Active Insufficiency

Previous studies have suggested that ankle position and hip position can influence hamstring strength, but none have considered the influence of both joint positions at the same time. The aim of the study was to investigate the effect of ankle and hip position on peak torque (PT), normalized PT (NPT), angle of PT (APT) and electromyographic (EMG) activity during isokinetic knee flexion. Thirteen physically active men performed three maximal isokinetic unilateral knee flexion repetitions at angular velocities of 60 and 180°/s on the isokinetic dynamometer. The individual EMG activity of the gastrocnemius (GL), biceps femoris (BFl) and semitendinosus (ST) muscles was detected using wireless SEMG system. Ankle and hip position had a significant impact on the PT and NPT (p < .05). Specifically, the highest PT and NPT were produced in the dorsal-flexion sitting position, then in the plantarflexion sitting position, followed by the dorsal-flexion in the supine position, while the lowest PT and NPT were produced in the supine position with plantarflexion for both angular velocities. Ankle and hip position and angular velocity have a significant impact on the APT: the PT occurred between 25 and 41° at 60°/s, and between 40 and 62° at 180°/s. Neither ankle nor hip position affected SEMG activity of BFl, ST and GL muscles for both angular velocities. Hip and ankle position influence the passive tension and active insufficiency, which ultimately affects hamstrings PT, but not muscle activity.