Randi Eidsmo Reinertsen

Effects of wearing aircrew protective clothing on physiological and cognitive responses under various ambient conditions.

Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0 degrees C at 80% RH, 23 degrees C at 63% RH and 40 degrees C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40 degrees C ambient temperature condition in comparison with 0 degrees C and 23 degrees C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40 degrees C than at 23 degrees C (p = 0.006) or 0 degrees C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0°C at 80% RH, 23°C at 63% RH and 40°C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40°C ambient temperature condition in comparison with 0°C and 23°C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40°C than at 23°C (p = 0.006) or 0°C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.

Effect of cold exposure (-15 degrees C) and salbutamol treatment on physical performance in elite nonasthmatic cross-country skiers

Abstract The effects of whole-body exposure to ambient temperatures of −15°C and 23°C on selected performance-related physiological variables were investigated in elite nonasthmatic cross-country skiers. At an ambient temperature of −15°C we also studied the effects of the selective β2-adrenergic agonist Salbutamol (0.4 mg × 3) which was administered 10 min before the exercise test. Eight male cross-country skiers with known maximal oxygen uptakes (V˙O2max) of more than 70 ml · kg−1 · min−1 participated in the study. Oxygen uptake (V˙O2), heart rate (fc), blood lactate concentration ([La−]b) and time to exhaustion were measured during controlled submaximal and maximal running on a treadmill in a climatic chamber. Lung function measured as forced expiratory volume in 1 s (FEV1) was recorded immediately before the warm-up period and at the conclusion of the exercise protocol. Submaximal V˙O2 and [La−]b at the two highest submaximal exercise intensities were significantly higher at −15°C than at 23°C. Time to exhaustion was significantly shorter in the cold environment. However, no differences in V˙O2max or fc were observed. Our results would suggest that exercise stress is higher at submaximal exercise intensities in a cold environment and support the contention that aerobic capacity is not altered by cold exposure. Furthermore, we found that after Salbutamol inhalation FEV1 was significantly higher than after placebo administration. However, the inhaled β2-agonist Salbutamol did not influence submaximal and maximal V˙O2, fc, [La−]b or time to exhaustion in the elite, nonasthmatic cross-country skiers we studied. Thus, these results did not demonstrate any ergogenic effect of the β2-agonist used.

Optimizing the performance of phase-change materials in personal protective clothing systems.

Phase-change materials (PCM) can be used to reduce thermal stress and improve thermal comfort for workers wearing protective clothing. The aim of this study was to investigate the effect of PCM in protective clothing used in simulated work situations. We hypothesized that it would be possible to optimize cooling performance with a design that focuses on careful positioning of PCM, minimizing total insulation and facilitating moisture transport. Thermal stress and thermal comfort were estimated through measurement of body heat production, body temperatures, sweat production, relative humidity in clothing and subjective ratings of thermal comfort, thermal sensitivity and perception of wetness. Experiments were carried out using 2 types of PCM, the crystalline dehydrate of sodium sulphate and microcapsules in fabrics. The results of 1 field and 2 laboratory experimental series were conclusive in that reduced thermal stress and improved thermal comfort were related to the amount and distribution of PCM, reduced sweat production and adequate transport of moisture.

Thermal manikin measurements--exact or not?

According to the European prestandard ENV 342:1998 [1], the thermal insulation of cold-protective clothing is measured with a thermal manikin. Systematic studies on the reproducibility of the values, measured with different types of clothing on the commonly used standing and walking manikins, have not been reported in the literature. Over 300 measurements were done in 8 different European laboratories. The reproducibility of the thermal insulation test results was good. The coefficient of variation was lower than 8%. The measured clothing should fit the manikin precisely, because poorly fitting clothing gave an error in the results. The correlation between parallel and serial insulation values was excellent and parallel values were about 20% lower than serial ones. The influence of ambient conditions was critical only in the case of air velocity. The reproducibility of thermal insulation test results in a single laboratory was good, and the variation was lower than 3%.

Manikin measurements versus wear trials of cold protective clothing (Subzero project).

The thermal insulation properties of clothing systems can be defined through physical measurements using thermal manikins or through wear trials using human test subjects. One objective of the European Subzero project was to define the relationship between physically measured thermal insulation values of cold-protective clothing and the corresponding physiological reactions on human test subjects. Four cold-protective clothing ensembles, intended for use in temperatures between 0 and −50°C, were measured with manikins in eight European laboratories and on human test subjects in four of these laboratories. The results showed that reasonably good reproducible values from the manikin tests can be achieved (CV <8%); however, the fit of the clothing on the manikin is a critical factor. There were greater individual differences in the wear trial results. Comparing the results from the manikin and the wear trials, good agreement in the thermal insulation values was shown if the amount of accumulated sweat was low. In these situations, which are normal when using cold protective clothing, the thermal comfort can also be determined with good accuracy by means of mathematical models based on manikin results. Special situations, e.g. for highly perspiring wearers, strong wind, or high friction between garment layers, need specific modelling; some suggestions have been made as a result of the Subzero project, but further research is required.

