Medical Physiology Online

Peer reviewed, open access journal. ISSN 1985-4811.

Cardiac inter-beat interval complexity is influenced by physical activity

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Benjamin J. Wilson1, Gus L. W. Hart2, and Allen C. Parcell3

1Department of Recreation Management and Youth Leadership, Brigham Young University, Provo, Utah; 2Department of Physics and Astronomy, Brigham Young University, Provo, Utah; 3Human Performance Research Center, Department of Exercise Sciences, Brigham Young University, Provo, Utah.

Correspondence to: Benjamin J. Wilson, 3838 S 1860 E, Salt Lake City, UT 84106, USA.

E-mail: benjaminjameswilson at gmail dot com

Submitted 25 Oct 2008; time to first decision 25 days; revision accepted and published 1 Jan 2009.


The complexity of physiological signals may be a more sensitive indicator of health than standard or average measurements. We examined cardiac inter-beat intervals of healthy subjects who are either physically active or sedentary to determine whether measures of complexity are more sensitive to subtle cardiac changes than standard measures. Subjects were pre-screened by self-report, and qualifying subjects were placed in either the active group (n = 10) or sedentary group (n = 10). Cardiac inter-beat intervals were recorded and subsequently analyzed using standard time and frequency domain heart rate variability measurements as well as multiscale entropy and the detrended fluctuation analysis, both measures of complexity. Of the measurements, the detrended fluctuation analysis was the only tool that significantly (P = 0.04) differentiated between the active and sedentary groups. This suggests that the complexity of physiologic signals is a more sensitive indicator of cardiac health than standard measures.


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Please cite this article as: Wilson BJ, Hart GLW, Parcell AC. Cardiac inter-beat interval complexity is influenced by physical activity. Medical Physiology Online, 1 Jan 2009, available from


Written by E.S. Prakash

January 1, 2009 at 1:34 AM

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