Endurance exercise with and without a thermal clamp: effects on leukocytes and leukocyte subsets

Abstract

To test how leukocyte responses to endurance exercise were modified by clamping body temperature, nine men (27.3 +/- 6.0 yr) completed four 80-min immersions to midchest at water temperatures of 23 or 39 degrees C; two tests included 40-min of cycle ergometer exercise at 65% of aerobic power. When the subjects were exercising, rectal temperature peaked at 39.1 +/- 0.4 degrees C in the warm water and 37.8 +/- 0.3 degrees C in the cool water. When the subjects were sitting in warm water, rectal temperature closely matched the core temperature during exercise in cool water, whereas when they were sitting in cool water, rectal temperatures decreased to 36.4 +/- 0.6 degrees C. Total and differential white cell counts were determined by using a Coulter counter, and cortisol and growth hormone concentrations were determined by radioimmunoassay; all data were adjusted for changes of blood and plasma volumes. Heat clamping during exercise substantially reduced the rise in white cell, lymphocyte, and granulocyte counts but not the increase in monocyte count. Clamping also abolished previously observed associations between cell counts and cortisol and weakened associations with growth hormone concentrations (D. A. McCarthy and M. M. Dale. Sports Med. 6: 333-363, 1988). We conclude that both exercise and a rise of core temperature contribute to the changes in white cell and subset counts during and immediately after moderate exercise. Both cortisol and growth hormone concentrations appear to be mediators of these responses.

Ambient Temperature and the Pituitary Hormone Responses to Exercise in Humans

“…5C). This is at odds with previous findings that have shown an augmented release of cortisol in the heat (Galbo et al 1979;Cross et al 1996;Hargreaves et al 1996). The difference might be due to (1) the fact that rectal temperature during the first 40 min of exercise in this study was similar in both conditions whilst others have found greater differences after 40 min of exercise (38.4 ± 0.1°C after 40 min at 35°C vs. 39.1 ± 0.2°C after 40 min at 40°C; Hargreaves et al 1996) or (2) the different ambient temperatures used.…”

“…It has been shown that cortisol concentrations are elevated both during exercise in the heat (Galbo et al 1979;Hargreaves et al 1996) and by passive heat exposure (Collins & Few, 1979;Moller et al 1989), and it has been reported that thermal clamping of body temperature abolishes the exercise-induced increase in cortisol concentrations (Cross et al 1996). It has also been shown that cortisol increases during swimming in water of different temperatures only if body temperature increases (Galbo et al 1979).…”

Acute dopamine/noradrenaline reuptake inhibition enhances human exercise performance in warm, but not temperate conditions

“…• C) in the temperate trial, with clamping of body temperature previously demonstrated to abolish exercise-induced cortisol secretion (Cross et al 1996). As previously reported (Piacentini et al 2004), bupropion did not significantly influence the serum cortisol or growth hormone response, whereas plasma ACTH and beta-endorphin concentrations were higher at the end of the TT in temperate ambient conditions.…”

Thermoregulatory and Immune Responses During Cold Exposure: Effects of Repeated Cold Exposure and Acute Exercise

“…Our observation that total leukocyte, granulocyte and lymphocyte counts rise in response to underwater cycle ergometer exercise is consistent with the findings reported by other investigators in our laboratory (23,82). Similarly, thermal clamping attenuated this leukocyte and granulocyte response.…”