Year

2012

Degree Name

Masters by Research

Department

School of Health Sciences

Abstract

Due to environmental and scenario constraints, a direct evaluation of the metabolic demand associated with work tasks can be difficult and sometimes impossible. Fortunately, many cardiorespiratory variables respond in a predictable fashion with increments in work rate and can serve as a surrogate means of approximating energy expenditure (├ůstrand and Ryhming, 1954; Durnin and Edwards, 1955). However, few authors have attempted to gain an understanding of how these variables interact under less than ideal conditions (Dauncey and James, 1978; Ceesay et al., 1989), when exposed various extraneous factors (e.g. hot environments). Thus, the aim of this project was to investigate the predictive utility of these variables during various exercise modes (whole-, lower- and upper-body exercise), with and without the influences of thermal strain (heat stress) and external loading. During each exercise mode, under both thermoneutral and hot conditions, predictions of oxygen consumption based on heart rate were significantly inferior to the most precise index, minute ventilation (P0.05). Furthermore, predictive equations derived from either lower- or whole-body exercise could be used interchangeably to predict oxygen consumption with significant precision during lower- or whole-body exercise, whereas during upper-body exercise, regression equations must be mode specific. This was also the case during external load carriage, where predictive equations derived from either loaded or unloaded conditions could be used interchangeably to predict oxygen consumption. However, based on heart rate, predictions of metabolic demand during load-carriage exercise were significantly inferior to minute ventilation predictions (P

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