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How much exercise is enough?

The steady stream of conflicting fitness advice is enough to make anyone want to throw in the towel. So how much exercise is enough?
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Walking, gardening and other forms of moderate exercise are keys to good health, many experts say. But wait, recent research suggests more heart-pounding activity may be required. Some health officials advocate 30 minutes of exercise a day, while others call for a full hour. The steady stream of conflicting fitness advice is enough to make anyone want to throw in the towel. So how much exercise is enough?

In trying to make sense of contradictory fitness headlines, experts say, it’s important to realize that exercise studies may reach opposing conclusions because they involve different age groups or sexes, people with different risk factors (some may already be at risk for heart disease, some may be overweight) or those with vastly different fitness levels to begin with.

So it’s not always possible to make direct comparisons from one study to the next. Findings that hold true for sedentary women in their golden years, for instance, may have little bearing on active college men.

And researchers do not all agree on how to interpret study findings and translate them into general recommendations for the public. Should the focus be on minimum exercise requirements, so people aren’t discouraged before they ever start, or on higher, more intense levels of activity that may offer greater benefit?

The bottom line is that no one knows the “ideal” amount of exercise. And one-size-fits-all exercise recommendations may not fit you. The perfect exercise prescription is likely to vary to some extent from one individual to the next, experts say, because of such factors as your age, health status and, importantly, your ultimate fitness goal.

What's your goal?
The “right” amount of exercise for you can depend greatly on what you’re hoping exercise will accomplish. Someone who is overweight and trying to shed pounds, for example, will probably have to exercise more than a thin person whose aim is to maintain good health, but less than someone in marathon training. Consider the following goals:

Staying healthy. If avoiding heart problems, diabetes and other diseases down the line is your main concern, health professionals say there is substantial research backing the advice in the 1996 Surgeon General’s report to strive for at least half an hour a day of moderate physical activity on most days.

Examples of moderate activity include brisk walking, swimming, raking leaves and even housework — as long as it’s somewhat intense, like scrubbing floors. You can break up the activity into three, 10-minute sessions if you like.

“Thirty minutes a day of moderate activity has a very significant health benefit,” says Catherine Jackson, professor and chair of the department of kinesiology at the California State University in Fresno and a spokesperson for the American College of Sports Medicine.

But that’s not to say that longer or more intense activity isn’t beneficial. It is, according to the Surgeon General’s report and other guidelines.

“That message gets lost,” says fitness researcher I-Min Lee, an associate professor of medicine at Harvard Medical School. “Most of the time we’re trying to get people just to the first level.”

Lee recommends that people aim for that first level — 30 minutes of moderate activity a day — and then ratchet things up if they can. “Once you’re comfortable at that level, see if you can build it up to an hour,” she says. Another way to get a more challenging workout is to increase the intensity by walking faster or jogging.

Dr. Richard Stein, chief of cardiology at the Brooklyn Hospital Center in New York and a spokesperson for the American Heart Association, agrees that people can get substantial heart benefit from half an hour of moderate activity — and that additional exercise may confer extra benefit.

“Most of the studies have shown that the more exercise you do, the better you are,” he says.

Recommendations issued last fall by the Institute of Medicine, an independent group that advises the government, urged at least an hour of moderate exercise a day for optimal health. But other experts have expressed concern that raising the bar so high may discourage sedentary people from ever exercising at all and give them the idea that lesser amounts of activity are a waste of time — which is not true.

Losing weight. If you’re like millions of Americans who are trying to shed excess pounds or prevent more from piling on, you may find that half an hour a day of moderate activity simply won’t work - at least not as effectively as you might like. This was another factor behind the IOM recommendation of an hour of exercise a day.

“If you’re trying to avoid weight gain, you’re probably going to need more exercise than if you’re trying to prevent heart disease,” Lee says.

Of course, we all know people who seem to eat whatever they want and never gain an ounce while others struggle continually to control their weight. As a result, some people will need to work much harder at losing weight than others.

To shed the extra pounds, it’s necessary to tap into the body’s stored fuel source — fat — by eating less and exercising more. How much less you need to eat and how much more you need to exercise — how long and at what intensity — will depend on various factors, including your current weight, diet and metabolism.

Looking like a swimsuit model. First off, realize that this may be an unreasonable, unattainable goal. Models and others with seemingly perfect bodies have genes that helped determine their coveted shape, and they may spend hours a day working out with professional trainers and severely limiting what they eat. What’s more, their cellulite can be airbrushed away.

That said, if you’re aiming for a buffer bod — the kind that is only attainable with hard work — you probably won’t be surprised to hear that gardening and housework aren’t likely to do much to help you achieve that goal.

How much aerobic exercise you need to burn fat and look fitter will depend on your metabolism, weight, diet and just how toned you want to be.

And weight training is key to developing that “sculpted” look. It also helps build strong bones and keep us functioning independently into old age. Experts recommend that most Americans strength train two to three days a week.

Every bit counts
Above all, the key point to keep in mind is that there is a wealth of research to date showing that exercise is good for us, and that the benefits are cumulative.

So if you can’t fit in as much physical activity as you would like on a given day, it’s still worthwhile to get some exercise, even if that means just taking the stairs a couple of times or going for a short, brisk walk.

Hard-core fitness enthusiasts and athletes can overdo it, training too hard and experiencing injuries, exhaustion and other complications as a result.

But the overwhelming majority of the U.S. population is at risk for the myriad diseases that can result from exercising far too little. About two-thirds of adults are not regularly active and a quarter get virtually no exercise at all, statistics show.

“Any exercise is better than none,” Lee says.