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−1 ⋅ day−1;r = 0.77), monounsaturated fatty acids (g ⋅ 1,000 kcal−1 ⋅ day−1;r = 0.79), the polyunsaturated fat-to-saturated fat ratio (r = −0.63), and the protein-to-carbohydrate ratio (r = −0.59). There were no significant correlations observed between any nutritional variables and preexercise C or the absolute increase in T and C after exercise. 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.
- steroid hormones
Address for reprint requests: W. J. Kraemer, Center for Sports Medicine, The Pennsylvania State Univ., 146 Rec Bldg., Univ. Park, PA 16802.
- Copyright © 1997 the American Physiological Society