Hand Skin Temperature Research Articles

The influence of cooling forearm/hand and gender on estimation of handgrip strength

Handgrip strength is essential in manual operations and activities of daily life, but the influence of forearm/hand skin temperature on estimation of handgrip strength is not well documented. Therefore, the present study intended to investigate the effect of local cooling of the forearm/hand on estimation of handgrip strength at various target force levels (TFLs, in percentage of MVC) for both genders. A cold pressor test was used to lower and maintain the hand skin temperature at 14°C for comparison with the uncooled condition. A total of 10 male and 10 female participants were recruited. The results indicated that females had greater absolute estimation deviations. In addition, both genders had greater absolute deviations in the middle range of TFLs. Cooling caused an underestimation of grip strength. Furthermore, a power function is recommended for establishing the relationship between actual and estimated handgrip force.Statement of relevance: Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force.Practitioner Summary: It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force.

Ultrasound‐guided lateral infraclavicular block evaluated by infrared thermography and distal skin temperature

Brachial plexus blocks cause changes in hand and digit skin temperature. We investigated thermographic patterns after the lateral infraclavicular brachial plexus block. We hypothesised that a successful lateral infraclavicular block could be predicted by increased skin temperature of the 2nd and 5th digits. We performed an ultrasound-guided lateral infraclavicular block in 45 patients undergoing upper limb surgery. The contralateral hand served as control and we obtained infrared thermographic images of both hands before the block and during the following 30 min. We defined areas of interest on the hands and analysed mean skin temperature of each area. Forty patients completed the study. Thirty blocks were successful, six were failures and four were partial failures. Four distinct patterns of skin temperature changes were revealed with highly significant changes in temperature, depending on block success. A simultaneous 1 °C ipsilateral increase in skin temperature of the 2nd and 5th digits predicted a successful block with a positive predictive value of 100%. A 5 °C difference in digit skin temperature compared with the contralateral hand had a positive predictive value of 96%, and a digit skin temperature ≤ 30 °C 30 min after performing the block had a predictive value of 100% for a failed block. Four different thermographic patterns were found. Simultaneous increases in skin temperature of both the 2nd and 5th digits predicted lateral infraclavicular block success with a positive predictive value of 100%. Digit skin temperature ≤ 30 °C 30 min after performing the block indicated block failure.

Seeing the body produces limb-specific modulation of skin temperature.

Vision of the body, even when non-informative about stimulation, affects somatosensory processing. We investigated whether seeing the body also modulates autonomic control in the periphery by measuring skin temperature while manipulating vision. Using a mirror box, the skin temperature was measured from left hand dorsum while participants: (i) had the illusion of seeing their left hand, (ii) had the illusion of seeing an object at the same location or (iii) looked directly at their contralateral right hand. Skin temperature of the left hand increased when participants had the illusion of directly seeing that hand but not in the other two view conditions. In experiment 2, participants viewed directly their left or right hand, or the box while we recorded both hand dorsum temperatures. Temperature increased in the viewed hand but not the contralateral hand. These results show that seeing the body produces limb-specific modulation of thermal regulation.

Psychophysiological Effects of Hand Massage in Geriatric Facility Residents

Geriatric facility residents experience easy decrease of their quality of life (QOL) compared with elderly people cared for in their own homes owing to environmental changes. Because complementary and alternative medicine is useful to improve QOL, a simple manual for hand massage for inexperienced volunteers was developed, and the physical and psychological effects of this method were examined. Thirty-six female geriatric facility residents (mean age, 84.5 years) were chosen. They were divided into two groups: the control and hand-massaged groups. In the hand-massaged group, females received 15 min hand massage from volunteers in accordance with a simple manual. No hand massage was performed in the control group. Before and after the treatment, a survey using a questionnaire (7 items; e.g., tension, fatigue) and physiological measurements (e.g., blood pressure, hand skin temperature), and measurement of cortisol and chromogranin A levels in saliva samples using enzyme-linked immunosorbent assay kits were carried out. Data were analyzed by two-way analysis of variance (ANOVA) to determine the effects of group and time on the dependent variables. The hand-massaged group showed greater increases in skin temperature than the control group, as shown by ANOVA (p<.05). Results showed that improvements of the scores in the questionnaire (condition and feel-good items) were greater in the hand-massaged group than in the control group (p<.05). Cortisol level increased in the control group, but was not statistically significantly different from that in the hand-massaged group, as shown by ANOVA. Chromogranin A level was also not significantly different between the two groups. These results confirmed the benefits of complementary and alternative medicine including touching and massage found in previous studies. Hand massage prompted relaxation in geriatric facility residents in this experiment.

