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Research review

How Does Exercise Affect Brain Health and Cognition?

By LaserMind Team ·

A woman jogging in a park in the evening sun
Photo: Tirachard Kumtanom on Pexels

The claim and where it comes from

"Exercise is good for your brain" is a common piece of brain-health advice. The idea rests partly on epidemiological research suggesting that physical activity benefits cognition [1], and partly on biology: in a well-known trial, a year of walking increased the size of the hippocampus in older adults [2].

Neither of those shows how much regular exercise improves thinking. That question needs randomised trials that measure cognition, and syntheses of those trials. This review looks at what they found, in whom, and why their conclusions differ.

What the studies measured

The research divides into two questions:

  • Chronic exercise: weeks or months of regular training, compared with a control group, with thinking tests before and after.
  • Acute exercise: one session, such as 20 minutes of cycling, with tests during or soon after it.

The outcomes are scores on cognitive tests, usually grouped as general cognition, memory and executive function (planning, inhibition, working memory and switching). The tests varied widely between studies, and many were designed mainly to detect impairment [3]. The populations range from children to people in their eighties, and from healthy volunteers to people with clinical conditions, which turns out to matter a great deal.

What the meta-analyses found

Adults over 50

A meta-analysis of randomised trials in community-dwelling adults older than 50 analysed 333 effect sizes from 36 studies [4]. Exercise improved cognitive function by a standardised effect of 0.29, and aerobic exercise, resistance training, multicomponent training and tai chi each showed a significant effect [4]. Sessions of 45–60 minutes at moderate intensity or higher were associated with benefits, and the results did not depend on the cognitive domain tested or on whether participants had cognitive impairment [4].

All ages, including clinical groups

The broadest synthesis is an umbrella review of 133 systematic reviews, covering 2,724 randomised trials and 258,279 participants of all ages, healthy and clinical [3]. Exercise improved general cognition (standardised effect 0.42), memory (0.26) and executive function (0.24) [3]. Memory and executive-function gains were larger in children and adolescents than in adults, low- and moderate-intensity exercise generally had larger effects, and the results held after excluding reviews rated low or critically low in quality [3].

The review also reports its weaknesses. On a standard quality checklist (AMSTAR-2), 94 of the 133 reviews were rated critically low and 19 low; only 20 were rated high [3]. The results varied a great deal between reviews, and after adjusting for possible publication bias, the estimated effects were about 0.3 for general cognition, 0.24 for memory and 0.20 for executive function [3]. Only five of the reviews were about resistance training on its own [3].

Healthy people only, with a stricter analysis

A 2023 umbrella review asked a narrower question: does regular exercise cause better cognition in healthy people? It examined 24 meta-analyses limited to randomised trials [5]. Most of them reported a positive overall effect, but the authors found low statistical power in the primary trials, selective inclusion of studies, publication bias and large variation in analytic decisions [5].

They then pooled the primary trials themselves. The benefit was small (d = 0.22), became substantially smaller after accounting for whether the control group was active and for differences between groups at the start (d = 0.13), and was negligible after correcting for publication bias (d = 0.05, with a confidence interval that included zero) [5]. The authors called for caution in claims and recommendations linking regular exercise to cognitive benefits in healthy people until more reliable causal evidence accumulates [5]. A correction published in 2026 clarified that the pooled analysis used 100 non-redundant trials and stated that the estimates and conclusions were unchanged [6].

Healthy older adults: a Cochrane review and a large trial

A Cochrane review of aerobic exercise in cognitively healthy people over 55 included 12 trials with 754 participants, lasting 8 to 26 weeks [7]. It found no evidence of benefit in any cognitive domain, compared either with another activity or with no intervention, even in trials where the exercise had improved fitness [7]. All the trials had a moderate or high risk of bias in at least some respects, and the review's searches ended in 2013 [7].

The LIFE trial randomly assigned 1,635 sedentary adults aged 70 to 89, who were at risk of mobility problems, to a 24-month physical activity program of walking, strength and flexibility exercises, or to health education workshops with some stretching; cognition was a secondary outcome [1]. After two years, scores on a processing-speed test and a word-list memory test did not differ between groups, and neither did any other cognitive measure [1]. In two subgroups, people aged 80 or over and people with poorer physical function at the start, executive function changed more favourably with exercise [1].

