Abstract
<title>Abstract</title> <p>Background. Patellar tendinopathy is a prevalent overuse injury in jumping athletes such as volleyball players, with a prevalence reaching up to 45%. It arises from repetitive landing impacts that overload the tendon due to altered neuromuscular control and inadequate force absorption by the muscle-tendon unit. Wearable inertial sensor assessment offers an objective and field-deployable approach to characterize landing kinematics in this population. This study aimed to identify kinematic and kinetic markers distinguishing symptomatic from asymptomatic players with patellar tendinopathy during unilateral vertical jumps. Methods. This cross-sectional study included thirty elite male volleyball players who performed single-leg countermovement jumps and single-leg drop jumps. Ten players exhibited patellar tendinopathy symptoms, confirmed by a Victorian institute of sports assessment – patellar score ≤ 80, pain localized to the patellar tendon during single-leg decline squatting, and pain mapping. Kinematic data were collected using 8 wearable inertial measurement units (IMUs, 100 Hz), and kinetic data using force platforms (1000 Hz). Results. The patellar tendinopathy group demonstrated widespread kinematic deficits across all joints and tasks. At the knee, lower range of motion, flexion angle at contact, peak flexion angle, and angle at peak eVGRF were observed across all jump conditions (p ≤ .04; g = 0.76–1.60). Force plate analysis revealed shorter flight time in the patellar tendinopathy group during single-leg countermovement (p = .044; g = 0.45). Limb symmetry index analysis confirmed lower knee range of motion and maximum flexion angle during single-leg countermovement (p ≤ .026; g = 0.90–0.93), as well as lower maximum knee flexion angle at the second single-leg drop jump landing (p = .045; g = 0.89). Conclusion. These findings underscore the potential of wearable inertial sensor-based unilateral jump landing assessments to discriminate individuals with patellar tendinopathy, offering a novel perspective on how patellar tendinopathy alters impact absorption strategies.</p>