Cardiac output (flow) is determined by a pressure gradient and a resistance g. Which of these variables do you think contributes most to the very large increase in flow in this athlete?

Cardiac output depends on the resistance mainly of the cardiac muscle walls.

Explanation:

The resistance of cardiac tissue also depends on its ability to distend in the sarcomero, that is, on the initial length of the contraction, the greater this, the greater the resistance, the greater the pumping efficiency, but the greater cardiac wear, this Situation occurs in people who are athletes or athletes since they have higher cardiac output but greater efficiency at the time of blood ejection, this is how they oxygenate the tissues better.