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Factors in breathing maneuvers that affect trunk electromyogram during manual lifting
1Institute of Physical Therapy, National Yang-Ming University, Taipei, Taiwan, Republic of China. kangmo@ms18.hinet.net
Spine
|October 24, 2002
Summary
Breathing maneuvers, specifically breathholding and air volume, significantly impact trunk muscle activation during lifting. Controlling these factors is crucial for accurate electromyogram analysis in future studies.
Area of Science:
- Biomechanics of human movement
- Respiratory physiology
- Exercise physiology
Background:
- Breathing influences spinal loading, but its effect on trunk muscle activation during activities remains debated.
- Variations in thoracic air volume may mediate the impact of breathholding on trunk muscles.
Purpose of the Study:
- To clarify the effect of breathholding on trunk electromyogram (EMG).
- To test if thoracic air volume, alongside glottis closure, influences trunk muscle activity during lifting.
Main Methods:
- A randomized laboratory experiment with seven healthy men performing standardized lifting tasks.
- Three breathing conditions: breathholding at tidal volume, breathholding at functional residual volume, and normal breathing.
- Measured surface EMG of external oblique, rectus abdominis, erector spinae, and latissimus dorsi, along with thoracic air volume and breathhold duration.
Main Results:
- Breathing maneuvers selectively increased external oblique muscle activation (P < 0.05) during breathholding.
- Reduced thoracic air volume during breathholding further amplified external oblique activation.
- Normal breathing decreased external oblique activation but increased diaphragmatic effort.
Conclusions:
- Both breathholding state and sustained air volume affect external oblique activation during lifting.
- These breathing parameters are critical confounding factors and must be controlled in trunk EMG studies.