How frequently should you take a break between training intervals? Researchers say the difference of just a couple of minutes in a break can be decisive in your training success. (Illustrative photo: Monkey Business Images / Shutterstock / NTB scanpix)
How frequently should you take a break between training intervals? Researchers say the difference of just a couple of minutes in a break can be decisive in your training success. (Illustrative photo: Monkey Business Images / Shutterstock / NTB scanpix)

Why is it so important to take breaks when you train?

ASK A RESEARCHER: Whether you’re training for endurance or strength — it pays to take breaks along the way.

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Once you get the exercise bug, it can be hard to take breaks. But as virtually every elite athlete will tell you, rest is an important part of training.

And there are physiological and psychological reasons behind the need to take a break, researchers say.

Why endless motion isn’t possible

There are several physiological reasons why you can't lift weights or run endlessly.

When you are moving, whether by lifting weights, running, cycling or walking, your brain sends electrical signals to the muscles you use to perform the movement. These signals go from the brain, through the spinal cord and to the muscles.

When the signals reach the muscles, the signals spread to all the muscle fibres connected to this nerve.

The electrical signals cause calcium ions to flow into the muscle cells from cavities where the ions stay at rest. These ions bind to specific proteins and start a muscle contraction.

This allows the muscle to create power, so you can lift weight or move your legs.

After the exertion, the ions flow back to where they came from and the same process can start again, allowing you to repeat the same movement again and again, be it weightlifting, running or cycling.

Bjarne Rud is an associate professor at the Norwegian School of Sport Sciences. (Photo: NIH)
Bjarne Rud is an associate professor at the Norwegian School of Sport Sciences. (Photo: NIH)

Don’t blame lactic acid

The calcium ion transfer system works until your muscles fatigue.

In this case, the muscle no longer releases enough ions to achieve the power you want in a contraction. And thus the muscle fails to do what the brain says.

There are, however, several other reasons why your muscles eventually stop working — although one reason isn’t lactic acid build up, contrary to popular belief.

A break allows the body to recover

When exercising at high intensity, be it heavy lifting or tough intervals, your muscles need energy right away. To provide that energy, the muscle breaks down its stores of creatine phosphate to create creatine and phosphate, which provide energy.

This process poses two problems for the muscle, however.

First, when phosphate accumulates in the muscle, it reduces the effect of calcium.

And second, muscles can use up their stock of creatine phosphate quite quickly.

That’s a really good reason to take a breather, says Bjarne Rud, a researcher at the Norwegian School of Sport Sciences. The body can rebuild its stocks of creatine phosphate in three to four minutes, he says.

Physical versus mental fatigue

Your muscles may however also fail you because you feel tired, even though physically, you may have more to give. So how do you know if your fatigue is mental or physical?

Thomas Bjørnsen is an associate professor at the University of Agder who is also affiliated with Olympiatoppen, an organization that is part of the Norwegian Olympic and Paralympic Committee and Confederation of Sports. His area of expertise is strength training.

He says without specialized testing equipment, it’s impossible to know the source of your fatigue. But even if it is in your head, it’s important to take a break.

“In the beginning, it’s not so important that you push yourself to exhaustion. It can actually be an advantage that you have something in reserve,” he says.

Thomas Bjørnsen is an associate professor at the University of Agder (Photo: UiA)
Thomas Bjørnsen is an associate professor at the University of Agder (Photo: UiA)

For example, if you are doing squats with lots of repetitions in one set and exhaust yourself, you simply won’t be able to do as many repetitions in the second set. In the end, your workout won’t be as effective, he says.

A three-to-four-minute break is optimal

Especially when you are training a specific muscle group, such as when you do squats, Rud says you should take a three-to-four-minute break between sets.

A 2016 study that investigated the difference between taking a one- or three-minute break between strength training sets showed that participants who took the three-minute break performed better with squats and bench presses, according to an article on the Norwegian Health Informatics website (in Norwegian).

Bjørnsen said taking a three-minute break is especially important if you are already in reasonably good shape.

"Those who are not well trained will have a strong response to training, so it won't matter so much for them if they take a break for one or three minutes. But the better trained you are, the more important it becomes to optimise your training", says Bjørnsen.

If you are already in good shape, the lenght of the break can determine how well you progress.

Rest days between workouts, too

The way the body’s musculature responds to the demands of exercise is another reason why taking entire rest days, or cross-training, can help your workouts be more effective. Cross-training is when you exercise to work a different group of muscles than you normally do, such as when a runner takes a break from their normal routine by cycling instead of running.

You have to allow your body time to respond so that the muscles and structures you have stimulated can develop, Rud says, whether it’s your muscles and connective tissue, or your heart and lungs.

He says this is a slow process, often taking several days, so that a rest day between strength sessions or hard runs can be a good idea.

Should you take time off from workouts?

Is it also useful to take long breaks from your work out regime?

Taking breaks isn't a bad idea, according to Rud, adding that by break he doesn't mean it's a good idea to hit the coach for an entire week.

"If you want to become stronger, or you want to become more fit, you have to train systematically and over time. Working out hard for a week and then taking a break for an entire week won't do the trick", he says.

Variation however is good idea. If you are training endurance, for instance, you can vary how hard you train from week to week, says the researcher. You can do one hard week, one middle intensity week, a low intensity week, and then back to a hard week.

"Basically, to sum it up - you need to take a sufficient amount of breaks, and you need variation, in order to reach your training goals", says Rud.

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Read the Norwegian version of this article on forskning.no