 4) normobaric hypoxia (0.13 FiO2) with music. All conditions were completed at 21°C with 50% relative humidity. Music was self-selected by each participant prior to the familiarisation session. The songs were assessed for their motivational qualities using the Brunel Music Scale Inventory (BMRI-2). Each experimental trial included a 15-min self-paced time trial on an arm bike, followed by a 60-s isometric maximal voluntary contraction (MVC) of the biceps brachii. Supramaximal nerve stimulation was used to quantify central and peripheral fatigue with voluntary activation (VA%) calculated using the twitch interpolation method. Subjective measures included motivation (MS) and mood using the Brunel Mood Scale (BRUMS). Results: Average power output (W) was reduced in hypoxia (p = 0.02) but increased with music (p = 0.001). MVC force (N) was reduced in hypoxia (p ≤ 0.026) whilst VA% of the biceps brachii was increased with music (p = 0.022). MS and BRUMS remained unchanged across all conditions (p ≥ 0.065). A main effect of hypoxia was observed on subjective scores of mental effort, breathing discomfort, and arm discomfort (p < 0.001). Conclusions: Music increased self-paced and maximal physical exertion through enhancing neural drive and diminishing detrimental mental processes. Therefore, music is a viable tool for enhancing performance at altitude.

14:36
A gender difference in acute recovery following strenuous exercise caused by cold-water immersion
PRESENTER: Ivo Tiemessen

ABSTRACT. Introduction: Almost all cold-water immersion (CWI) research focusses on male athletes, while Stephens et al. (2017) recently concluded that male and female athletes likely require different protocols due to a difference in cooling rate. Therefore, the purpose of this study is to examine if a gender difference exists in acute recovery after strenuous exercise caused by a standard CWI protocol.

Methods: Twenty healthy recreational athletes, including ten men and ten women, performed a multistage 20-meter shuttle run test and 50 drop jumps followed by a standard CWI protocol (14 minutes immersion in 12°C water). Power (squat jump height), strength (maximum voluntary isometric contraction) and acute muscle soreness (questionnaire) were tested before exercise and directly following CWI.

Results: CWI led to a higher power recovery (0.97 [0.41; 1.54]) for women compared to men and unclear differences for strength (0.12 [-0.06; 0.30] and muscle soreness (0.37 [-0.85; 1.59]). Additionally, a moderate correlation between body surface area to lean body mass ratio (Ad/LBM ) and acute power recovery (r = 0,42; p<0.05) was found.

Conclusions: A standard CWI protocol was more effective in the recovery of power for women compared to men. This gender difference is partly attributable to a higher Ad/LBM for women compared to men. The standard CWI protocol intensity (duration*temperature) concerning power recovery should accordingly be shorter for women compared to men.

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Two-minute hand immersion test for estimating finger skin temperature and manual dexterity during and after whole-body sub-zero cold air exposure

ABSTRACT. Introduction: The impairment of manual dexterity could be a potential risk factor for occupational accident in cold environment. It is well known that manual dexterity is correlated with finger skin temperature (Tfing), and there are wide individual variations in cold-induced vasomotor response in their extremities. This study investigated the validity of two-minute hand immersion test for estimating individual Tfing response and impairment of manual dexterity during and after whole-body cold exposure to sub-zero air.

Method: Eleven males participated in this study. At first, they conducted a simple skin temperature recovery test using a hand cold immersion for 2 min in 10°C water followed by 20-min rewarming in 20°C air. Second, they exposed to -20°C ambient air for 20 min with wearing cold protective clothes and gloves (around 2.2 clo), and then removed the protective clothes and rewarmed in 20°C for 40 min.  During the whole-body exposure test, they repeated pegboard tasks with gloves every 4 min and finger Tfing was continuously measured.

Results: There were wide individual variations in their Tfing response to the short time hand immersion test and whole-body sub-zero cold exposure. Tfing rewarming rate (°C/min) from 1 to 3 min after the hand immersion was significantly correlated with the rewarming rate after whole-body cold exposure (r=0.74, P<0.05) and the recovery time taken for rewarming Tfing to 20°C (r=-0.63, P<0.05). The manual dexterity was impaired during whole-body cold exposure and gradually recovered with rewarming, but it was not correlated with recovery of Tfing. The manual dexterity test with gloves might not be sensitive enough to assess the correlation with Tfing.

Conclusions: The validity of the two-minute hand immersion test was confirmed for predicting recovery of Tfing after whole-body cold exposure. This simple test could be used for assessing cold workers’ individual risk of cold injury in their extremities.

