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Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations
Published on: May 1, 2018
Submaximal fatigue of the hamstrings impairs specific reflex components and knee stability
Mark Melnyk1, Albert Gollhofer
1Institute of Sports and Sports Science, University of Freiburg, Schwarzwaldstrasse 175, 79117, Freiburg, Germany. mark.melnyk@sport.uni-freiburg.de
Summary
Hamstring muscle fatigue significantly increases anterior tibial translation, indicating reduced knee joint stability. This mechanical instability may contribute to anterior cruciate ligament (ACL) injuries in athletes.
Area of Science:
- Biomechanics
- Sports Medicine
- Neuromuscular Physiology
Background:
- Anterior cruciate ligament (ACL) ruptures are severe sports injuries with long recovery periods.
- Quadriceps and hamstring muscles are crucial for knee joint stability.
- Muscle fatigue is a potential factor contributing to ACL injuries.
Purpose of the Study:
- To investigate the effect of submaximal hamstring muscle fatigue on anterior tibial translation.
- To assess changes in knee joint stability due to hamstring fatigue.
Main Methods:
- 15 participants underwent submaximal hamstring fatigue exercises.
- Anterior tibial translation was measured using linear potentiometers at 30 degrees knee flexion with a 315 N force.
- Surface electromyography (EMG) recorded reflex latencies and hamstring muscle activity.
Main Results:
- Muscle fatigue significantly increased monosynaptic reflex latency.
- EMG amplitudes for short and medium latency components were significantly reduced.
- Anterior tibial translation significantly increased, indicating reduced knee stability.
Conclusions:
- Hamstring muscle fatigue is associated with a mechanical loss of knee stability.
- This decreased joint stability may increase the risk of ACL injuries.
- Reduced motor activity, rather than prolonged reflex latency, appears to be the primary cause of instability during fatigue.
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