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Effects of a functional knee brace on leg muscle function
J R Styf1, O Lundin, D H Gershuni
1Department of Orthopaedic Surgery, Göteborgs University, Sweden.
The American Journal of Sports Medicine
|November 1, 1994
Summary
Functional knee braces increase muscle pressure, leading to faster fatigue. This study found braced legs experienced significantly higher intramuscular pressure and a 35% shorter time to muscle fatigue.
Area of Science:
- Biomechanics
- Sports Medicine
- Physiology
Background:
- Functional knee braces are often used to support the knee joint during physical activity.
- The impact of these braces on underlying muscle physiology, particularly intramuscular pressure and blood flow, is not fully understood.
Purpose of the Study:
- To investigate the effects of a functional knee brace on local intramuscular pressures and blood perfusion pressure in the tibialis anterior muscle.
- To determine how knee brace use influences torque generation and the onset of muscle fatigue during ankle dorsiflexion.
Main Methods:
- Six volunteers performed ankle dorsiflexion exercises measured by a Kinetic Computerized ergometer.
- Intramuscular pressures, torque, and time to muscle fatigue were recorded in both braced and unbraced legs.
- Comparisons were made between braced and unbraced legs within each subject.
Main Results:
- Braced legs exhibited significantly higher intramuscular pressure at rest and during muscle relaxation.
- Muscle fatigue onset occurred 35% faster in the braced leg compared to the unbraced leg.
- Calculated local blood perfusion pressure was reduced in the braced leg due to elevated muscle relaxation pressure.
Conclusions:
- Increased muscle relaxation pressure caused by functional knee brace use may lead to premature muscle fatigue.
- This finding suggests a potential mechanism explaining reduced endurance in individuals using knee braces during exercise.