Cortisol and testosterone dynamics following exhaustive endurance exercise.

Abstract

Cortisol (C) and testosterone (T) are impacted significantly by prolonged endurance exercise with inverse responses. Increases in C are witnessed concurrently with decrements in T, possibly impacting recovery. This study was conducted to assess the dynamics of C and free T (fT) concentration and recovery time following an exhaustive endurance exercise session (EES). 12 endurance-trained males (X±SD: VO2max 66.3±4.8ml/kg/min, age 22.8±3.1years, body fat 11.0±1.4%, training 7.1±3.2years) completed a treadmill EES at ventilatory threshold (74.7±4.6% of VO2max; 96.9±10.8min). Basal blood C and fT were collected at baseline: -48, -24h, and immediately before (0h) the EES as well as immediately (+0h), +24h, +48h, and +72h after the EES. Blood glucose (G) was measured to confirm no undue influence on C. Statistically data were analyzed with repeated measures ANOVA (LSD post hoc). C (nmol/L) increased significantly from -48h (321±59) to +0h (701±178) (p<0.001), and displayed a baseline overshoot with +24h (209±67) being significantly lower than -48 and +0h (p<0.03). fT (pmol/L) decreased significantly from -48h (161±40) to +0h (106±38) (p<0.01) and remained lower at +24h (110±33) and +48h (129±30) (p<0.001). G remained stable throughout. A moderately negative correlation (r=-0.636, p<0.026) was found between C and fT at +0h. EES recovery may require 48h for C and 72h for fT to return to baseline values. Furthermore, C and fT were only correlated immediately post-exercise. Future research should perform more frequent measurements throughout time course.