Assessment of group acclimatization to heat and humidity

Ladell, W. S. S.

doi:10.1113/jphysiol.1951.sp004672

Cited by 67 publications

(60 citation statements)

References 6 publications

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“…Although this finding agreed with several older studies (Ladell et al, 1951;Wyndham et al, 1973;Shvartz et al, 1979) that have anecdotally reported a reduction in resting T re with HA, they claimed that their study was the first to report the significant effects of HA on resting T re using a controlled study design. Specifically, in order to obtain a stable resting T re during the HA period, some controls are imposed, such as on hydration level, 12-h exercise abstinence, gender of subjects, time of day for data collection and room temperature.…”

Section: Discussionsupporting

confidence: 63%

See 1 more Smart Citation

Effects of Short-term Exercise in the Heat on Thermoregulation, Blood Parameters, Sweat Secretion and Sweat Composition of Tropic-dwelling Subjects

Saat

Sirisinghe

Singh

et al. 2005

J. Physiol. Anthropol.

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This study investigates the effects of a shortterm aerobic training program in a hot environment on thermoregulation, blood parameters, sweat secretion and composition in tropic-dwellers who have been exposed to passive heat. Sixteen healthy Malaysian-Malay male volunteers underwent heat acclimation (HA) by exercising on a bicycle ergometer at 60% ofVO 2 max for 60 min each day in a hot environment (Ta: 31.1Ϯ0.1°C, rh: 70.0Ϯ4.4%) for 14 days. All parameters mentioned above were recorded on Day 1 and at the end of HA (Day 16). On these two days, subjects rested for 10 min, then cycled at 60% of V O 2 max for 60 min and rested again for 20 min (recovery) in an improvised heat chamber. Rectal temperature (T re ), mean skin temperature (T sk ) heart rate (HR), ratings of perceived exertion (RPE), thermal sensation (TS), local sweat rate and percent dehydration were recorded during the test. Sweat concentration was analysed for sodium [Na ϩ ] sweat and potassium. Blood samples were analysed for biochemical changes, electrolytes and hematologic indices. Urine samples were collected before and after each test and analysed for electrolytes.After the period of acclimation the percent dehydration during exercise significantly increased from 1.77Ϯ0.09% (Day 1) to 2.14Ϯ0.07% (Day 16). Resting levels of hemoglobin, hematocrit and red blood cells decreased significantly while [Na ϩ ] sweat increased significantly. For T re and T sk there were no differences at rest. T re , HR, RPE, TS, plasma lactate concentration, hemoglobin and hematocrit at the 40th min of exercise were significantly lower after the period of acclimation but mean corpuscular hemoglobin and serum osmolality were significantly higher while no difference was seen in [Na ϩ ] sweat and T sk . It can be concluded that tropicdwelling subjects, although exposed to prolonged passive heat exposure, were not fully heat acclimatized. To achieve further HA, they should gradually expose themselves to exercise-heat stress in a hot environment.

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Section: Discussionsupporting

confidence: 63%

“…For example, Ladell et al (1951) reported that in HA, involving 17 men for 9 days in a hot, humid (Ta: 38°C, rh: 80%) environment, the mean resting T re decreased 0.3°C over the course of the study. Wyndham et al (1973) heat acclimated men for nine successive days in warm air (32°C) that was fully saturated with water vapour (ϳ100% rh).…”

Section: Discussionmentioning

confidence: 99%

Effects of Short-term Exercise in the Heat on Thermoregulation, Blood Parameters, Sweat Secretion and Sweat Composition of Tropic-dwelling Subjects

Saat

Sirisinghe

Singh

et al. 2005

J. Physiol. Anthropol.

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“…Medical Research, London, N. W. 3 (Received 16 May 1962) The physiological changes which characterize acclimatization to heat have been frequently studied in the laboratory (Henschel, Taylor & Keys, 1943;Robinson, Turrell, Belding & Horvath, 1943;Horvath & Shelley, 1946;Eichna, Park, Nelson, Horvath & Palmes, 1950;Ladell, 1951;Bass, Kleeman, Quinn, Henschel & Hegnauer, 1955;Macpherson, 1960). The method used has been to mimic the natural situation with the subjects performing a carefully controlled work and rest routine for some hours each day in a controlled hot climate.…”

mentioning

confidence: 99%

Acclimatization to heat in man by controlled elevation of body temperature

Fox¹,

Goldsmith²,

Kidd³

et al. 1963

The Journal of Physiology

129

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“…This second conclusion is in our opinion the more important, for it is known that sweat collected from different parts of the body is different in its chemical composition (61,120,121,122,128), but a difference of the chemical ccnposition of sweat during rest and work states has not been reported in the literature. Another interesting observation was that thermal sweat has a larger osmotic deficit than does work sweat.…”

Section: Discussionmentioning

confidence: 79%