[Cross-spectral analysis of the stroke blood volume oscillations and R-R interval duration among men during different loadings].

The correlation of the stroke blood volume oscillations and the R-R interval duration was investigated among 125 healthy young men at rest, with controlled breathing, at tilt test, with mental and physical loadings with the help of the cross-spectral analysis. Maximums and minimums of the cross-spectral power for these indexes were found to be groupped in three frequency ranges: 0-0.04 Hz, 0.07-0.13 Hz and 0.15-0.4 Hz. The positive tops of the cross-spectral power had the biggest amplitude in the 0-0.04 Hz, 0.07-0.13 Hz frequency ranges in the most conditions; negative tops stipulated with breathing--in the 0.15-0.4 Hz frequency ranges. The structure of the cross-periodgrams changed reliably with different loadings if compared with lying position at rest. The maximum top amplitude of the cross-periodgram was reproduced at the largest extent with repeated changes in 235 +/- 31 days in the ranges of 0.07-0.13 Hz, having median frequency of 0.09-0.01 Hz in all conditions.