Lab 2-revised - Lab 2 VO2 max: Responses to Increasing Work...

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Lab 2 – VO2 max: Responses to Increasing Work Rates Purpose The purpose of this lab is to measure maximal oxygen consumption and establish the responses of heart rate (HR) and oxygen consumption (VO2) to increasing work rates on a cycle ergometer. Introduction Maximal Oxygen uptake (VO2max) is considered to be the single best indicator of cardiovascular performance. VO2max tests are widely used in clinical settings as a measure of general fitness and for the screening of cardiovascular disease. Abnormally low VO2max values indicate poor cardiovascular function due either to de-conditioning or some underlying disease. Since most of the energy for sustained physical work comes from the aerobic generation of ATP, VO2max is a good predictor of the maximal amount of work a person can perform for any moderately extended period of time (about 6-8 minutes). VO2max is the highest rate of oxygen consumption capable by an individual. It is dependent upon the maximal values for heart rate, stroke volume, and arteriovenous oxygen difference. It is a good indicator of cardiovascular performance and health but has little application to everyday life. Individuals rarely exercise at levels as high as VO2max nor do they stress their bodies to such an extent in daily activities. Therefore, submaximal VO2’s, and the associated heart rates (HR), stroke volumes (SV), and arteriovenous oxygen differences (a-v O2 diff), play a more significant role in the lives of the average person. This concept is apparent in the equation below known as the Fick Equation : VO2 = HR x SV x (a-v O2 diff) Arteriovenous-oxygen difference (a-v O2 diff) is essentially a measurement of the loss of oxygen bound to hemoglobin as it passes through the cell. As more oxygen is used to make more ATP, the partial pressure of O2 (PO2) in the cell decreases. This decrease in PO2 causes hemoglobin to release more of its bound oxygen into the cell. This results in a greater “loss” of oxygen by hemoglobin as it passes from the arterial side to the venous side of the cell; thus, a-vO2diff increases with work rate. Stroke volume (SV) is controlled by three factors:
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This note was uploaded on 07/24/2008 for the course KIN 325K taught by Professor Dingwell during the Spring '07 term at University of Texas at Austin.

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Lab 2-revised - Lab 2 VO2 max: Responses to Increasing Work...

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