Association of strength with patellar tendinopathy in female runners

Muscle weakness and muscle imbalance may lead to musculotendinous injuries since the energy absorption capacity of the affected muscle tendon unit is reduced. The purpose of this study was to investigate the maximum strength and strength endurance of the thigh musculature in healthy female runners (F: n=26) and female runners suffering from patellar tendinopathy (PT: n=20). Isokinetic strength measurements were recorded in a seated position. Primary outcome variables were maximum concentric and eccentric peak torque (at 60°/s) and concentric hamstrings-quadriceps-quotient (HQQ). Secondary outcome variables were relative peak torques [Nm/kilogram] and eccentric endurance quotient calculated as the ratio of muscle strength at the end of a 1-minute exercise compared to at the beginning of the exercise period. The primary outcome variables were analyzed using Student's t-test for each measure (α = 0.05). Secondary outcome variables were qualified descriptively. The results showed no statistically significant differences between injured and healthy female runners in concentric and eccentric peak torque or HQQ. Secondary outcome variables also failed to show inter-group differences. We therefore conclude that these variables are not relevant with respect to PT in female runners.