Analyzing the effect of having energy drinks on metabolic, sympathetic and myogenic function by wavelet transforms using laser Doppler Flowmetry

The wavelet transform technique, a time-frequency method with logarithmic frequency resolution, was used to analyze the effect of having energy drinks (ED) using laser Doppler Flowmetry technique LDF100C (Biopac systems Inc.) by determining physiological activities after having energy drinks on 12 healthy human subjects. Traditional Fourier analysis does not provide sufficient resolution to reveal characteristic low frequencies. For this, time frequency analysis was performed. After having energy drinks, it is observed that the amplitude of blood perfusion signal increases around two fold. The physiological activities which include five different frequency intervals (FI) of total spectrum (0.0095-1.6 Hz), each of them related to endothelial or metabolic (0.0095-0.02 Hz), sympathetic or neurogenic (0.02-0.06 Hz), myogenic (0.06-0.15 Hz), respiratory (0.15-0.4 Hz) and cardiac or heart (0.4-1.6 Hz) activity, was also measured in BPU2/Hz before and after having energy drinks by further analyzing frequency spectrum of the blood perfusion signal using Discrete Wavelet transform. We observed a significant change in these activities after having energy drinks. The amplitude of frequency spectrum of LDF signal related to metabolic and sympathetic activity increase around five fold. A little change is observed in myogenic function which increases around three fold.