Understanding the cognitive benefits of exercise for children
Does your child's daily schedule encourage physical fitness? Or is your kid stuck in a rut -- perhaps even a school system -- that leaves little time for physical activity?
We often hear about exercise as a remedy for poor health and child obesity. But exercise for children is important for other reasons too.
It appears to stimulate brain growth and boost cognitive performance. It helps kids focus. It may make it easier for kids to learn and achieve.
So when adults create environments that prevent kids from being active, we aren't only undermining their health. We're also making it harder for kids to succeed in school.
But how do we know all this?
At the Salk Institute, Henriette van Pragg and her colleagues
compared sedentary mice with mice that ran an average of 3 miles each
night on a running wheel (van Pragg et al 1999).
Compared with the couch potatoes, the aerobically-challenged mice showed dramatic brain growth.
Specifically, the hippocampus—-a brain region associated with learning and memory--was twice as large.
In addition, the brain cells of the aerobic mouse could sustain longer bouts of "long-term potentiation," the increased efficiency of communication between neurons that occurs after neurons fire.
Better learning, too
Did these changes translate into better learning? Indeed they did. Mice who exercised performed better on a spatial learning task (finding their way through a water maze).
Why does it work?
Exercise is known to improve mood. Might that explain these results? Perhaps animals learn better when they feel better.
The explanation sounds plausible and may account for some of the effect. But it seems pretty clear there is more going on.
Since the late 1990s, research has revealed that aerobic exercise
(For reviews, see Cotman and Berchtold 2002 and von Pragg 2008).
Much of what we know about the cognitive effects of exercise comes from brain research on rodents, not humans. But some studies have been conducted on kids, and the results suggest that aerobic exercise can make children more focused and less impulsive.
When kids have been challenged with cognitive tasks that require lots of concentration and attentional control, individuals with higher aerobic fitness have performed with more accuracy, and sometimes faster reaction times, too (Moore et al 2013; Wu et al 2011; Voss et al 2011; Hillman et al 2005; Hillman et al 2009b; Raine et al 2016).
For example, school children
were asked to view some images of animals and make quick judgments
about them ("Is it a cat or a dog?"), physically fit kids had faster reaction times, and their brains showed evidence of more
extensive processing during the task (Hillman et al 2005). Other brain research suggests that fit kids are better at filtering out task-irrelevant information (Kamijo et al 2015).
Studies also indicate that fit children tend to have greater brain volume in the hippocampus, a brain region associated with memory (Chaddock-Heyman et al 2014), and these kids show signs of enhanced long-term retention. In one study, kids memorized new places on a map equally well, regardless of their fitness levels. But when they were tested on their retention the following day, the higher fitness children performed better (Raine et al 2013).
Intriguing? Yes. But these studies report correlations only. They can't prove causation. What if more focused, quick-thinking kids are more likely to seek out physical activity? That could explain the results. We need randomized, controlled experiments (Janssen et al 2014). And in recent years, there have been several.
Exercise and attention
Does a quick bout of exercise make kids more attentive?
In one recent experiment, kids who ordinarily performed poorly on attention tasks improved their accuracy when tested shortly after "moderate acute exercise" -- 20 minutes of walking on a treadmill (Drollette et al 2014).
Another experiment randomly assigned 56 school kids to one of three morning school sessions:
who got two bouts of morning exercise performed better on a test of
attention, and this was true even after the researchers adjusted for
baseline differences in attention and children's involvement in sports
And what about ADHD? When researchers tested the effects of short-term exercise on kids diagnosed with ADHD, they found that aerobic activity gave these kids a special boost, altering their brain activity in ways that might enhance self-discipline (Pontifex et al 2013).
These studies address immediate, short-term responses to exercise, and lend support the idea that school recess periods -- breaks for play and physical activity -- can enhance attention in the classroom. But there are also studies that address long-term benefits of exercise for children.
