Role of aerobic capacity and body mass index in the age-associated
decline in heart rate variability.
Byrne, Evan A., Jerome L. Fleg, Peter V. Vaitkevicius, Jeanette Wright
& Stephen W. Porges.
University of Maryland - College Park MD 20742, Gerontology
Research Center, NIA, Baltimore MD 21224
APStracts 3:0230A, 1996.
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 oxygen
consumption (VO2peak) during treadmill testing, and relative weight
(body mass index, BMI) in 164 healthy normotensive adults (75 men)
ages 19-87 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 (0.10 Hz, 0.06-0.10 Hz), were extracted from
3-minute ECG 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 to 21.1 percent
independent variance to RSA and 13.2 to 17.3 percent independent
variance to 0.10 Hz HRV. VO2peak did not contribute significantly to
RSA or 0.10 Hz 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.
Received 22 March 1995; accepted in final form 18 March 1996.
APS Manuscript Number A313-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96