Compare the response of stroke volume during exercise between sedentary and highly trained individuals

Answer 1

A fit, sedentary individual's SV plateaus at a relative workload of 40 percent VO2 max, and it is maintained relatively constant up to 100 percent VO2 max. However, in the highly trained endurance athlete, SV continues to increase up to 100 percent VO2 max. The appearance of the plateau of SV at 40 percent VO2 max in the sedentary, healthy individual appears to be related to a balance between cardiac filling time and volume and the rate of venous return and its effect on the cardiac filling volume. The continuously increasing SV up to VO2 max in the endurance-exercise trained athlete suggests that the venous return volume entering the heart for each increase in HR is greater, enables a greater ejection fraction volume to be achieved for each beat via the Frank–Starling mechanism, and increases in myocardial contractility in direct relation to the progressively increasing VO2 required for the increasing workloads.