For instance, what happens if you enroll previously sedentary kids in a program of daily physical exercise? One randomized, controlled study of overweight children found that 40 minutes a day of aerobic exercise improved executive function, that aspect of intelligence that helps us pay attention, plan, and resist distractions (Davis et al 2007).
Another experiment replicated these results, and found that 13 weeks of aerobic exercise was also linked with improved math skills and increased activity in the bilateral prefrontal cortex, a brain region associated with executive function (Davis et al 2011).
Similarly, when Keita Kamijo and colleagues randomly assigned 20 youngsters (aged 7-9 years) to an after-school exercise program, kids who got 70 minutes of moderate to vigorous physical activity each day showed improvements solving tasks that taxed executive control and working memory (Kamijo et al 2012). Kids in a control group did not.
And a recent randomized study of more than 220 school children found that kids assigned to engage in 60 minutes of daily, after-school aerobic activities performed better on tests of focus and cognitive flexibility--the ability to switch between tasks while maintaining speed and accuracy (Hillman et al 2014).
So we've got evidence that exercise can improve a child's ability to focus. But does that translate into better academic performance? There is reason to think so.
Physical exercise and academic achievement
Studies suggest that physical exercise yields short- and long-term benefits on achievement in the classroom.
For instance, one experiment found that a 20 minute session of walking boosted children's subsequent performance on tests of reading, spelling, and arithmetic (Hillman et al 2009a). Another study found that kids who exercised 10-20 minutes prior to a math test outperformed kids in sedentary control group (Howie et al 2015).
And the long-term? As noted above, one randomized study found that kids showed improved mathematics skills after a 13-week exercise program (Davis et al 2011), and other research indicates similar benefits.
In an experiment performed by Daniel Ardoy and colleagues on 67 adolescents, some kids were assigned to get 4 sessions each week of high intensity PE. After four months, these kids performed better than other kids on tests of cognitive ability and earned higher grades at school (Ardoy et al 2014). Adolescents assigned to less intense PE workouts showed no showed no cognitive improvements over kids in the control group (Ardoy et al 2014).
More recently, kids who were assigned a daily schedule with more physical activity breaks outperformed their control-group peers in mathematics and reading (Tomporowski 2016).
A safe bet...but make it fun
Can we assume that exercise will help every child perform better in school? Perhaps not. In some studies of aerobic exercise, the reported effects have been small or non-existent. As Caitlin Lees and Jessica Hopkins (2013) argue, we need more rigorous research to better understand what's going on. We need to learn more about the details -- including how the effects vary by intensity, frequency, and type of exercise being performed.
But the results aren't "mixed" in the sense that we don't know if exercise is good or bad for the brain. Clearly, it's good for the brain. Nor are the results "mixed" in the sense that we don't know if exercise during the school day helps or hurts academics.
When researchers conducted a meta-analysis of 59 studies published over the previous 60 years, they found that physical activity has a decidedly positive effect on children's achievement and cognitive outcomes (Fedewa and Ahn 2011).
There is no evidence that it's detrimental, which is striking if you consider that time spent by children in recess and physical education class is time diverted from academic study.
When schools have allocated more time for physical activity, they tend to see cognitive improvements. The worst case scenario is that kids become more fit and healthy, while their academic achievement levels remain the same (Keely and Fox 2009).
So school policies aimed cutting recess or PE -- in order to make more time for academics -- are misguided. We've got nothing to lose by encouraging kids to exercise, and much to gain. But there’s a catch: Exercise should be fun.
The mouse experiments are based on voluntary wheel-running. When rodents are forced to exercise, they don’t always reap the benefits.
Thus, it's important to find fun forms of aerobic exercise for children. Structured activities--like team sports or dance lessons--are good options. But so are nature walks, tree-climbing, roller-skating, and playing hide-and-seek.
In fact, play--like exercise--is good for the brain. Perhaps the most effective forms of exercise for children combine both high levels of physical activity and elements of play.
