From the beginning of recorded history, philosophers and health professionals have observed that regular physical activity is an essential part of a healthy life. Hippocrates wrote the following in On Regimen in Acute Diseases, about 400 BC:
Eating alone will not keep a man woman well; he she] must also take exercise. For food and exercise, while possessing opposite qualities, yet work together to produce health. . . . And it is necessary, as it appears, to discern the power of various exercises, both natural exercises and artificial, to know which of them tends to increase flesh and which to lessen it; and not only this, but also to proportion exer- cise to bulk of food, to the constitution of the patient, to the age of the individual . . . (21)
Over the past four decades, thousands of studies have examined the relationship between physical activity and the risk of various diseases and death. The overwhelming conclusion is that regular participation in physical activity results in a reduced risk of numerous diseases and death from all causes. As shown in figure 1.4, regular participa- tion in physical activity reduces the risk of death from all causes by about 40% (relative risk decreased from 1.0 to 0.6). Doing physical activity on a regular basis also has been shown to have a similar impact on the following (33):
• Cardiorespiratory health: Physical activity reduces the risk of heart disease and stroke, lowers blood pressure (BP), improves the blood lipid profile, and increases CRF.
• Metabolic health: Physical activity reduces the risk of developing type 2 diabetes and helps to control blood glucose in those who already have type 2 diabetes.
• Musculoskeletal health: Physical activity slows the loss of bone density that occurs with aging, and it lowers the risk of hip fractures. In addition, it improves pain management in people with arthritis. Finally, progressive muscle-strengthening activities increase or preserve muscle mass, strength, and power.
• Cancer: Physically active people have a signifi- cantly lower risk of colon cancer and breast cancer. In addi- tion, there is some evidence that physical activity reduces the risk of endometrial cancer and lung cancer.
• Mental health: Physical activity lowers the risk of depression and age-related cognitive decline, and it improves the quality of sleep.
• Functional ability and fall prevention: Physical activity reduces the risk of functional limitations (e.g., ability to do activities of daily living), and for those older adults at risk of falling, physical activity is safe and reduces this risk.