Comfort and performance of power line maintainers' gloves during electrical utility work in the cold

Electrical utility workers wear thick rubber gloves and often work in the cold. To document the challenge of working in the cold and the effectiveness of different glove/liner combinations in keeping workers' hands warm. Ten experienced male electrical utility employees worked in a controlled temperature walk-in chamber at -20 °C for 45 minutes for each of five glove conditions: standard five-finger rubber gloves with cotton liners and gauntlets, mitten style gloves, a prototype wool liner, and two heating options; glove or torso. Dependent measures were maximum grip force, skin temperatures, finger dexterity and sensitivity to touch, ratings of perceived effort and a rating of thermal sensation. Participants' hand skin temperatures decreased, they perceived their hands to be much colder, their finger sensitivity decreased and their ratings of perceived exertion increased, however their performance did not degrade over the 45 minute trials. The mitten-style gloves showed a smaller drop in skin temperature for the 3rd and 5th digits (p< 0.05) than the other glove conditions. Mitten style gloves kept workers' hands warmer than the standard five finger glove.

Effects of two types of clothing offering different thermal insulation to the extremities upon nocturnal secretion of urinary 6-sulfatoxymelatonin and sleep propensity

This study investigated skin temperature, the nocturnal secretion of urinary 6-sulfatoxymelatonin (aMT-6s), and self-estimated sleep propensity in subjects living in a thermally neutral environment but wearing two types of clothing which provided different thermal insulation to the extremities. The experiment was conducted from 21:30 h on day 0 to 06:30 h on day 2 in an environmental chamber controlled at 24 ± 0.2 °C and a relative humidity of 50 ± 5%. Seven healthy female volunteers participated twice, while wearing “covering” or “exposing” types of clothing. The “covering” type of experimental clothing consisted of long-sleeved shirts, full-length trousers and socks (Type L, weighing 1042 g); the “exposing” type of clothing consisted of half-sleeved shirts and knee-length trousers (Type H, weighing 747 g). During nocturnal sleep (from 22:30 h to 06:30 h), all subjects were covered by two thin sheets made of 100% cotton. When wearing Type H clothing, the nocturnal fall of forehead skin temperature tended to be greater (p = 0.07) and hand skin temperature was significantly lower during time awake (p < 0.05) with a greater nocturnal increase (p < 0.05). The distal-to-proximal skin temperature gradient, DPG, (a measure of the process of thermal regulation) was significantly lower with Type H clothing during times awake and asleep (p < 0.01 and p < 0.05, respectively), but the increase of DPG during the sleep period was greater with Type H clothing (p < 0.01). Type H clothing was also associated with a significantly greater secretion of nocturnal urinary aMT-6s during the first half of sleep (p < 0.05). Sleeping Inventory tests indicated that the subjects with Type H clothing had better subjective scores for sleepiness, sleep initiation, and sleep maintenance (all p < 0.05), and slightly less worries (0.05 < p < 0.10). These results suggest that clothing type uncovering the extremities in a thermally neutral environment of 24 °C might induce a greater day-night variation in heat loss and a larger nocturnal increase in skin temperature in the distal regions and promote more sleepiness and a more rapid sleep onset via increased urinary aMT-6s secretion in the first half of sleep period. It is suggested that these changes might be related to the role of the sympathetic nervous system in thermoregulation and melatonin secretion.

