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Loads on the lumbar trunk during level walking
R Cromwell1, A B Schultz, R Beck
1Department of Physical Therapy, University of Health Sciences/Chicago Medical School, Illinois 60064.
Summary
This study estimated internal lumbar trunk loads during walking. Peak erector spinae muscle contractions were around 140 N per side, indicating spine compressions of 1.2 times body weight.
Area of Science:
- Biomechanics
- Human Movement Analysis
- Spinal Physiology
Background:
- Understanding the internal forces on the lumbar trunk during locomotion is crucial for injury prevention and rehabilitation.
- Previous research has often relied on estimations or simplified models for trunk loading during dynamic activities like walking.
Purpose of the Study:
- To estimate the internal loads acting on the lumbar trunk during level walking.
- To quantify muscle contraction forces within the lumbar trunk during gait.
Main Methods:
- Measured myoelectric activity of eight trunk muscle pairs in 10 healthy males during isometric exertions and level walking at two cadences (72 and 120 steps/min).
- Calibrated muscle force/activity relationships using static tasks.
- Employed a 22-muscle biomechanical model to predict muscle forces during walking based on calibrated myoelectric data.
Main Results:
- Peak contraction forces for iliocostalis muscles were approximately 55 N per side.
- Total erector spinae peak contractions were estimated at 140 N per side.
- Other monitored muscles showed less than 15 N per side contraction forces, suggesting peak trunk compression of 1.2 times body weight and moments of 15 Nm.
Conclusions:
- The study provides quantitative estimates of lumbar trunk muscle forces during level walking.
- Findings suggest that walking generates significant, but manageable, compressive loads and moments on the lumbar spine.
- This data can inform the design of interventions aimed at reducing spinal load during daily activities.