Exercise 'snacks' can benefit the body and brain
The official line on exercise in many places around the world is that we should aim for about 2½ hours of moderate-intensity activity each week, or about half that if it’s ‘vigorous’. I’m not a particularly prescriptive person, and generally believe that that the best exercise is the type we do consistently. And the reality is that some people lack the time, energy or inclination to carve out portions of their day to exercise on a stationary exercise bike, run the streets or do laps in the pool.
Partly because of this, in the last couple of years I’ve grown interested in the concept of ‘exercise snacking’. As the name suggests, this involves brief bouts of exercise – perhaps just climbing a couple of flights of stairs – that break up a day otherwise spent largely sitting down.
I’ve found that prolonged sitting tends to be less of an issue for people who commute to work. But, as I know from my own experience, a day working from home can quite easily have us ossifying at our desks.
A 2022 review [1] looked at the effects of exercise snacks – typically short bursts of vigorous activity lasting a minute or less. It concluded that they show real potential for improving fitness and metabolic health in people who are generally inactive. It makes sense that those most in need stand to benefit most – they are, after all, starting from the lowest base.
However, recent research suggests that the benefits of exercise snacks extend to the brain, and are not confined to the unfit. A review published as a ‘preprint’ (meaning it has not yet been peer-reviewed) pooled the results of 25 ‘randomised controlled trials’ [2] involving people ranging from children to older adults. In this type of trial, participants are randomly allocated either to the intervention (in this case, exercise snacking) or to a ‘control’ condition, such as staying seated or carrying on as usual, and the outcomes are then compared.
In this review, an exercise snack was defined as a bout of activity lasting up to 10 minutes, repeated at least twice a day with at least 30 minutes between bouts. The interventions varied considerably, spanning aerobic, resistance and mixed exercise, with examples including stair climbing, stationary cycling, running on the spot and jumping jacks.
Overall, exercise snacks led to a small-to-moderate improvement in cognitive function. The clearest benefits were in cognitive flexibility (the ability to switch between tasks or ways of thinking) and inhibitory control (the ability to resist impulses and distractions and stay on task). Working memory (the ability to hold and manipulate information in a way that is important for learning, reasoning and problem-solving) and attention moved in the right direction, but these effects were small and not statistically significant.
Exactly how this works is not known; the review’s authors acknowledge that the trials did little to explore mechanisms. One leading theory, though, is that exercise boosts levels of neurotransmitters (brain chemicals) such as noradrenaline (also known as ‘norepinephrine’) and dopamine, which help sharpen alertness and focus. These chemicals act on a region called the ‘prefrontal cortex’ – the front part of the brain, just behind the forehead – which is important for, among other things, reasoning, problem-solving, planning, decision-making and self-control. Notably, cognitive flexibility and inhibitory control, the abilities that benefited most in this review, depend heavily on this part of the brain.
Some benefit appears soon after a single session, though the effect after just one day was small. The bigger gains came when exercise snacking was kept up over several weeks, and in real-world school and workplace settings rather than the laboratory. More intense snacks, and longer gaps between them, were also linked to greater benefits.
Again the review has not been peer-reviewed, and these findings are probably best seen as promising rather than definitive. However, I do think they likely add to the body of evidence which supports exercise snacks as a practical, real-world way to support physical and mental wellbeing.
At home, there are plenty of options for exercise snacks: a quick walk round the block, a minute or two on a mini-trampoline, or a few press-ups, squats or kettlebell swings.
In the office, options tend to be more limited. However, a brisk walk between calls, or taking the stairs rather than the lift throughout the day, may well be enough. Based on this research, it’s worth putting a bit of effort in – brisk rather than strolling – and spreading snacks through the day rather than bunching them together.
References:
1. Islam H, Gibala MJ, Little JP. Exercise snacks: a novel strategy to improve cardiometabolic health. Exercise and Sport Sciences Reviews. 2022;50(1):31–37.
2. Li G, Xia Y, Yin M, Han B, Li H, Li Y. Effects of exercise snacks on cognitive function: a systematic review and three-level meta-analysis. https://www.preprints.org/manuscript/202609.0087