Altenburg TM, Chinapaw MJ, and Singh AS. 2015. Effects of one versus two bouts of moderate intensity physical activity on selective attention during a school morning in Dutch primary schoolchildren: A randomized controlled trial. J Sci Med Sport. pii: S1440-2440(15)00236-4.
Ardoy DN, Fernández-Rodríguez JM, Jiménez-Pavón D, Castillo R, Ruiz JR, and Ortega FB. 2014. A physical education trial improves adolescents' cognitive performance and academic achievement: the EDUFIT study. Scand J Med Sci Sports. 24(1):e52-61
Chaddock-Heyman L, Hillman CH, Cohen NJ, and Kramer AF. 2014. III. The importance of physical activity and aerobic fitness for cognitive control and memory in children. Monogr Soc Res Child Dev. 79(4):25-50.
Colcombe, S. & Kramer, A.F. 2003. Fitness effects on the cognitive function of older adults: A meta-analytic study. Psychological Science, 14, 125-130.
Cotman, C.W. & Berchtold, N.C. 2002. Exercise: a behavioral intervention to enhance brain health and plasticity. Trends in Neurosciences, 25 (6), 295-301.
Davis CL, Tomporowski PD, Boyle CA, Waller JL, Miller PH, Naglieri JA, Gregoski M. 2007. Effects of aerobic exercise on overweight children's cognitive functioning: a randomized controlled trial. Res Q Exerc Sport. 78(5):510-9.
Davis CL, Tomporowski PD, McDowell JE, Austin BP, Miller PH, Yanasak NE, Allison JD, Naglieri JA. 2011.Exercise improves executive function and achievement and alters brain activation in overweight children: A randomized, controlled trial. Health Psychol. 30(1):91-8
Dietrich, A. & Sparling, P.B. 2004. Endurance exercise selectively impairs prefrontal-dependent cognition. Brain and Cognition, 55 (3), 516-524.
Drollette ES, Scudder MR, Raine LB, Moore RD, Saliba BJ, Pontifex MB, Hillman CH. 2014. Acute exercise facilitates brain function and cognition in children who need it most: an ERP study of individual differences in inhibitory control capacity. Dev Cogn Neuroscience 7:53-64.
Fedewa AL and Ahn S. 2011. The effects of physical activity and physical fitness on children's achievement and cognitive outcomes: a meta-analysis. Res Q Exerc Sport. 82(3):521-35.
Guiney H and Machado L. 2012. Benefits of regular aerobic exercise for executive functioning in healthy populations. Psychonomic Bulletin & Review. DOI 10.3758/s13423-012-0345-4.
Howie EK, Schatz J, and Pate RR. 2015. Acute Effects of Classroom Exercise Breaks on Executive Function and Math Performance: A Dose-Response Study. Res Q Exerc Sport. 86(3):217-24.
Kamijo K, Takeda Y, Takai Y, Haramura M. 2015. Greater aerobic fitness is associated with more efficient inhibition of task-irrelevant information in preadolescent children. Biol Psychol. 110:68-74.
Kamijo K, Pontifex MB, O’Leary KC, Scudder MR, Wu C-T, Castelli DM, and Hillman CH. 2011. The effects of an afterschool physical activity program on working memory in preadolescent children. Dev Sci. 14(5): 1046–1058.
Keely TJH and Fox KR. 2009. The impact of physical activity and fitness on academic achievement and cognitive performance in children. Int Rev Sports Exercise Physiology 2(2): 198-214.
Hillman CH, Pontifex MB, Castelli DM, Khan NA, Raine LB, Scudder MR, Drollette ES, Moore RD, Wu CT, Kamijo K. 2014. Effects of the FITKids Randomized Controlled Trial on Executive Control and Brain Function. Pediatrics pii: peds.2013-3219. [Epub ahead of print]
Hillman CH, Buck SM, Themanson JR, Pontifex MB, Castelli DM. 2009a. Aerobic fitness and cognitive development: Event-related brain potential and task performance indices of executive control in preadolescent children. Dev Psychol. 45(1):114-29.
