While many studies have characterized the responses of hormones and inflammatory indicators to resistance and cardiovascular exercise, few have evaluated the immediate effects of a graded exercise test (GXT) on these biomarkers. To date, no reports have revealed how cortisol, dehydroepiandrosterone (DHEA), testosterone, and C-reactive protein (CRP) are altered in response to a GXT in a military population. Understanding the hormonal and inflammatory reactions following acute maximal exercise may provide insight into optimizing performance and readiness in the armed forces.
PURPOSE: This pilot study assessed changes in salivary cortisol, DHEA, testosterone, and CRP immediately after a GXT.
METHODS: Eleven U.S. Navy active-duty men (mean ± SD age, 31.9 ± 6.1 years) completed a GXT using the Bruce protocol in a laboratory setting. Saliva samples were collected with oral swabs at pre-GXT, then at 4, 15, 30, and 45 min post-GXT. Samples were assayed for all analytes in duplicate.
RESULTS: The catabolic hormone, cortisol, increased on average by 30.6% ± 6.5 at 30 min post GXT, F(0.18,16.97) = 4.36, p = 0.03, ηp2 = 0.33. Post hoc tests revealed differences between baseline and 30 min post-GXT (p = 0.02, 95% CIΔ: 0.03-0.42). DHEA concentrations were moderately stable throughout the study timeline, appearing to increase slightly at 30 min post-GXT, F(8513.38, 24) = 2.39, p = 0.08, ηp2 = 0.29. Testosterone levels increased substantially from baseline and peaked at 15 min post-GXT, for an average increase of 21.7% ± 8.9, with a marked decline and return to a value resembling baseline at 45 min post-GXT, F(8346.05, 8.70) = 5.86, p = 0.03, ηp2 = 0.54. CRP concentrations remained comparable to baseline and relatively constant throughout the post-GXT observation period.
CONCLUSION: Acute maximal exercise seems to affect catabolic and anabolic hormones in a fashion similar to both aerobic (vigorous, long duration) and anaerobic (acute) exercise. The observed changes in cortisol were consistent with the increased energy demands, and physiological recovery, from aerobic exercise. The rise in testosterone was comparable to that observed following acute anaerobic training. CRP was surprisingly unaffected, indicating that the physiologic demands of a GXT may be too brief to provoke a response.