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Salivary cortisol and α‐amylase responses to repeated bouts of downhill running
Author(s) -
Mckune Andrew J.,
Bach Christopher W.,
Semple Stuart J.,
Dyer Barry J.
Publication year - 2014
Publication title -
american journal of human biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.559
H-Index - 81
eISSN - 1520-6300
pISSN - 1042-0533
DOI - 10.1002/ajhb.22605
Subject(s) - amylase , saliva , repeated measures design , analysis of variance , endocrinology , medicine , hydrocortisone , zoology , chemistry , biology , biochemistry , statistics , mathematics , enzyme
Objectives To determine the hypothalamic‐pituitary‐adrenal (HPA) axis and sympathoadrenal (SA) system response to repeated bouts of downhill running. Methods Eleven active but untrained males (age: 19.7 ± 0.4 y; VO 2peak 47.8 ± 3.6 ml/kg/min) performed two 60 min bouts of downhill running (−13.5% gradient), separated by 14 days, at a speed eliciting 75% of their VO 2peak on a level grade. Saliva samples were collected before (baseline), after, and every hour for 12 h and every 24 h for 6 days after each run. Salivary cortisol and α‐amylase levels were measured as markers of the HPA axis and SA response, respectively. Results were analyzed using repeated measures ANOVA (12 h period: 2 × 14; 24 h intervals 2 × 7, P ≤ 0.05) with Tukey post‐hoc tests where appropriate. Paired samples t ‐tests were used to compare collapsed data vs. baseline measurements. Results There were no significant group × time interactions for cortisol or α‐amylase for the hourly samples up to 12 h after each run, nor for the 24 h samples up to 6 days later. The 24 h samples for α‐amylase showed a significant group effect between runs (Run 1: 69.77 ± 7.68 vs. Run 2: 92.19 ± 7.67 U/ml; P = 0.04). Significant time effects were measured for both cortisol (decreased 2 h to 12 h post‐run) and α‐amylase (elevated immediately after, 1 h and 2 h post‐run) ( P < 0.001). Conclusion The 24 h period group effect for salivary α‐amylase suggested an adaptation in the sympathoadrenal system that may alter the systemic inflammatory response to exercise‐induced muscle damage but may also reflect enhanced mucosal immunity. Am. J. Hum. Biol. 26:850–855, 2014. © 2014 Wiley Periodicals, Inc.