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Physiological and Subjective Responses from Wearing a Winter Cap on Elderly Males in a Cold Environment
PRESENTER: Joonhee Park

ABSTRACT. Introduction: The rate of hat wearing for elderly Korean males in winter is high. This seems to be related to hair loss in elderly males. However, there have been few studies on the head and a hat in terms of heat loss under cold stress. We examined the physiological and psychological effects of wearing a winter cap at rest in a cold environment. Method: Seven older males (76.2±4.0 yr) participated in the two seperate trials: with a winter cap (CAP) and without a winter cap (CON). The experiment was conducted in a climatic chamber (an air temperature 7.8±0.3℃ with 43±2 %RH) for 60 min in a sitting position. The cap consisted of 50 % wool and 50 % polyester and its insulation (Icl) measured on a thermal manikin was 0.02 clo. Besides the cap, all subjects wore the same experimental clothes (estimated clothing insulation excluding sneakers: 1.50 clo). Microclimates at the vertex of the head, rectal and skin temperatures, heart rate, as well as subjective perceptions were measured. Results: Microclimate temperature at the vertex was 6.9oC higher in CAP than that in CON (p<0.01). Microclimate humidity at the vertex was lower in CAP only during the last 5 min than that in CON (p<0.01). Forehead skin temperature in CAP was higher than that in CON (p<0.01). Also, during the last 5 min, rectal temperature was higher in CAP than that in CON (p<0.05). Unlike CAP, heart rate in CON during the last 5 min decreased significantly compared to that during the initial 5 min. There were no statistical differences in thermal comfort and humidity sensation between CAP and CON. Subjects felt less cold only on the head/face in CAP than in CON (p<0.01). Conclusions: Wearing a cap for elderly males positively affected body temperature regulation in cold environments.

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The influence of mechanical cues and friction coefficients on the wetness perception of the human index fingerpad.

ABSTRACT. Introduction: Despite not possessing skin wetness receptors, humans often experience wet stimuli (eg. holding a drink, touching a damp cloth). We now know that our brains instead form a comprehensive perception of wetness by integrating a range of external stimuli, such as thermal (eg. evaporative cooling) and mechanical (eg. adhesion). However, little research exists on how mechanical cues and perceived surface roughness influence skin wetness perception. We therefore aimed to quantitatively assess the impact of roughness across a range of wet stimuli on perceived roughness and skin wetness in static and dynamic interactions.

Method: Five adult females (29.6 ± 4.6y; BMI 24.0 ± 1.7) performed blind perceptual tests consisting of static and dynamic interactions with stimuli varying in volume (ie. 0 ml, 10 ml, 25 ml) and roughness (ie. low, medium and high friction coefficients; 0.43, 0.45 and 0.49 respectively). We recorded wetness and roughness perceptions during contact using a dichotomy of choice method (wet/dry; smooth/rough) and 100 mm visual analogue scales (very wet/very dry; smooth/rough).

Results: Participants discriminated between different wetness levels with larger volumes eliciting greater wetness sensations (P<0.001). However, we found that participants could not discriminate between the different friction coefficients (P=0.743). Despite this, we found that participants tended to associate greater wetnesses with smoother sensations (P<0.001). No distinct relationship was observed in either roughness (P=0.687) or wetness (P=0.609) perceptions between static and dynamic interactions.

Conclusions: We conclude that there is correlation between friction coefficients and perceived roughness, which is influenced by applied volume. Although different friction coefficients could not be differentiated, the associated mechanical cues play a role in the magnitude estimations of different wet stimuli. These fundamental insights are relevant to optimise the feel of absorbent products.

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Health over wealth: Formalised feedback concerning occupational heat stress across multiple European industries

ABSTRACT. Introduction: The European Commission Heat-Shield Project exists to minimize the impact of occupational heat stress (OHS) on five key European industries (agriculture, construction, manufacturing, transportation and tourism). Often, scientific recommendations are produced without input from the real-world end-users. Therefore, to counteract this oversight, the purpose of this investigation was to host meetings with European stakeholders from the aforementioned industries to identify their current state of knowledge and attitudes towards OHS. Method: Five workshops were held in Florence, Italy; Tønder, Denmark; Rome, Italy; Nicosia, Cyprus; and Ljubiana; Slovenia. Mixed qualitative and quantitative standardized questionnaires and focus group discussions were used to obtain attendee feedback. Notes from the focus groups and questionnaires were collated, and relevant themes were identified. Results: Feedback was collected from 72 people representing a variety of occupations, including: extrusion workers, manufacturers, farmers, shop stewards, company doctors, employers, policy makers and legislators. On average (range), workers had 15 (1-33) years of industry-experience and reported that heat stress moderately affected their work-performance [score of 3 (1-4) on a four-point scale] for 3 (0-12) months per year. On a scale out of 10, worker safety (9; 2-10) scored higher than preventing company productivity losses (7; 1-10) for combatting OHS. A prominent discussion theme that emerged was feeling under-informed concerning OHS. Further, differences in company resources necessitate prioritizing effective, feasible and low-cost cooling interventions in dissemination materials. Interventions best-regarded by stakeholders included: having a pre-made heat mitigation plan, utilizing hot weather notification services, adding pre-planned rest breaks in cool areas, changing work hours, ensuring hydration and optimizing clothing. Conclusions: Protecting worker-health is prioritized over productivity in the five selected European industries, regardless of occupation; however, knowledge and attitudes toward OHS vary widely. Several interventions (highlighted above) were agreed to be best suited to combat OHS from both a scientific and real-world perspective.

