Differential muscle activation patterns and kinematics during the nordic hamstring exercise and the maximum-speed single-leg bridge test

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 better resembling sprinting, but a direct comparison to the NHE and published sprint kinematics is lacking. This cross-sectional study compared muscle activation of the semitendinosus, biceps femoris, gluteus maximus, medial gastrocnemius, and rectus femoris, hip and knee joint angles and angular velocities, external force, and estimated MTU lengths between the MS-SLBT and NHE in 17 healthy male recreational athletes. It also examined their correspondence with published sprint kinematics and MTU length data. Overall, the MS-SLBT elicited greater peak activation than the NHE in the semitendinosus (109% vs. 82%MVIC) and biceps femoris (104% vs. 88%MVIC). Peak hamstring activation and external force during the MS-SLBT occurred at longer hamstring MTU lengths, and at joint angles (approximately 40° hip flexion and 35° knee flexion) more closely resembling the late swing phase of sprinting. These findings suggest that the MS-SLBT provides an assessment of hamstring performance under demands mimicking the late swing phase of sprinting.