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Endurance athletes' stroke volume does not plateau: major advantage is diastolic function
1York University, Toronto, Canada.
Medicine and Science in Sports and Exercise
|September 1, 1994
Summary
Endurance athletes exhibit continuously increasing stroke volume during exercise, unlike untrained individuals who reach a plateau. This enhanced cardiac output in athletes is primarily driven by improved ventricular filling.
Area of Science:
- Cardiovascular Physiology
- Exercise Physiology
Background:
- Understanding cardiac adaptations to endurance training is crucial for optimizing athletic performance.
- Left ventricular function during exercise is a key determinant of maximal oxygen uptake.
Purpose of the Study:
- To compare left ventricular function, including stroke volume, left ventricular ejection time (LVET), and diastolic filling time (DT), between endurance-trained and untrained individuals during incremental exercise.
- To elucidate the mechanisms underlying augmented stroke volume in endurance athletes.
Main Methods:
- Simultaneous measurements of stroke volume, LVET, and DT were performed in seven endurance-trained and seven untrained young adult males.
- Subjects exercised on a cycle ergometer at matched heart rates ranging from 90 to 190 bpm.
Main Results:
- Untrained subjects' stroke volume plateaued at 120 bpm, while trained subjects showed a continuous increase to maximal heart rate.
- Trained subjects had significantly longer LVET and shorter DT throughout incremental exercise.
- At 190 bpm, ventricular emptying and filling rates were 20% and 71% greater in trained versus untrained subjects, respectively.
Conclusions:
- Endurance-trained athletes demonstrate a progressive increase in stroke volume to maximal exertion without a plateau.
- Augmented stroke volume in athletes results from enhancements in both ventricular filling and emptying, with ventricular filling being the predominant factor.