Hormonal and inflammatory responses in prepubertal vs. pubertal male children following an acute free-weight resistance training session.

PURPOSE: Examine the acute hormonal and cytokine responses to free-weight resistance training in trained prepubertal and pubertal male children.

METHODS: Prepubertal (n = 21; age 11.4 ± 1.1 years; Tanner I-II) and pubertal male children (n = 20; age 15.8 ± 0.7 years; Tanner III-V) conducted a moderate-intensity free-weight resistance training program to failure with venous blood sampling before (pre), immediately after (post) and during the recovery phase of the program (post-15,-30 min). Growth hormone (GH), insulin-like growth factor-I (IGF-I), cortisol, testosterone, IL-6, and TNF-α were analyzed in serum samples. Biological maturation was assessed according to the stages of the Tanner scale.

RESULTS: There was a significant time-by-group interaction in IGF-I response (p = 0.044; η2  = 0.209) and testosterone (p < 0.001; η2  = 0.508), indicating a greater change in the pubertal group compared to the prepubertal group. Both groups significantly increased post-exercise GH levels (p < 0.05). Only the prepuberal group significantly increased levels of IL-6 at all post-exercise time points (p < 0.05). Both groups showed a significant (p < 0.05) increase in TNF-α levels compared to resting levels.

CONCLUSION: These data suggest that acute testosterone and IGF-I response following resistance training differ between trained prepubertal and pubertal male children. Moderate-intensity resistance training performed to failure may thus have different effects in trained prepubertal and pubertal male children, which should be considered when giving training advice.

TRIAL REGISTRATION: Clinical trials number: NCT05022992.