Fitter bodies, fitter brains

Is the structure and function of the brain different in fitter people compared to less fit individuals? The short answer is yes, there is established research that supports the idea that regular physical activity is responsible for important structural changes in the brain, and this can be seen in people who have different physical fitness levels.

Regular physical activity affects brain function at the cellular, systemic and behavioural levels. Physical activity is critical for healthy brain development, which can lead to better academic and learning outcomes in children. For example, children who are active for as little as 20 minutes a day have better test scores1, attention 2 and more active brains overall 2 compared to less physically active children. Physical activity benefits to cognitive development are apparent from the very beginning of life (e.g. birth through to 5 years of age) 3. It has been shown that not moving enough negatively influences brain health, counteracting the benefits you would normally see when performing physical activity 4

Indeed, not all sedentary time is created equal; a recent systematic review found that although reading is beneficial to cognitive development in early childhood (i.e. birth to age 5 years) screen time is not 5

We know that physical activity increases blood oxygen saturation 6 and angiogenesis 7 in brain areas that are responsible for task performance. More specifically, the positive effects of physical activity on prefrontal cortex and hippocampus brain areas have been observed in several studies 8–10. Even the molecular architecture and behaviour of the basal ganglia has been implicated to be directly influenced by physical activity 11. In a recent meta-analysis on children’s physical activity, academic performance and cognitive function it was found that 13 out of 20 physical activity interventions had significant, positive effects on academic performance 12. There is indeed a strong mind-body connection, where fitter bodies create the environment for fitter brains to flourish 13.

FitBack’s authors 15–20 and others 21–26 have shown a positive relationship of cardiorespiratory fitness with behavioural and brain outcomes in young people. At a behavioural level, the different physical fitness tests (i.e., the ALPHA-fitness battery 27) included in the FitBack project have shown to be positively related TO a better cognitive performance, better executive functioning, better intelligence and better academic performance 17,19. At a brain structural level, we have found that while cardiorespiratory is mainly related to grey matter (i.e., total and regional cortical and subcortical volume, and cortical thickness) 28,29, muscular strength is selectively related to white matter volume and integrity) 30,31. In addition, cardiorespiratory fitness is related to resting-state functional connectivity between hippocampal subregions and frontal regions 1>.

To sum up, children with higher fitness level have healthier brains. This has been simply illustrated by a study from the ActiveBrains projects that has shown for first time that fitter children have larger brains 18, as in the following infographic.

