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Bilateral performance symmetry during drop landing: a kinetic analysis
P K Schot1, B T Bates, J S Dufek
1Department of Human Kinetics, University of Wisconsin-Milwaukee 53201.
Medicine and Science in Sports and Exercise
|September 1, 1994
Summary
Lower extremity function is not always symmetrical, challenging biomechanics assumptions. This study found meaningful bilateral differences in joint moments and ground reaction forces during drop landings.
Area of Science:
- Biomechanics
- Human movement analysis
- Sports medicine
Background:
- The assumption of bilateral symmetry in lower extremity function is widespread in biomechanics.
- Unilateral injuries suggest this assumption may be flawed.
- Previous bilateral function analyses yield conflicting results due to methodology and movement types.
Purpose of the Study:
- To investigate concurrent bilateral lower extremity performance during a symmetrical movement task.
- To quantify bilateral variability and asymmetry in ground reaction forces and joint moments.
Main Methods:
- Ten subjects performed 25 drop landings from 60 cm over 3 days.
- Concurrent vertical ground reaction forces (VGRF) and joint moments (JM) were measured bilaterally.
- Bilateral variability (BV) and bilateral asymmetry (BA) were calculated for each trial.
Main Results:
- Bilateral variability was lower for VGRF (12.8%) than for JM (25.3%).
- Bilateral asymmetry was more frequent in VGRF variables (52.5%) than JM variables (16.7%).
- The magnitude of identified BA exceeded group BV and BA, indicating biomechanically significant differences.
Conclusions:
- Lower extremity function exhibits meaningful bilateral asymmetry, contradicting the symmetry assumption.
- Joint moments show greater asymmetry than vertical ground reaction forces.
- These findings have implications for understanding injury development and optimizing movement analysis.