Countermovement jump force-time waveforms in male adolescent footballers with growth-related musculoskeletal pathology.

Introduction: Growth-related musculoskeletal pathology is common in adolescent athletes, although associated changes in countermovement jump force-time characteristics remain poorly understood. This exploratory repeated-measures biomechanical analysis examined whether adolescent footballers with current or historical growth-related pathology, including Osgood-Schlatter disease (OSD) and prior pars interarticularis fracture, displayed limb-specific differences in double-leg countermovement jump (DL-CMJ) force-time waveforms not evident using discrete performance metrics alone. Methods: Five male academy footballers completed 15-20 DL-CMJ testing sessions, representing presentations of developing OSD, resolved OSD, resolved OSD with prior pars fracture, and two pain-free reference athletes. Limb-specific vertical ground reaction force waveforms were time-normalised and analysed using one-dimensional Statistical Parametric Mapping. Results: Athletes with growth-related pathology displayed phase-specific waveform asymmetries, altered propulsive work distribution, and divergent reversal timing patterns compared with pain-free reference athletes. Force-time differences were observed both during symptomatic periods and in athletes with historical pathology who remained pain-free at the time of testing. Discussion: These findings suggest that waveform analysis may provide additional insight into movement strategies associated with growth-related musculoskeletal pathology beyond conventional countermovement jump metrics. Further longitudinal investigation in larger cohorts is required to determine the clinical relevance of these observations.