Resting-Exercise Salivary Cortisol Responses: Detecting the Magnitude of Hormonal Change Over Time.

This study investigated the validity of salivary cortisol responses to reflect blood cortisol responses relative to the magnitude of change observed over time in the hormone. Male subjects (n=25) conducted four experimental sessions (ES) where blood (B) and saliva (S) were obtained before (PS) and after (PoS) a 30 min resting control, 40%, 60%, and 80% of maximal aerobic capacity (VO2max) exercise ES. B and S specimens were analyzed by standard biochemical procedures. Hormonal concentrations changes were assessed by using absolute delta (DA) values (PoS - PS) and percent change (PC) calculations ((PoS-PS)/PS × 100) for each B and S specimen. Subsequent DA and PC values were correlated (Pearson) for each B-S specimen pairing (n=100; n=25 × 4 ES). Results indicate the magnitude of change (PoS vs. PS) in S cortisol is more valid and strongly associated (p<0.001) with corresponding B changes (the "gold standard") when expressing the data as delta values using absolute hormonal concentrations as compared to percent change expression.