A single session of exercise

A 2012 meta-analysis pooled 79 studies with 2,072 participants, mostly young adults, who did a cognitive task during, immediately after or some time after one bout of exercise [8]. The overall effect was positive and small (g = 0.097), and similar in all three timings [8]. When people were tested within 10 minutes of finishing, performance was worse, and the largest benefits appeared 11–20 minutes after exercise [8]. After exercise, the clearest effects were on executive-function tasks, and memory measures showed no significant change [8].

A 2024 Bayesian meta-analysis of 113 studies with 4,390 healthy young adults reached a similar conclusion: a small benefit for cognition (g = 0.13) and faster reaction times, with improvements in working memory and inhibition among the executive-function tasks [9].

So a walk before studying may help a little, especially if you leave a few minutes before you start, but the effects in these studies were small and were measured during or soon after the exercise.

Landmark single studies: exercise and the hippocampus

A widely cited trial randomly assigned older adults to a year of walking three days a week, building up to 40 minutes a session, or to stretching and toning classes; 120 participants with complete brain scans were analysed [2]. In the walking group the hippocampus, a brain region involved in memory, grew by about 2%, while it shrank by about 1.4% in the control group [2].

The memory result is easy to misread. Both groups improved on the spatial memory test, and the walking group did not improve more than the stretching group [2]. Within the walking group, people whose hippocampus grew more also improved more on the memory test [2].

This is one study, and its main finding is about brain structure. A later meta-analysis of 14 controlled trials (737 participants) found no significant effect of aerobic exercise on total hippocampal volume, but a positive effect on the left hippocampus, which came mainly from less shrinkage over time in the exercise groups [10]. Findings like these are useful background on how exercise might affect the brain. They are not evidence that exercise improves memory in daily life. What is neuroplasticity? explains why a change on a scan and a change in thinking are separate questions.

Why the results conflict

Different populations. The umbrella review that found small-to-moderate effects included children and clinical groups, and found larger gains in children and adolescents [3]. The review that found negligible effects after bias correction was limited to healthy people [5]. Both can be right: effects may be larger in some groups than in healthy adults.

Control groups. When the comparison group does an active alternative, such as stretching classes or health education, the benefit shrinks [5]. In the hippocampus trial, the stretching group improved on the memory test as much as the walkers [2].

Small trials and selective publication. Many primary trials had low statistical power, and correcting for publication bias removed most of the pooled effect in healthy people [5]. Most reviews in the larger umbrella review were rated critically low in quality [3].

Dose findings that disagree. One meta-analysis linked benefits to sessions of 45–60 minutes at moderate intensity or more [4]. The umbrella review found larger effects for low- and moderate-intensity exercise and for shorter interventions of one to three months [3]. A meta-regression of 80 trials in healthy people found a small summary effect, larger after coordinative exercise than other types, and smaller in women than in men [11]. These comparisons are made between studies, not within them, so none of them is a reliable guide to the best type or dose.

What about dementia?

The trials in this review measured test scores over weeks to two years. They were not designed to show who later develops dementia. In the LIFE trial, which did track it, mild cognitive impairment or dementia occurred in 13.2% of the exercise group and 12.1% of the health-education group over two years, a difference that was not significant [1]. Whether exercise changes anyone's long-term risk of dementia is not established by this evidence, and we make no such claim. If you are worried about your memory or your risk, talk to a doctor.

Exercise guidelines are health guidance

The World Health Organization's 2020 guidelines recommend that adults do 150–300 minutes of moderate-intensity aerobic activity a week, or 75–150 minutes of vigorous activity, or an equivalent combination, plus muscle-strengthening activities on two or more days a week [12]. Older adults are advised to add varied activity that emphasises balance and strength on three or more days a week, and the guidelines stress that some physical activity is better than none [12].

These recommendations cover health as a whole, from mortality, heart disease and diabetes to mental health, cognitive health and sleep, and rest on reviews of the associations between activity and those outcomes [12]. They tell you how much to move for your health. They do not measure how much exercise improves performance on thinking tests, which is the question of this review, so we cite them as health guidance only. If you have a health condition or have not exercised for a long time, check with a doctor before starting.

