Sunday, November 22, 2009

More on Exercise

The December copy of Nutrition Action, a monthly newsletter published by Center for Science in the Public Interest - - (highly recommended by this writer) has some interesting data on exercise that is a good balance to holiday eating. Here is a summary:

New Brain Cells: Exercise increases blood flow to the brain, and stimulates the growth of new brain cells, synapses, and new blood capillaries. In a study at the University of Illinois, older men and women on an aerobic training program showed an increase in brain volume after 6 months. A control group doing toning and stretching did not develop greater brain volume. The abilities to make logical connections, to navigate in space, and to plan and make decisions are all improved with aerobic exercise.

Cancer protection: Studies on exercise and colon cancer show that the most active people are about 21% less likely to be diagnosed with this disease than the least active people. Numerous studies have shown that women who engage in moderate to vigorous exercise are less likely to get breast cancer. One (but not the only) protective mechanism may be preventing weight gain – weight gain is associated with cancers of the breast (after menopause), colon, uterus, pancreas, and esophagus.

Insulin Sensitivity: Both aerobic exercise and strength training increase the ability of insulin to move blood glucose (sugar) into cells. This is important in the prevention or treatment of diabetes, because in this disease cells become resistant (insensitive) to insulin. As a result, glucose levels rise in the blood instead of entering into cells. Both aerobic and strength training increase the amount of a protein called a glucose transporter, which moves glucose into cells.

­Sitting is dangerous!: A Canadian Study looked at 17,000 adults in a fitness survey, and found that mortality rates after 12 years were related to the amount of time people spent sitting. The mortality rate was 20% in people who sat most of the day, 12% in those who sat about half the day, and 6% in those who rarely sat down. The take home message – stand up and move around. Thirty minutes of exercise a day does not counteract the effects on muscles of prolonged sitting, which in turn effects the regulation of insulin and blood glucose.

Visceral Fat: Fat that lies inside the abdominal cavity is linked to insulin resistance, diabetes, and heart disease and is thus more dangerous than fat found under the skin. A daily brisk 30 minute walk will help to decrease visceral fat – but inactivity results in a rise of visceral fat with aging.

Stroke and Heart Disease: Aerobic exercise lowers the risk of both stroke and heart attack. Aim for 30 minutes or more of brisk walking or other exercise 5-6 days a week.

Blood Pressure: Aerobic exercise can lower blood pressure –the effect may be moderate, but some people are able to get off blood pressure medications.

Broken Bones: Weight bearing aerobic exercise and strength training will help to lessen osteoporosis. A study from Harvard showed that walking for at least 4 hours a week was associated with a 41% lower risk of hip fracture compared with women who walked less than 1 hour a week. More time spent standing was also associated with lower risk. Older people who are physically active are also less likely to fall. Balance and strength training are important to prevent falls

Depression and Anxiety: Numerous studies have shown that physical activity helps to relieve depression. Researchers at Princeton and the University of Colorado are finding that in animals and in the human animal, regular aerobic exercise helps to relieve stress and anxiety.

Exercise in West Marin or where you live: We have a wonderful variety of opportunities to move our bodies here at home: hiking trails, some quite steep and all beautiful, beach walking and running, a new bike path, numerous classes in our community centers, including folk, African, and ballroom dancing, special classes for seniors, and two fitness centers. I’ve left out the soccer fields, aerobic gardening and a lot more. For those who need help to get started, I suggest the buddy system: find a friend, make plans together, and keep each other on track. Hopefully we can all look as good as the Obamas one day.

Sadja Greenwood, MD, MPH past issues on this blog

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