Eccentric Force and Regional Biceps Femoris Muscle Excitation During Conventional and 80° Hip-Flexed Nordic Curl.

Abstract

Hamstring injuries are prevalent in high-intensity sports. The lesion often occurs with concomitant knee extension and hip flexion. The Nordic curl has been suggested to prevent such injury, mainly due to its eccentric hamstring activation. The objective of this study is to assess the eccentric force output and the regional biceps femoris excitation (proximal, mid, and distal) during conventional and 80° of hip flexion of Nordic curl. Thirty-nine participants (17 men: 22.6 [2.03]y, 1.71 [0.09]m, 73.6 [13.3]kg; and 22 women: 24.4 [6.02]y; 1.64 [0.08]m; 62.2 [10.5]kg) were included in the study. Hamstring strength was analyzed through a load cell and muscle activation assessed with an electromyographer in 3 muscle portions (proximal, mid, and distal). Mixed factorial analysis of variance was used to rate the differences. The conventional Nordic curl showed higher muscle activation compared with the hip-flexed Nordic curl (P = .001). No differences were observed in other factorial analysis. The findings suggest that conventional Nordic curl induces higher biceps femoris muscle excitation across compared with 80° hip-flexed Nordic curl. No differences were noted in muscle strength. The same force output with distinct levels of muscle activation may provide a progression system to implement hamstring training for injury prevention or even for exercise routine.