What this means at LaserMind

LaserMind grades aerobic exercise and resistance training E2 (conditional evidence) for general cognition. The broad umbrella review found small average benefits [3], but most of its reviews were rated critically low in quality, and the stricter analyses in healthy people found the benefit negligible or absent [5][7][1]. Until the evidence agrees, we do not call it strong. The method pages and our brain health habits page present exercise as a long-term habit for health, not a quick fix for memory or focus.

In practice:

  • Exercise for your health first. The guidelines give the targets [12], and any benefit for thinking is a possible bonus.
  • Choose what you will keep doing. The reviews disagree on the best type and dose, so a routine you can keep up is a better target than a perfect plan.
  • Don't expect an instant boost. Single sessions had small effects, and performance right after hard exercise can be worse [8].
  • Be sceptical of brain-scan claims. A larger hippocampus in one trial did not come with better memory than in the control group [2].

What the research says

◆ SupportedAcross many trials and populations, regular exercise improved scores on tests of general cognition, memory and executive function on average, with small-to-moderate effects that varied widely [3][4].
◇ ConditionalThe size of the benefit in healthy people: after accounting for active controls, baseline differences and publication bias, it became negligible in one umbrella review [5], and a Cochrane review and a large two-year trial in older adults found no cognitive benefit [7][1]. Single sessions had small effects that depended on timing and on the task [8][9]. Aerobic exercise increased hippocampal volume in one trial [2]; across trials it mainly reduced shrinkage of the left hippocampus [10].
✕ Not establishedThe best type, intensity or amount of exercise for thinking [11]. That exercise keeps dementia away: in the one large trial that tracked it, new cases did not differ [1].

Try it on LaserMind

▶ Reflection Prompts

Once a week, add your active minutes to the check-in note, next to your focused minutes and sleep, and compare only with your own earlier weeks.

What research has not established

  • Most trials measured cognition with laboratory or screening tests over weeks or months. They say little about everyday thinking or about decades of exercise.
  • The two umbrella reviews used different methods and populations, so their numbers are not directly comparable. One pooled effects reported by reviews across healthy and clinical groups [3]; the other re-analysed primary trials in healthy people only [5].
  • Participants always know whether they are exercising. An active control group rules out effects of expectation only if both groups expect to improve as much, which almost no psychological intervention studies check [13].
  • The hippocampus trial and the LIFE trial each studied older adults; their results may not apply to younger people.
  • Moderator findings on type, intensity and duration come from comparisons between studies and disagree with each other.

Frequently asked questions

Should I exercise before an exam or a study session? A short walk is a reasonable choice, but don't expect much. In the 2012 meta-analysis, effects were small, memory measures did not change significantly, and people tested within 10 minutes of finishing did worse [8].

Which kind of exercise is best for the brain? The evidence cannot say. Aerobic, resistance, multicomponent training and tai chi all had positive effects in one meta-analysis of older adults [4], and the reviews disagree on intensity and type. Pick something you enjoy and will keep up, within the health guidelines.

Does exercise lower the risk of dementia? That has not been shown in trials. In the LIFE trial, two years of structured activity did not change how many older adults developed mild cognitive impairment or dementia [1]. If you are concerned about your memory, see a doctor.

What the research says

Last evidence check 2026-10-17
Conditional evidence

An umbrella review of 133 systematic reviews found that exercise, including aerobic and resistance training, improved general cognition, memory and executive function; effects were small, varied between groups, and most of the reviews were rated critically low in quality. Other abilities [3]

Not supported

In healthy people, a stricter umbrella review of randomised trials found the benefit negligible after correcting for publication bias, and a Cochrane review and a two-year trial of 1,635 older adults found no cognitive benefit. Other abilities [5][7][1]

Conditional evidence

In a one-year trial with older adults, walking three times a week increased the size of the hippocampus by about 2%. Spatial memory improved about as much in the stretching control group; within the walking group, a larger increase went with a larger memory gain. Health [2]

