Not too long ago a reader asked, “Calorie for calorie burned, is intense aerobic exercise better for you?"
It’s a logical question, without a simple answer. It depends, in part, on how you define “better,” but also on the type of exercise you’re doing, as well as your goals, overall health, fitness level, personal preferences and schedule. Clearly, if you can run or walk vigorously for 30 minutes, that will provide greater benefits (notably for heart health and calorie burning) than walking more slowly. But what if, as our reader wondered, you do the moderate exercise longer so that it burns as many calories as the shorter intense workout— but without the huffing and puffing. Is it just as good, or maybe even better?
Most (but not all) research indicates that, for a given calorie expenditure, vigorous exercise is more beneficial, at least for cardiovascular health, according to a 2011 paper in the Annual Review of Public Health. “Regular fast running requires physiologic capacities that cannot be developed by walking slowly, no matter how much slow walking is done,” the authors wrote.
Exercise intensity: what’s the sweet spot?
At the very least, being able to do strenuous exercise is a marker for good health. So it’s not surprising that observational studies find that vigorous exercisers are at lower risk for chronic diseases and tend to live longer than those who do moderate exercise.
However, other studies show that the amount of exercise is also important. This can be measured in calories, minutes or miles per week. For instance, some classic studies, including one that followed Harvard alumni for decades, have suggested that the key to heart health and decreased mortality rates is to burn a fair number of calories (in the Harvard study, at least 1,500 calories a week) in recreational activity, regardless of its intensity.
Still, some other observational studies do give moderate exercisers the edge. It may be, in part, because moderation in exercise habits tends to go along with moderation in other habits—and moderation is often the sweet spot when it comes to good health.
At some point the benefits of exercise plateau. For instance, training 15 hours a week for marathons probably won’t keep you healthier than, say, five hours of aerobic exercise a week. Plus, the wear and tear of very prolonged and/or intense exercise can result in overuse injuries and other problems.
Low-Intensity Exercise & Fat
Low-intensity exercise is often promoted in aerobics classes as a way to maximize fat metabolism. Does easier exercise burn more fat? The answer may surprise you.
Exercise intensity: the basics
It’s easy to get confused by different exercise guidelines from government agencies, expert groups and health gurus. Do you need 30 or 60 minutes a day for health benefits? Every day or just most days? Does the exercise have to be done in a continual session or can it be done in many short bouts?
The clearest guidelines come from the American College of Sports Medicine and the American Heart Association. These advise that healthy people do moderateintensity aerobic exercise for at least 150 minutes a week—for instance, at least 30 minutes five days a week. Or you can do vigorous aerobic exercise for at least 75 minutes a week—or else do some combination of moderate and vigorous activities. On average, one minute of vigorous activity is considered equivalent to two minutes of moderate activity. Up to a point, the more exercise you do each week, the greater the benefits, especially for weight control.
Studies show that 10-minute workouts (and probably even shorter ones) are fine, as long as they add up to the weekly minimums. These shorter workouts may better fit your schedule. Plus, they can break up long periods of sitting, which is an added benefit, recent research has found.
Moderate intensity means working hard enough to raise your heart rate and break a sweat, yet still being able to carry on a conversation. This includes brisk walking (typically about four miles per hour) and even strenuous house cleaning or gardening.
Vigorous exercise, such as running, tennis and jumping rope, increases heart rate and sweating even more. It helps boost HDL (“good”) cholesterol and may be especially beneficial for improving insulin sensitivity and certain other metabolic factors.
Advice for exercise beginners
Simply put, you should exercise most (or all) days and work up to more strenuous activities, if possible. Any exercise is good, but more—in terms of duration or intensity— is better, within reason.
If you are sedentary and over 65, or are younger with a condition such as arthritis or obesity, you should start with easier goals. Get guidance from a health care provider, physical therapist or certified athletic trainer.
If, like most Americans, you are largely sedentary, don’t be discouraged or intimidated by exercise hurdles that are too high. Walking briskly for an hour a week is a good initial goal, working up to 30 minutes five times a week. In fact, the greatest relative benefits come from improvements in the least active people. That is, going from little or no exercise to a modest exercise program has bigger payoffs than going from a moderate to an intense regimen.