Exercising in Bursts

Just how little physical activity do you need?

Forget the Richards Simmons-style, spandex-clad workouts of the 1980s — much less activity is required to gain real health and longevity benefits, research suggests.

In “No Sweat: How the Simple Science of Motivation Can Bring You a Lifetime of Fitness” (Amacom, 2015), behavior expert and exercise coach Michelle Segar argues for a new tack. Most people believe exercise has to be difficult and painful, Segar says — the no-pain, no-gain school of exercise thought. But there are substantial health benefits in even small amounts of moderate activity, she says: “Anything is better than nothing, period.”

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In fact, Segar argues, we may need even less than current medical guidelines recommend. In 2008, when a panel of U.S. experts released the Physical Activity Guidelines for Americans, the weight of medical evidence suggested we should be getting 150 minutes of moderate exercise, or 75 minutes of vigorous exercise, every week. (You can break up those totals into 30-minute segments a day, five days a week, or half that for vigorous exercise.) Yet in our increasingly time-pressed world, few people reach even those levels.

For example, just replacing sitting with standing for two hours a day reduces all-cause mortality by 10 percent, according to a report from the Journal of the American College of Cardiology. It’s the jump from total inactivity to at least some activity that produces the most dramatic health gains — that’s why, say the authors of the report, echoing Segar: “Any physical activity is better than none.”

Short bursts of activity may even offer benefits nearly equal to exercising for longer periods of time. A study released in 2014 found small amounts of slow jogging offered virtually the same health benefits as running much more. The study looked at the running habits of more than 50,000 American adults over 15 years, a quarter of whom were occasional or consistent runners. The difference between runners and nonrunners was significant: those who ran at all had a 30 percent reduced risk of death from any cause, and a 45 percent reduced risk of death from cardiovascular disease, regardless of smoking status, age, gender, or weight. Yet those who ran the least and the slowest — less than an hour a week, or five to 10 minutes a day, at a slow jog of up to six miles an hour — saw essentially the same benefits as those running almost three hours a week. What seemed to matter most was running at all, even for a handful of minutes a day.

One explanation for why that might be lies in something called high-intensity interval training. Sometimes called Tabata training — after Izumi Tabata, the scientist who developed the technique for Japanese Olympians in the 1980s — it’s an exercise trend that may sound too good to be true, yet has bona fide medical benefits.

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Interval training intersperses all-out bursts of exertion with brief periods of rest. In doing so, it essentially trades time for effort. The “7-minute workout,” which helped popularize Tabata intervals in the United States, suggests performing 12 familiar exercises such as jumping jacks for 30 seconds each, followed by 10 seconds of rest, for a total of seven minutes. Most accounts forget to mention the authors suggest repeating the circuit once or twice more to make a 20-minute workout, in accord with current guidelines for vigorous exercise.

Twenty minutes is a powerful number: one study found interval training for 20 minutes more effective at reducing body fat and decreasing insulin resistance than 40 minutes of steady exercise. After 15 weeks, only the interval training group had lost body fat — 15 percent of it, after adjusting for various factors.

Yet even less could do. In other studies, just three or four minutes of intervals have improved exercise capacity and blood pressure along with other markers of health. The catch: it’s vigorous-intensity activity that makes the difference.

If you’d like to incorporate more movement in your life, Segar says, a half-hour of activity per day is a good goal. Any activity counts, whether it’s standing while you work at a desk, gardening, taking the stairs, or heading out to the park at lunchtime to eat. Breaking up that half-hour into three 10-minute intervals may even be better than one 30-minute session: a 2012 study found three 10-minute intervals were better at reducing blood pressure over a 24-hour period than a single session. Try starting with just one 10-minute walk a day, then work your way up to three 10-minute walks over a month or two.

For the more athletically inclined, if a few minutes of exertion sounds like a good tradeoff for better health, begin slowly and check with your doctor first, particularly if you’re over 50 or have ever had a heart condition. Make your “all-out” intervals as easy as you need to, gradually increasing exertion over a period of weeks to months. And if you’re older, don’t be intimidated: intervals as small as six seconds have improved health and the ability to perform daily activities in seniors.

The key, Segar suggests, is finding sustainable forms of activity that you enjoy and work for you — even if it’s only a few minutes at a time.

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