title: Role of aerobic capacity and body mass index in the age-associated decline in heart rate variability.
abstract: The extent to which age-associated changes in aerobic capacity and body composition modulate the age-associated decline in heart rate variability (HRV) is unknown. We therefore measured HRV, peak O2 consumption (VO2peak) during treadmill testing, and relative weight (body mass index; BMI) in 164 healthy normotensive adults (75 men, age 20-87 yr) from the Baltimore Longitudinal Study on Aging. Two components of HRV, respiratory sinus arrhythmia (RSA; 0.12-0.40 Hz) and 0.10-Hz variability (0.06-0.10 Hz), were extracted from 8-min electrocardiogram recordings in the supine, seated, and standing postures. RSA, 0.10-Hz variability, and VO2peak varied inversely with age; BMI was unrelated to age. Age contributed 15.5-21.1% independent variance to RSA and 13.2-17.3% independent variance to 0.10-Hz HRV. VO2peak did not contribute significantly to RSA or 0.10-Hz HRV beyond the effect of age in any posture. There were no consistent independent contributions of BMI to HRV. Thus, in this population-based sample, age-associated changes in aerobic capacity and relative body weight do not provide the primary explanation for the decline in HRV observed with advancing age.
authors.affiliation: University of Maryland, College Park 20742, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Byrne
authors.forename: J L
authors.initials: JL
authors.lastname: Fleg
authors.forename: P V
authors.initials: PV
authors.lastname: Vaitkevicius
authors.forename: J
authors.initials: J
authors.lastname: Wright
authors.forename: S W
authors.initials: SW
authors.lastname: Porges
mesh_terms: D000328:Adult; D000332:Aerobiosis / Q000502:physiology; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015308:Anaerobic Threshold / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology*; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011187:Posture / Q000502:physiology; D012044:Regression Analysis; D012727:Sex Characteristics