title: Effects of physical conditioning on cardiac autonomic function in healthy middle-aged women.
abstract: The purpose of this study was to determine whether moderate exercise training affects heart rate variability (HRV) and spontaneous baroreflex (SBR) function in healthy middle-aged women. Thirty-two sedentary women aged 40-59 yr were divided into four groups depending on reproductive state (premenopausal, PrM or postmenopausal, PoM, and training group (exercise or sedentary control group). The electrocardiographic R-R interval and systolic blood pressure (finger plethysmograph) were measured at rest during paced breathing at 16 breaths/min in the left lateral decubitus, sitting, and free standing postures, and during upright cycling at 40% maximal heart rate reserve (MHRR). After initial testing, the exercise groups underwent a 12 week walking program. After training, both exercise groups (PrM and PoM) had a longer R-R interval in all conditions, a higher SBR slope in the sitting and standing posture and lower sympathetic modulation in the standing posture, than the control groups and pre-training levels. During exercise, vagal modulation was higher and sympathetic modulation was lower in both exercise groups compared to pre-training values. Vagal modulation is increased following moderate intensity aerobic conditioning in middle-aged women.
authors.affiliation: School of Physical and Health Education, School of Nursing and Department of Physiology, Queen's University, Kingston, ON, Canada, K7L 3N6.
authors.forename: Paula R
authors.initials: PR
authors.lastname: Myslivecek
authors.forename: C Ann
authors.initials: CA
authors.lastname: Brown
authors.forename: Larry A
authors.initials: LA
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001341:Autonomic Nervous System / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D011187:Posture; D016138:Walking / Q000502:physiology*