title: [Time-variant AR spectral method for non-stationary heart rate variability signal under gravitational stress].
abstract: In order to study the nonstationary heart rate variability (HRV) signals under gravitational stress, a time-variant autoregressive spectral estimation method has been implemented, which made it possible to study dynamically the process of cardiac autonomic regulation during various gravitational stresses. The HRV signals obtained from 8 subjects during seated-LBNP testing before and after a six-month aerobic training were analyzed by the implemented algorithm. The obtained time-variant spectra might clearly reveal the time course of changes of decrease in HFn and increase in LF/HF, reflecting the time course of cardiac vagal withdrawal and indices with time during seated-LBNP were increased in most of the subjects. In brief, our work shows that the method of time-variant AR spectrum analysis for non-stationary HRV signals makes it possible to elucidate the dynamics of cardiac autonomic regulatory activity under gravitational stress and to detect the subtle changes in HRV after aerobic training.
authors.affiliation: Department of Aerospace Physiology, The Fourth Military Medical University, Xi'an.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Zheng
mesh_terms: D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D015444:Exercise / Q000502:physiology; D006112:Gravitation; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008150:Lower Body Negative Pressure; D008955:Models, Cardiovascular; D010809:Physical Fitness / Q000502:physiology*