A comparison between rhythms in forehead skin and rectal (core) temperature in sedentary subjects living in a thermally neutral environment

In human circadian rhythm research, rectal temperature is the traditional gold standard for estimating core temperature, but the measurement of rectal temperature is inconvenient and unacceptable to some subjects. This study examined whether the circadian rhythm of forehead skin temperature would be an alternative to that of rectal temperature in sedentary subjects living in a thermally neutral environment. Six healthy female volunteers participated as subjects for 37.5 h, from 21:30 h on day 0 to 06:30 h on day 2. They were tested twice while wearing two different types of clothing. One type of clothing covered the whole body except the head and hands (Type L); the other exposed the head and distal extremities (Type H). Subjects lived in a climatic chamber controlled at 23.8 ± 0.2 °C and 60 ± 5% RH with light intensity of 500 lux from 06:30 to 19:30 h, 100 lux from 19:30 to 22:30 h and 0 lux from 22:30 to 06:30 h. Rectal temperature and skin temperatures at seven sites were recorded continuously at 10 min intervals. The extent to which the circadian rhythms of forehead and hand skin temperature mirrored that of rectal temperature was determined by cross-correlation and cosinor analyses. Cross-correlation analysis of data from the group or individuals, and whether wearing Type L or Type H clothing, indicated that the profile of forehead skin temperature was similar to that of rectal temperature, with highly significant positive correlation coefficients (r = 0.9099–0.9744) and time lags of 0.17–0.33 h. By contrast, the profile of hand skin temperature was approximately in antiphase, with smaller correlation coefficients (though still highly significant: r = 0.6036–0.7526), and with time lags of 11.00–14.11 h. Cosinor analysis indicated that the acrophase of the circadian rhythm of forehead skin temperature for individuals was slightly, but not significantly, earlier than that of rectal temperature with both types of clothing (0.54 ± 0.68 and 0.35 ± 0.64 h with Type L and Type H clothing, respectively). The circadian rhythm of forehead skin temperature showed a significantly greater amplitude and lower mesor than rectal temperature, whether wearing Type L or Type H clothing. Individuals’ data gave 0.38 ± 0.09 and −2.92 ± 0.31 °C, respectively, with Type L clothing and 0.40 ± 0.26 and −2.86 ± 0.35 °C with Type H clothing; these differences were not significantly different between the two types of clothing. It is concluded that, in sedentary subjects living in a thermally neutral environment, forehead skin temperature gives information regarding phase and some aspects of amplitude that can act as substitutes for rectal temperature data.

Acral coldness in migraineurs

In search for new biomarkers of vascular disturbances accompanying migraine, we compared the facial and hand skin temperatures in 41 women, including 12 migraine patients during the headache-free period and 29 healthy controls. Compared to the controls, the acral skin temperatures were lower in migraineurs, especially in those with right-sided headache. Our findings suggest that migraine is associated with a peripheral coldness possibly due to abnormal autonomic vascular control. The cold nose and hands may represent easily assessable biomarkers of these disorders.

Spatially defined modulation of skin temperature and hand ownership of both hands in patients with unilateral complex regional pain syndrome

Numerous clinical conditions, including complex regional pain syndrome, are characterized by autonomic dysfunctions (e.g. altered thermoregulation, sometimes confined to a single limb), and disrupted cortical representation of the body and the surrounding space. The presence, in patients with complex regional pain syndrome, of a disruption in spatial perception, bodily ownership and thermoregulation led us to hypothesize that impaired spatial perception might result in a spatial-dependent modulation of thermoregulation and bodily ownership over the affected limb. In five experiments involving a total of 23 patients with complex regional pain syndrome of one arm and 10 healthy control subjects, we measured skin temperature of the hand with infrared thermal imaging, before and after experimental periods of either 9 or 10 min each, during which the hand was held on one or the other side of the body midline. Tactile processing was assessed by temporal order judgements of pairs of vibrotactile stimuli, delivered one to each hand. Pain and sense of ownership over the hand were assessed by self-report scales. Across experiments, when kept on its usual side of the body midline, the affected hand was 0.5 ± 0.3°C cooler than the healthy hand (P < 0.02 for all, a common finding in cold-type complex regional pain syndrome), and tactile stimuli delivered to the healthy hand were prioritized over those delivered to the affected hand. Simply crossing both hands over the midline resulted in (i) warming of the affected hand (the affected hand became 0.4 ± 0.3°C warmer than when it was in the uncrossed position; P = 0.01); (ii) cooling of the healthy hand (by 0.3 ± 0.3°C; P = 0.02); and (iii) reversal of the prioritization of tactile processing. When only the affected hand was crossed over the midline, it became warmer (by 0.5 ± 0.3°C; P = 0.01). When only the healthy hand was crossed over the midline, it became cooler (by 0.3 ± 0.3°C; P = 0.01). The temperature change of either hand was positively related to its distance from the body midline (pooled data: r = 0.76, P < 0.001). Crossing the affected hand over the body midline had small but significant effects on both spontaneous pain (which was reduced) and the sense of ownership over the hand (which was increased) (P < 0.04 for both). We conclude that impaired spatial perception modulated temperature of the limbs, tactile processing, spontaneous pain and the sense of ownership over the hands. These results show that complex regional pain syndrome involves more complex neurological dysfunction than has previously been considered.

