Why we should exercise — and why we don't
You already know that exercise is good for you. What you may not know is just how good — or exactly what qualifies as exercise.
A deluge of studies have documented the health benefits of exercise. What's impressive about the research, aside from the sheer volume, is the number of conditions exercise seems to prevent, ameliorate, or delay.
We're used to hearing about exercise fending off heart attacks. If you're physically active, your heart gets trained to beat slower and stronger, so it needs less oxygen to function well; your arteries get springier, so they push your blood along better; and your levels of "good" HDL cholesterol go up.
It's also not much of a surprise that physical activity helps prevent diabetes. Muscles that are used to working stay more receptive to insulin, the hormone that ushers blood sugar into cells, so in fit individuals blood sugar levels aren't as likely to creep up.
But exercise as a soldier in the war against cancer? It seems to be, and on several fronts: breast, colon, endometrial, perhaps ovarian. Some research suggests that it takes quite a lot of exercise to make a difference: four to seven hours of moderate to vigorous activity a week. Three studies have found that if you've had colon cancer or breast cancer, physical activity reduces the chances of it coming back.
To top things off, moving the body seems to help the brain. Several studies have found that exercise can reduce the symptoms of depression, and it changes the brain in ways similar to antidepressant medications. In old age, physical activity may delay the slide of cognitive decline into dementia, and even once that process has started, exercise can improve certain aspects of thinking.
Most evidence suggests that the choice of the kind of activity is far less important than whether to be active at all. About half of adult Americans don't meet one of the most oft-cited guidelines, which calls for 30 minutes of moderate-intensity activity (a fast walking pace) most days of the week — and you can accumulate that total in bouts of 10 to 15 minutes.
Clearly some of us are less athletic than others — and some unathletic individuals were simply born that way. Twin studies suggest that about half of the difference in physical activity among people is probably inherited. And researchers are making headway in identifying particular genes that may influence how we respond to physical exertion.
But genetic explanations for behaviors like exercising only go so far. Many other influences come into play: family, neighborhood, cultural attitudes, historical circumstances. Research has shown, not surprisingly, that active children are more likely to have parents who encouraged them to be that way.
The trip of a thousand miles begins...
The federal government is scheduled to release new physical activity guidelines sometime in October 2008. The scientific committee that advised the guideline writers concluded that current research supports the standard advice to get 30 minutes of moderate-intensity exercise most days of the week. So in that spirit, we've made several suggestions for ways to become a little bit more physically active.
- Take the far away spot. Walking from the farthest corner of the parking lot will burn a few calories. If it's a parking garage, head for the roof and use the stairs.
- Walk to the next stop. If you take a bus or train, don't wait at the nearest stop. Walk to the next one. Or, at the end of your journey, get off a stop early and finish up on foot.
- Adopt someone as your walking, jogging, or biking buddy. Adding a social element to exercise helps many people stick with it.
- Be part of the fun. Adults shouldn't miss a chance to jump into the fray if kids are playing. Climbing on the jungle gym (be careful!) and swinging on a swing will strengthen muscles and bones and set a good example.
- Put on your dancing shoes. Exercise doesn't have to be done in a straight line. Dancing can get your heart going and helps with balance. Dance classes tend to have lower dropout rates than gyms. Or just turn up the volume at home and boogie.
- Clean house. Even if you have a cleaning service, you can take responsibility for vacuuming a couple of rooms yourself. Fifteen minutes burns around 80 calories. Wash some windows and do some dusting and you've got a pretty decent workout — and a cleaner house.
- Grow a garden. No matter how green the thumb, the digging, the planting, the weeding, and the picking will ramp up your activity level and exercise sundry muscles.
- Use a push mower. Even if you have a large lawn, pick a small part of it to mow in the old-fashioned way. You get a nice workout, you're not burning any gas, and it's usually quieter. The same reasoning favors the rake over the leaf blower.
- Think small. Small bouts of activity are better than knocking yourself out with a workout that will be hard to replicate.
- Be a stair master. Take the stairs instead of the elevator or escalator whenever you can. It's good for your legs and knees, and your cardiovascular health will benefit from the little bit of huffing and puffing. Don't overdo. One flight at a time.
October 2008 update