References

  1. Sink, K. M., Espeland, M. A., Castro, C. M., Church, T., Cohen, R., Dodson, J. A., Guralnik, J., Hendrie, H. C., Jennings, J., Katula, J., Lopez, O. L., McDermott, M. M., Pahor, M., Reid, K. F., Rushing, J., Verghese, J., Rapp, S., & Williamson, J. D. (2015). Effect of a 24-Month Physical Activity Intervention vs Health Education on Cognitive Outcomes in Sedentary Older Adults: The LIFE Randomized Trial. Jama, 314(8), 781. https://doi.org/10.1001/jama.2015.9617
  2. Erickson, K. I., Voss, M. W., Prakash, R. S., et al. (2011). Exercise training increases size of hippocampus and improves memory. PNAS, 108(7), 3017–3022. https://doi.org/10.1073/pnas.1015950108
  3. Singh, B., et al. (2025). Effectiveness of exercise for improving cognition, memory and executive function: A systematic umbrella review and meta-meta-analysis. British Journal of Sports Medicine. https://doi.org/10.1136/bjsports-2024-108589
  4. Northey, J. M., Cherbuin, N., Pumpa, K. L., Smee, D. J., & Rattray, B. (2018). Exercise interventions for cognitive function in adults older than 50: a systematic review with meta-analysis. British Journal of Sports Medicine, 52(3), 154–160. https://doi.org/10.1136/bjsports-2016-096587
  5. Ciria, L. F., Román-Caballero, R., Vadillo, M. A., Holgado, D., Luque-Casado, A., Perakakis, P., & Sanabria, D. (2023). An umbrella review of randomized control trials on the effects of physical exercise on cognition. Nature Human Behaviour, 7(6), 928–941. https://doi.org/10.1038/s41562-023-01554-4
  6. Ciria, L. F., Román-Caballero, R., Vadillo, M. A., Holgado, D., Luque-Casado, A., Perakakis, P., & Sanabria, D. (2026). Author Correction: An umbrella review of randomized control trials on the effects of physical exercise on cognition. Nature Human Behaviour. https://doi.org/10.1038/s41562-026-02532-2
  7. Young, J., Angevaren, M., Rusted, J., & Tabet, N. (2015). Aerobic exercise to improve cognitive function in older people without known cognitive impairment. Cochrane Database of Systematic Reviews, 2015(4). https://doi.org/10.1002/14651858.CD005381.pub4
  8. Chang, Y. K., Labban, J. D., Gapin, J. I., & Etnier, J. L. (2012). The effects of acute exercise on cognitive performance: A meta-analysis. Brain Research, 1453, 87–101. https://doi.org/10.1016/j.brainres.2012.02.068
  9. Garrett, J., Chak, C., Bullock, T., & Giesbrecht, B. (2024). A systematic review and Bayesian meta-analysis provide evidence for an effect of acute physical activity on cognition in young adults. Communications Psychology, 2(1), 82. https://doi.org/10.1038/s44271-024-00124-2
  10. Firth, J., Stubbs, B., Vancampfort, D., Schuch, F., Lagopoulos, J., Rosenbaum, S., & Ward, P. B. (2018). Effect of aerobic exercise on hippocampal volume in humans: A systematic review and meta-analysis. NeuroImage, 166, 230–238. https://doi.org/10.1016/j.neuroimage.2017.11.007
  11. Ludyga, S., Gerber, M., Pühse, U., Looser, V. N., & Kamijo, K. (2020). Systematic review and meta-analysis investigating moderators of long-term effects of exercise on cognition in healthy individuals. Nature Human Behaviour, 4(6), 603–612. https://doi.org/10.1038/s41562-020-0851-8
  12. Bull, F. C., Al-Ansari, S. S., Biddle, S., Borodulin, K., Buman, M. P., Cardon, G., Carty, C., Chaput, J.-P., Chastin, S., Chou, R., Dempsey, P. C., DiPietro, L., Ekelund, U., Firth, J., Friedenreich, C. M., Garcia, L., Gichu, M., Jago, R., Katzmarzyk, P. T., … Willumsen, J. F. (2020). World Health Organization 2020 guidelines on physical activity and sedentary behaviour. British Journal of Sports Medicine, 54(24), 1451–1462. https://doi.org/10.1136/bjsports-2020-102955
  13. Boot, W. R., Simons, D. J., Stothart, C., & Stutts, C. (2013). The Pervasive Problem With Placebos in Psychology: Why Active Control Groups Are Not Sufficient to Rule Out Placebo Effects. Perspectives on Psychological Science, 8(4), 445–454. https://doi.org/10.1177/1745691613491271