Guidelines on exercise are there to guide people on how much they need to do to maintain their health. These recommendations are the minimum amount suggested. Because, when it comes to exercise, the more you do, the better it is for your physical and mental wellbeing. But where do these thresholds come from? Can you benefit from doing less? And how little exercise is too little?

Current and Past Guidelines

The guidelines for exercise have changed over the decades. As new science came to light, the minimal recommended amount has gone down. The earliest guidelines, in 1978, stressed exercising at a moderate to high intensity for 20 to 45 minutes, 3-5 times per week. This was followed in 1995 by recommending a minimum of 150 min/wk, or 20-30 min on most days. A key point to the guidelines was you could accumulate this time in 10 minute bouts.

The most recent guidelines (2020) kept everything the same except the 10 minute minimum has been removed. They also encourage targeting up to 300 minutes per week of moderate activity or 150 minutes per week of vigorous activity. Moderate activity includes things such as brisk walking, easy cycling and pushing a lawn mower. Vigorous activity includes running, cycling, tennis and shovelling.

The minimum 10 minute bout was removed because there wasn’t any evidence to support it. The health benefits from activity start from the very first step. And continue from there in a linear fashion until about 60 minutes per day. After which, the benefits taper off. Thus, even doing less than the recommended guidelines is better than not being active at all.

Despite these guidelines requiring only 20-30 minutes of activity on most days, they are hardly followed. Only about half of adults meet this amount. People commonly say they don’t have enough time to exercise. This is one reason why exercise research has focused on how little exercise one can do and still get benefit. And more and more studies are demonstrating the benefits of even small amounts of exercise.

The Science of Less and Less Exercise

Early research into bursts of exercise began with high intensity interval training or HIIT. This consists of short bursts of high intensity exercise (30 seconds to 4 minutes) interspersed with active rest and repeated three or more times. This type of exercise may be superior to continuous exercise in improving fitness. And because HIIT is done at a high intensity, it takes less time.

An evolution of HIIT is the exercise snack. Exercise snacks are essentially the short bursts of HIIT spaced out throughout the day. While the ideal length of the exercise snack isn’t known, climbing three flights of stairs, three times per day, three days per week for six weeks resulted in improvements in fitness in non-exercisers.

Repeated over the days, weeks and years, these short bursts add up to improved health. As little as 15 minutes of vigorous activity in a week was associated with an 18% lower chance of early death. This is similar to another study indicating 10 minutes per week can increase lifespan. It’s important to note, however, these were comparisons to people who do no activity.

Intensity Matters- Somewhat

When it comes to exercise intensity, vigorous activity seems to offer greater long-term health protection than moderate activity. While both are beneficial, vigorous activity is associated with lower chances of early death than moderate activity. This is likely because vigorous activity has a greater effect on increasing your cardiorespiratory fitness. And fitness is one of the strongest predictors of heart disease and early death. Perhaps more so than smoking, high blood pressure, cholesterol and diabetes.

Short bouts (1-2 minutes) of non-exercise vigorous activity performed three or more times per day were associated with a nearly 40% lower chance in early death. These types of vigorous activities occur in day-to-day life and include running up the stairs, playing with children or carrying groceries up a hill. Even regular exercisers benefited from these brief bouts of vigorous activities in addition to their exercise sessions.

However, there’s also benefit in activity breaks even of lower intensity. Studies of prolonged sitting have indicated that getting up and doing light activity, such as easy walking, is effective at lowering blood sugar and blood pressure. When sitting (or not moving), your body slows down. Similar to a car which automatically shuts off at a stop light. The longer you don’t move, the more your body shuts down. But getting up every 20 to 30 minutes doing some light activity for two minutes can counteract this.

It’s All Relative

The above studies have generally studied people who don’t exercise. In this case, the benefits start from the very first step, first minute, and so on. And it doesn’t have to be something that looks like traditional exercise. It can literally be running for the bus.

But the benefits you get depends on your starting point. If you’re doing at least 20-30 minutes of moderate or vigorous activity each day, don’t change that. But know that by adding in short bursts of activity throughout the day, you’ll be doing yourself a favour.

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