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Left ventricular adaptations following short-term endurance training
Jack M Goodman1, Peter P Liu, Howard J Green
1Faculty of Physical Education and Health, Univ. of Toronto, 55 Harbord St., Toronto, Ontario, Canada M5S 2W6. jack.goodman@utoronto.ca
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 28, 2004
Summary
Short-term endurance training rapidly enhances left ventricular (LV) function during exercise. Six days of training increased stroke volume (SV) via improved LV filling, leading to better cardiac output and exercise tolerance.
Area of Science:
- Cardiology
- Exercise Physiology
- Sports Science
Background:
- Endurance training (ET) induces cardiovascular adaptations.
- Left ventricular (LV) functional responses to exercise intensity are crucial for performance.
Purpose of the Study:
- To investigate the effects of short-term ET on LV adaptation and functional response to graded exercise.
- To assess changes in LV volumes, ejection fraction, and cardiac output following a brief training period.
Main Methods:
- Eight untrained men underwent 6 days of daily ET (2 h/day at 65% VO2max).
- LV function was assessed using radionuclide angiography at rest and during incremental exercise (53%, 68%, 83% VO2max) pre- and post-training.
- Measurements included LV ejection fraction, end-diastolic volume, and end-systolic volume.
Main Results:
- ET increased plasma volume (11.4%) and VO2max, while decreasing maximal heart rate.
- Exercise stroke volume (SV) significantly increased at all work rates post-training due to enhanced LV end-diastolic volume.
- LV ejection fraction improved at the highest workload, and cardiac output was higher post-training.
Conclusions:
- Short-term ET rapidly improves LV functional response to exercise.
- Increased SV is primarily mediated by the Frank-Starling mechanism (enhanced LV filling), not altered contractility.
- These adaptations, including volume-induced bradycardia, may benefit prolonged exercise performance.