Central Frequency of Low Frequency Component of HRV Estimates Sympathetic Activity During Dynamic Exercise, Standing and Paced Breathing Maneuvers

摘要

In 25 healthy subjects we assessed the effects of the maneuvers supine position (S), dynamic exercise (DE), standing (ST), controlled breathing (CB) and DE recovery (DER) on the time-courses of' central frequencies and powers of the low and high frequency components of RR (_CFLF_RR, pLF_RR' pHF_RR), systolic (_CFLFsp,pLF_sp) and diastolic (_CFLF_DP, pLF_DP) pressures, estimated by a time-frequency distribution, and on the pLF_RR/pHF_RR and _CFLF_RR/pHF_RR ratios. Relative to S, significant mean values changes (p<; 0.03) were: _CFLF_RR and pHF_RR increased in CB and decreased distinctively in ST and DE; _CFLF_RR/pHF_RR decreased in CB and increased distinctively in ST, DE and DER; pLF_RR only decreased pronouncedly in DE; mean RR (RR_m) decreased in CB, ST, DE and DER. pLF_RR/pHF_RR means were similar in ST, DE and DER. In S, CB, ST and DER, _CFLF_RR was greater (p<; O.005) than _CFLF_DP and _CFLF_SP· Correlations of _CFLF_RR with pHF_RR and RR_m were: 0.78±0.07 and 0.64±0.12 respectively. Our findings that _CFLF_RR: estimates the sympathetic activity (SA) level of each maneuver, is strongly correlated with pHF_RR, improves the estimating capability of the ratio in DE, and is greater than _CFLF_DP, support that _CFLF_RR is a trustable SA indicator, relevantly in DE, and that the modulatory frequency of the cardiac sympathetic branch is greater than the vasomotor one.