Salivary Cortisol and Related Responses to Prolonged Exercise

High levels of cortisol are associated with negative affective states such as anxiety (1) and depression (2). conversely, low cortisol levels have been related to positive psychological states (3). furthermore, it has been reported that fit individuals demonstrate attenuated cortisol responses to acute exercise (4), although the salivary cortisol response to sustained exercise has not been examined. following approval of the study procedure by the university's human ethics committee, nine healthy male (mean±s, age 23.9±3.1 years; height 1.79±0.7 m; mass 73.5±6.3 kg; body fat 12.7±1.7%, hr rest 58±9 beat.min1 and voimzx 56.9±4 ml.kg'vmin1) volunteered to participate in the study. the acute exercise condition was a continuous exercise over 90 minutes on a motor-ised treadmill. unstimulated whole saliva was collected over a 5-min period into pre-weighted tubes during the week prior to commencement of exercise, before exercise and on repeated occasions up to 48 hours after the exercise trial. samples were analysed for cortisol and osmolality, and cortisol to osmolality ratio was calculated. salivary cortisol was used to measure activation of the pituitary-adrenal cortical system. the drg salivary cortisol elisa kit (drg diagnostics, germany) was used for the quantitative measurement of cortisol in saliva samples. data were analysed using an analysis of variance (anova) with repeated measurements. there was a main effect of time (f3,24=13.9, p= 0.01) on body mass (73.5±6.2 vs. 72.4±5.8). mean heart rate and perceived exertion during the continuous exercise were 142±15 and 10.611.1 respectively. the pattern of change in salivary response, including salivary volume, flow rate, cortisol concentration, cortisol secretion rate and cortisol to osmolality ratio did not differ between overall time points (p> 0.05). a main effect of time on salivary osmolality was also evident (f6,4g=5.36, p< 0.05). it is concluded the salivary cortisol is relatively stable during prolonged exercise.