Thermoregulatory changes in the cold induced by physical training in humans

Abstract

It has previously been demonstrated that metabolic heat production (M) during cold exposure at rest was related to maximal oxygen uptake (VO2max). Consequently, an increase in VO2max could allow an increase M in the cold. The aim of the present study was therefore to test this hypothesis. Eight male volunteers undertook interval training (periods of 25% VO2max of 30-s duration and 110% VO2max of 60-s duration until exhaustion, five times a week over 8 weeks) to increase VO2max. Both before and after this physical training, they were subjected to a 10 degrees, 5 degrees and 1 degrees C 2-h cold air test in a climatic chamber. During the cold exposure, rectal temperature (Tre), tympanic temperature (Tty) mean skin temperature (Tsk) and M were measured as well as the time to onset of shivering (t) and body temperatures (Tre, Try and Tsk) at t. The results showed that physical training involved an increase in VO2max (14%-15%, P < 0.05). During the cold exposure, Tre was higher after training both at 10 degrees, 5 degrees and 1 degree C (P < 0.05) whereas Tty, TSk and M were not significantly changed. However, an increase in the sensitivity of the thermoregulatory system was attested by a decreased t at higher Tsk. These slight physiological changes found after training were not related to the increases in VO2max. In conclusion, this study demonstrated that interval training induced slight thermoregulatory changes unrelated to changes in VO2max and it suggested that M during cold exposure could be related mainly to the level of VO2max observed before training, since increases in VO2max did not modify M.

Thermoregulation in the cold after physical training at different ambient air temperatures

“…Similar results have been previously reported by Henane et al (1977) and Savourey and Bittel (1998) after a similar interval training in a comfortable ambient temperature but for longer durations, 3 months (Henane et al 1977) and 2 months (Savourey and Bittel 1998) compared with 1 month in the present study. Body mass and body fat content did not change after the physical training and after the acclimation period.…”

“…The duration of the training protocol was identical between the two groups (10 min at the beginning up to 60 min at the end of the training period). This protocol was chosen because it is known to modify thermoregulatory responses, as previously reported (Henane et al 1977;Savourey and Bittel 1998).…”

“…Indeed, Adams and Heberling (1958) reported an increased metabolic heat production ( & M) at 10°C whereas Keatinge (1961) found the reverse at 6°C and Kollias et al (1972) and Shvartz et al (1977) showed no change at 10°C after various physical training regimes. Recently, our laboratory (Savourey and Bittel 1998) has demonstrated that an interval training programme performed in comfortable ambient air temperature induces a higher rectal temperature (T re ) response at rest during 2-h exposures at various temperatures (1, 5, and 10°C). This change was unrelated to & max V O 2 changes but was related to an increase in the sensitivity of the thermoregulatory system in the cold.…”

Cold Stress Effects on Exposure Tolerance and Exercise Performance

“…Most cross-sectional comparisons of aerobically fit and less fit persons find no relationship between maximal aerobic power and temperature regulation in cold, and in studies purportedly demonstrating a relationship, differences in thermoregulation appear more likely attributable to anthropometric differences between the aerobically fit and less fit participants than to an effect of maximal aerobic power per se (20). Longitudinal studies have shown interval training to have no measurable effects on thermoregulatory responses to cold (207), and while endurance training was shown to improve the cutaneous vasoconstrictor response during cold water immersion, that effect had little impact on deep body temperature changes during cold exposure (277). There is some evidence (102) to suggest that the maximum shivering intensity is related to maximum oxygen consumption (VO 2max ).…”

National Athletic Trainers' Association Position Statement: Environmental Cold Injuries

“…In addition, exercise training has been suggested to enhance the peripheral vasoconstriction response, which would conserve body heat but possibly increase peripheral cold injury risks. [87][88][89][90][91] Sex. The hypothermia injury rate for females is 2 times higher than for males.…”