Exercise and circulating Cortisol levels: The intensity threshold effect

Abstract

This study examined the influence of exercise intensity upon the cortisol response of the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, we examined exercise at intensities of 40, 60, and 80% maximal oxygen uptake (VO2max) in an attempt to determine the intensity necessary to provoke an increase in circulating cortisol. Twelve active moderately trained men performed 30 min of exercise at intensities of 40, 60, and 80% of their VO2max, as well as a 30-min resting-control session involving no exercise on separate days. Confounding factors such as time of day--circadian rhythms, prior diet--activity patterns, psychological stress, and levels of exercise training were controlled. Cortisol and ACTH were assessed in blood collected immediately before (pre-) and after (post-) each experimental session. Statistical analysis involved repeated measures analysis of variance and Tukey post-hoc testing. The percent change in cortisol from pre- to post-sampling at each session was: resting-control, 40, 60, and 80% sessions (mean+/-SD) =-6.6+/-3.5%, +5.7+/-11.0%, +39.9+/-11.8%, and +83.1+/-18.5%, respectively. The 60% and 80% intensity magnitude of change was significantly greater than in the other sessions, as well as from one to another. The ACTH responses mirrored those of cortisol, but only the 80% exercise provoked a significant (p<0.05) increase pre- to post-exercise. The calculated changes in plasma volume for the resting-control, 40%, 60%, and 80% sessions were: +2.2+/-3.0%, -9.9+/-5.0%, -15.6+/-3.5%, and -17.2+/-3.3%, respectively. Collectively, the cortisol findings support the view that moderate to high intensity exercise provokes increases in circulating cortisol levels. These increases seem due to a combination of hemoconcentration and HPA axis stimulus (ACTH). In contrast, low intensity exercise (40%) does not result in significant increases in cortisol levels, but, once corrections for plasma volume reduction occurred and circadian factors were examined, low intensity exercise actually resulted in a reduction in circulating cortisol levels.

Effects of Acute Prolonged Strenuous Exercise on the Salivary Stress Markers and Inflammatory Cytokines

“…It is well known that physical and mental stress elicit the release of cortisol from HPA axis, by which stress can modulate various immune responses 33) . Exercise in the present study could cause comparable increases in saliva cortisol levels to those observed in previous studies 34,35) . Cortisol is important hormone in the regulation of intermediate metabolism and stress.…”

Efeitos agudos do treinamento concorrente sobre os níveis séricos de leptina e cortisol em adultos jovens sobrepesados

“…The influence of external factors may also modify the cortisol response when in submaximal exerce, which may be extremely remarkable 19 . However, if exercise is below the critical threshold intensity, the cortisol levels may not increase above the rest levels, or may really become reduced 23 , corroborating Viru apud Hackney 19 , who also state that in the same exercise absolute intensity cortisol may present low response from the practice of an exercise training program. Never the less, if submaximal exercise is above the critical threshold intensity, then the cortisol levels will initially increase and subsequently enter in plateau (steady state exercise) 24 .…”

“…Therefore, in the same absolute intensity of exercise, cortisol may present low response from the practice of an exercise training program.In the submaximal exercise, the cortisol response is more variable and influenced by many external factors 19 . If the intensity is below the critical threshold, then the cortisol levels may not increase above the rest levels, or may become in fact reduced 23 . However, if it is above the critical threshold intensity, then the cortisol levels will initially increase and subsequently enter a plateau (steady-state exercise) 24 , since while cortisol increases during exercise, at the end of it many alterations and possible effects of this hormone occur during the early recovery 25 .…”

“…Never the less, if submaximal exercise is above the critical threshold intensity, then the cortisol levels will initially increase and subsequently enter in plateau (steady state exercise) 24 . Many investigations 17,23,25,[50][51][52][53] which propsoed to analyze the exercise effect on the plasma cortisol levels pointed significant increase during and after exercise. According to Viruand Viru 54 , cortisol increase observed during exercise is crucial to the control and regulation of the energetic metabolism and hence, to exercise performance.…”

Examination of associations between chaos in the home environment, serum cortisol level, and dietary fat intake among parents of preschool-age children

“…Serum cortisol only measures the level of circulating cortisol at the point of sampling. Circulating cortisol levels can be influenced by factors such as recent exercise (Hill et al 2008), sleep quality (Gonnissen et al 2013), and acute stress (Foley and Kirschbaum 2010). We did not collect data on these variables at the time of blood collection, which is a limitation of our study design.…”