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The independent and interactive effect of thermal stress and mental fatigue on fine and gross manipulative tasks

ABSTRACT. Introduction: Many occupations (e.g. military) require performance of fine and gross manipulative tasks (e.g. operating equipment or vehicles) under thermal and mental stress. We aimed to quantify the effects of thermal stress and mental fatigue on fine and gross manipulation. Method: Seven healthy males (21.1±1.3y) partook in 6 separate 40-min trials characterised by a different combination of 3 ambient temperatures (HOT: 37°C, 40%RH; NEUTRAL: 21°C, 40%RH; COLD: 7°C, 40%RH) and 2 mental fatigue states (mental fatigue, MF; no mental fatigue, No-MF). Participants performed a fine (O’Connor dexterity test) and a gross (Hand-Tool test) manipulation task at the start and end of trials. Performance changes (%) were determined. To induce mental fatigue, participants performed 35 minutes of arithmetic problems during MF trials only. We monitored participants’ rectal temperature (Trec) and hand skin temperature (Tsk_hand) continuously and assessed reaction time (Hand-Click test) and subjective mental fatigue (5-point scale) prior to the tasks. Results: Trec remained stable during trials. Thermal stress (p<0.001), but not mental fatigue (p=0.290), modulated Tsk_hand (+3.3°C [95%CI +0.2, +6.5] during HEAT trials; -7.5°C [-10.7, -4.4] during COLD trials). Mental fatigue (p=0.022), but not thermal stress (p=0.646), decreased reaction time (~9%) and increased subjective fatigue (~50%). Thermal stress and mental fatigue had an interactive effect on fine manipulation (p=0.040), with HEAT-No-MF and COLD-No-MF decreasing performance by 15.7% [-1.4, 32.7] and 21.8% [4.7, 38.9], while HEAT-MF, COLD-MF, and NEUTRAL-MF by 36.0% [18.9, 53.0], 34.5% [17.5, 51.6], 36.4% [19.4, 53.4], respectively. Gross manipulation was affected by mental fatigue only (i.e. 29.8% [16.2, 43.4] performance decrement across all thermal conditions; p=0.002). Conclusions: Thermal stress-induced impairments in fine manipulation are increased by mental fatigue; yet combined stressors’ effects are no greater than that of mental fatigue alone, which also impairs gross manipulation. Mental fatigue poses a greater challenge to manipulative tasks than thermal stress.

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Prediction of thermal variables during exercise in cold, wet, and windy conditions using a six-cylinder thermoregulatory model
PRESENTER: John Castellani

ABSTRACT. Introduction: Thermoregulatory models predict deep body (Tdeep) and skin (Tskin) temperatures under various cold-weather conditions. These models have not been validated against data during cold-air exposure while wearing wet clothing. Purpose: Compare the six-cylinder thermoregulatory model (SCTM, Xu and Werner, 1997) to data collected during exercise in wet clothing in cold and windy conditions. Methods: The data set used for model comparison was from Castellani et al. (2001). Thirteen volunteers completed rest/walk cycles for up to 6 hours in 5°C air while wearing an Army uniform (1.1 clo dry insulation, estimated at 35% of this with wet clothing manikin evaluation). For the first 10 min of every hour, the clothing was saturated during 10 min of simulated rain (5.4 cm/hour); this was followed by 45 minutes of walking at 1.34 m/s at a 5.4 m/s wind velocity. Tdeep, mean Tsk, local Tskin (Tthigh and Tcalf = Tleg; Tforearm and Ttricep = Tarm, Tsubscap = Ttorso), and metabolic rate (MR) between actual and predicted values were compared to each other using root mean square deviation (RMSD) statistic vs. the standard deviation (SD). Results: The RMSD and SD, respectively, were 0.37 and 0.32 for Tdeep, 3.82 and 2.27 for mean Tsk, 6.33 and 2.75 for Tleg, 4.03 and 2.14 for Tarm, 3.72 and 4.36 for Ttorso, and 83.5 and 46.8 for MR. SCTM over predicted Tdeep by 0.08°C, mean Tskin by 3.28°C, Tleg by 5.89°C, Tarm by 3.73°C, and Ttorso by 2.30°C. MR was under predicted by 77 W. Conclusion: During exercise in cold, wet, and windy conditions, the bias across time for Tdeep was within ±0.1°C. Higher model predictions of Tskin were likely due to the fact that evaporative heat loss caused by water absorption in clothing was not taken into account. Author views not official U.S. Army or DOD policy

