Extreme body cooling and psychomotor performance

The effect of exposure to cold on dexterity and temperature of the skin and hands

Objectives. This study aimed to determine the impact of low temperature (-1 °C, +5 °C) on manual dexterity and hand skin temperature after 1 h of exposure when using two types of protective gloves. Methods. Ten male participants wore double gloves or single gloves, when spending 1 h in a climatic chamber at -1, +5 or +20 °C. Before and after the cold exposure, measurements of mean weighted body skin temperature, hand skin temperature, the Purdue Pegboard Test and hand grip strength were performed. Results. There were statistically significant differences in the values of mean weighted body skin temperature and left and right hand skin temperature between the study variants. Conclusion. No effect of cold exposure (-1 °C, +5 °C) on manual dexterity was observed, but there was an effect of -1 °C temperature change on weighted mean skin temperature and hand skin temperature during 1 h of exposure. The decrease in both right and left hand skin temperature after cold exposure was the largest for -1 °C while using single gloves, and differed significantly from the other variants.

Effects of EVA glove on hand dexterity at low temperature and low pressure

Hand dexterity is an important index to assess whether extravehicular activity (EVA) gloves are appropriately designed. Pressurized gloves and low temperature environments can both cause a decrease in hand dexterity. However, due to the difficulty in performing tests under extreme conditions, there has been no report on dexterity tests with gloves under pressure and low temperature. To fill this gap, we performed a dexterity test of EVA gloves with twelve male volunteers involved under the extreme conditions, which were created in the low-pressure simulation cabin with vaporized liquid nitrogen used to cool it down. A total of nine conditions were designed. Purdue pegboard test and nut fastening test were improved before being applied in a hand dexterity test. Completion times for both tests, finger temperatures and cold feeling of the hand were recorded and analyzed. Results showed that the completion times for both tests increased either as the temperature decreased or as the pressure increased. Furthermore, a combined effect of low temperature and pressure was observed. The study provides evidence in support of astronaut training and optimization of EVA glove productivity.

Hand and finger dexterity as a function of skin temperature, EMG, and ambient condition

OBJECTIVE

This article examines the changes in skin temperature (finger, hand, forearm), manual performance (hand dexterity and strength), and forearm surface electromyograph (EMG) through 40-min, 11 degrees C water cooling followed by 15-min, 34 degrees C water rewarming; additionally, it explores the relationship between dexterity and the factors of skin temperature, EMG, and ambient condition.

BACKGROUND

Hand exposure in cold conditions is unavoidable and significantly affects manual performance.

METHOD

Two tasks requiring gross and fine dexterity were designed, namely, nut loosening and pin insertion, respectively. The nested-factorial design includes factors of gender, participant (nested within gender), immersion duration, muscle type (for EMG), and location (for skin temperature). The responses are changes in dexterity, skin temperature, normalized amplitude of EMG, and grip strength. Finally, factor analysis and stepwise regression are used to explore factors affecting hand and finger dexterity.

RESULTS

Dexterity, EMG, and skin temperature fell with prolonged cooling, but the EMG of the flexor digitorum superficialis remained almost unchanged during the nut loosening task. All responses but the forearm skin temperature recovered to the baseline level at the end of rewarming. The three factors extracted by factor analysis are termed skin temperature, ambient condition, and EMG. They explain approximately two thirds of the variation of the linear models for both dexterities, and the factor of skin temperature is the most influential.

CONCLUSION

Sustained cooling and warming significantly decreases and increases finger, hand, and forearm skin temperature. Dexterity, strength, and EMG are positively correlated to skin temperature. Therefore, keeping the finger, hand, and forearm warm is important to maintaining hand performance.

APPLICATION

The findings could be helpful to building safety guidelines for working in cold environments.

A meta-analysis of performance response under thermal stressors

OBJECTIVE

Quantify the effect of thermal stressors on human performance.

BACKGROUND

Most reviews of the effect of environmental stressors on human performance are qualitative. A quantitative review provides a stronger aid in advancing theory and practice.

