Hamstring injury prevention in soccer: Before or after training?

Area of Science:

• Sports Medicine
• Exercise Physiology
• Biomechanics

Background:

• Nordic hamstring exercises (NHE) are crucial for enhancing eccentric hamstring strength and preventing injuries in athletes.
• The optimal timing of NHE within a football training program remains unclear.
• Understanding muscle adaptations to NHE timing is essential for program design.

Purpose of the Study:

• To investigate the effects of a 12-week NHE program on eccentric hamstring strength, muscle activity, and architectural adaptations.
• To compare the outcomes when NHE is performed before versus after football training sessions.
• To determine if exercise timing influences strength gains and muscle remodeling.

Main Methods:

• Randomized controlled trial with amateur soccer players assigned to control (core exercises), NHE before training (NHE_BEF), or NHE after training (NHE_AFT) groups.
• Eccentric knee flexor strength and muscle activity (sEMG) of biceps femoris (BF) and medial hamstring (MH) were measured.
• Ultrasonography assessed BF muscle thickness, pennation angle, and fascicle length.

Main Results:

• Both NHE_BEF and NHE_AFT groups showed significant increases in peak torque (11.9% and 11.6%) compared to controls.
• Increased biceps femoris sEMG was observed in both NHE groups.
• NHE_AFT led to greater increases in muscle thickness and pennation angle, while NHE_BEF showed greater fascicle length increases.

Conclusions:

• A 12-week NHE program effectively enhances eccentric hamstring strength and muscle activity regardless of timing relative to football training.
• The timing of NHE influences specific muscle architectural adaptations, suggesting differential remodeling effects.
• NHE_AFT may promote hypertrophy and pennation changes, whereas NHE_BEF might favor fascicle lengthening.