title: Physiological interdependence of the cardiovascular and postural control systems under orthostatic stress.
abstract: The cardiovascular system has been observed to respond to changes in human posture and the environment. On the same lines, frequent fallers have been observed to suffer from cardiovascular deficits. The present article aims to demonstrate the existence of interactions between the cardiovascular and postural control systems. The behavior of the two systems under orthostatic challenge was studied through novel adaptations of signal processing techniques. To this effect, the interactions between the two systems were assessed with two metrics, coherence and phase lock value, based on the wavelet transform. Measurements from the cardiovascular system (blood pressure), lower limb muscles (surface electromyography), and postural sway (center of pressure) were acquired from young healthy adults (n = 28, men = 12, age = 20-28 yr) during quiet stance. The continuous wavelet transform was applied to decompose the representative signals on a time-scale basis in a frequency region of 0.01 to 0.1 Hz. Their linear coupling was quantified through a coherence metric, and the synchrony was characterized via the phase information. The outcomes of this study present evidence that the cardiovascular and postural control systems work together to maintain homeostasis under orthostatic challenge. The inferences open a new direction of study for effects under abnormalities and extreme environmental conditions.
authors.affiliation: School of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada; and.
authors.forename: Amanmeet
authors.initials: A
authors.lastname: Garg
authors.affiliation: Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: Da
authors.initials: D
authors.lastname: Xu
authors.affiliation: Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Laurin
authors.affiliation: Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada ablaber@sfu.ca.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Blaber
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D017704:Baroreflex; D001794:Blood Pressure; D002319:Cardiovascular System / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D004856:Postural Balance; D011187:Posture; D013997:Time Factors; D055815:Young Adult
keywords: EMG; blood pressure; cardiovascular system; orthostatic challenge; postural control