You may have heard about the U.S government recommendation that healthy Americans get 30 minutes of moderate-intensity exercise a day. But another government report urges twice that amount. So, which plan is for you?
The answer, of course, is "it depends." We'll break that down momentarily. But first, here's some background. The 30-minutes-a-day mandate comes from the Centers for Disease Control and Prevention (CDC), and the hour-a-day plan from the Dietary Guidelines for Americans 2005, published jointly by the departments of Health and Human Services and Agriculture.
The CDC's recommendation is intended to help people achieve and maintain adequate fitness. The Dietary Guidelines have the same goal — as well as to help prevent gradual weight gain.
Health and fitness
Regular exercise can improve overall health and decrease risk of heart disease, type 2 diabetes and other maladies. To reap such benefits, adults should strive for 30 minutes of activity on most days of the week.
For the sedentary, the main challenges are getting started and sticking with exercise long enough to see progress.
"You can start with a few 10-minute periods in the first week and then work up to 30 minutes of continuous activity over 2 or 3 weeks," says Bill Kohl, Ph.D., lead epidemiologist and team leader of the CDC's Physical Activity and Health Unit.
And don't expect an instant transformation of your physique. It will take at least a few weeks for you to notice fat loss or muscle tone improvements. But by starting to exercise, you are laying the foundation for that betterment and taking the all-important first steps.
Exercising for weight maintenance and loss
So far, so good. Now it gets stickier. It's a safe bet that most people fear gradual weight gain. And it's an even safer wager that most of us will not find an hour a day to exercise. We don't dispute the logic in the Dietary Guidelines, but here's a more manageable piece of reality. You can lose weight with less than hour a day of exercise. But how much weight you lose depends on that annoying constant in weight management — how much you eat.
To shed fat, no matter what your exercise level, you must burn more calories than you consume. Shoot for a deficit of around 300 calories a day. That's a safe level that won't leave you gnawing at your coat sleeve or passing out from a lack of nutrition.
Never too old
Elderly people should strive to meet the 30-minutes-a-day mark, says Wojtek Chodzko-Zajko, Ph.D., head of the Department of Kinesiology and Community Health at the University of Illinois at Urbana-Champaign.
Those of advancing years may have issues — like low bone density or stiff joints — that limit activity. So, they should adjust their routines to avoid injury. But no matter what the rest of their regimen looks like, older folks should incorporate balance and strength exercises to help lessen their risk of falling.
Just like other newbies, older adults who are sedentary should start out slowly with a moderate-intensity activity like walking. They should begin with 2 or 3 sessions a week that last 10 minutes each.
"The goal is to build activity into their daily lives and get used to that," Chodzko-Zajko says. "Then they can add other components such as strength training and flexibility."
Examples of strength-building activities for older adults include light weight lifting, training with resistance bands and even household chores such as scrubbing the floor. (Not that we're suggesting your floor needs cleaning.) To improve flexibility, older adults should seek activities that lengthen their muscles, like swimming, yoga or basic stretching programs.
Setting the pace
"Moderate intensity is when you feel yourself beginning to perspire, but you could still carry out a conversation," Chodzko-Zajko says. You could achieve this in any variety of activities, from brisk walking, gardening and tennis to house cleaning, swimming and bicycling.
But be honest with yourself about how hard you're working. A light walk around the block or a saunter through the tomato patch that prompts neither sweat nor a quickened heart rate doesn't count as "moderate."
If you're already hitting the 30-minute, moderate-intensity benchmark, you can further boost your fitness — and burn more calories — by bumping up the intensity or extending the length of time of your workouts.
Vigorous activity — one that results in an elevated heartbeat and difficulty in carrying on a conversation — puts more oxygen demands on your body, which means that more calories are mobilized to help shuttle oxygen to your muscles.
We know high-intensity exercise sounds hard — and it is. But the upside is that you can achieve real benefit in less time than if you were working out at a moderate intensity level. For example, take that 30-minute light jog you've been doing. Kick it up a notch, and you're done in 20 minutes. But there's one important caution here. You shouldn't go hard every workout. Varying your workouts — both intensity and range of activities — gives your body the appropriate time to recover and keeps exercise more interesting for you. And once you've established an exercise routine, you should take one full day per week to rest.
Fitting it in
Don't feel you have to block out all your exercise time at once. Numerous studies show that activity in bouts of as little as 10 minutes each — like doing a couple laps up and down the stairs at work — burns calories and enhances fitness. Ideally, you'll do enough to add up to your daily target. But even if you can't, any activity is better than none. Even on the most harried weeks, try to get some exercise on most days. This will help establish a habit, and before long you'll feel antsy on the days you don't exercise.
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