Stress Hormones and the Immunological Responses to Heat and Exercise

Abstract

This review focuses on the response of "stress" hormones to heat, exercise (single or repeated bouts), and combinations of these stimuli, with particular reference to their impact upon immune function. Very hot conditions induce a typical stress response, with secretion of catecholamines and cortisol. The catecholamines induce a demargination of leukocytes, and cortisol subsequently causes cells to migrate to lymphoid tissue. Sustained exercise, even in a thermally comfortable environment, induces a larger hormonal response than moderate thermal stress. With moderate exercise, increases in leukocyte numbers are related mainly to plasma norepinephrine concentrations, but with more intense exercise epinephrine concentrations assume a major importance. As exercise continues, plasma cortisol levels also rise, inducing an influx of neutrophils from bone marrow and an efflux of other leukocyte subsets. A combination of exercise and heat stress augments both hormonal and leukocyte responses. But these changes seem to be reversed if temperatures are clamped by exercising in cold water. If a second bout of exercise is performed with an inter-test interval of 30-45 min, neither hormone concentrations nor immune responses show any great cumulative effect under temperate conditions. However, in a hot environment the second exercise bout induces a larger and more persistent neutrophilia. Training influences these various responses mainly by decreasing the stress imposed when exercising at a given absolute work-rate.

Circulating hematopoietic progenitor cells in runners

“…ALTHOUGH EXERCISE IS CONSIDERED a physiological stimulus for cell release by the bone marrow (5), surprisingly few data are available on circulating hematopoietic precursors in athletes. Erythrocyte production was studied relative to athlete's anemia (25) and to assess the effects of intermittent hypoxic exposure on exercise performance (1).…”

“…The rationale to study myeloid precursors in athletes is that intense and prolonged exercise increases white blood cell (WBC) and neutrophil [polymorphonuclear neutrophil (PMN)] counts (5,16), partly through mobilization of marginated PMNs (5) associated with increased endogenous plasma glucocorticoids (15). PMN activation also occurs during exercise, as indicated by increased plasma PMN elastase (8).…”

Ventilatory changes in heat-stressed humans with spinal-cord injury

“…It may relate to changes in carbon dioxide sensitivity with heating, 21 catecholamine production, [22][23][24] a direct interaction of the preoptic anterior hypothalamus on respiratory control centres, [25][26][27][28] or some combination of these factors.…”

Desempenho De Indivíduos Com Dermopigmentação Submetidos À Prática De Exercício Físico

“…Estudos demonstraram que este sistema, quando relacionado ao exercício físico como modelo mensurável de indução ao estresse também sofre alterações funcionais consideráveis 6,[8][9][10][11] .…”

“…Além disso, sabe-se que o exercício físico como um dos fatores de indução ao estresse também contribui para que ocorram alterações funcionais neste sistema 6,9,10,11 .…”