Chapter 44
Exercise and the Heart
1. What is the difference between physical activity and exercise?
2. What is the difference between isometric and isotonic exercise?
3. What is the training effect?
4. What are the acute cardiovascular changes that occur with exercise?
5. What are the chronic cardiovascular changes that occur with exercise?
The increase in cardiac output associated with isotonic exercise creates a volume load that results in left ventricular dilation with minimal increase in wall thickness. The vasoconstriction and increased afterload associated with isometric exercise produces a pressure load that results in left ventricular hypertrophy without dilation.
6. How is exercise intensity defined?
7. How much exercise is necessary to maintain cardiovascular fitness?
8. What is the effect of exercise on cardiac risk factors?
Exercise has beneficial effects on hypertension, diabetes, hyperlipidemia, and obesity. In addition, exercise has favorable effects on endothelial function, thrombosis, inflammation, and autonomic tone (Table 44-1).
TABLE 44-1
BENEFICIAL EFFECTS OF ENDURANCE EXERCISE ON ATHEROSCLEROTIC RISK FACTORS
FACTOR | EFFECT OF EXERCISE |
Hypertension | Modest ↓ in both SBP (approximately 4 mm Hg) and DBP (approximately 3 mm Hg) |
Diabetes | ↑ Insulin sensitivity, ↓ hepatic glucose production, preferential use of glucose over fatty acids by exercising muscle |
Hyperlipidemia | Significant ↓ in TG, modest ↑ in HDL, minimal change in LDL |
Obesity | Modest weight loss (2-3 kg), ↓ in body fat necessary to maintain weight loss |
Thrombosis | ↓ Fibrinogen, ↓ platelet activation |
Endothelial function | Improved vasodilation, possibly through ↑ NO synthesis |
Autonomic tone | ↑ Vagal tone, ↓ sympathetic tone |
Inflammation | ↓ Inflammatory markers (CRP, TNF-α, IL-6) |
9. Do endurance training and resistance training have similar benefits?