Final answer:
The statement is true; during maximal exercise, up to 85% of cardiac output can be diverted to the muscles, with blood flow being redirected as per the body's needs for oxygen and nutrients.
Step-by-step explanation:
The statement that 15-20% of systemic blood flow goes to skeletal muscles and during maximal exercise, 85% of cardiac output can be diverted to working skeletal muscles is True. During rest, a smaller portion of blood flow is directed to the muscles compared to exercise. However, when an individual engages in maximal exercise, their cardiovascular system must redistribute blood flow to supply the working skeletal muscles, the heart, and the lungs adequately. This dramatic shift in blood distribution is vital to meet the increased oxygen and nutrient demands of active muscles and to remove metabolic waste products efficiently.
Well-trained aerobic athletes, in particular, can experience a substantial increase in cardiac output during maximal exercise, seeing it soar from about 5.3 liters per minute at rest to over 30 liters per minute. Accompanying this will also be an increase in blood pressure to ensure that sufficient blood reaches the muscles. The body's ability to redirect blood follows the principles of vascular homeostasis and involves mechanisms such as vasodilation and vasoconstriction, regulated by nerve and hormone signals, as well as the action of precapillary sphincters.