How often do you need to exercise to get stronger?

Unlike food snacking, the more exercise snacks we have the better. The more frequently we move, even in small quantities, the more benefit we receive.

But how frequently do we need to exercise if we want to get stronger?

This is a question that has fascinated Professor Ken Nosaka, director of Exercise and Sports Science at Edith Cowan University. It has driven a body of research, which has found that daily exercise snacks – defined in the study as three seconds of movement – five times a week for a month can power a 12 per cent increase in strength and muscle size.

While any kind of movement is good for us, Nosaka’s research found that spreading the snacks out across the week makes more of a difference to strength than saving them all for one big weekly exercise meal. It also found that slow eccentric exercises, like lowering a kettle bell, the downward phase of a push-up, walking downhill or even sitting down very slowly, is more effective for building strength than concentric (the lifting, upward phase of a movement).

Still, he wondered what the tipping point was for these gains. Can you still get benefits from snacking on exercise two or three times a week?

In a new study, published in the European Journal of Applied Physiology, Nosaka took 26 young healthy adults (who hadn’t done resistance training in the last six months) and randomly assigned them to one of two groups, which performed a single three-second eccentric arm contraction (similar to extending your arm from bent to straight in a bicep curl) on an exercise machine, using the heaviest load they could handle. The first group did the exercise twice a week for a month and the second group did the exercise three times a week for a month.

The two-day a week group didn’t improve significantly, however the three-day a week group became 3.9 per cent stronger. While this result is small, it’s still noteworthy, according to Nosaka.

“Even this amount of small amount of exercise can still make a difference for your body,” he says. “It’s a starting point.”

And starting points are important when the majority of Australians don’t meet the physical activity guidelines of 150 minutes of moderate to vigorous activity and two strength sessions each week, nor do they move enough generally throughout the day.

The difference 3.9 per cent more strength can make differs person to person, but may improve our ability to carry out daily tasks, says Professor Tim Olds from the University of South Australia’s school of Allied Health and Human Performance.

And although five days of contractions is better than three – just as 10,000 steps is better than 6000 – it’s important to understand the tipping point where we start to see a meaningful difference.

“It never ceases to surprise me how just a tiny stimulus can produce gains like that,” says Olds.

Though most people don’t have access to the kind of equipment used in the study, Nosaka adds that there are equivalent exercises we can do at home, including lifting a heavy dumbbell with both arms, and lowering it slowly with one arm.

“We have found that using a dumbbell approximately two-thirds of our maximal strength can still have similar effect to that by maximal contraction using a machine,” he says, adding that using our body weight is another way to simulate the exercise.“Sit down on a chair slowly. Then you can put more weight to one leg, if possible, or sitting to a chair slowly with one leg for more challenge.”

For tiny exercise snacks to be effective, they need to be hard, says Olds. “The intensity effect is what’s important here. You’re effectively trading off intensity against time.”

Along with intensity, eccentric exercises have particular properties that increase our strength.

We can lower up to 200 per cent of the weight we can lift, for instance. And eccentric exercises also create more muscle damage.

“The muscle fibres are lengthening, but they’re trying to contract at the same time, and so they’re basically being pulled apart,” Olds says. “This causes damages, and it’s that, and the repair of it, which is thought to account for the benefits that one gets from eccentric training.”

The takeaway, beyond the need for three sessions (or snacks) a week to get stronger, is that we should not underestimate the power of every move we make.

“Every muscle contraction counts,” says Nosaka. “It can make a difference. It is better to do even one contraction a day than nothing.”

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