A comprehensive isokinetic dynamometry profile highlights a weakness in eccentric knee extensor strength in recreationally active males and females

Isokinetic dynamometry represents the gold standard measure of strength, but there is a lack of consensus regarding data collection. The aim of this study was to develop a comprehensive protocol considering contractile speed and modality, and to use this model to generate normative data for recreational athletes. Twenty male and 20 female, non-sport-specific but recreationally active participants completed isokinetic trials at 60, 180 and 300°/sec in eccentric and concentric modes for the knee flexors and extensors. Males generated significantly greater peak torque in extension and flexion, across both modalities and all speeds. Concentric strength demonstrated the expected decrease in torque with increasing isokinetic speed. Eccentric hamstring strength demonstrated a constant value across speeds, as expected; however, eccentric quadriceps strength decreased at the faster speeds. Furthermore, eccentric quadriceps strength was lower than predicted from extrapolation of the concentric curve to zero velocity. Strength ratios derived from peak torque data, including ipsi-lateral, dynamic control and fast:slow ratios, demonstrated no difference for sex. The sex differences in peak torque across modality and speed suggest increased injury risk for female athletes where functional demands are equivalent. Eccentric quadriceps weakness might be indicative of a lack of specific adaptation in this recreational cohort, with implications for preventative and rehabilitative strategies.