Exploring the effects of combined Nordic and reverse Nordic hamstring exercises on physical fitness in prepubertal male soccer players

Introduction This study aimed to examine the effects of combined Nordic Hamstring and Reverse Nordic exercises on measures of physical fitness in prepubertal male soccer players. Methods The eccentric training program lasted 8 weeks, with two sessions per week, each lasting approximately 20 min and performed immediately after the warm-up of regular soccer training. A total of 34 prepubertal male soccer players were recruited and randomly assigned at the group level to either the eccentric training group ( n = 17; age = 12.44 ± 0.24 years, maturity offset = −1.27 ± 0.28) or the active control group ( n = 17; age = 12.40 ± 0.22 years, maturity offset = −1.15 ± 0.35). Physical fitness was assessed through measures of linear sprint performance (10 & 20 m), change of direction (505 test), agility (Y-shaped agility test), and vertical (countermovement jump) and horizontal jump performance (standing long jump). Results and discussion The findings showed moderate group-by-time interactions for all fitness measures [effect size (d) = 0.62–1.16]. Post hoc analyses revealed small-to-moderate improvements in the eccentric training group across all performance measures (d = 0.31–1.18), while no significant changes were observed in the control group for any fitness measure. In conclusion, our findings support the effectiveness, practicality, and safety (no injuries reported) of the eccentric training program for improving physical fitness in prepubertal male soccer players.