title: Cardiorespiratory dynamics: sensitivity of the on-transition to endurance-training status.
abstract: This project investigated the sensitivity of oxygen uptake (VO(2)) dynamics to training-induced physiological changes, across a broad spectrum of endurance-training histories. Forty subjects participated: sedentary (n = 10), active healthy (n = 10), regular runners (n = 10), and competitive distance runners (n = 10). Subjects completed a cycle step-function protocol, to elicit a steady state at 60% maximal work rate. Breath-by-breath data were collected for VO(2) and cardiac frequency (f(c)), and modelled mathematically, and used to determine the average response times to attain 20%, 40%, 60%, 80% and 100% of the respective steady states. The between-group comparisons for both VO(2) and f(c) revealed significantly faster response times to 40%, 60%, 80% and 100% of the induced response, for the better trained subjects (P < 0.05). In general, this technique permitted differentiation between the VO(2) and f(c) response dynamics of non-elite subjects from a broad range of endurance-training histories, with differences becoming more pronounced as subjects approached the steady state.
authors.affiliation: Department of Biomedical Science, University of Wollongong, Northfields Avenue, Wollongong NSW 2522, Australia. nigel_taylor@uow.edu.au
authors.forename: N A
authors.initials: NA
authors.lastname: Taylor
authors.forename: M A
authors.initials: MA
authors.lastname: Osborne
authors.forename: T L
authors.initials: TL
authors.lastname: Bube
authors.forename: J M
authors.initials: JM
authors.lastname: Stocks
mesh_terms: D000293:Adolescent; D000328:Adult; D006321:Heart / Q000502:physiology*; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D010101:Oxygen Consumption; D010807:Physical Endurance; D012143:Respiratory Physiological Phenomena; D012420:Running / Q000502:physiology