Comparison of electromyographic activity during Nordic hamstring exercise and exercise in lengthened position

Changes in Amplitude of Hamstring Electromyographic Activity and Its Peak Location During Nordic Hamstring Exercise by Adding External Load

This crossover trial aimed to investigate whether additional loading of unilateral Nordic hamstring exercise on a sloped platform would increase the biceps femoris long head electromyographic activity. Participants were randomly allocated to unilateral Nordic hamstring exercise under three conditions: bodyweight only (BW) or BW with an added weighted ball of 3 kg (BW + 3 kg) or 6 kg (BW + 6 kg), respectively. The biceps femoris long head electromyographic activity was significantly higher for BW + 6 kg (p < .001) than for BW and BW + 3 kg (p < .01). Therefore, adding a load to unilateral Nordic hamstring exercise on a sloped platform might be effective for rehabilitation and prevention of hamstring strain injury recurrence.

Biceps Femoris Muscle is Activated by Performing Nordic Hamstring Exercise at a Shallow Knee Flexion Angle

The semitendinosus (ST) muscle is primarily used during Nordic hamstring exercise (NHE), which is often prescribed for preventing hamstring injury, though the biceps femoris long head (BFlh) muscle that is more susceptible to injuries. Thus, this study aimed to identify the modulation of BFlh muscle activity with different knee flexion angles during NHE using an inclined platform. Fourteen male athletes performed NHE and maintained their position at maximum inclination (NH). Subjects also performed isometric NHE using a platform inclined to 50° (ICL) and 40° (ICH), and the knee flexion angle was controlled to 50° and 30°. The electromyography (EMG) activity of the BFlh, ST, semimembranosus, gluteus maximus, elector spinae, and rectus abdominus muscles was determined during each exercise. The EMG of the ST was higher than that of the BFlh during NHE and the highest of all muscles in all exercises (p < 0.05). Moreover, the activity of the BFlh tended to be higher than that of the ST for ICH than for ICL, regardless of the knee joint angle. The activity of the BFlh becomes equivalent to that of the ST during NHE at a knee flexion angle of less than 50°. These results indicate that performing NHE at a shallow knee flexion angle will enhance the activity of the BFlh muscle.