Abstract Background It is well-established that strength training (ST) improves physical fitness in young athletes. However, its specific effects on hormonal changes in female soccer players are unresolved. Objectives We examined the influence of a twelve-week ST program conducted twice per week on soccer-related measures of physical fitness and hormonal profiles in adolescent elite female soccer players. Methods Twenty-four elite young female soccer players aged 15.3 ± 0.9 years (body-mass-index BMI: 20.8 ± 1.9 kg/m²) and Tier 4 training and performance caliber participated in this study. Players were randomly assigned to either an ST group (STG, n = 12) or an active control group (CG, n = 12). Several parameters were determined pre- and post-training including absolute and relative to kg body mass 1-RM in bench/leg press, countermovement jump (CMJ), linear sprint speed (5-m, 10-m, 30-m sprints), speed of changing directions (T-test with and without ball), sport-specific efficiency (Yo-Yo Intermittent Level1 YYIRTL1) and repeated shuttle sprint ability (RSSA). Cortisol (C), testosterone (T), growth hormone (GH), and insulin-like growth factor 1 (IGF-1) were assessed using blood samples collected after 12 h of fasting, before and after the ST program. Results No significant baseline between-group differences were observed. Statistically significant group-by-time interactions were found for muscle strength measures (e.g., relative 1-RM leg press, p = 0.046, d = 0.59), vertical jump performance (e.g., CMJ, p = 0.007, d = 1.28), and soccer-specific performance (e.g., RSSA Mean , p 0.05). Conclusion While the ST program significantly improved physical fitness in adolescent female Tier 4 soccer players, no substantial changes were observed in hormonal markers. These findings suggest that ST-related physical adaptations observed in this population may not be directly linked to the hormonal markers measured in this study. Trial registration Clinical trial number PACTR202504552619186 https://pactr.samrc.ac.za/Search.aspx Date of registration: 14/04/2025. “Retrospectively registered” Our study adheres to CONSORT guidelines.
Darragi et al. (Mon,) studied this question.