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Power spectral analysis of the surface electromyogram during shivering
Aviation, Space, and Environmental Medicine
|December 1, 1986
Summary
This study found that electromyogram (EMG) power spectrum during shivering did not change over 80 minutes of cold exposure. This indicates no muscle fatigue or cooling effects on shivering EMG frequency content.
Area of Science:
- Physiology
- Biomedical Engineering
Background:
- Shivering is a physiological response to cold, involving involuntary muscle contractions.
- Understanding the electromyogram (EMG) frequency content during shivering can provide insights into muscle activity and potential fatigue or cooling effects.
Purpose of the Study:
- To analyze the frequency content of EMG signals during shivering.
- To investigate whether the EMG power spectrum changes with the duration of shivering in a cold environment.
Main Methods:
- Six males were exposed to 5°C for 80 minutes while shivering was induced.
- EMG signals from the masseter muscle were recorded, digitized, and analyzed using Fourier analysis to calculate the power spectrum and centroid frequency (fc).
- Skin and rectal temperatures were monitored throughout the exposure.
Main Results:
- Mean skin temperature dropped significantly, while rectal temperature showed a slight initial rise followed by a decline.
- EMG activity was observed within 5 minutes, with a centroid frequency (fc) of 177.2 ± 6.2 Hz after 10 minutes.
- The predominant EMG power spectrum band was 60-120 Hz, and importantly, no significant changes in the EMG power spectrum were observed despite increasing shivering intensity over the 80-minute exposure.
Conclusions:
- The EMG power spectrum during shivering remains stable over an 80-minute cold exposure.
- These findings suggest that shivering, under these conditions, does not induce changes in EMG frequency content indicative of muscle fatigue or significant muscle cooling.