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Exercise-induced knee joint laxity in distance runners
H V Johannsen1, T Lind, B W Jakobsen
1Department of Orthopaedic Surgery, Aarhus County Hospital, University of Aarhus, Denmark.
British Journal of Sports Medicine
|September 1, 1989
Summary
Exercise temporarily increases knee joint laxity in runners, particularly at 30 degrees of flexion. This temporary increase in knee laxity may be due to ligament changes and muscle fatigue.
Area of Science:
- Sports Medicine
- Biomechanics
- Orthopedics
Background:
- Knee joint laxity can be influenced by physical activity.
- Understanding exercise-induced laxity is crucial for developing effective ligamentous repair materials.
Purpose of the Study:
- To investigate the immediate effects of running exercise on knee joint laxity in recreational runners.
- To determine if exercise-induced laxity is a physiological response.
Main Methods:
- Utilized a computerized goniometer (Acufex KSS) to measure knee flexion, tibial rotation, and anterior-posterior tibial displacement.
- Assessed static and dynamic knee joint laxity in 20 recreational runners before and after a 30-minute running session.
- Measured anterior tibial displacement during eccentric quadriceps activity with added weight.
Main Results:
- A maximum 16% increase in mean total anterior-posterior laxity was observed at 30 degrees of knee flexion post-exercise.
- Increased laxity at 30 degrees persisted 30 minutes post-exercise, while laxity at 90 degrees returned to or fell below pre-exercise levels.
- Anterior tibial displacement showed a maximum 18% increase in total anterior-posterior laxity post-exercise.
Conclusions:
- Running exercise can induce a temporary increase in knee joint laxity.
- This exercise-induced laxity is likely a combination of true ligamentous changes and reduced muscle tone in fatigued muscles.
- Findings may inform the development of ligament replacement materials mimicking physiological laxity.