The physiology of exercise

ABSTRACT

Determinants of physiological responses to exercise are based on type, intensity, duration, environmental conditions and health and functional status of the individual. OXYGEN CONSUMPTION AND INDIRECT CALORIMETRY determinants of oxygen consumption (VO2), pulmonary ventilation, gas exchange, cardiac performance, expression of exercise data, absolute or relative metabolic equivalent (METs). MEASUREMENT AND APPLIED MEANING OF FUNCTIONAL CAPACITY (VO2max) - direct measurement (maximal vs submaximal) - estimation (maximal vs submaximal *mechanical efficiency *prediction of heart rate (HRmax) - rating of perceived exertion - mode of testing - criterion measure of cardiorespiratory endurance. Energy cost of exercise can be assessed by indirect calorimetry, respiratory quotient and fuel utilization. NORMAL RESPONSES TO ACUTE EXERCISE ARE OBSERVED IN THE FOLLOWING SYSTEMS CARDIOVASCULAR heart rate, stroke volume, blood pressure and blood flow distribution. PULMONARY tidal volume, respiratory frequency, ventilatory threshold. SKELETAL MUSCLE blood flow, oxygen extraction and energy sources. METABOLISM fuel mobilization, endocrine responses. NORMAL ADAPTATIONS TO CHRONIC EXERCISE ARE OBSERVED SIMILARLY IN THE SYSTEMS CARDIOVASCULAR heart rate, stroke volume, cardiac output and heart volume, blood flow, blood pressure and peripheral vasculature, blood volume and composition. PULMONARY tidal volume, frequency and ventilatory threshold. SKELETAL MUSCLE hypertrophy, motor unit recruitment, fiber type, capillarisation, mitochondrial density and glucose uptake. METABOLISM VO2max mechanical efficiency, lactate threshold, fuel mobilization, endocrine responses and body composition. PATHOPHYSIOLOGICAL CONSIDERATIONS IN DIABETES Low initial VO2max and reduced ability to training, inappropriate endocrine responses, muscle fiber type, lactate threshold, capillary density, blood viscosity, oxygen delivery, obesity and chronic complications, e.g. cardiovascular, retinopathy and neuropathy.(AU)