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Glomerular proteinuria increases as bicarbonate and carbon dioxide decrease at altitude.
PRESENTER: Kelsey E. Joyce

ABSTRACT. Introduction: Glomerular leak, characterised by increases in urinary alpha-1 acid glycoprotein (orosomucoid, uORM) occurs with ascent (and decreasing pO2). Hypothesised mechanism(s) include hypoxia and disturbances in acid-base balance. Uncoupling the relative effects of each at altitude is difficult, however, it would be beneficial to understand any relationship(s) between uORM and other arterial measures besides pO2 - such as changes in bicarbonate (HCO3-), carbon dioxide (pCO2), base excess (BE), and pH. The purpose of the present study was to examine uORM excretion in conjunction with blood gas components during ascent to high altitude. Methods: Twenty-three individuals ascended to Whymper Hut (5035m), Mt Chimborazo, Ecuador over the course of 6 days (Day 1, 2800m to Day 6, 5035m). Arterialised ear lobe blood gases were obtained each morning and analysed using the Abbott iStat. Twenty-four hour urine samples were collected daily with aliquots frozen (dry ice) and transported back to Birmingham (140m) where they remained at -80 degrees C until analysed for uORM by radial immunodiffusion. Statistical analyses were performed on complete data sets from Days 1-6 (n=17) using IBM SPPS. Repeated measures ANOVA (with Bonferroni correction), Pearson’s rank, and Spearman’s rho were used where appropriate with significance set to p<0.05. Results: 24-hour urinary uORM excretion (ug/min) progressively increased with ascent (by days, p<0.01), while arterial pO2, pCO2, HCO3-, and BE decreased with ascent (all p<0.01). pH showed no significant changes during ascent (Day 1, 7.436±0.020 thru Day 6, 7.432±0.022). With ascent, 24-hour uORM excretion was correlated with decreasing mean daily: pO2 (p = 0.017; r=-0.891), pCO2 (p<0.01; r=-0.966), and HCO3- (p=0.029; r = -0.857) but not pH (p=0.753) or BE (p=0.095). Conclusion: Increasing glomerular leak of uORM with ascent to altitude is negatively correlated with changes in pO2, pCO2 and HCO3-, however, the relevance of hypoxia or hypocarbia to the mechanism(s) underlying the leak remain unclear.

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Predicting Core Temperature during Exercise in Arctic Conditions using Observed Heart Rate
PRESENTER: Beau Yurkevicius

ABSTRACT. INTRODUCTION: ECTemp (Buller et al. 2013) uses observed heart rate (HR) to predict core temperature (Tc) changes. However, it has only been validated in moderate to hot ambient temperatures (Tamb, 18-45°C). It has not been validated during work in Arctic environments where Tamb often falls below 0°C.

PURPOSE: Assess ECTemp using HR and Tc data from two Arctic field training exercises (FTX) and evaluate its ability to accurately predict Tc using HR.

METHODS: HR and Tc data from two FTXs (Castellani et al. 2017) were used. In FTX 1, 8 men performed 46 hours of intermittent ski marches (ISM; Tamb: -18 to -6°C, wind speed: 5-13m/s). In FTX 2, 9 men performed 43 hours of ISM (Tamb¬: -17 to -3°C, wind speed: 0.3-19m/s). The baseline observed Tc was used as the starting point for the model prediction. Minute-by-minute HR values were input into the model which predicted the corresponding Tc. Hourly data points were used to evaluate the model over the 40+ hours of ISM. The root mean square deviation (RMSD) was calculated for each data set. Predictions were considered valid if the RMSD fell below the standard deviation (SD) of the observed Tc values. Non-parametric Bland-Altman plots were used to determine the level of agreement between the observed and predicted temperatures for the ECTemp model using ±0.4°C as a qualitative physiological threshold for Tc assessment.

