Ankle joint angle influences hamstring fine-wire and high-density electromyography activity in ramp isometric knee flexions

This study aimed to examine whether fixing the ankle in dorsiflexion vs in plantarflexion affects knee flexion torque and hamstrings activity during ramp isometric contractions. Ten pairs of fine wires were inserted into the four heads of the hamstrings and 15-channel high-density electromyography (EMG) arrays were attached over the biceps femoris long head (BFLH) and semitendinosus (ST) muscles of the right leg of 12 young males. Results suggest that higher hamstrings EMG activity is reached in BFLH, ST and BF short head when the ankle is plantar flexed vs dorsiflexed at 20° knee flexion (but not at 90° knee flexion). This suggests that plantar flexion should be applied when prescribing hamstring exercises requiring a near-extended knee.