How Much Exercise Do You Really Need?

Posted by on Apr 29, 2015 in Fitness, Health | No Comments
How Much Exercise Do You Really Need?

The benefits of exercise are clear, but how much should you be doing each week? And how hard should you work out?

It turns out that most of us could stand to squeeze more exercise into our day. But we can probably get away with moderate exercise like walking.

Exercising Lags Behind Screen Time

Illustration: gorilla watching television on a couch (Pixabay)If you’re wondering how much to exercise each day, the government has a quick answer for you. The current U.S. guidelines for physical activity for adults are:

  • at least 150 minutes a week of moderate-intensity aerobic exercise; or 75 minutes a week of vigorous-intensity exercise; or some combination
  • for extra health benefits: up to 300 minutes a week of moderate-intensity aerobic exercise; or 150 minutes a week of vigorous-intensity exercise; or some combination
  • moderate- or high-intensity strength-training activities on two or more days a week

At a bare minimum, that comes out to about 21 minutes a day of moderate-intensity physical activities like brisk walking, leisurely bicycling, doubles tennis, or gardening.

In comparison, the average American watches almost five hours of traditional television each day, according to a 2014 report by the Neilsen media ratings company. So while we spend a lot of time catching up on The King of Thrones or binge watching Netflix, we may not be giving our bodies the same kind of attention they deserve.

That means you are missing out on the benefits of regular physical activity, such as:

  • maintaining a healthy weight
  • reducing your risk of heart disease, type 2 diabetes, and metabolic syndrome
  • lowering your risk of certain cancers
  • boosting your mood and improving your mental health
  • strengthening your muscles and bones (the “use it or lose it” benefit)
  • making it easier to do your daily activities, especially as you get older
  • increasing your chances of living longer

Who doesn’t want all of those? Especially the last one. A longer life means more seasons of the Simpsons to watch (it will still be on in 30 years, won’t it?).

Studies Identify Best Exercise Dose

Moderate exercise: girl walking in a party dress with balloons (Pixabay)While the benefits of exercise are clear, knowing exactly how much time to put in at the gym, the walking track, the stairs at work, or even in the garden is difficult.

Two recent studies, though, shed some light on the possible best “dose” of exercise. Both of these studies were impressively large (in science, unlike in other areas of life, size often matters) and were published recently in JAMA Internal Medicine.

In one of the studies, researchers at the National Cancer Institute, Harvard University and other institutions looked at the exercise habits of more than 661,000 adults, most of them middle-aged. Researchers gathered the data from six ongoing health surveys.

It was no surprise that people who didn’t exercise at all had the highest risk of dying early over a 14-year-period. Again, the “use it or lose it” motto comes to mind, although in this case it’s your entire body that’s on the line.

But when people met the government’s exercise guidelines (150 minutes per week of moderate-intensity exercise), their risk of early death dropped by 31 percent. A nice boost from just 21 minutes per day of walking (easily attainable if you live in a city without a car).

The greatest benefit, though, came for people who exercised three times more than recommended, or 450 minutes per week (a little more than an hour a day) of moderate-intensity exercise. Their risk of premature death dropped by 39 percent. After that, the benefits plateaued, although super-exercisers didn’t lose any of the life-lengthening benefits.

Adding Vigorous Exercise Boosts Benefits

Colorful exercise: runners painted bright colors in a race (Pixabay)The other study came up with similar results. After looking at health survey data for more than 200,000 adults, Australian researchers found that people who met the exercise guidelines — even if they only exercised moderately — had a lower risk of early death.

This study, though, also showed that spending part of that time doing more vigorous exercise, such as running or mountain biking, provided even greater benefits — an extra 9 percent drop in the risk of dying early for those who exercised vigorously for one-third of the time; and 13 percent for those who did even more vigorous exercise.

One limitation of these studies is that they relied on people’s ability to recall their exercise habits, which might not always be accurate. The studies were also not randomized clinical trials, so it’s impossible to say that exercise decreased the risk of death, only that the two are strongly related.

These findings, though, are consistent with other studies that show that exercise is good for you. So don’t wait any longer to start exercising. Even brisk walking can have lifelong benefits. If you already exercise regularly, consider ramping it up with longer and more intense workouts.

But if you are like most people and have trouble finding time to exercise, take a look at how much television you watch during the week. Try swapping an hour of screen time for an hour of health-boosting exercise.

Or you could try working out while catching up on your favorite shows. Or even powering your TV with a bicycle — no pedaling means no screen time.
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References

  • Arem H, Moore SC, Patel A, Hartge P, Berrington de Gonzalez A, Visvanathan K, Campbell PT, Freedman M, Weiderpass E, Adami HO, Linet MS, Lee IM, & Matthews CE (2015). Leisure Time Physical Activity and Mortality: A Detailed Pooled Analysis of the Dose-Response Relationship. JAMA Internal Medicine PMID: 25844730
  • Gebel K, Ding D, Chey T, Stamatakis E, Brown WJ, & Bauman AE (2015). Effect of Moderate to Vigorous Physical Activity on All-Cause Mortality in Middle-aged and Older Australians. JAMA Internal Medicine PMID: 25844882

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