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Phase plane analysis of physical working capacity Boyd, William Robert

Abstract

The purpose of this study was to determine the relationship of selected measurements from the phase plane loop of the brachial pulse wave to physical working capacity as measured on a bicycle ergometer. The selected measurements were: 1. +ṗ(x) which indicates the pulse pressure¹ when maximum positive rate of change of pressure occurs. 2. + ṗ(y) which is a measure of the maximum positive rate of change of pressure. 3. - ṗ(x) which indicates the pulse pressure when maximum negative rate of change of pressure occurs. 4. - ṗ(y) which is a measure of maximum negative rate of change of pressure. 5. + ṗ/- ṗ which is the ratio of maximum positive rate of change of pulse pressure to maximum negative rate of change of pulse pressure. 6. Pr./Ṗr. which is the ratio of pulse pressure to maximum rate of change of pulse pressure. Thirty-two young male adults underwent a bicycle ergometer testing procedure in which physical working capacity (PWC₁₇₀) was determined. On the testing day a resting phase plane loop was first recorded. The PWC₁₇₀ test was then administered, followed by the immediate recording of a post-exercise loop. Two subsequent loops were then recorded at recovery intervals of five and ten minutes. Thus, twenty-four direct loop measurements were obtained from each subject. In addition, the difference between each post-exercise loop measurement and the corresponding resting value was calculated making a total of forty-two loop variables per subject. A large correlation matrix was constructed in which all loop variables as well as PWC₁₇₀, PWC₁₇₀ divided by body weight, body weight, and the slope of the PWC₁₇₀ plotted line (see Appendix A) were included. The following results were observed. PWC₁₇₀ correlated significantly with: 1. immediate post-exercise -ṗ(y). 2. immediate post-exercise +ṗ/-ṗ. 3. immediate post-exercise - rest Pr./Ṗr. No loop variables correlated significantly with PWC₁₇₀ divided by body weight. However, body weight alone correlated significantly with: 1. immediate post-exercise +ṗ/-ṗ. 2. immediate post-exercise - rest +ṗ/-ṗ. The slope of the PWC₁₇₀ plotted line correlated significantly with: 1. immediate post-exercise +ṗ/-ṗ. 2. immediate post-exercise -ṗ(y). 3. resting -ṗ(y). A stepwise multiple regression analysis calculated by computer indicated that the sum of the independent contributions of three variables accounted for 42.7% of the total variance of PWC₁₇₀. These were: 1. immediate post-exercise - rest Pr./Ṗr. 2. immediate post-exercise -ṗ(y). 3. 5 minute post-exercise +ṗ(x). The multiple R between these three loop variables and PWC₁₇₀ was .65 ¹The term "pulse pressure" as used here does not have the conventional meaning, i.e. the difference between systolic and diastolic pressures, but refers to any given point along the range between systolic and diastolic pressures.

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