Power Spectral Analysis of the Surface Electromyogram during Shivering,
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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The purpose of this study was to describe the frequency context of the electromyogram ENG recorded during shivering and determine if the EMG power spectrum changed as a function of the shivering duration. Six semi-nude males were exposed to cold air 5 C, 20 rh for 80 min while quietly sitting. Rectal T subscript re and mean skin T subscript sk temperatures were recorded. Shivering of the masseter muscle was determined using bipolar surface electrodes. The power spectrum was calculated from eight serial 0.25s EMG samples by Fourier analysis from a frequency of 4 through 480 Hz. The eight power spectra were averaged and centroid frequency f subscript c calculated. Vigorous shivering was observed within 5 min after entering the cold chamber. Although shivering intensity increased with time, the EMG power spectrum exhibited no significant changes. These results suggest that the EMG power spectrum during shivering did not exhibit changes characteristic of muscle fatigue or muscle cooling during the 80-min cold air exposure. Originator supplied keywords include Cold Exposure, Hypothermia, Muscular Fatigue.
- Anatomy and Physiology