Relationship between quadriceps strength performance and knee joint function during single-leg hop test in runners...

To investigate differences in isokinetic quadriceps strength and knee joint function during single-leg hop test between runners with patellofemoral pain (PFP) and healthy runners, and their relationship.

Controlled and correlational study.

Biomechanics laboratory.

24 runners with PFP and 17 healthy individuals.

Quadriceps torque and power were assessed by the isokinetic dynamometer. Kinematics and kinetics, including joint moment, power, and joint work were collected via 3D motion capture and force plates during the hop test. Group differences were tested with Two-way ANOVA, and Partial correlation assessed the relationship between quadriceps strength and hop biomechanics.

No group differences in quadriceps strength were identified (p ≥ 0.618). PFP group displayed increased hip work (p = 0.020) and contribution (p = 0.016), but reduced knee work contribution (p = 0.029) during single-leg hop test. Quadriceps strength correlated with knee function during the hop test in controls (r ≥ 0.485, p ≤ 0.048) but not in PFP group (r ≤ 0.287, p ≥ 0.208).

Runners with PFP exhibited no quadriceps weakness but used a more hip-dominant strategy. Quadriceps strength was correlated with hop biomechanics in healthy individuals, but this relationship was disrupted in runners with PFP.