Author(s): SANO, Y., KAWABATA, M., VAN HOOREN, B., MURASE, M., NAGANO, Y., WATANABE, H., TAKAHIRA, N., Institution: KITASATO UNIVERSITY GRADUATE SCHOOL, Country: JAPAN, Abstract-ID: 812

INTRODUCTION:
The Nordic Hamstring Exercise (NHE) is widely used to assess hamstring strain injury (HSI) risk, but the joint angles and resulting hamstring muscle-tendon unit (MTU) lengths are dissimilar to sprinting, which may limit sensitivity. The Maximum-Speed Single-Leg Bridge Test (MS-SLBT) was developed to assess hamstring function at joint angles resembling sprinting [1]. Recent evidence indicates that hamstring strength from a single-leg isometric bridge test performed in joint configurations similar to the MS-SLBT, as well as hamstring strength derived from the NHE, independently predict HSI risk. However, it remains unclear whether the biomechanical and neuromuscular demands imposed by the MS-SLBT and NHE differ. Therefore, this study aimed to compare muscle activation, kinematics, kinetics, and estimated hamstring MTU lengths between the MS-SLBT and NHE, and to examine their similarity to published sprint data.
METHODS:
A cross-sectional observational study was conducted in 17 recreational male athletes. During the MS-SLBT, participants performed in a supine position with the knee flexed to 30°, placing the heel on a 40-cm platform and raising the buttock as fast and as high as possible by pushing through the heel. During the NHE, participants slowly lowered the trunk forward from a 90° knee-flexed position with the ankles fixed. Muscle activation of the semitendinosus and biceps femoris, as well as external force, were assessed. Hip and knee joint angles were obtained using a markerless motion capture system, and these data were used to estimate hamstring MTU lengths using established equations. Statistical analyses were performed using paired t-tests or Wilcoxon signed-rank tests, with the significance level set at p < 0.05.
RESULTS:
The MS-SLBT elicited greater peak activation than the NHE in the semitendinosus (109% vs. 82%MVIC, p = 0.008) and biceps femoris (104% vs. 88%MVIC, p = 0.017). Peak hamstring activation and external force during the MS-SLBT occurred at longer hamstring MTU lengths (p < 0.001). Specifically, peak activation during the MS-SLBT occurred at approximately 40° of hip flexion and 35° of knee flexion, joint angles that more closely resemble those reported during the late swing phase of high-speed sprinting (approximately 40–60° of hip flexion and 15–40° of knee flexion). In contrast, peak hamstring activation during the NHE occurred at joint positions of approximately 15° of hip flexion and 50° of knee flexion.
CONCLUSION:
The MS-SLBT elicited greater ST and BF activation than the NHE. Furthermore, peak muscle activation and peak external force during the MS-SLBT occurred at longer estimated MTU lengths and at joint angles that more closely resemble those associated with HSI occurrence than the NHE.
REFERENCE:
[1] Sano Y, Kawabata M, Van Hooren B, et al. A practical assessment of hamstring muscle endurance and fatigue using the maximum-speed single-leg bridge test. BMC Sports Sci Med Rehabil. 2025;18(1):18