CV Responses to Acute Exercise

Increased heart rate (linear) as a direct function of the SA Nore. Neural control starts to lose predominance as the intensity of exercises increases. No change with maximal heart rate.
Increased stroke volume. Affected by heart rate, preload, afterload, contractility.

troke volume increases until about 40-60% of maximum capacity, then levels off. Per Gladhill, stroke volume does not plateau in endurance athletes. Postmenopausal women may hit a peak, then decline. Stroke volume is the factor that separates the athlete from the non-athlete. If there is a plateau, then an increase in Cardac Output is the result of an increase in heart rate.

Systolic blood pressure increases with exercise because cardiac output increases, which means more blood is being pumped out of the heart. The diastolic blood pressure does not change much - draining through the system. Changes in the diastolic blood pressure greater than 10mm Hg is reason to stop exercising.

Mean arterial pressure is the average of the systolic and diastolic blood pressure, and describes the average driving pressure for movement of blood. Since the heart is in diastole for 2/3 of each beat, then MAP is determined calculating DBP + 1/3(SBP-DBP).

Total Peripheral Resistance decreases with exercise.

av-O2 Difference is the difference between the amount of oxygen in the arteries and the amount of oxygen in the veins. This tells us how efficiently the muscles are extracting and using oxygen. During exercise, this difference increases.