Wednesday, September 12, 2007

Role of Exercise in Weight Loss and Wellness

An excellent online calculator for exercise may be found at the Freedieting website. You can enter a target number for minutes of exercise, or number of calories to burn, and find out how long (or how many) various exercises are needed for you. For a 210 lb. man, a half-hour of basketball will burn 400 calories. For a 160 lb. woman, a slow walk is about 150 calories per half-hour, or twice that number for a typical step aerobics workout. Another very useful calculator for calories burned includes household and occupational activities. (For example, scrubbing floor on hands and knees for a half-hour is 300 calories for a large guy. I think I'll stick to volleyball.) There's a similar calculator for both sports and everyday activities at The Fitness Jumpsite. Looking more closely at these charts I see entries like sleeping 100/hr and computer work 160/hr. That confirms the numbers for a given activity are total numbers, not extra calories compared to sitting around doing nothing. (So burning 300 calories in an hour of low impact exercise is only 200 'extra' calories burned above your basal metabolism rate.)

Let's look at few examples of the role of exercise for weight loss. First, 45 minutes of basketball twice a week is an extra 650 calories per week, or a pound per month. That could improve if it motivates you to eat better, or might see no actual gain if it makes you hungry or you 'reward' yourself with a huge bowl of ice cream! Walking briskly five times a week for a half-hour is about 500 calories per week over sitting around doing nothing, taking seven weeks to lose a pound. These numbers may not seem huge, but they're an effective improvement over the long term and provide many other advantages. Besides, they add up. When I started playing volleyball twice a week for several hours I was a bit disappointed by the lack of any quick weight loss. Taking over four months to even see a ten pound loss was frustrating at first. Then the consistency of the slow weight loss, the enjoyment of the sport, and the feeling that what was coming off was going to stay off, changed my attitude toward exercise. Sticking with it, after playing for a year and a half, I had lost forty pounds and was feeling much better.

There are several benefits to regular exercise, besides the extra calories burned.

1) It's good for your heart and your health. The heart itself is a muscle that benefits from cardiovascular/aerobic exercise. It doesn't take a tremendous amount of time for this benefit, about 3x per week for 20 minutes. (5x for 40-60 minutes is even better, but that's a much bigger time committment.) By aerobic exercise it doesn't have to be an "aerobics class", but anything that gets your heart goin' and keeps it goin' over an extending time like tennis or cycling (target 60-70% of max heart rate, which is around 220-your age).
2) Exercise improves muscle strength and flexibility, and helps to reduce risk of injury when you're not working out.
3) Increasing the amount of muscle mass relative to fat in your body will increase your base metabolism and burn more calories even when not exercising. How much seems to be a matter of some debate. Strength training and resistance exercise is more effective at building lean muscle mass than cardiovascular exercise.
4) Regular exercise can help reduce the risk for the following
- High blood pressure — Regular aerobic activities can lower blood pressure.
- Cigarette smoking — Smokers who become physically active are more likely to cut down or stop smoking.
- Diabetes — People at their ideal weight are less likely to develop diabetes. Physical activity may also decrease insulin requirements for people with diabetes.
- High levels of triglycerides — Physical activity helps reduce triglyceride levels. High triglycerides are linked to developing coronary artery disease in some people.
- Low levels of HDL — Low levels of HDL ("good") cholesterol (less than 40 mg/dL for men/less than 50 mg/dL for women) have been linked to a higher risk of coronary artery disease. Recent studies show that regular physical activity can significantly increase HDL cholesterol levels and thus reduce your risk.
5) Other health benefits of regular exercise
- Physical activity builds healthy bones, muscles and joints, and reduces the risk of colon cancer. Millions of Americans suffer from illnesses that can be prevented or improved through regular physical activity.
- Physical activity also helps psychologically. It reduces feelings of depression and anxiety, improves mood and promotes a sense of well-being.
- The 1996 Surgeon General's Report on Physical Activity also suggests that active people have a lower risk for stroke.
(Source: American Heart Association. The American Heart Association also has a useful PDF called "How Can Physical Activity Become a Way of Life?")

Choose some activity you enjoy, preferably with a friend whose company you enjoy,
and get movin'!

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