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Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations
Published on: May 1, 2018
Quadriceps and hamstrings coactivation during common therapeutic exercises.
Rebecca L Begalle1, Lindsay J Distefano, Troy Blackburn
1Sports Medicine Research Laboratory, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. rbegalle@email.unc.edu
Journal of Athletic Training
|August 15, 2012
Summary
The single-limb dead-lift and lateral-hop exercises demonstrated the most balanced quadriceps and hamstrings muscle activation, which is crucial for anterior cruciate ligament (ACL) injury prevention and rehabilitation.
Area of Science:
- Biomechanics
- Exercise Physiology
- Sports Medicine
Background:
- Anterior cruciate ligament (ACL) loading is influenced by anterior tibial shear force and knee valgus moment.
- Quadriceps and hamstrings muscle coactivation significantly impacts these forces, affecting ACL injury risk.
- Identifying exercises promoting balanced muscle activation is vital for ACL rehabilitation and prevention.
Purpose of the Study:
- To quantify and compare quadriceps-to-hamstrings (Q:H) coactivation electromyographic (EMG) ratios during common closed kinetic chain exercises.
- To identify exercises that may reduce ACL loading by balancing muscle activation.
Main Methods:
- A cross-sectional study was conducted in a research laboratory setting.
- Twenty-seven healthy, physically active volunteers participated.
- Surface EMG measured vastus medialis, vastus lateralis, medial hamstrings, and biceps femoris activity during 9 randomized closed kinetic chain exercises to calculate Q:H ratios.
Main Results:
- A significant main effect of exercise on Q:H ratios was observed (P < .001).
- The single-limb dead-lift exercise exhibited significantly smaller Q:H ratios compared to the single-limb squat.
- Transverse-lunge, lateral-lunge, and forward-lunge exercises showed the largest Q:H ratios.
Conclusions:
- Exercises like the single-limb dead-lift, lateral-hop, transverse-hop, and lateral band-walk promote the most balanced quadriceps and hamstrings coactivation.
- These exercises show potential for use in ACL injury prevention and rehabilitation programs.
- They can be progressively incorporated into post-injury recovery protocols.
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