Answer:
heart rate, stroke volume
Step-by-step explanation:
Cardiac output describes the volume of the blood being pumped by heart per unit time.
Cardiac output is product of heart rate, or number of heart beats per minute and stroke volume which is volume of the blood which is being pumped from ventricle per beat.
Exercise stimulates sympathetic nervous system which in turns increases heart rate and makes heart contract with force greater than the normal; which also increases the stroke volume. As, a result Cardiac output increases.