Does muscle imbalance affect fatigue after soccer specific intermittent protocol?

Area of Science:

• Sports Science
• Exercise Physiology
• Biomechanics

Background:

• Muscle strength imbalances, particularly between hamstrings and quadriceps (H:Q ratio), are common in soccer players.
• These imbalances may influence performance and injury risk during demanding physical activity.

Purpose of the Study:

• To investigate how pre-existing muscular strength imbalances affect the impact of soccer-specific exercise-induced fatigue on the H:Q ratios of professional soccer players.

Main Methods:

• Twenty-one male professional soccer players were assessed for knee extensor (KE) and flexor (KF) concentric (con) and eccentric (ecc) strength at two speeds.
• Players performed an exhaustive soccer-specific exercise protocol followed by repeat strength testing.
• Participants were categorized into balanced (BG) or unbalanced (UNBG) groups based on their baseline H(con):Q(con) ratio.

Main Results:

• Both groups showed significant reductions in KE(con) and KF(con) strength post-exercise.
• Eccentric KF strength at 180° s⁻¹ decreased significantly only in the balanced group.
• The H(con):Q(con) and H(ecc):Q(con) ratios decreased significantly post-exercise in the balanced group but not in the unbalanced group.

Conclusions:

• The effect of soccer-specific exercise-induced fatigue on hamstring:quadriceps strength ratios is dependent on the player's baseline muscular strength balance.
• Future research and injury prevention strategies should consider the modulating role of muscular strength balance in soccer player fatigue.