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Relaxation phenomenon in lumbar trunk muscles during lateral bending
D D Raftopoulos1, M C Rafko, M Green
1Department of Mechanical Engineering, The University of Toledo, Toledo, Ohio, USA.
Clinical Biomechanics (Bristol, Avon)
|August 7, 2013
Summary
Researchers studied lumbar trunk muscle activity during lateral bending. A relaxation phenomenon was observed in erector spinae muscles, but not in lateral oblique abdominal muscles during these tasks.
Area of Science:
- Biomechanics
- Human physiology
- Musculoskeletal research
Background:
- Understanding lumbar trunk muscle function is crucial for preventing back injuries.
- Previous research identified a flexion-relaxation phenomenon in erector spinae during forward bending.
- The behavior of these muscles during lateral bending remains less understood.
Purpose of the Study:
- To investigate myoelectric activity and muscle tensions in lumbar trunk muscles during lateral bending.
- To determine if a relaxation phenomenon occurs in erector spinae and lateral oblique abdominal muscles during lateral trunk postures.
- To compare electromyography (EMG) findings with biomechanical model estimations.
Main Methods:
- Subjects performed tasks involving varying degrees of lateral trunk bending.
- Myoelectric activity of lumbar trunk muscles was recorded.
- Biomechanical models were used to estimate muscle tensions during these tasks.
Main Results:
- A relaxation phenomenon was observed in the erector spinae muscles during quiet standing in a laterally-bent trunk position.
- This erector spinae relaxation was qualitatively similar to the previously reported flexion-relaxation phenomenon.
- No muscle relaxation was observed in the lateral oblique abdominal muscles in laterally-bent postures.
Conclusions:
- The erector spinae muscles exhibit a relaxation response during sustained lateral bending, analogous to their behavior during flexion.
- Lateral oblique abdominal muscles do not show a similar relaxation phenomenon during lateral bending.
- These findings contribute to a more comprehensive understanding of lumbar muscle control during complex trunk movements.
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