Skin temperature responses to cold stress in patients with severe motor and intellectual disabilities

Patients with severe motor and intellectual disabilities (SMID) often suffer from autonomic nervous system disturbances. At the same time, the caregivers of patients with SMID face challenges to understand the patients’ chronic health problems effectively by simply observing them. Therefore, recognizing specific symptoms is important to improve support for SMID. We investigated the autonomic nervous function in patients with SMID with skin vasomotor responses to cold stimuli. The relationship of the results of cold stress and autonomic symptoms observed by the main caretakers was also examined. We analyzed 38 patients with SMID. Their hand skin temperature was measured before and after cold stimuli using infrared thermography. A ‘distal-dorsal difference’ (DDD) at baseline, and the recovery rate of the second fingertip and dorsum were calculated. All main caregivers filled out questionnaires evaluating autonomic symptoms. The recovery rate of the second fingertip and dorsum after cold stimuli was lower than 80% in 64% and 60% patients, respectively. The baseline DDD was greater than 1°C in 84% of the patients. A DDD>1°C was associated with a reduced recovery rate. All caregivers recognized some autonomic-related symptoms. Patients with constipation or snoring demonstrated a reduced recovery rate. However, none of the observed symptoms can predict the presence of a reduced rate with cold stimuli in a statistically significant way. This study showed excessive sympathetic nerve activities in patients with SMID. The baseline DDD could be a valuable parameter accessing their microvascular circulation. To improve the life of a person with SMID, accessing autonomic function using a noninvasive method, such as thermography is warranted without directly observed symptoms.

Changes of motor evoked potentials during descending thoracic and thoracoabdominal aortic surgery with deep hypothermic circulatory arrest

Paraplegia is a serious complication of descending and thoracoabdominal aortic aneurysms (dTAAs and TAAAs) surgery. Motor evoked potentials (MEPs) enable monitoring the functional integrity of motor pathways during dTAA and TAAA surgery. Although MEPs are sensitive to temperature changes, there are few human data on changes of MEPs during mild and deep hypothermia. Therefore, we investigated changes of MEPs in deep hypothermic circulatory arrest (DHCA) in dTAA and TAAA surgery. Fifteen consecutive patients undergoing dTAA and TAAA surgery using DHCA were enrolled. MEPs were elicited and recorded during each degree Celsius change in nasopharyngeal temperature during both the cooling and rewarming phases. Hand and leg skin temperature were also recorded simultaneously. In the cooling phase MEP amplitude decreased lineally in both the hand and leg. The MEP disappeared at ~16°C in both the hand and leg in 10 of 15 patients, but was still elicited in 5 patients. In the rewarming phase MEP in the hand recovered before the temperature reached 20°C for eight patients and 25°C for the other seven patients. In contrast, MEP in the leg recovered below 20°C for two patients and 30°C for three patients. For the other eight patients MEP waves did not recover during the rewarming phase. In the cooling phase of DHCA, MEP disappeared at ~16°C in some patients but was still elicited in others. MEP recovered below 25°C in the hand. Recovery of MEP in the leg was, however, extremely variable.

