Muscle Activity and Kinematics During Three Hamstring Strengthening Exercises Compared to Sprinting: A Cross-Sectional Study

Background: During sprinting, the biceps femoris long head predominantly gets injured, while hamstring strengthening exercises predominantly activate the semitendinosus more
effectively. Understanding how joint dominance influences hamstring activity may offer clarity on the appropriate exercise selection in strengthening programs.
Purpose: This study compared 3 hip-dominant hamstring exercises (the rocker, perpetuum mobile fast and slow; PMfast and PMslow) and the Nordic Hamstring exercise (NHE) on their potential to simulate sprint-like activity and kinematics.
Methods: Muscle activity of the posterior kinetic chain (mm. biceps femoris, semitendinosus, gluteus maximus and gastrocnemius medialis) was measured with surface electromyography (sEMG) during every exercise and treadmill running at 75% of the individual maximal sprint velocity in 8 male athletes (age: 24.0 years ± SD 2.9; body mass: 76.8 kg ± 7.7; height: 1.79 m ± 0.08). sEMG data was normalized to maximal sprinting. 3D-motion capture was employed to assess hip and knee angles.
Results: This study revealed higher activity of the hamstrings for the explosive exercises ranging from 63.9% [95%CI: 56.3-71.5%] (rocker) to 49.0% [95%CI: 40.4-57.6%] (PMfast) vs. 34.0% [95%CI: 29.1-38.9%] (NHE) to 32.1% [95%CI: 26.9-37.3%] (PMslow). The rocker especially showed highest hamstring and m. gluteus maximus activity. M. biceps femoris consistently showed higher activity than m. semitendinosus across all exercises in peak (mean difference: 0.16, [95%CI: 0.07-0.26]) and average (mean difference: 0.06, [95%CI: 0.01-0.11]) activity. PMfast, PMslow and NHE demonstrated lower hip flexion angle of peak hamstring activity than the rocker and high-speed running and every exercise showed lower hamstring elongation stress than during high-speed running.
Discussion: Hamstring activity is comparable to high-intensity treadmill running for NHE and PMslow, and higher for the rocker and PMfast. M. gluteus maximus activity varied, with the rocker and PMfast showing higher activity than in sprinting. All examined exercises demonstrated their
peak activity at short hamstring muscle length.