Pulmonary oxygen uptake kinetics and exercise intensity: Inferences and implications

Turner, Anthony Pierce (2003) Pulmonary oxygen uptake kinetics and exercise intensity: Inferences and implications. PhD thesis, University of Glasgow.

Abstract

The kinetic features of the pulmonary oxygen uptake (VO2) response to exercise provide insight into the functional status of the cardiovascular, respiratory and muscular systems, in terms of exercise tolerance in health and disease. The focus of the current research was to improve current understanding of VO2 kinetics, with particular reference to reliable and accurate modelling and interpretation. Three studies have been carried out: 1. The dependence of VO2, intramuscular oxygenation status and arterialised blood lactate response on the work-recovery duty cycle duration during intermittent cycling suggests that the functional intensity of dynamic exercise is determined not only by the work rate per se, but also the manner of its imposition. Differences in the average VO2 relationship with lactate concentration, compared to constant work rate exercise, demand revision of conventional exercise intensity description. 2. A "priming" bout of supra-critical power cycling significantly reduces the magnitude of the VO2 slow component, with no discernible effect on the fundamental component VO2 kinetics, during subsequent sub-critical power, but supra-lactate threshold, cycling. The tolerable duration of this exercise was reduced in some, but not all, subjects, raising interesting questions regarding the determinants of the power-duration hyperbola and its relationship with VO2 kinetics. 3. Demonstration that the duration of the Phase I portion of the VO2 response during the rest-to-20W transition is prolonged in some, but not all, patients diagnosed with moderate-to-severe chronic obstructive pulmonary disease has called into question traditional modelling strategies employed to characterise the VO2 fundamental component in this population. Speeding of the overall VO2 kinetics as a result of an 8- week exercise-training programme is demonstrated by a significantly speeded fundamental VO2 component. Exact details of the mechanisms underpinning VO2 kinetics in health and disease remain conjectural, but discussion has now directed opinion to the potential for VO2 kinetics to be obscuring regional differences within the exercising musculature. That VO2 kinetics can be determined using sub-maximal exercise, even in severely debilitated patient populations, highlights the utility of this approach when assessing the combined function of the respiratory, cardiovascular and muscular systems responsible for O2-delivery and O2-utilisation in patient populations. However, subsequent modelling of the VO2 kinetics must be physiologically justified and the interpretation appropriate.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Kinesiology, physiology.
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: Ward, Prof. Sue
• Date of Award: 2003
• Depositing User: Enlighten Team
• Unique ID: glathesis:2003-71032
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 09 May 2019 14:28
• Last Modified: 01 Jun 2021 10:41
• URI: https://theses.gla.ac.uk/id/eprint/71032