Cardiovascular Response to Exercise
Exercise triggers a complex integration of neural and local metabolic factors to match oxygen delivery with vastly increased muscle demand.
1. Hemodynamic Changes
| Parameter | Change | Mechanism |
|---|---|---|
| Cardiac Output | Increased |  HR (primary) and SV. |
| Systolic BP | Increased | Increased CO overrides vasodilation. |
| Diastolic BP | No change / Slight ↓ | Massive arteriolar vasodilation in muscles. |
2. Local Metabolic Control
During exercise, skeletal muscle experiences functional hyperemia. Local metabolic byproducts cause profound vasodilation:
- CHHAP: CO2, H+ (lactic acid), Histamine, Adenosine, Potassium ions.
3. Exam Must-Knows
- Heart Rate: Increases initially due to vagal withdrawal, followed by increased sympathetic discharge.
- Venous Return: Enhanced by the “skeletal muscle pump” and the respiratory pump (deeper breathing).
- Chronic Training: Results in cardiac remodeling (athlete’s heart), characterized by increased stroke volume and lower resting HR (bradycardia).
Physiology Board Hint: Always distinguish between dynamic (aerobic) and static (isometric) exercise. Dynamic exercise causes a slight decrease or no change in diastolic BP due to peripheral vasodilation, whereas static exercise causes a significant increase in both systolic and diastolic BP due to mechanical compression of blood vessels.