RESULTS: Model predicted Tc across time was higher than observed Tc. In FTX 1, RMSD was 0.83 with a corresponding SD of 0.31 and 17% of values falling within the ±0.4°C threshold. In FTX 2, RMSD was 0.56 with a corresponding SD of 0.42 and 63% of values falling within the ±0.4°C threshold.

CONCLUSION: ECTemp over-predicts Tc when using observed HR as a predictor during 40+ hours of intermittent work in Arctic environments.

Disclaimer: Author views not official US Army or DOD policy.

14:36
Does practice make perfect in the cold? A study of motor skill training for cold performance.

ABSTRACT. Rationale: Little is known about how to best prepare persons for motor performance in cold conditions. It is unclear if principles of training specificity would apply because cold exposure reduces sensorimotor feedback and cognitive function. The current study investigates the effect of cold or thermoneutral training on performance of the Grooved Pegboard task. Methods: Twenty persons (11M, 9F, mean age 31.2 ± 5.44) were randomly assigned to either a cold (5M, 5F) or thermoneutral (6M, 4F) training group. Prior to each repetition of the task during training, the cold training group immersed their hand in cold water (2 °C) while the thermoneutral group immersed their hand in thermoneutral water (34 °C). Participants were tested at baseline, at retention after training, and at a delayed retention period of 24hrs. During baseline and retention testing, participants performed the task twice; once after immersing their hands in cold water and once after immersing their hands in thermoneutral water. On day one, participants were tested at baseline and then performed 20 repetitions of the task according to their respective group assignment. Following this, participants were tested once again in an immediate retention test. On day two, delayed retention tests were performed. Time to completion and number of errors were recorded during testing. Errors were defined as the number of times a peg was dropped or when subjects picked up multiple pegs at once. Results: There were no differences in time to completion during the delayed retention test between thermoneutral and cold-trained groups (T(18) = 0.80, p = 0.434). The cold trained group however made fewer errors than the thermoneutral training group during delayed retention testing (p < 0.05). Conclusion: The main finding of this study was that dexterity but not speed in cold conditions was improved by cold training.

14:36
Comfort rating for Upholstery Systems

ABSTRACT. Introduction: Nowadays long-distance drives or sitting workplaces are normal. As consequence a human sit up to 7.5 h per day. Therefore, the comfort while seating is getting more and more important. The comfort of upholstery systems such as car seats, office chairs or upholstered furniture is influenced by different ergonomic properties in particular thermophysiological comfort.

Method: There are different methods for rating the comfort of upholstery systems: Thermophysiological comfort of an upholstery can be characterized by Hohenstein Skin Model (sweating guarded hot plate) according to ISO 11092. With the Skin Model the specific thermophysiological quantities of textiles as layers are determined. Under stationary measurement of the Skin Model the water vapor resistance Ret is determined, which characterizes the insensible sweating. Higher sweating rates (sensible sweating) can be described by buffering capacity of water vapor Fd and buffering capacity of liquid sweat kf. In the next step a sitting human can be simulated by the sweating buttocks model or thermal, sweating manikin “Sherlock” (Newton type by Thermetrics). By combining these measurement systems with humidity sensors within in the upholstery the moisture management of an upholstery system can be determined. Further pressure distribution of a sitting person can be qualified by measurements with a pressure pad. Handheld scanner systems like Artec Eva, Creaform Revscan and or low-cost devices as the Kinect sensor offer the opportunity to scan objects like seats. The 3D information of seats, chairs or furniture can be compared with 3D data of target groups. As a result, the contact area can be identified in regard of size and shape.

Conclusions: Comfort of upholstery systems depends on different aspects: thermophysiological rating, skin sensory behaviour, ergonomic fitting and e.g. pressure distribution of a sitting person. For good comfort ratings of upholstery systems it is recommendable to characterize several of these aspects.

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Optimizing safety by customization in conjunction with whole-body cryotherapy
PRESENTER: Pat Viroux

