Tiny bursts of exercise once an hour could boost your cognition at school or at work, adding to the evidence of how important it is to take occasional breaks.
“Exercise improves pretty much every domain you can think of, including cognition over the long term. The interesting thing here is that this is immediate,” says Mike Trott at the University of Queensland in Australia, who wasn’t involved in the research.
It is well known that exercise is good for our overall health, cognitive powers and mental health, but it can be hard for adults to hit the World Health Organization’s recommended minimum weekly levels of physical activity of 150 minutes of moderate-intensity activity or 75 minutes of vigorous activity. About 31 per cent of adults fail to hit these targets, so interest is rising in “exercise snacks”: sessions of physical activity that last no more than 10 minutes, performed at least twice a day.
Advertisement
In the past few years, studies have found that short bursts of exercise can help keep your heart healthy or add years to your life. To see if they can similarly boost our brains, Yongming Li at Shanghai University of Sport in China and his colleagues reviewed 25 randomised controlled trials investigating the cognitive effects of exercise snacks.
The review included a total of 1115 people of all ages, with the mean age of participants in the studies ranging from 8 to 78 years. They involved people sitting for hours, interrupted by a couple of minutes of exercise either every 30 minutes or every hour.
The exercises included yoga, chair-based stretching, climbing two flights of stairs, walking on a treadmill, resistance exercises, stationary cycling, or high-intensity exercises like running on the spot for a minute or leg raises and jumping jacks.
The researchers found that these short bursts of exercise gave a modest immediate boost to working memory, cognitive flexibility, attention span and the ability to ignore impulsive reactions, assessed across the studies by a statistical measure known as Hedges’ g. With this measure, 0.2 indicates a small effect, 0.5 a medium one and 0.8 or above a large effect. Overall, the measure for the study was 0.24.
The cognitive benefits were stronger if the exercise habit continued for several weeks (g = 0.51), and if it happened in school or in the workplace (g = 0.61).
It is hard to interpret the overall effect size because the youngest and oldest people in the study were at very different stages of cognitive development, says Mark Hamer at University College London. However, he thinks the findings are plausible.
“It’s interesting with the kids in particular and this concept of trying to break up lessons, which could involve a teacher getting the kids to stand up or jump on the spot,” he says.
The review also found that gaps of an hour between exercises provided slightly more of a boost than gaps of 30 minutes, which makes sense biologically, says Trott.
The leading hypothesis for how exercise affects the brain is that it makes the body release dopamine and noradrenaline, increasing blood flow, he says. This gets everything working a little bit better, and studies show that, over longer periods of time, this can boost the size of the hippocampus, which is involved in memory, and the performance of the prefrontal cortex, which is involved in focus and decision-making.
“The immediate effects of dopamine and noradrenaline last for over an hour, so if the exercise snacks are more frequent than that, any extra effect is going to be really small because you’re still riding the wave of the first one,” says Trott.
Current health messaging about taking breaks during the day is generally based on evidence of cardiovascular and metabolic effects, and the exercise snack work adds to evidence of how beneficial it is to break things up frequently, says Hamer. “Even if that’s just by standing up or going up and down the stairs.”
Preprints DOI: 10.20944/preprints202609.0087.v1