Testosterone and cortisol in relationship to dietary nutrients and exercise

Volek, Jeff S., William J. Kraemer, Jill A. Bush, Thomas Incledon, and Mark Boetes.
Testosterone and cortisol in relationship to dietary nutrients and resistance exercise.
J. Appl. Physiol.82(1): 49?54, 1997.

Manipulation of resistance exercise variables (i.e., intensity, volume, and rest periods) affects the endocrine response to exercise; however, the influence of dietary nutrients on basal and exercise-induced concentrations of hormones is less understood. The present study examined the relationship between dietary nutrients and resting and exercise-induced blood concentrations of testosterone (T) and cortisol (C). Twelve men performed a bench press exercise protocol (5 sets to failure using a 10-repetitions maximum load) and a jump squat protocol (5 sets of 10 repetitions using 30% of each subject’s 1-repetition maximum squat) with 2 min of rest between all sets. A blood sample was obtained at preexercise and 5 min postexercise for determination of serum T and C. Subjects also completed detailed dietary food records for a total of 17 days. There was a significant (P<0.05) increase in postexercise T compared with preexercise values for both the bench press (7.4%) and jump squat (15.1%) protocols; however, C was not significantly different from preexercise concentrations. Significant correlations were observed between preexercise T and percent energy protein (r=-0.71), percent energy fat (r=0.72), saturated fatty acids (g ?1,000 /kcal /day, r=0.77), monounsaturated fatty acids (g ?1,000 /kcal /day, r=0.79), the polyunsaturated fat-to-saturated fat ratio (r=-0.63), and the protein-to-carbohydrate ratio (r=-0.59)…. These data confirm that high-intensity resistance exercise results in elevated postexercise T concentrations. A more impressive finding was that dietary nutrients may be capable of modulating resting concentrations of T.