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Self-selected manual lifting technique: functional consequences of the interjoint coordination
R Burgess-Limerick1, B Abernethy, R J Neal
1Department of Human Movement Studies, University of Queensland, Australia.
Human Factors
|June 1, 1995
Summary
This study reveals how individuals lift light loads, detailing joint coordination and muscle activation. Optimal lifting mechanics involve specific sequences of knee, hip, and lumbar extension for enhanced back extensor strength.
Area of Science:
- Biomechanics
- Human Movement Science
- Kinesiology
Background:
- Understanding lifting mechanics is crucial for preventing injuries.
- Previous research has focused on different lifting postures and loads.
Purpose of the Study:
- To analyze the kinematic and electromyographic patterns during self-selected lifting movements.
- To investigate the coordination between the knee, hip, and lumbar joints during load lifting.
Main Methods:
- Kinematic and electromyographic analysis of 39 subjects lifting light loads.
- Estimation of hamstring length changes using hip and knee angular kinematics.
- Calculation of relative phase between adjacent joints to assess coordination.
Main Results:
- Subjects adopted an intermediate stoop-squat posture.
- A consistent joint coordination pattern was observed, intensifying with increased load mass.
- Knee extension preceded hip extension, followed by lumbar vertebral joint extension.
- Early lifting phase showed delayed hamstring shortening and coactivation of knee extensors and hamstrings, suggesting tendinous action.
Conclusions:
- The observed joint coordination enhances back extensor strength during lifting.
- Tendinous action of hamstrings may contribute to hip extension.
- Findings provide insights into efficient and safe lifting strategies.