METHOD

Meta-analytic methods were applied to the available literature on thermal stressors and performance. A total of 291 references were collected. Forty-nine publications met the selection criteria, providing 528 effect sizes for analysis.

RESULTS

Analyses confirmed a substantial negative effect on performance associated with thermal stressors. The overall effect size for heat was comparable to that for cold. Cognitive performance was least affected by thermal stressors, whereas both psychomotor and perceptual task performance were degraded to a greater degree. Other variables were identified that moderated thermal effects.

CONCLUSION

Results confirmed the importance of task type, exposure duration, and stressor intensity as key variables impacting how thermal conditions affect performance. Results were consistent with the theory that stress forces the individual to allocate attentional resources to appraise and cope with the threat, which reduces the capacity to process task-relevant information. This represents a maladaptive extension of the narrowing strategy, which acts to maintain stable levels of response when stress is first encountered.

APPLICATION

These quantitative estimates can be used to design thermal tolerance limits for different task types. Although results indicate the necessity for further research on a variety of potentially influential factors such as acclimatization, the current summary provides effect size estimates that should be useful in respect to protecting individuals exposed to adverse thermal conditions.

Finger dexterity, skin temperature, and blood flow during auxiliary heating in the cold

The primary purpose of the present study was to compare the effectiveness of two forms of hand heating and to discuss specific trends that relate finger dexterity performance to variables such as finger skin temperature (T(fing)), finger blood flow (Q(fing)), forearm skin temperature (T(fsk)), forearm muscle temperature (Tfmus), mean weighted body skin temperature (Tsk), and change in body heat content (DeltaH(b)). These variables along with rate of body heat storage, toe skin temperature, and change in rectal temperature were measured during direct and indirect hand heating. Direct hand heating involved the use of electrically heated gloves to keep the fingers warm (heated gloves condition), whereas indirect hand heating involved warming the fingers indirectly by actively heating the torso with an electrically heated vest (heated vest condition). Seven men (age 35.6 +/- 5.6 yr) were subjected to each method of hand heating while they sat in a chair for 3 h during exposure to -25 degrees C air. Q(fing) was significantly (P < 0.05) higher during the heated vest condition compared with the heated gloves condition (234 +/- 28 and 33 +/- 4 perfusion units, respectively), despite a similar T(fing) (which ranged between 28 and 35 degrees C during the 3-h exposure). Despite the difference in Q(fing), there was no significant difference in finger dexterity performance. Therefore, finger dexterity can be maintained with direct hand heating despite a low Q(fing). DeltaH(b), Tsk, and T(fmus) reached a low of -472 +/- 18 kJ, 28.5 +/- 0.3 degrees C, and 29.8 +/- 0.5 degrees C, respectively, during the heated gloves condition, but the values were not low enough to affect finger dexterity.

Relationship between body heat content and finger temperature during cold exposure

The purpose of the present experiment was to examine the relationship between rate of body heat storage (S˙), change in body heat content (ΔHb), extremity temperatures, and finger dexterity. S˙, ΔHb , finger skin temperature (Tfing), toe skin temperature, finger dexterity, and rectal temperature were measured during active torso heating while the subjects sat in a chair and were exposed to −25°C air. S˙ and ΔHb were measured using partitional calorimetry, rather than thermometry, which was used in the majority of previous studies. Eight men were exposed to four conditions in which the clothing covering the body or the level of torso heating was modified. After 3 h, Tfing was 34.9 ± 0.4, 31.2 ± 1.2, 18.3 ± 3.1, and 12.1 ± 0.5°C for the four conditions, whereas finger dexterity decreased by 0, 0, 26, and 39%, respectively. In contrast to some past studies, extremity comfort can be maintained, despite S˙ that is slightly negative. This study also found a direct linear relationship between ΔHb and Tfing and toe skin temperature at a negative ΔHb. In addition, ΔHb was a better indicator of the relative changes in extremity temperatures and finger dexterity over time than S˙.

