Effects of Altering Trunk Position During Landings on Patellar Tendon Force and Pain

PURPOSE: To verify the immediate effects of altering sagittal plane trunk position during jump-landings on lower limb biomechanics, patellar tendon force and pain of athletes with and without patellar tendinopathy.

METHODS: Twenty-one elite male athletes were categorized into 3 groups, athletes with patellar tendinopathy (TG, n=7), asymptomatic athletes with patellar tendon abnormalities (AG, n=7) and asymptomatic athletes without tendon abnormalities (CG, n=7). A biomechanical evaluation was conducted while the athletes performed drop landings from a bench in a self-selected trunk position (SS). Afterwards, the athletes were randomly assigned to land with either a flexed trunk position (FLX) or an extended trunk position (EXT). Variables of interest for this study included sagittal plane peak kinematics, kinetics, patellar tendon force and pain during the landing tasks.

RESULTS: Peak patellar tendon force, knee extensor moment and knee pain decreased in the FLX landing compared to the SS landing, regardless of group. In addition, peak patellar tendon force, knee extensor moment and vertical ground reaction force were smaller in the FLX landing compared to the EXT landing. The TG had smaller peak ankle dorsiflexion than the CG during jump-landings, regardless of trunk position.

CONCLUSION: Landing with greater trunk flexion decreased patellar tendon force in elite jumping athletes. An immediate decrease in knee pain was also observed in symptomatic athletes with a more flexed trunk position during landing. Increasing trunk flexion during landing might be an important strategy to reduce tendon overload in jumping athletes.