Research article - (2021)20, 216 - 221
DOI:
https://doi.org/10.52082/jssm.2021.216
Effect of Different Slopes of the Lower Leg during the Nordic Hamstring Exercise on Hamstring Electromyography Activity
Toshiaki Soga1, Daichi Nishiumi1, Atsuya Furusho1, Kei Akiyama2, Norikazu Hirose1,2,
1Graduate School of Sport Sciences, Waseda University, Tokyo, Japan
2Faculty of Sport Sciences, Waseda University, Tokyo, Japan

Norikazu Hirose
✉ Faculty of Sport Sciences, Waseda University, Tokyo, Japan
Email: toitsu_hirose@waseda.jp
Received: 01-01-2021 -- Accepted: 02-02-2021
Published (online): 05-03-2021

ABSTRACT

The purpose of this study was to examine whether the NHE with an increased lower leg slope angle would enhance hamstring EMG activity in the final phase of the descend. The hamstring EMG activity was measured, the biceps femoris long head (BFlh) and the semitendinosus (ST). Fifteen male volunteers participated in this study. Subjects performed a prone leg curl with maximal voluntary isometric contraction to normalize the hamstring EMG activity. Subsequently, subjects performed the NHE, with the help of a certified strength and conditioning specialist, while the lower leg slope angle were randomly set at 0° (NH), 20° (N20), and 40° (N40). To compare hamstring EMG activity during the NHE variations, the knee flexion angle was set in the range from 0° to 50°, divided into five phases (0–10°, 10–20°, 20–30°, 30–40° and 40–50°), where 0° indicated that the knee was fully extended. To calculate the knee extension angular velocity, the knee flexion angle divided by time, and break point angle (BPA) was the angle at which 10°/s was exceeded. In the statistical analysis, a two-way repeated measures ANOVA was used for the hamstring EMG activity and a one-way repeated measures ANOVA was used for the BPA. The EMG activity of the BFlh and the ST in N20 and N40 was significantly higher than in NH at knee flexion angle of 0–20° (p < 0.05). For the BPA, NH (57.75° ± 13.28°), N20 (36.27° ± 9.89°) and N40 (16.26° ± 9.58°) were significantly higher in that order (p < 0.05). The results of this study revealed that the NHE with an increased lower leg slope angle shifted the BPA to the lower knee flexion angle and enhanced the hamstring EMG activity in the final phase of the descent.

Key words: Sports injuries, injury recurrence, hamstring muscles, electromyography, rehabilitation exercise, resistance training

Key Points
  • The NHE with an increased lower leg slope angle enhances the hamstring EMG activity in the final phase of the descent.
  • The NHE with an increased lower leg slope angle shifts the BPA to the lower knee flexion angle.
  • The NHE with an increased lower leg slope angle may be an important rehabilitation exercise to prevent recurrence of HSIs.








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