Physiological criteria for functioning of hands in the cold: a review

Hands are important instruments in daily life. Without hands man is hardly able to function independently. Proper functioning of the hands is determined by several physiological parameters. These physiological parameters in turn are influenced by environmental factors. In this view of the literature, physiological processes in manual dexterity are described and the influence of a cold environment on separate physiological processes is studied. In general, cold means loss of dexterity. For reasons of safety and performance, it is important to restrict the loss of manual dexterity. For this purpose, in this study minimum criteria are given for all separate physiological components. Most important minimum criteria are: a local skin temperature of 15 degrees C, a nerve temperature of 20 degrees C and a muscle temperature of 28 degrees C. Only during maximum dynamic work is a muscle temperature of 38 degrees C recommended. These temperatures are average values, and of course individual differences are evident.

Finger skin temperature and manual dexterity - some inter-group differences

The relationship between finger skin temperature (FST) and performance was demonstrated with four manual dexterity tasks all of which were performed by black and white, male and female subjects. At air temperatures below 24 degrees C the white subjects tended to have warmer FSTs than the black subjects; white subjects were also able to equal the performance of the black subjects at air temperatures as much as 6 degrees C below that required by the black subjects.

The persistence and transfer of voluntary hand-warming in natural and laboratory cold settings after 1 year

Hayduk (1980) used a classical conditioning-biofeedback overlap (CBO) design to teach six volunteers to warm their hands in an ambient temperature of - 14 degrees C. He found voluntarily warmed hands to be more dexterous, more sensitive, and less painful in the cold laboratory setting than unwarmed hands. The present paper reports a 1-year follow-up of five of Hayduk's original six volunteers. Ability to hand-warm was reevaluated, both at room temperature and at - 14 degrees C and was found to be essentially unchanged from post-training performance of the previous year. The effects of hand-warming on performance, sensation, and cold pain were remeasured in the cold laboratory and found to be essentially unchanged from the effects following training the previous year. Finally, the volunteers were asked to describe the degree to which they had used their hand-warming, and the circumstances under which they had used it, in natural settings throughout a Canadian winter. The volunteers reported only minimal use of hand-warming, primarily to reduce cold pain.

Increasing hand efficiency at cold temperatures by training hand vasodilation with a classical conditioning-biofeedback overlap design

The prolonged exposure of hands to cold environments leads to substantial cold pain and severe deterioration of manual dexterity, finger dexterity, hand strength, and tactile sensitivity. This study taught volunteers to warm their hands at -14 degrees Celsius and measured the hand efficiency effects. The subjects were six male and female nonsmoking volunteers. All research was conducted in a cold chamber during the warm summer months to eliminate seasonal factors. A combined multiple-baseline/ABA single-subject design with multiple replications was used. Each subject's hand performance was obtained for both hands in warm and in cold conditions. One hand was trained and both hands were retested in the cold. The second hand was trained and both hands were retested in the cold. Finally, the subject inhibited warming while in the cold (treatment removal) and both hands were tested again. The treatment itself used biofeedback instrumentation to extend and enlarge previously classically conditioned vasodilative episodes. The procedure was found to be effective for bringing about temperature changes in the cold. Large treatment effects were found on all hand efficiency measures. The results suggest wide implications for the workplace, for theory, and for future research.

Diver performance in cold water

Twelve experienced divers repeatedly performed several representative underwater work tasks for 90-min. sessions at water temperatures of 50°, 60°, and 70° F. Time to complete the task was the primary performance measure; choice reaction time, with mental arithmetic as loading task, and four physiological measurements were also recorded. The subjects worked in 6 1/2 ft. of water wearing full 3/16-in.-thick wet suits and SCUBA equipment. Performance on all tasks except mental arithmetic tended to decrease as water temperature decreased. Most performance measures also showed a significant decrement over time and a significant time-by-temperature interaction. The general trend in performance measures was also reflected in several of the physiological measurements.