The objective of this stdy was to evaluate knee joint dynamics in elite volleyball players with and without a history of patellar tendinopathy, focusing on mechanical energy absorption and generation. Thirteen elite male players with and without a history of patellar tendinopathy performed maximum-effort volleyball approach jumps. Sagittal plane knee joint kinematics, kinetics, and energetics were quantified in the lead limb using data obtained from a force platform and an 8-camera motion analysis system. Vertical ground reaction forces (VGRF) and pelvis vertical velocity (PVV) at takeoff were examined. The tendinopathy group demonstrated significant reductions (approximately 30%) in net joint work and net joint power compared to controls during the eccentric phase of the jump, with no differences in the concentric phase. Positive to negative net joint work and net joint power ratios were significantly higher in the tendinopathy group: net joint work ratio 1.00 (95% CI 0.77-1.24) versus 0.76 (0.64-0.88) for controls; net joint power 1.62 (1.15-2.10) versus 1.00 (0.80-1.21). There were no significant differences in net joint moment, angular velocity, or range of motion. Peak VGRF was lower for the tendinopathy group, while average VGRF and PVV were similar.
Patellar tendinopathy is associated with differences in sagittal plane mechanical energy absorption at the knee during maximum-effort volleyball approach jumps. Net joint work and net joint power may help define underlying mechanisms, adaptive effects, or rehabilitative strategies for individuals with patellar tendinopathy.
Sorenson SC, Arya S, Souza RB, Pollard CD, Salem GJ, Kulig K. Knee Extensor Dynamics in the Volleyball Approach Jump: The Influence of Patellar Tendinopathy. J Orthop Sports Phys Ther. 2010 May 27, onlne article ahead of print