Date of Award

Spring 1-1-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Integrative Physiology

First Advisor

William C. Byrnes

Second Advisor

Alena M. Grabowski

Third Advisor

Rodger Kram

Fourth Advisor

Robert S. Mazzeo

Fifth Advisor

Edward L. Melanson

Abstract

The measurement of steady state oxygen consumption (V̇O2) and carbon dioxide production (V̇CO2) are used to assess oxidative energy expenditure (EE) during exercise. The quantification of EE is used to understand the interactions of body systems (e.g. skeletal muscle, cardiovascular, and respiratory) during exercise as well as to classify cardio-respiratory health, predict performance, prescribe training intensities, optimize pacing, manage nutrition, and estimate EE. Although the energy demand for muscle force generation primarily determines EE, other factors influence energetics during exercise, namely, whole-body efficiency (i.e. gross efficiency, GE), thermoregulatory responses, prior exercise, and the intensity of the exercise bout itself. The influence of these factors on EE impacts the quantification, interpretation, and implementation of practical applications based on EE, which ultimately affects an individual’s performance and overall health.

In Chapter II, we demonstrate that using power-specific GE values improves the accuracy of estimating EE from mechanical power during cycling. In Chapter III, we demonstrate an attenuation of the progressive increase in V̇O2 and EE when cooling during 60 minutes of cycling at an individual’s lactate threshold. In Chapter IV, we demonstrate that prior supramaximal cycling transiently increases energetics during cycling intensities below the lactate threshold. In Chapter V, we demonstrate that the linear relationship of V̇O2 and EE to mechanical power is increased above the lactate threshold during a graded cycling test. Altogether, the results of these studies demonstrate that these select factors should be considered when quantifying EE and when developing and implementing practical applications based on the quantification of EE. If not considered, this will likely compromise exercise performance and may impair health.

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