Chapter 9Health Benefits of Physical Activity

Our unhealthy lifestyle We participate in work and leisure activities that are far less active than in the past. We produce and eat more food than we should. We control our environment with very little expenditure of physical energy. We subject ourselves to more and unusual stressors.

What the Surgeon General says 1.People of all ages, both male and female, benefit from regular physical activity. 2.Significant health benefits can be obtained by including a moderate amount of physical activity on most days of the week. 3.Additional health benefits can be gained through greater amounts of physical activity. 4.Physical activity reduces the risk of premature death and certain diseases, and promotes mental health.

What the Surgeon General says (cont.) 5.More than 60 percent of American adults do not regularly exercise, and 25 percent are not active at all. 6.Nearly half of American youth years of age are not vigorously active on a regular basis, and activity declines during adolescence. 7.Daily enrollment in physical education classes declined among high school students from 42 percent in 1991 to 25 percent in Interventions to promote physical activity in schools, work sites, and health care settings are being evaluated.

Fitness and mortality The more active you are, the less likely you are to die prematurely. A modest increase in physical activity can have a substantial benefit. The reduction in risk of overall mortality from improving cardiorespiratory fitness from low to moderately fit is approximately the same as stopping smoking.

The relationship between physical activity and cardiorespiratory fitness versus all- cause mortality is inverse.

Fitness and cardiovascular disease Physical activity decreases the risk of developing cardiovascular diseases –Coronary heart disease –Stroke –Hypertension –Peripheral vascular disease

The relationship between physical activity and the cardiovascular diseases (coronary heart disease, stroke, hypertension, and peripheral vascular disease) is inverse.

Elevated levels of certain blood lipids (total cholesterol, chylomicrons, VLDL, LDL, IDL, lipoprotein a, and triglycerides) are positively related to the risk of coronary heart disease.

High levels of high-density lipoproteins (HDL) protect against the development of coronary heart disease.

Body weight and health Relationship between body weight and mortality is disease specific. Low body weight is beneficial with respect to coronary heart disease and diabetes mellitus. For hypertension and kidney disease, death is associated with both low and high body weight. For pneumonia, influenza and suicide, death is more likely at low body weight.

Ratio of actual to predicted mortality versus body mass index (BMI) for causes of death

Fat cells and obesity Hypertrophic obesity—normal number of fat cells, which are twice as large as those of a non-obese person Hyperplastic obesity—higher number of enlarged fat cells Number of fat cells in the human body is established during –Latter part of gestation –First year of infancy –Adolescent growth spurt Once established, the number of fat cells usually remains constant despite weight gain or loss The size of fat cells change with weight gain or loss

Exercise and weight loss work together Calories are expended during physical activity. Additional calories are expended after exercise. Physical activity helps to maintain the basal metabolic rate (BMR), whereas caloric restriction alone usually results in a decrease in BMR. Moderate exercise does not increase and may decrease appetite. Spot reducing does not work. Visit Physical Activity and Weight Control at and the American Obesity Association Homepage at

A good weight loss program, according to the ACSM Provides a caloric intake not lower than 1,200 kilocalories a day for adults Includes food acceptable to the dieter Provides a negative caloric balance resulting in gradual weight loss Includes the use of behavior modification Includes an endurance exercise program Provides that the new eating and physical activity habits can be maintained for life

Exercise and cancer The level of physical activity is inversely related to the risk of developing colon cancer. Activity patterns during adolescence and early adulthood may influence the risk of developing cancers of the uterus, ovaries, cervix, vagina, and breasts. No studies provide evidence of a direct cause-and-effect relationship between physical activity and prevention of cancer.

The relationship between physical activity and the risk of developing colon cancer is inverse.

How exercise can help individuals with diabetes Exercise can help type 1 diabetics improve control of blood glucose levels by increasing insulin sensitivity. For type 2 diabetics, regular exercise improves insulin sensitivity and glucose tolerance.

How physical activity may reduce the risk of osteoporosis During adolescence: –By aiding the development of bone mass and density During middle age: –By helping to maintain bone mass and density In post-menopausal women: –By supplementing the effect of estrogen therapy if prescribed on the retention and development of bone density Visit the National Osteoporosis Foundation at

Factors to consider when developing an exercise program for post-menopausal women The wrong type of exercise can do more harm than good. Weight training can improve bone density while increasing muscular strength and balance. Adequate calcium intake is essential. Exercise is not a substitute for estrogen replacement therapy if prescribed. Visit Physical Activity and Health, Women at

Some effects of physical activity on mental health More positive outlook Greater self-esteem Enhanced ability to respond to stressors Reduced symptoms of depression Positive effects on trait and state anxiety

High fit individuals are less likely than low fit individuals to suffer from anxiety or depression.