Characteristics of Hamstring Electromyographic Activity and the Break-Point Angle during Nordic Hamstring Exercise at...

Area of Science:

• Biomechanics
• Sports Medicine
• Exercise Physiology

Background:

• The Nordic hamstring exercise (NHex) is effective in reducing hamstring injury risk.
• However, the semitendinosus (ST) muscle shows greater activation than the biceps femoris long head (BFlh) during NHex, despite the BFlh being more susceptible to injury.

Purpose of the Study:

• To investigate the electromyographic (EMG) activity of hamstring muscles (BFlh and ST) and the break-point angle (BPA) during NHex.
• To compare these parameters with different ankle joint positions: plantar flexion (PF), dorsiflexion (DF), and DF with sole support (DFS).

Main Methods:

• Twelve healthy male volunteers participated in randomized exercise sessions.
• EMG activity of BFlh and ST muscles was measured for dominant and non-dominant limbs.
• The BPA was recorded using an IMU sensor, with statistical analysis via repeated measures ANOVA.

Main Results:

• EMG activity of the BFlh muscle was significantly affected by ankle position in both legs (p < 0.05).
• BFlh activity was significantly higher in PF compared to DF and DFS in the dominant leg (p < 0.05).
• No significant differences in BPA were observed across the different ankle positions (p > 0.05).

Conclusions:

• NHex elicits greater BFlh muscle activation in the plantar flexion ankle position compared to dorsiflexion.
• This suggests that modifying ankle positioning during NHex may enhance its effectiveness in targeting the BFlh muscle.
• Further research could explore optimal NHex variations for injury prevention.