Effects of acute or chronic heat exposure, exercise and dehydration on plasma cortisol, IL-6 and CRP levels in trained males.

Costello, J.T., Rendell, R. A., Furber, M., Massey, H.C., Tipton, M.J., Young, J.S. and Corbett, J., 2018. Effects of acute or chronic heat exposure, exercise and dehydration on plasma cortisol, IL-6 and CRP levels in trained males. Cytokine. (In Press)

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DOI: 10.1016/j.cyto.2018.01.018

Abstract

This study examined the acute and chronic effects of euhydrated and hypohydrated heat exposure, on biomarkers of stress and inflammation. Eight trained males [mean (SD) age: 21 (3) y; mass: 77.30 (4.88) kg; V̇O2max: 56.9 (7.2) mL·kg−1·min−1] undertook two heat acclimation programmes (balanced cross-over design), once drinking to maintain euhydration and once with restricted fluid-intake (permissive dehydration). Days 1, 6, and 11 were 60 min euhydrated exercise-heat stress tests (40 °C; 50 % RH, 35% peak power output), days 2–5 and 7–10 were 90 min, isothermal-strain (target rectal temperature: 38.5 °C) exercise-heat sessions. Plasma was obtained pre- and post- exercise on day 1, 2, and 11 and analysed for cortisol, interleukin-6 (IL-6), and C-reactive protein (CRP). Cortisol and CRP were also assessed on day 6. IL-6 was elevated following the initial (acute) 90 minute isothermal heat strain exercise-heat exposure (day 2) with permissive dehydration ( (pre exercise: 1.0 pg.mL-1 [0.9], post-exercise: 1.8 pg.mL-1 [1.0], P = 0.032) and when euhydrated (pre-exercise: 1.0 pg.mL-1 [1.4], post-exercise: 1.6 pg.mL-1 [2.1], P = 0.048). Plasma cortisol levels were also elevated but only during permissive dehydration (P = 0.032). Body mass loss was strongly correlated with Δcortisol (r = -0.688, P = 0.003). Although there was a trend for post-exercise cortisol to be decreased following both heat acclimation programmes (chronic effects), there were no within or between intervention differences in IL-6 or CRP. In conclusion, acute exercise in the heat increased IL-6 and cortisol only when fluid-intake is restricted. There were no chronic effects of either intervention on biomarkers of inflammation as evidenced by IL-6 and CRP returning to basal level at the end of heat acclimation.

Item Type:Article
ISSN:1043-4666
Uncontrolled Keywords:Thermoregulation; Stress; Extreme environments; Acclimatization; Acclimation
Group:Faculty of Management
ID Code:30230
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:19 Jan 2018 16:02
Last Modified:20 Mar 2018 11:45

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