ABSTRACT. Introduction: Whole-body cryotherapy (WBC) is associated with significant drops in skin temperature. General skin temperature drops are in the range between 10-20°C. Recent findings illustrate that at specific body locations, local skin temperature drops might even be larger, implying drops that might cause harm to the individual. This study investigated the skin temperature responses as the derivative from the treatment dose, specific body location and personal characteristics. Next, we aimed to develop and validate an algorithm to a priori correct the WBC treatment dose to ensure a safe exposure for each individual. Methods: 20 volunteers, 10 male and 10 female, were exposed to 2 different WBC protocols (one at -110°C for 2,5 minutes and one at -130°C for 3 minutes) while assessing skin- and core temperature, thermal comfort and sensation at 15 minutes prior to 45 minutes after exposure. The Fiala thermal Physiology and Comfort (FPC) numerical simulation model (Fiala et al. 1999, 2016) adapted for cryotherapy applications was used to assess the impact of personal characteristics on the stimulation settings in relation to safety. Results: The results show that skin response is always rapid though very sensitive to variations in personal anthropometric settings. The body fat content (BF) and the so-called fat free mass index (FFMI) were found to a significantly affect the personal skin temperature response and thus the protocol settings. Following the validation tests, parametric simulation for different personal configurations will be performed to study the influence of personal characteristics on local skin cooling responses. The influence of each parameter on predicted local skin response will be assessed using the goodness-of-fit of linear regression analysis with stepwise variable selection. Conclusions: Local skin responses to WBC are very sensitive to variations in personal characteristics. Results of the parametric simulation and linear regression analysis are expected in the coming months.

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Investigation on the effects of moisture management boots’ linings in improving feet thermal comfort in moderate temperature environments

ABSTRACT. Introduction: Impermeable rubber material greatly restricts heat and moisture dissipation from the feet to the ambient, leading to profuse sweating, odour and even blister in feet, which are frequent complaints in occasions such as hiking, creek walking and working in the garden (Shimazaki et al., 2016). The purpose of this study was to investigate whether moisture management linings could improve feet thermal comfort in moderate temperatures. Methods: Three typical moisture management lining fabrics were examined, i.e., 1) warp- knitted spacer fabric with chemical treatment, 2) Coolcore fabric with special knit structure to drag sweat away from skin (Coolcore, LLC), and 3) the normal polyester fabric was also studied for comparison. The specifications of the fabrics were listed in Table 1. Human trials were conducted to assess the effectiveness of the boots with the three fabrics. Six healthy university students performed moderate- intensity exercise (i.e., walking at 5 km/h for 50 min and standing for 10 min) in a climate chamber with air temperature of 25 oC and 60% RH. Foot temperature and subjective ratings (i.e., thermal, wetness and comfort sensations) were recorded. Table 1. Specifications of the three lining fabrics Lining fabric Fiber Content Weight (g/m2) Thickness (mm) Water absorption rate (g/h) (FZ/T 01071-2008) Water drying rate (g/h) (GB/T 21655.1-2008) Warp-knitted fabric 100%P 434 2.96 12.8 0.87 CoolCore fabric 100%P 159 0.55 15.5 0.65 Polyester fabric 100%P 203 0.65 8.2 0.41 Results: Coolcore and warp-knitted spacer lining fabrics showed significantly lower foot temperatures compared to polyester fabric from the 5th min to the 15th min, and from the 10th min to the 15th min of the test, respectively (p<0.05) (figure 1). Coolcore lining fabric also significantly improves comfort sensation compared to the other lining fabrics (p<0.05). Figure 1. Time-course changes of foot temperature (a), thermal (b), wetness (c) and comfort sensations (d) Conclusions: Using lining fabrics with good moisture management properties improve feet thermal comfort in moderate temperature environments. References: Shimazaki, Y., Matsutani, T., Satsumoto, Y., 2016. Evaluation of thermal formation and air ventilation inside footwear during gait: The role of gait and fitting. Applied Ergonomics 55, 234-240.

14:36
On using a smart local heating blanket to improve body thermal comfort in a cold environment

ABSTRACT. Introduction: The bedding system plays an important role in regulating the bed micro-environment, which significantly affects the sleep quality of human body, even more than room environment. Survey results indicate that most rural residents in North and Northwest China prefer improving their bed climate instead of increasing the whole room temperature in winter. Using a heating blanket is a common strategy to improve their sleeping thermal comfort and quality. However, the heating blankets currently available cannot ensure body thermal comfort, because they were developed without considering body thermal physiological characteristics. Methods: A smart local heating blanket was designed in this study. The carbon fibre heating elements are embedded in the blanket. A temperature controller is installed to control the surface temperature of the blanket steady in feet, buttocks and shoulder regions, and the respective temperature setpoints, i.e., 42, 37, 32°C, were used in this test. Two polyester quilts, foam mattress and the smart heating blanket were used as the bedding items. The experimental condition was set as 4.9 °C, 57% RH, and air velocity of 0.17 m/s. Eight female subjects were involved in two test scenarios: no heating condition (CON) and heating condition (HEAT). The experiment duration was set as 8 h; the mean skin temperature, core temperature, heart rate, local and whole thermal sensation and comfort sensation were recorded. Results: The results showed that HEAT increased local skin temperatures at heated body parts and mean skin temperature, whereas there was no significant difference in core temperature and heart rate. Besides, thermal and comfort sensations in both the local and the whole body were all greatly improved in HEAT, and the ratings are near ’thermal neutral’. Conclusions: The research findings demonstrated that the smart heating blanket could improve both the local and whole body thermal comfort in cold environments.

