Effect of exhaustive exercise on myocardial performance
Possible changes in cardiac functional capacity in the intact heart following prolonged exhaustive exercise are investigated. Cardiac output, coronary blood flow, aortic blood pressure, left ventricular pressure, maximum rate of left ventricular pressure development and maximum rate of left ventricular pressure relaxation were measured in eight chronically instrumented adult mongrel dogs run at a constant work load to exhaustion signalled by the animals' refusal or inability to continue. All cardiovascular parameters, with the exception of stroke volume, are found to increase significantly during the transition from rest to steady-state exercise at about 75% of maximum heart rate. In the transition from steady state to exhaustion, only the maximum rates of left ventricular pressure development and relaxation are observed to increase significantly, while all other values exhibited no significant change. Similarly, no significant changes are observed in measurements of maximum cardiac parameters before and after exhaustion. Results indicate that cardiac function and hemodynamic parameters are not depressed at exhaustion in dogs despite observed ultrastructural changes.
- Research Organization:
- California University, Los Angeles
- OSTI ID:
- 5672986
- Journal Information:
- J. Appl. Physiol.: Respir., Environ. Exercise Physiol.; (United States), Vol. 51
- Country of Publication:
- United States
- Language:
- English
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