Comparison of thermal manikins of different body shapes and size

Differences between manikins may be present due to manikin body shapes (male versus female). In order to examine such differences a study was designed. Comparisons were carried out based on: (1) tight versus loose clothing; (2) serial versus parallel calculation models; (3) even versus uneven clothing (insulation) distribution; and (4) the effect of donning clothes. Differences were observed between female and male manikins depending on body shape. However, these differences were within the range that was observed in the Subzero project, and were comparable with differences between manikins of male body shapes. Manikins behaved differently according to clothing adjustments. Tight-fitting clothes resulted in smaller differences. The effects of donning clothes were more pronounced with the serial calculation model, while the results generated by the serial and parallel calculation models differed more if the insulation was unevenly distributed (24% and 12% respectively). In order to examine the effect of body size, two baby manikins were compared to an adult manikin. The experimental conditions involved air layer insulation measurements (AL), lying on the back on an insulating surface (OB), and lying on the back on an insulating surface, covered with a sheet (OBS, baby manikins only). The acquired AL insulation for all manikins were very similar. The insulation value of adult manikin tested under condition OB differed from the others. This was related to flexible joints allowing the arms and legs to be in contact with the insulating surface, while baby manikins retained their arms and legs in the air. The baby manikins performed similarly in OBS tests.

The thermoneutral zone when wearing aircrew protective clothing

Abstract The aim of this study was to determine the thermoneutral zone (TNZ) in subjects wearing aircrew protective clothing. TNZ were first defined in naked subjects to a temperature range of 28–31°C. Wearing aircrew protective clothing caused a displacement of the TNZ to 10–14°C ambient temperature ( T a ). Discomfort increased at ambient temperatures above this range, as a result of increases in metabolic rate, mean skin temperature (MST) and sweating. The practical implication of this study is that cockpit temperature in Sea King helicopters should be regulated to lie between 10°C and 14°C ( T a ) in order to prevent heat stress in pilots when wearing aircrew protective clothing.

Effect of ambient temperature on female endurance performance.

Ambient temperature can affect physical performance, and an ambient temperature range of -4 °C to 11 °C is optimal for endurance performance in male athletes. The few similar studies of female athletes appear to have found differences in response to cold between the genders. This study investigated whether ambient temperature affects female endurance performance. Nine athletes performed six tests while running on a treadmill in a climatic chamber at different ambient temperatures: 20, 10, 1, -4, -9 and -14 °C and a wind speed of 5 m s(-1). The exercise protocol consisted of a 10-min warm-up, followed by four 5-min intervals at increasing intensities at 76%, 81%, 85%, and 89% of maximal oxygen consumption. This was followed by an incremental test to exhaustion. Although peak heart rate, body mass loss, and blood lactate concentration after the incremental test to exhaustion increased as the ambient temperature rose, no changes in time to exhaustion, running economy, running speed at lactate threshold or maximal oxygen consumption were found between the different ambient temperature conditions. Endurance performance during one hour of incremental exercise was not affected by ambient temperature in female endurance athletes.

Performance on a work-simulating firefighter test versus approved laboratory tests for firefighters and applicants.

Aim. Firefighters must meet minimum physical demands. The Norwegian Labour Inspection Authority (NLIA) has approved a standardised treadmill walking test and 3 simple strength tests for smoke divers. The results of the Trondheim test were compared with those of the NLIA tests taking into account possible effects of age, experience level and gender. Methods. Four groups of participants took part in the tests: 19 young experienced firefighters, 24 senior male firefighters and inexperienced applicants, 12 male and 8 female. Results. Oxygen uptake (VO2) at exhaustion rose linearly by the duration of the treadmill test. Time spent on the Trondheim test was closely related to performance time and peak VO2 on the treadmill test. Senior experienced firefighters did not perform better than equally fit young applicants. However, female applicants performed poorer on the Trondheim test than on the treadmill test. Performance on the Trondheim test was not closely related to muscle strength beyond a minimum. Conclusion. Firefighters completing the Trondheim test in under 19 min fit the requirements of the NLIA treadmill test. The Trondheim test can be used as an alternative to the NLIA tests for testing aerobic fitness but not for muscular strength. Women’s result of the Trondheim test were poorer than the results of the NLIA treadmill test, probably because of their lower body mass.

Exercise-induced asthma in adolescents: Challenges for physical education teachers

Asthma is the most common chronic medical condition that school-teachers are likely to encounter among their pupils. This study aimed to identify the needs of physical education teachers in dealing with adolescents with exercise-induced asthma, study their self-reported knowledge of asthma and identify future topics for education about exercise-induced asthma. A questionnaire was drawn up on the basis of the requirements that had emerged in the course of interviews with 18 physical education teachers. One hundred and six physical education teachers at secondary schools in the city of Trondheim and colleges in Sør-Trøndelag County in Norway answered the questionnaire (65% response rate). Eighty-two physical education teachers (78.1%) had pupils with asthma in their sports classes, and 89.4% answered positively regarding their need for advice on teaching pupils with asthma. Twenty-seven (25.9%) reported that they had sufficient knowledge to teach adolescents with asthma. Topics about asthma, its management and activities suitable for asthmatics were given high priority by the teachers.