Assessment of exercise-induced changes of the microcirculation by wavelet transformation

of the microcirculation by spectral analysis of laser doppler signals based on wavelet transformation. Non-invasive blood flowmeasurements (Laser Doppler Spectroscopy LDS) were performed (depth of measurement approx. 1 and 8 mm) on the forearm in 13 healthy non-smoking males before and after a standardized cycling exercise. Blood flow signals were analysed by wavelet transformation in five defined frequency intervals which are proposed to reflect local and central regulatory mechanisms as well as heartbeat and respiration. The mean amplitude of the total spectrum (0,009-2 Hz) and the absolute and relative amplitude of each particular interval were calculated. The total spectral amplitude and the absolute amplitude of each particular interval increased significantly (1 and 8 mm, p < 0,05). Normalized with respect to the total spectrum, the 0,06-0,2 Hz frequency interval amplitude (myogenic activity) increased (p < 0,05) while 0,6-2 Hz frequency amplitude (heartbeat) decreased (8 mm, p < 0,05). Concerning the measuring depth, a significantly higher amplitude of the total spectrum occurred in the deeper tissue (p < 0,05). It has been demonstrated that LDS in combination with wavelet transformation is a valuable tool for use in the evaluation of exercise induced changes of the microvascular blood flow.