Hillman CH, Pontifex MB, Raine LB, Castelli DM, Hall EE, Kramer AF. 2009b. The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children. Neuroscience. 159(3):1044-54.
Hillman CH, Castelli DM, and Buck SM. 2005. Aerobic fitness and neurocognitive function in healthy preadolescent children. Medicine and science in sports and exercise 37(11): 1967-1974.
Kramer AF, Colcombe SJ, McAuley E, Scalf PE, and Erickson KI. 2005. Fitness, aging and neurocognitive function. Neurobiol Aging. 2005 Dec;26 Suppl 1:124-7.
Lees and Hopkins 2013. Effect of aerobic exercise on cognition, academic achievement, and psychosocial function in children: a systematic review of randomized control trials. Prev Chronic Dis. 10:E174.
Molteni, R., Wu, A., Vaynman, S., Ying, Z., Barnard, R.J. & Gómez-Pinilla, F. 2004. Exercise reverses the harmful effects of consumption of a high-fat diet on synaptic and behavioral plasticity associated to the action of brain-derived neurotrophic factor. Neuroscience, 123 (2), 429-440.
Moore RD, Wu CT, Pontifex MB, O'Leary KC, Scudder MR, Raine LB, Johnson CR, and Hillman CH. 2013. Aerobic fitness and intra-individual variability of neurocognition in preadolescent children. Brain Cogn. 82(1):43-57.
Pontifex MB, Saliba BJ, Raine LB, et al. 2013. Exercise improves behavioral, neurocognitive, and scholastic performance in children with attention-deficit/hyperactivity disorder. J Pediatr. 162:543-551.
Raine LB, Scudder MR, Saliba BJ, Kramer AF, and Hillman C. 2016. Aerobic Fitness and Context Processing in Preadolescent Children. J Phys Act Health.13(1):94-101.
Raine LB, Lee HK, Saliba BJ, Chaddock-Heyman L, Hillman CH, and Kramer AF. 2013. The influence of childhood aerobic fitness on learning and memory. PLoS One. 2013 Sep 11;8(9):e72666.
Schmidt M, Jäger K, Egger F, Roebers CM, and Conzelmann A. 2015. Cognitively Engaging Chronic Physical Activity, But Not Aerobic Exercise, Affects Executive Functions in Primary School Children: A Group-Randomized Controlled Trial. J Sport Exerc Psychol. 37(6):575-91.
Tomporowski, P.D. 2003. Effects of acute bouts of exercise on cognition. Acta Psychol (Amst), 112, 297-324.
Tomporowski PD. 2016. Exercise and Cognition. Pediatr Exerc Sci. 28(1):23-7.
van Praag H, Christie BR, Sejnowski TJ, Gage FH 1999. Running enhances neurogenesis, learning, and long-term potentiation in mice. Proc Natl Acad Sci USA, 96, 13427-31.
Voss MW, Chaddock L, Kim JS, Vanpatter M, Pontifex MB, Raine LB, Cohen NJ, Hillman CH, and Kramer AF. 2011. Aerobic fitness is associated with greater efficiency of the network underlying cognitive control in preadolescent children. Neuroscience 199:166-76.
Wu CT, Pontifex MB, Raine LB, Chaddock L, Voss MW, Kramer AF, Hillman CH. 2011. Aerobic fitness and response variability in preadolescent children performing a cognitive control task. Neuropsychology. 25(3):333-41.
Content of "The cognitive benefits of exercise for children" last modified 3/15
Image credits for "Exercise for children":
Title image of kids running by Jackson Elizabeth, US Fish and Wildlife
Image of child running on the beach by Black Imp Photography
Imagine of boys playing with ball by cahilus / wikimedia commons
Image of girls on swing by Hartcreations/istock