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Verification of Teq Method for Thermal Comfort Prediction in Automotive Cabins

ABSTRACT. Introduction: A thermal comfort evaluation based on the Equivalent temperature and Comfort Zone Diagram is the well known method defined by standard ISO 14505-2 where principles, measurement procedure, measurement equipment, and evaluation of thermal comfort are described. The aim of the contribution is to show how this method could be applied in testing processes of air distribution system for ventilation of automotive cabin and which steps are necessary for successful application.  
Method: The equivalent temperature method is typically base on using of measurement system with actively heated surfaces and calculation of equivalent temperature. Above mentioned measurement systems are typically thermal manikins or special sensors. Then Comfort Zone Diagram (CZD) is used for thermal sensation and thermal comfort evaluation. This is standard description of method for laboratory environment but for application in testing process of specific customer the situation is much more complicated. At the beginning the method has to be adopted by the company employees and they should be familiar with the method at the end of this phase. Then the next step is pilot measurement to proof that thermal comfort evaluated by method (thermal manikin + Teq + CZD) is correlated with sensation of real test subjects (environment and setting typical for customer's tests are used) and the method could be really helpful for customer's purposes. If this is successfully pass, next step is to design and perform the tests based on customer's demands to test features of air distribution system or tuning the control algorithms of other HVAC technologies.      
Results: The results from pilot evaluation of thermal comfort prediction (measurement by Newton manikin system) against test subjects' data are presented. Three different environments (+10, +25 and +32 degree C) and two different middle class car cabin were tested. Important parameters of the tests were setting of air distribution system as well. The thermal sensation vote from ten main body parts and overall thermal comfort were collected via questionnaire and compared with prediction from Teq method. The typical deviation between averaged subjects data and thermal manikin prediction was less than one standard deviation. Conclusions: The evaluation of local thermal sensation prediction based on Teq and Comfort zone diagram method versus test subject data was made. The accuracy of prediction was sufficient and discrepancy was within one standard deviation. We can concluded that Teq method is applicable for prediction of thermal comfort in environment of automotive car cabin and could be helpful tool for testing of air distribution system, HVAC technologies and their control algorithms.

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Menthol application on the skin modulates thermal perceptoins but not heat loss, ventilatory, and cerebrovascular responses in resting heated humans

ABSTRACT. Introduction: Menthol activates transient receptor potential melastatin 8 (TRPM8), providing cool sensation. Previous studies reported that menthol application on the skin leads to cool sensation and improves thermal comfort, whereas it might attenuate heat loss responses of cutaneous vasodilatation and sweating in exercising humans. However, whether menthol application on the skin modulates thermal perceptions and the heat loss responses in passively-heated resting humans is unknown. Also, hyperthermia causes hyperventilation (so called hyperthermia-induced hyperventilation) and cerebral hypoperfusion in resting heated humans. However, whether these responses during severe hyperthermia at rest are modulated by menthol application on the skin remains to be determined. Method: In thirteen healthy young males, 3% menthol solution (menthol trial) or control solution (control trial) was applied to the trunk and arm skin (pre-heating only), then lower-body hot water immersion (42°C, 34 ± 8 min) was conducted in a room temperature of 25°C. Body temperatures, skin blood flow, sweat rate, minute ventilation, middle cerebral artery mean blood velocity, and thermal sensation and comfort were assessed throughout. Results: Heating time was longer in the menthol than control trials (32 ± 8 vs. 37 ± 6 min), but oesophageal and mean skin temperatures similaly increased to ~38.6°C and ~37.5°C, respectively, in both trials. Thermal sensation was lower in the menthol trial (i.e., felt cooler) at ≥5 min of heating. Also, thermal comfort was lower in the menthol trial (felt more comfortable) at 20-25 min into heating. Passive heating increased skin blood flow, sweat rate, and minute ventilation, whereas it decreased middle cerebral artery mean blood velocity. However, these responses did not differ between the trials. Conclusions: Our results suggest that 3% menthol application on trunk and arm skin improves thermal sensation and comfort, but it does not affect heat loss, ventilatory, and cerebrovascular responses during severe hyperthermia at rest.