Fitter kids have bigger brains


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  2. Hillman C.H., Pontifex M.B., Raine L.B., Castelli D.M., Hall E.E., Kramer A.F. The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children. Neuroscience. 2009;159(3):1044-1054.
  3. Carson V, Hunter S, Kuzik N, et al. Systematic review of physical activity and cognitive development in early childhood. J Sci Med Sport. 2016;19(7):573-578.
  4. Voss MW, Carr L.J., Clark R, Weng T. Revenge of the “sit” II: Does lifestyle impact neuronal and cognitive health through distinct mechanisms associated with sedentary behavior and physical activity? Ment Health Phys Act. 2014;7(1):9-24.
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  8. Kramer A.F., Erickson KI. Capitalizing on cortical plasticity: influence of physical activity on cognition and brain function. Trends Cogn Sci. 2007;11(8):342-348.
  9. Hillman C.H., Erickson KI, Kramer AF. Be smart, exercise your heart: exercise effects on brain and cognition. Nat Rev Neurosci. 2008;9(1):58-65.
  10. Bherer L, Erickson KI, Liu-Ambrose T. A review of the effects of physical activity and exercise on cognitive and brain functions in older adults. J Aging Res. 2013;2013.
  11. Chaddock LE. KI Shaurya Prakash R., VanPatter M., Voss MW, Pontifex MB, Raine LB, Hillman CH, Kramer AF (2010) Basal Ganglia Volume Is Associated with Aerobic Fitness in Preadolescent Children. Dev Neurosci. 32:249-256.
  12. Sember V, Jurak G, Kovač M, Morrison SA, Starc G. Children’s Physical Activity, Academic Performance, and Cognitive Functioning: A Systematic Review and Meta-Analysis. Front Public Heal. 2020;8.
  13. Sember V, Morrison SA. The Mind-Body Connection: How Physical Activity and Physical Fitness Affect Academic Performance. University of Primorska Press; 2018
  14. Sember V, Morrison SA. The Mind-Body Connection: How Physical Activity and Physical Fitness Affect Academic Performance. University of Primorska Press; 2018. 
  15. Esteban-Cornejo I, Stillman CM, Rodriguez-Ayllon M, et al. Physical fitness, hippocampal functional connectivity and academic performance in children with overweight/obesity: The ActiveBrains project. Brain Behav Immun. 2021;91:284-295. 
  16. Mora‐Gonzalez J, Rodríguez‐López C, Cadenas‐Sanchez C, et al. Active commuting to school was inversely associated with academic achievement in primary but not secondary school students. Acta Paediatr. 2017;106(2):334-340. 
  17. Cadenas-Sanchez C, Migueles JH, Esteban-Cornejo I, et al. Fitness, physical activity and academic achievement in overweight/obese children. J Sports Sci. 2020;38(7):731-740. 
  18. Cadenas‐Sanchez C, Migueles JH, Erickson KI, Esteban‐Cornejo I, Catena A, Ortega FB. Do fitter kids have bigger brains? Scand J Med Sci Sports. 2020;30(12):2498-2502.
  19. Mora-Gonzalez J, Esteban-Cornejo I, Cadenas-Sanchez C, et al. Physical fitness, physical activity, and the executive function in children with overweight and obesity. J Pediatr. 2019;208:50-56. 
  20. Ortega FB, Campos D, Cadenas-Sanchez C, et al. Physical fitness and shapes of subcortical brain structures in children. Br J Nutr. 2019;122(s1):S49-S58. 
  21. Chaddock L, Erickson KI, Prakash RS, et al. Basal ganglia volume is associated with aerobic fitness in preadolescent children. Dev Neurosci. 2010;32(3):249-256. 
  22. Chaddock L, Erickson KI, Prakash RS, et al. A neuroimaging investigation of the association between aerobic fitness, hippocampal volume, and memory performance in preadolescent children. Brain Res. 2010;1358:172-183. 
  23. Donnelly JE, Hillman CH, Castelli D, et al. Physical activity, fitness, cognitive function, and academic achievement in children: a systematic review. Med Sci Sports Exerc. 2016;48(6):1197. 
  24. Etnier JL, Nowell PM, Landers DM, Sibley BA. A meta-regression to examine the relationship between aerobic fitness and cognitive performance. Brain Res Rev. 2006;52(1):119-130. 
  25. Santana CCA, Azevedo LB, Cattuzzo MT, Hill JO, Andrade LP, Prado WL. Physical fitness and academic performance in youth: A systematic review. Scand J Med Sci Sports. 2017;27(6):579-603. 
  26. Marques A, Santos DA, Hillman CH, Sardinha LB. How does academic achievement relate to cardiorespiratory fitness, self-reported physical activity and objectively reported physical activity: a systematic review in children and adolescents aged 6–18 years. Br J Sports Med. 2018;52(16):1039. 
  27. Ruiz JR, Castro-Piñero J, España-Romero V, et al. Field-based fitness assessment in young people: the ALPHA health-related fitness test battery for children and adolescents. Br J Sports Med. 2011;45(6):518-524. 
  28. Esteban-Cornejo I, Cadenas-Sanchez C, Contreras-Rodriguez O, et al. A whole brain volumetric approach in overweight/obese children: Examining the association with different physical fitness components and academic performance. The ActiveBrains project. Neuroimage. 2017;159:346-354. 
  29. Esteban-Cornejo I, Mora-Gonzalez J, Cadenas-Sanchez C, et al. Fitness, cortical thickness and surface area in overweight/obese children: The mediating role of body composition and relationship with intelligence. Neuroimage. 2019;186:771-781. 
  30. Rodriguez-Ayllon M, Esteban-Cornejo I, Verdejo-Román J, et al. Physical fitness and white matter microstructure in children with overweight or obesity: the ActiveBrains project. Sci Rep. 2020;10(1):1-9. 
  31. Esteban-Cornejo I, Rodriguez-Ayllon M, Verdejo-Roman J, et al. Physical fitness, white matter volume and academic performance in children: findings from the ActiveBrains and FITKids2 projects. Front Psychol. 2019;10:208. 

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