Wavelet analysis of lumbar muscle oxygenation signals during whole-body vibration: implications for the development of localized muscle fatigue

Abstract

The objective of this study was to assess the effects of whole-body vibration (WBV) on lumbar muscle oxygenation oscillations in healthy men based on the wavelet transform of near-infrared spectroscopy signals. Twelve healthy participants were exposed to WBV at frequencies of 3, 4.5 and 6Hz while muscle oxygenation signal was monitored before, during and recovery from WBV. With spectral analysis based on wavelet transform of NIR signal, six frequency intervals were identified (I, 0.005-0.0095Hz; II, 0.0095-0.02Hz; III, 0.02-0.06Hz; IV, 0.06-0.16Hz; V, 0.16-0.40Hz and VI, 0.40-2.0Hz). It was found that the muscle oxygenation oscillations at 4.5Hz in the frequency intervals I, II and III was lower during WBV compared with that of at 3Hz. Present results demonstrated WBV at 4.5Hz induced lower oscillatory activities than that of at 3Hz. The lower oscillatory activities might indicate a decrease in the efficiency of oxygen supply to the oxygenated tissue and such mechanism might contribute to the development of local muscle fatigue.