Essential role of weekly high-frequency plyometric training to enhance physical performance 2 and manage muscle soreness in male adolescent soccer players

Purpose: this study aims to investigate the effects of volume-matched plyometric training (PT) with different frequency distributions on physical performance and muscle soreness in adolescent soccer players. Methods: Thirty-four sub-elite players were allocated into two groups: PLYO-1 (n = 17, age 1=16.02±0.26 years) underwent one PT session per week, while PLYO-3 (n = 17, age = 15.81±0.37 years) underwent three volume-matched PT sessions per week. The PT program lasted 9 -weeks with an initial weekly volume of ~55 -foot contacts, increasing by 10% per week. The 7-point Likert scale was employed to assess the perceived muscle soreness before and after each PT session. All players were tested for countermovement horizontal (CMHJ) and vertical (CMVJ) jumps, 10-m sprint and change of direction (COD) performance using the modified 505 test (505mod). Results: After the 9- week experimental period, both groups exhibited significant improvements in CMHJ distance (p < 0.001; d = −0.55) and CMVJ variables (jump height and modified reactive strength index, p < 0.001; d = −0.34 and d = −0.33), and 505mod time (COD deficit) (p < 0.001, d = 1.09). However, no improvements were observed in the 10-m sprint time for PLYO-1 and PLYO-3 (p > 0.911, d = −0.12). The changes in perceived muscle soreness were significantly lower for PLYO-3 compared with PLYO-1 (p < 0.001, d = 1.04) throughout the experimental period. Conclusions: Employing weekly volume-matched PT conducted at different frequencies can help to maintain, or even enhance, jump and COD performance, while differently impacting muscle soreness.