Region-dependent hamstrings activity in Nordic hamstring exercise and stiff-leg deadlift defined with high-density...

Area of Science:

• Biomechanics
• Sports Medicine
• Neuroscience

Background:

• Recent research indicates region-specific metabolic activity in hamstring muscles during injury prevention exercises.
• The neural underpinnings of these metabolic differences remain largely unexplored.

Purpose of the Study:

• To investigate regional differences in the neural activation of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles.
• To compare muscle activity patterns during the Nordic hamstring exercise (NHE) and stiff-leg deadlift (SDL).

Main Methods:

• Twelve healthy males performed NHE and SDL.
• High-density electromyography (HD-EMG) recorded BFlh and ST muscle activity.
• Activity was analyzed across distal, middle, and proximal regions during the eccentric phase.

Main Results:

• ST overall activity was significantly higher than BFlh in NHE, unlike in SDL.
• NHE demonstrated distinct regional activation patterns for both ST (distal lowest) and BFlh (distal highest).
• Regional differences in muscle activity were less pronounced during SDL compared to NHE.

Conclusions:

• Hamstring muscle activity is heterogeneous during common injury prevention exercises.
• HD-EMG is a valuable tool for detailing hamstring muscle activation.
• Findings suggest exercise-specific neural recruitment strategies within the hamstring muscles.