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Exercising Your Right to Live Longer
It can be rather bewildering, frankly. We all know by
now -- duh -- that we're supposed to exercise. Great minds have tackled these questions, and are tackling them again, with new federal exercise guidelines due out this summer. But one of the conclusions is already known: Exercise is just about the closest thing to a magic bullet that modern medicine can recommend. It's very, very good for you for a long list of reasons that we'll get to in a minute. Think evolutionarily. We are all animals, not that different from zebras, lions, dogs, etc. Animals do not lie on the couch all day eating potato chips and watching TV. (Okay, maybe your zebra does, but he probably wouldn't if he had the choice.) Animals are built to run around, hunt, eat, sleep, procreate and then do it all again. They probably even like the running around part. Studies suggest that rodents, when put in cages with little wheels to run on as well as toys to play with, prefer the exercise wheels. In other words, our animal souls think of exercise as fun and essential, not some unwanted burden imposed by experts. Okay, so you're not buying that. But you're still determined to exercise and you can't possibly do it all -- the strength training with weights, the yoga for flexibility, the brisk walking or running or swimming for cardiovascular fitness. What's most important? Simple: The aerobic, cardiovascular stuff, in other words, getting your heart rate up. This doesn't mean strength training is not important -- it is, for building muscle mass and stronger bones. Stretching and flexibility are important, too. But if you have to choose, do the exercise that has been shown overwhelmingly to prolong life and reduce chronic disease. A number of epidemiological
studies show that 30 minutes a day of moderate intensity physical
activity is enough to significantly reduce the risk of many
diseases, including heart disease, hypertension, stroke, diabetes,
certain cancers and hip fractures, said Dr. I-Min Lee, an associate
professor of medicine at Harvard Medical That may not be enough to achieve and maintain weight loss, cautioned William J. Evans, chief of the nutrition, metabolism and exercise lab at the University of Arkansas for Medical Sciences. "But there is no question that 30 minutes a day is enough to make a significant difference in life expectancy and health." So how hard do you have to work
at it? The experts waffle a bit on this. But very roughly, if you're
a 30 year old, you should exercise aerobically at a heart rate of
between 155 and 165; if you're 40, it's 145 to 155; if you're 50,
it's 140 to 150. If you're 60, it's 130 to 140. If you're 70, it's
125 to 135. (The actual formula is slightly complicated, but here it
is. Take the number 220 and subtract your age, say, 60. That gives
160. That's an estimate of your maximal heart rate. Now subtract
your average resting heart, say 60, from this, which gives 100. Then
you take 70 percent of that number (100), which gives 70. Add that
number (70) to your resting The goal of 30 minutes a day
comes from guidelines set in 1995, when a team of exercise
physiologists and doctors from the federal Centers for Disease
Control and Prevention and the American College of Sports Medicine
and others tried to figure out what to recommend for average
Americans, most of whom, then as now, didn't exercise. Though they
recommended 30 minutes a day, they softened this by saying people
could "accumulate" 30 minutes in three bouts of 10 minutes each, a
more The new guidelines expected out
this summer will probably recommend the same. The difference, said
Dr. Bill Kraus, a cardiologist and exercise guru at Duke University
Medical Center, is that "when those [1995] guidelines were written,
no one had a clue." Today, they do, especially for the question of
intermittent versus continuous exercise. In one study published in
1999, exercise physiologist John Jakicic at the University of
Pittsburgh found that for weight loss, body composition,
improvements in blood pressure, cholesterol and blood sugar, it made
no difference whether the exercise was continuous or intermittent.
That makes sense, he said, because those factors "are all about
energy burn." The only place in which continuous exercise was better
was in fitness measures (like one that physiologists called "VO2
max"), a measure of the efficiency with which the heart and lungs
get For weight control, a report in 2002 from the Institute of Medicine, an arm of the National Academy of Sciences, concluded that 30 minutes of exercise a day is "insufficient" to maintain healthy weight. It probably takes 60 minutes, especially if you've been overweight Steven Blair, president of the Dallas-based Cooper Institute, a leading exercise research center, is a case in point. "I need even more than an hour of vigorous exercise. I have run nearly every day for 35 years and now, at 65, I run 25 miles a week, which is a lot for a fat, old man." Even so, he's gained 25 to 30 pounds. But exercise clearly helps to some extent with weight control, even if you make no changes in diet. At Duke University, cardiologist Kraus and his team took 240 typical Americans -- sedentary, overweight men and women aged 40 to 65 with mild to moderate cholesterol problems -- and divided them into four groups for a 6-month study. There was no change in diet for anyone. Over the six months of the study, the control group -- typical, non-exercising Americans -- gained three pounds. The other groups lost weight, with those who exercised more at a higher intensity losing more weight than the gentle exercisers. The bottom line, says Kraus, is this: Any exercise is better than none, and more is better than less.
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