Effects of a 12-week integrated core and plyometric training program on tennis skills, agility, strength, and balance in adolescent tennis players

Background and Study Aim. Tennis performance in adolescents depends on the development of agility, strength, balance, and sport-specific skills. During the growth period, optimizing training strategies is essential to enhance performance without increasing injury risk. There is a growing interest in combining core and plyometric exercises within structured training programs. This study aimed to examine the effects of a 12-week integrated core and plyometric training program on tennis-specific skills (ITN score), agility, lower-body strength, and dynamic balance in adolescent tennis players aged 12–14 years. Materials and Methods. Twenty-two junior male players were recruited and block-randomized into two groups: an experimental group (integrated core and plyometric training plus regular tennis) and a control group (regular tennis only). Five participants withdrew from the study. The final sample consisted of 17 players (experimental n = 8, control n = 9). Pre- and post-tests included the ITN, Pro-Agility Test, Squat Jump (SJ), Countermovement Jump (CMJ) using the BTS SportPlate™, and the Star Excursion Balance Test (SEBT). Shapiro-Wilk tests confirmed that all variables were normally distributed, satisfying the assumptions for parametric testing. Data analysis included repeated measures ANOVA, post hoc comparisons, effect sizes, and Pearson correlation coefficients. Results. Repeated measures ANOVA revealed significant group × time interactions for ITN score (F = 12.34, p = 0.003, η² = 0.45), Pro-Agility Test (F = 7.45, p = 0.015, η² = 0.38), and SEBT (F = 6.56, p = 0.018, η² = 0.35). No significant interactions were found for SJ or CMJ. Pairwise comparisons showed large effects for ITN improvement (experimental group: Mean Diff = –1.2, p = 0.001, d = 1.20) and Pro-Agility time (experimental group: –0.23 s, p = 0.004, d = 0.85). SEBT scores increased by 6.1 points (p = 0.003, d = 0.92). A moderate negative correlation (r = –0.52, p < 0.05) was found between agility gains and ITN improvements. Conclusions. The 12-week integrated program significantly improved tennis skills, agility, and dynamic balance compared to regular training alone. However, it had minimal impact on vertical jump performance. These results support incorporating core and plyometric training into youth tennis programs to enhance sport-specific performance.