The rubber hand illusion increases histamine reactivity in the real arm

Summary Most people are convinced that their body parts are in fact their own, but in some clinical conditions, this sense of ownership can be lost [1]. Perceptual illusions, most famously the rubber hand illusion (RHI) [2], demonstrate that a sense of ownership over a body part (or an entire body [3]) that is not in fact ours can be easily induced in healthy volunteers. But does illusory ownership over an artificial body part have consequences for the real body part, the one that has been ‘replaced'? Recent data show the RHI induces a small but robust drop in skin temperature of the real hand. That is, blood flow to the ‘disowned' hand seems to be selectively reduced [1]. Such a finding is particularly relevant to the immune system because a primary role of the immune system is to ‘discriminate self from non-self' [4]. We predicted that the innate immune system may be upregulated in a manner consistent with rejection of the replaced hand. Consistent with this prediction, we report here that the RHI increases histamine reactivity, which is a key final pathway of the innate immune response and has been implicated in autoimmune disorders, including multiple sclerosis [5]. Our finding has direct implications for autoimmune disorders and a range of neurological and psychiatric conditions characterised by a disrupted sense of ownership over one's body (see [1] for a list of conditions), and has broader implications that extend well beyond previous assertions about the mind-body link.

Selective Left Subclavian Ligation in Total Aortic Arch Replacement

The left subclavian artery (LSA) is usually difficult to manipulate in total aortic arch replacement procedures if it is displaced by huge false lumens in the ascending aorta or right hemiarch. We summarize our experience of selectively ligating the deeply located LSA in total aortic arch replacement and stented "elephant trunk" implantation procedures for Stanford type A aortic dissection. Data of 29 patients with deep LSA undergoing total arch replacement and stented "elephant trunk" implantation from January 2008 to June 2010 were reviewed. The LSA was ligated because of the difficult exposure (21 males, 8 females, age 19 to 55). Collateral circulation of the circle of Willis and bilateral vertebral arteries were assessed thoroughly by preoperative imaging and intraoperative observations. If collateral circulation was sufficient, LSA was ligated; if insufficient, an additional bypass graft was created from the ascending aorta to the left axillary artery. Twenty-eight patients survived the operation with 1 early death. Postoperative blood pressures were lower in the left arm than in the right (78±17.3 vs 126±3.7 mm Hg, p<0.01), but oxygen saturation, skin temperature, and strength of the left hand were normal. The surviving patients have been followed for 16.6±9.0 months (6 to 36) and none had symptoms of LSA steal syndrome or arm ischemia. Ligation of the LSA after strict evaluation of collateral circulation could be safe for type A dissection patients if the exposure is insufficient, and this method can simplify the operation significantly.

Effect of cold immersion on grip force, EMG, and thermal discomfort

This study has investigated the effect of gender, cold and warm immersion on hand skin temperature, grip MVC, EMG, and discomfort. In this study, twelve male and twelve female participants immersed their hands in a cold water tank for 40 min followed by warm water immersion for 15 min, during which all performance measures were collected. Structural equation model was applied to examine relationship among skin temperature, gender, anthropometrics, and MVC. The results indicate that the cold immersion had an enormous effect on skin temperature, which subsequently affected the MVC. Gender had significant impact on skin temperature and MVC, and MVC was also affected by palm length. Due to adaptation, participants experienced greater discomfort at the beginning of the cold immersion and the discomfort diminished after 4 min. During warm immersion, the EMG resumed its baseline after 15 min which indicates that the muscle performance was fully recovered after 15 min of warm immersion. Relevance to industry Statement indicating the relevance of the findings for ergonomics practice. Performance of the workers exposed to different temperature conditions is a common problem in industries. This study was designed to test the MVC, EMG, thermal discomfort sensation and hand skin temperature response to cold and warm immersion of the human forearm. The result can help to protect workers who work in cold immersion occupations such as fisherman, fish filleters, and divers.

Lack of clinically detectable acute changes on autonomic or thermoregulatory functions in healthy subjects after transcranial direct current stimulation (tDCS)

