Acute Responses of Testosterone to Submaximal Resistance Exercise in Children vs. Adults
Authors:Eric Adams, Dr. Daniel Judelson, Hoang Pham, Dr. Daniela Rubin
- Dr. Daniela Rubin, Associate Professor of Kinesiology, California State University, Fullerton
- Dr. Daniel Judelson, Associate Professor of Kinesiology, California State University, Fullerton
Background: At rest, children have lower testosterone concentrations (T) than men. Previous research showed acute increases in T of adolescent males following resistance exercise. We tested the hypothesis that prepubescent and mid-pubertal children would not display an acute T response to a bout of submaximal resistance exercise (RE) of sufficient intensity to increase T in adult males. Methods: Twelve lean children (ages 9±1 years, height 141±10cm, mass 31±7kg, body fat 18.3±4.7%) (six boys/six girls), seven developmental stage I, two developmental stage II, and three developmental stage III, were compared to ten lean men (ages 23±2 years, height 177±5cm, mass 77±6kg, body fat 12.7±2.9%). This study was approved by the CSUF Institutional Review Board (HSR# 12-0477 & 12-0479). Exercise consisted of a 5-minute warm-up on a cycle ergometer followed by 6 sets of 10 repetitions per leg of step-ups wearing a weighted vest with 1-minute rest between sets. Step height was standardized to 20% of the subject’s height, and the vest weight was standardized to 50% of the subject’s lean body mass measured by DEXA. Blood samples for serum T were obtained from an indwelling catheter pre-exercise (PRE), immediately post-exercise (IP), and post-exercise at 15 (P-15), 30 (P-30), and 60 (P-60) minutes. Results: There were no significant differences in T between boys and girls so they were analyzed as a group. Overall, T were significantly lower in children than adults (0.64±1.09 vs. 19.84±1.19nmol/L respectively; P<0.01), and there was a significant group by time interaction (P<0.01). T did not significantly change over time in children (P>0.9) but adult T significantly increased from PRE to IP (9.6% increase; P<0.02), returning to baseline by P-15. Conclusion: The T of children who had not gone through full puberty were much lower than the adults' and did not respond to an acute bout of resistance exercise.