“Microdosing ” originally meant taking tiny amounts of psychedelics (such as mushrooms) to enhance mood or performance, with fewer side effects.
But the term has taken off to mean anything where you incorporate a much lower “dose” of something – and still reap the benefits.
So, does this work for exercise? If you can’t make time for a 30-minute run, will shorter bursts of activity do anything for your health?
The minimum you should move
According to the World Health Organization (WHO), adults should aim each week for either a minimum of 150 minutes of moderate intensity aerobic exercise – meaning it’s hard to hold a conversation – or 75 minutes of vigorous intensity – you are gasping for air at the end of it. Or you can do a combination of moderate and vigorous activity.
This can include activities such as brisk walking, cycling, running, swimming or rowing, and team sports such as football and basketball.
If you exercise every day, you’d need to do 20–30 minutes of these activities. Or you might do a couple of longer training sessions or matches two or three times a week.
WHO guidelines also recommend including muscle-strengthening activities (such as lifting weights, or high-impact exercise like sprinting) at least twice a week.
Incidental activity – unplanned or everyday movement, such as playing with kids or walking to the bus stop – may contribute to your physical activity levels over the week.
So, yes, housework can count. For example, chores like mopping and vacuuming tend to have a similar physical demand as going for a walk.
While this activity wouldn’t be considered vigorous, it could contribute to your moderate intensity minutes.
So, do smaller chunks work?
Yes, the good news is doing small amounts of exercise throughout the day is just as effective as doing one long session.
In fact, it may have some additional benefits.
A 2019 review of 19 studies looked at this question, involving more than 1,000 participants. It found multiple, shorter “chunks” of exercise in a day improved heart and lung fitness and blood pressure as much as doing one longer session.
The most common way this exercise was compared in the 19 studies was with one group doing three ten-minute bouts of exercise five days a week, and another doing one 30-minute session, five days a week.
Even very short bouts might help
Another 2019 study in young adults examined the effect of short “exercise snacks” on fitness. While small, it had some interesting and positive results.
The exercise “snack” group did three very short sessions per day, three times a week, for six weeks. Each session involved a light two-minute warm-up, followed by a 20-second maximal effort sprint – where you push as hard as you can – and then a one-minute cool-down.
In total: just three minutes and 20 seconds of exercise, three times a day, three days a week.
The control group did one session a day, three days a week, but it was longer – a total of ten minutes. It involved a two-minute warm-up, followed by three 20-second sprints, with three minutes of light recovery between sprints, then a one-minute cool-down.
Similar research has suggested this same approach can have positive effects on lowering cholesterol levels. However, it may not provide enough total exercise time to lose weight.
The research outlined above suggests the shorter your exercise session, the harder you need to push.
So you might need to adapt your exercise to increase intensity . For example, one minute of maximal intensity exercise might be worth two minutes of moderate intensity exercise.
Basically, if you’re short on time you will get more bang-for-your-buck by going harder.
So, is it worth still doing longer sessions?
For health and general fitness, the research suggests there aren’t downsides to breaking a long workout into smaller chunks.
If you are training for a longer duration event (maybe a 10 kilometre run, a 30km ride, or even a marathon), you will need to do some longer sessions . This will ensure your muscles and joints are prepared to tolerate the demands of the event, and help your body adapt to maximise performance on the day.
For mental health, there is also some evidence to suggest doing more than the recommended minimum exercise might be better.
For example, two recent meta-analyses (studies which review the available evidence) found that around one hour of moderate intensity exercise a day can significantly improve anxiety and depression symptoms.
But these studies didn’t compare the benefits of one session versus chunks, so it’s likely you can still break up your exercise across the day and feel an effect.
Any exercise is better than none. If you struggle for time, as little as three minutes a day, spread across three sessions, can have a positive effect on our health.
But don’t forget – the shorter the session, the harder it needs to be.
Written by Hunter Bennett Lecturer in Exercise Science, University of South Australia
