Decreased Hip Flexion during Spike Jump-Landings after Fatigue is Predictive of Patellar Tendinopathy in Volleyball.

Context: Patellar tendinopathy (PT) is a highly prevalent overuse injury in volleyball. However, little is known if and how the risk for developing PT is increased through fatigue-induced alterations during repetitive jump-landing activities in volleyball.

Objective: The purpose of this study was to explore fatigue-induced risk factors for PT during a spike jump-landing task in volleyball.

Design: Prospective cohort study.

Setting: 3D biomechanical laboratory screening.

Patients or other participants: Seventy-nine adult, male volleyball players.

Main outcome measure(s): At baseline (pre-season), 3D full-body kinematics and kinetics were collected while performing a spike jump before and after a volleyball-specific fatigue protocol. Throughout the season, players were followed for the occurrence of PT and survival analysis with competing risks was performed to identify significant predictors for the development of PT (p < 0.05).

Results: During follow-up, 10 of the 79 players developed PT (13%). Players with significantly less hip flexion during the horizontal landing/push-off phase of the spike jump after fatigue were at higher risk for developing PT (HR = 0.898; 95% CI 0.826 to 0.977; p = 0.023) as well as players with a significantly more elongated rectus femoris muscle-tendon unit (HR = 3.258; 95% CI 1.136 to 9.343; p = 0.032).

Conclusions: Despite the low (injured) sample size of this study, preliminary research findings indicate less hip flexion and more elongated rectus femoris muscle-tendon units during landing after fatigue as potential risk factors for developing PT. Future prevention programs for PT may wish to focus on hip-specific exercises and technique modifications (e.g., more hip flexion during landing) under fatigued circumstances.