Modulating the Nordic Hamstring Exercise from 'zero to hero' - A stepwise progression explored in a high-performance athlete.

Abstract

The Nordic Hamstring Exercise (NHE) is commonly implemented to selectively improve eccentric knee flexor strength. However, the exercise's standard version (levelled shanks, extended hip joint) is too strenuous for most individuals whose muscle activity rapidly decreases at extended knee angles. Hitherto, a gradual approach to the exercise is missing. This exploratory CASE study investigated elite performance to introduce a stepwise progression to the NHE. The purpose was to determine to which extent exercise modifications (shank inclination, additional load, hip flexion) alter NHE mechanics. One male long jumper (33years, 171cm, 69kg) with high NHE expertise performed 20 exercise variations. The corresponding kinematics, kinetics and electromyographic activity of the biceps femoris long head (BFlh) and semitendinosus (ST) were evaluated. Exercise variations demonstrated gradually increased peak moments (PM) from 69% ('zigzag' pose) to 154% (inclined bent single-leg version) compared to a standard NHE. Shank inclination and additional load elicited small to moderate effects on PM, BFlh and ST (0.24≤d≤0.72), whereas hip flexion largely affected all tested parameters (2.80≤d≤6.66), especially muscle activity (-63% BFlh;- 55% ST). These insights assist practitioners and scientists to design multifaceted stepwise NHE progressions by creating differentiated stimuli which best match the strength capacities of each individual and address its specific needs.