Time-Frequency Analysis of Endogenous Calf Skeletal Muscle Vibromyograms

Calf skeletal muscle pump activity is essential for maintaining adequate venous and interstitial fluid flows in the dependent body. Correspondingly, failure of this extracorporeal pump leads to a host of acute and chronic physiological complications. The focus of this study is to assess the calf muscle pump contractility, more specifically through analysis of soleus muscle firing dynamics, in supine and seated positions, utilizing vibromyography (VMG). We have extended our previous investigations which relied on Fourier analysis of VMG recordings by utilizing wavelet-based time-frequency analysis to characterize the intrinsically non-stationary peripheral postural muscle dynamics during quiet sitting. Our objective was to identify the fibers types responsible for muscle pump activity during sitting, by looking for significant increases in activity in specific muscle fiber groups when a subject assumes an upright position from recumbency, and examine their temporal dynamics