Respiratory sinus arrhythmia (RSA) was examined in aerobically trained (AT) and untrained (NT) college-aged males during 12 periods consisting of a 3-min sitting baseline, six common 3-min absolute exercise stages, and five 3-min recovery stages that followed voluntary exhaustion to determine the relationship of work and training status to parasympathetic influence upon the heart. RSA systematically decreased during absolute exercise, was observed at heart rates (HR) above 100 beats·min-1, and progressively increased during recovery. Additionally, independent of work stages, comparative regression analyses were conducted for both the exercise and recovery phases, separately, in which HR was regressed on RSA, as well as RSA on%˙VO2max, to contrast the obtained relationship for the AT and NT. No differences were revealed as a function of endurance training status as the slopes and intercepts obtained for the two groups from each of these analyses were similar. The within-subject correlations between RSA and%˙VO2max, calculated for each of the individuals across all 12 periods, were consistently negative. Between-subjects correlations of RSA with RR and tidal volume were predominantly nonsignificant, indicating that RSA, as measured here, is independent of individual differences in ventilatory activity and, as such, can be compared between groups during exercise. The findings demonstrate that RSA is detectable during both exercise and recovery, even at HR beyond 100 beats·min-1, and reveals a similar relationship to HR and metabolic state in both aerobically trained and untrained populations.
Departments of Kinesiology, Health Education, and Human Development(Institute for Child Study) University of Maryland, College Park, MD 20742-2611; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75235-9034; Performance Enhancement Consultants, Inc., Olney, MD 20832; and Human Performance Laboratory, Ball State University, Muncie, IN 47306
Submitted for publication October 1996.
Accepted for publication November 1997.
Address for correspondence: Bradley D. Hatfield, Department of Kinesiology, University of Maryland, College Park, Maryland 20742-2611. E-mail:firstname.lastname@example.org.