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Principles of Radiant Heat Exchange between Humans and their Environment – a model study

ABSTRACT. Introduction: Radiant heat exchange between humans and their environment has not received a lot of attention. Some basic models have been developed, such as by Lotens, and a major EU research project was conducted to study effects of color and heat reflective clothing. Yet, recently new technologies have emerged that would allow engineering of emissive, reflective and even transmissive properties of clothing. Method: In this paper an overview of the basic equations and principles of radiant heat exchange will be discussed and the application of these to clothing and fabric engineering will be discussed. Basic heat exchange theory will be applied and equations derived and then the predictions will be compared to some fabric studies and other data from the literature. Results: The results will show from a theoretical perspective how engineering of radiant properties will help heat loss increase or reduction and under what conditions it may have unintended consequences. Novel emissive, reflective and transmissive properties will be judged on their expected added value. Furthermore, the data will show how thermal infrared cameras can be used for analysis of clothing insulation and human heat exchange. Conclusions: The development of this model will further support specific fabric engineering to attenuate radiant heat exchange as well as serve as a theoretical framework to help understand the relevance of radiant heat exchange for humans, and measure it, in a variety of environments.

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Extreme heat policies for sport and physical activity – an international review

ABSTRACT. Introduction: Evidence-based extreme heat policies are needed for the management and mitigation of heat stress risk in sport and physical activity (PA). Our aim was to determine the quality of publically available sport and PA heat-protection advice from government and sport organisations internationally. Method: We combined “weather”, “guidelines” and “physical activity” terms to systematically search websites for advice from: major international sporting event organisations; government, sports medicine and Olympic summer games organisations in Anglosphere countries and former and future countries hosting major international sporting events; and the six most popular outdoor club sport organisations in each Anglosphere country. We included English advice only. Quality was the presence(1) or absence(0) of 13 components considered crucial for the management and mitigation of heat stress risk and covered the areas of vulnerable populations, measurement and use of environmental parameters, prevention and treatment of heat-illness, ease-of-use and evidence-base. A quality score was given from 0-13 based on the total number of components present, with high scores denoting high quality; data presented as mean. Results: 133 documents (score:4) were retrieved from 52 (26%) of 198 organisations in 37 countries. Short documents e.g. PA fact sheet (n=122, score:4), had ease-of-use with mostly well presented, lay terminology but lacked evidence-based prevention, treatment and environmental cut-offs. Sport heat-policies (n=7, score:5) prioritised game cancellation often without apparent evidence and other prevention strategies or treatments. Position statements (n=4, score:9) were evidence-based but were unclear how environmental parameters should be measured and lacked ease-of-use and prioritisation of prevention strategies. Conclusions: We found low online accessibility to sport and PA heat-protection advice. Predominantly, advice was either good quality with poor ease-of-use, or vice-versa. The general public and sporting communities need greater access to usable, good quality sport and PA heat-protection advice in policy form to guard against heat illness.

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Implication of drop in footwear comfort for the physiological needs in obese users

ABSTRACT. Introduction:

It has been shown that obesity is a factor that alters: the gait pattern, the foot structure and the loads. In general, overweight and obese people, with respect to normal-weight people, show feet with larger dimensions, lower arch, greater plantar pressures and balance deficiencies. Epidemiological research indicates there is a higher rate of falling among those who are obese.

This work is aimed at analysing the functional effect of two casual footwear models, one flat and the other with some Drop*, in the distribution of the plantar pressures of obese users. (*Drop: height difference between the heel and the forefoot of the shoe)

Methodology:

Two models of comparable casual shoes were selected with different Drop: flat =0cm and Drop=1cm. The participants in the study were a total of 20 subjects with BMI 29±5Kg/m2 with shoe size 42±2EU.

The distribution of the plantar pressures in dynamic conditions was recorded and analysed with the Pedar® Insoles system that included the Pedar-X Expert software (Novel GMBH, Munich, Germany). Data were recorded for 60 seconds with a frequency of 50 Hz. 3 areas of the foot were established: the forefoot, the midfoot and the hindfoot. The normalised absolute maximum pressures (kPa/kg) and the contact area (cm2) were calculated in the midstance phase of the tread.

Data were analysed with the SPSS Software v. 20 for Windows® (IBM, Chicago, USA), with significance level P <0.05 and a t-test for related samples.

Results:

The footwear model with some drop significantly decreased pressures in both the forefoot and hindfoot areas, indicating a shock absorbing effect.

Conclusions:

In response to the functional health, safety and comfort needs of overweight and obese users, the use of shoe models with some drop is recommended as opposed to flat shoe models. Footwear designs that reduce the pressures and improve balance will be positive for the user. It would be necessary to conduct further research to assess the effect of different footwear models in the movement pattern, including stability.