Expansion
Dynamic exercise is a volume load; static exercise is a pressure load
Expansion
Dynamic (isotonic) exercise, such as running or swimming:
- Large rise in cardiac output
- Fall in systemic vascular resistance
- Modest rise in mean arterial pressure
- A volume load on the heart, producing eccentric hypertrophy in trained athletes
Static (isometric) exercise, such as weightlifting:
- Modest rise in cardiac output
- Rise in systemic vascular resistance, because sustained contraction mechanically compresses vessels within the muscle
- Large rise in both systolic and diastolic pressure
- A pressure load, producing concentric hypertrophy
The clinical relevance is in advice after cardiac disease. Isometric effort, often combined with a Valsalva manoeuvre, raises afterload abruptly and is poorly tolerated in aortic stenosis, aortic aneurysm and poorly controlled hypertension, whereas moderate dynamic exercise is beneficial.