Originally Published: March 16, 2014 6 a.m.
While the importance of regular physical activity for maintaining strength, cardiovascular fitness and a healthy body weight are well known, the effects of exercise on the prevention of disease, especially cancer, may not be as familiar. However, organizations like the American Cancer Society (ACS) and American Heart Association (AHA) list regular physical activity, in addition to avoiding tobacco products, maintaining a healthy weight and eating a low-fat, plant-based diet, as one of the most important lifestyle behaviors for the prevention of chronic disease. In fact, scientists estimate that these healthy habits could prevent nearly two-thirds of all cases of chronic illnesses, including cardiovascular disease, cancer, diabetes and obesity.
According to the ACS, approximately one-third of all cancer cases in the United States are linked to poor diet and lack of physical activity. Exercise appears to protect against some types of cancer in several ways. Since abdominal obesity is linked to an increased risk of developing breast, prostate and colon cancers, physical activity may protect individuals by helping them maintain a healthy body weight. Exercise may also prevent cancer by promoting healthy levels of a number of hormones, including estrogen and insulin, and by boosting the immune system.
In recent years, scientists have determined that the metabolic syndrome, a condition marked by abdominal obesity, low HDL-cholesterol, elevated levels of blood triglycerides, high blood pressure and elevated blood sugar, is a major contributor to the development of diabetes, cardiovascular disease and some cancers. Lack of physical activity contributes significantly to the development of the metabolic syndrome, while increased physical fitness has been shown to prevent, and, even reverse this condition.
Scientists have also found that long periods of inactivity, like watching TV or sitting at a desk for several hours, reduces the body's ability to move fats (in the form of triglycerides) and sugar (glucose) from the blood and into muscle cells, where they are normally used as fuel. Elevated blood levels of glucose and triglycerides increase the risk of cardiovascular disease and diabetes. Indeed, sedentary behavior (just sitting too much) is now called 'the sitting hazard' and is considered a major risk factor for many chronic conditions.
Fortunately, many types of physical activity, if performed on a regular basis, can provide protection from disease. Even light activities, like housework, gardening, gentle calisthenics, or walking, can be beneficial, especially if these activities reduce your total sitting time at work or at home.
Individuals who are able to engage in moderate or vigorous exercise should consider these recommendations endorsed by the ACS and AHA for the prevention of chronic disease.
Adults: 150 minutes of moderate intensity or 75 minutes of vigorous intensity activity per week (or a combination).
Children and teens: 1 hour of moderate or vigorous intensity activity each day, with vigorous activity at least three days per week.
Moderate exercise includes: brisk walking, yoga, hiking on level terrain.
Vigorous exercise includes: jogging, backpacking, aerobics.
Up to 300 minutes of moderate intensity activity, or 150 minutes of vigorous activity per week, may provide additional protection. Studies also suggest that short exercise sessions, lasting from 20 to 30 minutes, are beneficial, and can help many individuals reach their total weekly exercise goals.
If you have a chronic disease or concerns about your current level of fitness, consult your doctor before starting any exercise program. Also consider asking for professional help in choosing activities that are right for you. Because the total time spent engaged in regular activity is more important than exercise intensity, remember to start slowly to avoid injuries and keep moving!