Comparison of the decrease in strength between hamstrings and quadriceps during isokinetic fatigue testing in...

Area of Science:

• Sports Medicine
• Biomechanics
• Exercise Physiology

Background:

• Muscle imbalance, particularly in agonist/antagonist ratios, is a known pathological factor.
• Previous research focused on quadriceps strength loss due to fatigue, with limited investigation into hamstring fatigue.
• Understanding fatigue-induced strength decline in thigh muscles is crucial for injury prevention.

Purpose of the Study:

• To assess the differential decline in hamstring and quadriceps muscle strength during fatigue.
• To determine if fatigue affects the hamstring to quadriceps strength ratio.
• To investigate the impact of fatigue on muscle endurance ratios in professional soccer players.

Main Methods:

• Utilized an isokinetic dynamometer for endurance testing on 27 professional soccer players.
• Measured fatigue-induced strength decline in hamstring and quadriceps muscles over a set number of repetitions.
• Compared maximal strength ratios with endurance ratios under fatigue conditions.

Main Results:

• Hamstring strength declined significantly more than quadriceps strength after 15 repetitions (dominant leg) and 40 repetitions (nondominant leg).
• A decrease in the endurance ratio compared to the maximal strength ratio was observed in the dominant leg after 30 repetitions.
• Hamstring strength decline diverged from quadriceps strength decline in both legs during fatigue states.

Conclusions:

• Fatigue differentially impacts hamstring and quadriceps strength, leading to an imbalance in their resistance to fatigue.
• This imbalance in thigh muscle stabilizing function may elevate the risk of injury during strenuous physical exertion.
• Findings suggest that fatigue-induced strength divergence is a critical factor in athletic performance and injury risk assessment.