Neuromodulatory techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have been increasingly studied as possible treatments for many neurological and psychiatric disorders. tDCS is capable of inducing changes in regional cerebral blood flow in both cortical and subcortical structures, as shown by positron emission tomography studies, and might conceivably affect hypothalamic and autonomic nervous system functions. However, it remains unknown whether acute changes in autonomic or hypothalamic functions may be triggered by conventional tDCS protocols. To verify whether tDCS, when performed with a bipolar cephalic montage, is capable of inducing acute changes in autonomic or hypothalamic functions in healthy subjects. Fifty healthy volunteers were studied. tDCS was performed with the anode over the C3 position and the cathode over the right supraorbital region. Subjects received either real or sham tDCS. Parameters assessed before and after a 20-minute session included blood pressure, tympanic thermometry, hand skin temperature, heart rate and ventilatory rate. Plasma concentrations of cortisol were also measured in a sub-set of 10 participants. A repeated-measures, mixed-design ANOVA showed significant changes in hand skin temperature (P= .005) and cortisol levels (P < .001) after both real and sham stimulation. There were no statistically significant changes in any of the other measurements. The changes in hand temperature and cortisol levels, having occurred in both the sham and experimental groups, probably reflect a non-specific stress response to a new procedure. There were no significant changes in autonomic functions, ventilation rate or core body temperature that can be attributed to conventional tDCS applied to healthy volunteers.

난방환경에서 온(溫)맵시 착용에 따른 생리적 반응 및 주관적 감각

This study tests the performance of the recommended winter dress OnMapsi for an office worker through the analysis of skin temperature changes according to the heating environment. We tested and compared the effects of with/without undergarments for 4 male subjects in an artificial-climate chamber with two air temperatures of <TEX>$19^{\circ}C$</TEX> and <TEX>$22^{\circ}C$</TEX>, <TEX>$50{\pm}10%$</TEX> R.H. During the 60 minute experiment that simulated office work, the subjective feelings (that included thermal, humidity and comfort sensation, and skin temperature) were measured at equal intervals. The results show that the forehead and chest skin temperatures were not affected by air temperature or clothing type, while the hand and foot skin temperatures were affected at <TEX>$0.3-0.9^{\circ}C$</TEX> depending on clothing type and <TEX>$1.9-2.2^{\circ}C$</TEX> depending on air temperature. The mean skin temperature was decreased by the experimental time pass more with regular formal wear than with OnMapsi. The second experiment located the ambient temperature in which subjects wearing OnMapsi show equal skin temperaturesto those without undergarments at <TEX>$22^{\circ}C$</TEX>. Therefore it is possible to decrease heating temperatures to <TEX>$18-21^{\circ}C$</TEX> in the office for winter OnMapsi wear that produces a skin temperature and thermal sensation that is the same as those at <TEX>$22^{\circ}C$</TEX>.

Assessment of Combined Effects From Exposure to Cold Stress, Hand-arm Vibration and Noise

PP-29-175 Background/Aims: The aim of this study conducted in a climatic chamber was to evaluate the combined effects of exposure to cold stress, noise, and hand-arm vibration on noise-induced temporary threshold shift, manual dexterity, and blood pressure by adopting Taguchi method. Methods: A total of 23 healthy volunteers without previous significant noise exposure and smoking history were recruited to participate in this study. All hearing threshold levels at 8 different frequencies (250–8000 Hz) of better ear were measured in an audiometric booth by using the ascending method in 5 dB steps. Dexterity, blood pressure, and heart rate were also measured by Purdue Pegboard test and Crown PM-9000, respectively. Results: The result shows that hearing loss is mainly induced by noise exposure, and was also enhanced by low temperature exposure and hand-arm vibration. The hand-skin temperature, manual dexterity, and mean arterial pressure were affected by exposure to cold environment, and related health effect was increasing with exposure period. No significant difference was observed both on blood pressure and heart rate in this study. Conclusion: In conclusion, further investigation of the combined effects on workers by co-exposure to various hazards is needed. The implement of occupational hazard exposure administration is important for prevention of occupation diseases and health promotion of workers.

Comparison of heat dissipation response between Malaysian and Japanese males during exercise in humid heat stress

This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).

Comparison of thermoregulatory responses to heat between Malaysian and Japanese males during leg immersion

The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese) natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages: 22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m(-2) h(-1)) and Japanese (83.2 ± 6.4 g m(-2) h(-1)) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese (0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function.

Hand and Finger Dexterity as a Function of Skin Temperature, EMG, and Ambient Condition

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. Hand exposure in cold conditions is unavoidable and significantly affects manual performance. 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. 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. 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. The findings could be helpful to building safety guidelines for working in cold environments.