Testosterone and cortisol response to acute intermittent and continuous aerobic exercise in sedentary men

Purpose: Different types of physical activity can induce different hormonal and physiological responses. In this study, we examined the testosterone, cortisol, creatine kinase (CK) and lactate dehydrogenase (LDH) response to acute intermittent (IE) and continuous (CE) aerobic exercise in sedentary men. Methods: In this single-blinded randomised crossover study, eleven sedentary healthy males completed protocols (CE and IE) on two different days separated by a 1-week washout period. CE comprised 40 min of running on a treadmill at 60% of reserve heart rate. IE consisted of 40 min of running on a treadmill with intensity alternating between 50% (2 min) and 80% (1 min) of reserve heart rate. Blood samples were taken before and immediately after each exercise session. Results: Serum testosterone concentrations increased significantly after IE (+8.0%, P = 0.021) and decreased non-significantly after CE (−5.8%, P = 0.409). The IE response was greater than the CE response (P = 0.01). Cortisol concentration decreased in both IE and CE exercise (P = 0.001 and P = 0.016, respectively), by −33.6 and −34.6%, respectively. The testosterone to cortisol ratio increased significantly after both forms of exercise (IE: P = 0.003; CE: P = 0.041). CK concentrations significantly increased from PRE to POST (IE: +20.6%, P = 0.001; CE: +26.5%, P = 0.046). Despite the increase in concentrations of LDH, the changes were not significant (F_{(3, 30)} = 1.01, P = 0.402; IE: +11.4% and CE: +23.1%). Conclusions: In summary, it seems that intermittent exercise can be more useful in the development of body anabolic processes in sedentary men due to pronounced increases in testosterone.