Key Points
- To review the physiological mechanisms regulating central blood volume and cardiac filling in endurance athletes, highlighting how cardiac structural adaptations contribute to orthostatic intolerance.
- Synthesized physiological literature on central blood volume, cardiac filling pressures, and stroke volume dynamics during orthostasis.
- Evaluated cardiovascular adaptations across endurance training, spaceflight, and prolonged bed rest to formulate a unifying biomechanical model.
- Orthostatic intolerance in endurance-trained individuals is driven not only by altered baroreflex function but also by structural changes that cause disproportionate reductions in stroke volume during standing.
- The Frank-Starling mechanism explains the divergence in cardiac filling responses between acute deconditioning states and long-term endurance training adaptations.
Structured PICO
PPopulationEndurance athletes
Structural cardiovascular adaptations to endurance training may paradoxically predispose athletes to orthostatic intolerance by causing a large decrease in stroke volume during orthostasis.