title: Effects of breathing patterns and light exercise on linear and nonlinear heart rate variability.
abstract: Despite their use in cardiac risk stratification, the physiological meaning of nonlinear heart rate variability (HRV) measures is not well understood. The aim of this study was to elucidate effects of breathing frequency, tidal volume, and light exercise on nonlinear HRV and to determine associations with traditional HRV indices. R-R intervals, blood pressure, minute ventilation, breathing frequency, and respiratory gas concentrations were measured in 24 healthy male volunteers during 7 conditions: voluntary breathing at rest, and metronome guided breathing (0.1, 0.2 and 0.4 Hz) during rest, and cycling, respectively. The effect of physical load was significant for heart rate (HR; p < 0.001) and traditional HRV indices SDNN, RMSSD, lnLFP, and lnHFP (p < 0.01 for all). It approached significance for sample entropy (SampEn) and correlation dimension (D2) (p < 0.1 for both), while HRV detrended fluctuation analysis (DFA) measures DFAα1 and DFAα2 were not affected by load condition. Breathing did not affect HR but affected all traditional HRV measures. D2 was not affected by breathing; DFAα1 was moderately affected by breathing; and DFAα2, approximate entropy (ApEn), and SampEn were strongly affected by breathing. DFAα1 was strongly increased, whereas DFAα2, ApEn, and SampEn were decreased by slow breathing. No interaction effect of load and breathing pattern was evident. Correlations to traditional HRV indices were modest (r from -0.14 to -0.67, p < 0.05 to <0.01). In conclusion, while light exercise does not significantly affect short-time HRV nonlinear indices, respiratory activity has to be considered as a potential contributor at rest and during light dynamic exercise.
authors.affiliation: a Institute of Sport Science, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany.|b Institute of Exercise Physiology and Public Health, Rostock, Mecklenburg-Vorpommern, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weippert
authors.affiliation: b Institute of Exercise Physiology and Public Health, Rostock, Mecklenburg-Vorpommern, Germany.
authors.forename: Kristin
authors.initials: K
authors.lastname: Behrens
authors.affiliation: b Institute of Exercise Physiology and Public Health, Rostock, Mecklenburg-Vorpommern, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Rieger
authors.affiliation: c University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany.
authors.forename: Mohit
authors.initials: M
authors.lastname: Kumar
authors.affiliation: a Institute of Sport Science, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Behrens
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000523:psychology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D012119:Respiration; D013990:Tidal Volume / Q000502:physiology
keywords: analyse des fluctuations redressées; autonomic nervous system; blood pressure; complexity; complexité; correlation dimension; corrélation de dimension; detrended fluctuation analysis; dynamic exercise; entropie; entropy; exercice dynamique; heart rate variability; paced breathing; pression sanguine; regularity; respiration rythmée; régularité; système nerveux autonome; variabilité du rythme cardiaque