Fitness and Intelligence

A young boy is afraid of the dark. How will he find the courage to face his blackened room when the lights go out at bedtime? He must either realize he has nothing to fear in the dark, or he must have confidence in his own strength to contest the things he fears. In time, he will learn the absence of light does not change the basic circumstances of his surroundings. If he is safe in his bedroom with his lights on, he remains safe when the lights go out. He will learn to recognize the shadows of his room and noises of his house as bookcases and creaky floorboards, and know they can do him no harm. Or perhaps he scored the winning goal in a soccer game at school that day. Perhaps he defended himself against a bully. Undoubtedly, he will feel more self-confident in light of these physical accomplishments, maybe confident enough to face whatever comes in the dark. So either greater intelligence or greater physical prowess will contribute to his discovery of courage. And once he finds this courage, he will have a greater urge to further satisfy his curiosity about the darkness and to find more opportunities for physical achievement.

Fitness and IntelligenceThe previous example illustrates a complementary relationship between scalable, secondary virtues. Courage, intelligence and physical fitness combine to support and strengthen one another, and, as I intend to argue at a later date, help promote the primary ethical precept of human inviolability. However, I should first begin by providing further evidence for the relationship between secondary virtues, and the role played by physical fitness in particular. In this essay, I examine data which supports the connection between fitness and intelligence. A variety of research demonstrates increased physical activity and fitness improves learning ability and increases cognitive performance over time. While some evidence exists in support of the converse relation (that increased mental activity and intelligence are correlated with improved physical fitness), further study is required to substantiate that claim.

A 2013 study by researchers at the University of Illinois tested forty-eight nine- and ten-year-old children on their ability to learn new information. The study cited previous research which demonstrated a relationship between lower physical fitness and reduced academic achievement and cognitive function for tasks requiring perception, memory and cognitive control. The Illinois researchers selected twenty-four students in the top 30% and twenty-four students in the bottom 30% of aerobic fitness for their age and gender as measured by a treadmill test. Each group contained an approximately equal number of boys and girls with no significant differences in socioeconomic status, ADHD symptoms or scores on an intelligence test. The scientists asked the students to use an iPad to learn the made-up names of ten fictional regions on a map and tested their memories the following day. Within each group of twenty-four, some students only studied on the first day while others received mock tests during their study sessions. On the test day, students in each group were tested either by free recall or cued recall.

Though the researchers observed no differences in initial learning ability, the children in the high-fitness group outperformed those in the low-fitness group during testing, with the former averaging 54.2% correct responses to the latter’s 44.2% correct. The disparity was further exaggerated with the less successful, study-only strategy; high-fitness students outscored low-fitness students 43.0% to 25.8% when both were subject to this condition. Based on these results, the researchers concluded that improved fitness can boost learning and memory in children, and that the fitness-associated performance benefits are greatest in more challenging initial learning conditions.1,2

Furthermore, as demonstrated by a 2013 study by United Kingdom researchers, increased physical activity is correlated with long-term improvements in academic performance. The study measured the amount of time 5,000 eleven-year-olds born between 1991 and 1992 participated in daily physical activity over three to seven days, as well as how intensely they exercised using an accelerometer. The researchers then compared the children’s activity levels with their academic performance in English, math and science, and found the more moderate to vigorous physical activity a child had, the higher they scored on their tests. The activity-associated performance increase was especially true for girls and their science scores, and this relationship persisted as the girls aged. In general, physical activity at age 11 was linked to academic performance at age thirteen for both boys and girls. For boys ages fifteen and sixteen, each seventeen-minute exercise period produced an increase in the students’ academic scores, while eleven-year-old girls saw a similar jump in their scores for every twelve minutes a day they exercised.3

The relationship between physical activity and cognitive performance holds for a range of ages. A 2001 study published in the Annals of Behavior Medicine demonstrated that senior citizens who walk regularly showed significant improvement in memory skills compared to their more sedentary counterparts. Walking also improved the subjects’ learning ability, concentration and abstract reasoning, and researchers observed that 57% of people who walked as little as twenty minutes a day reduced their risk of stroke.4 A University of California study observed a positive correlation between brain function and physical activity level (including routine walking and stair-climbing) in a sample of 6,000 women over an eight-year period. 24% of the women who walked the least (one half-mile per week) showed significant declines in their cognitive test scores, versus only 17% of the most active women, who averaged seventeen miles per week. For every extra mile the subjects walked per week, researchers observed an average of 13% lower chance of cognitive decline.5

These studies, and others like them, demonstrate a strong correlation between increased physical activity and improved cognitive ability. But does the reverse relationship hold? Does high cognitive activity correspond to increased physical fitness? Perhaps, according to research at the Cleveland Clinic Foundation, where scientists discovered humans can strengthen a muscle just by thinking about exercising it. For five minutes a day, five days per week over twelve weeks, thirty healthy young adults imagined using either the muscle of their little finger or their elbow flexor. Subjects were instructed to think as strongly as they could about moving the muscle in question and to make the imaginary movement feel as real as possible. Compared to a control group which performed no imaginary exercises and displayed no strength gains, the subjects who focused on moving their little finger increased their pinky muscle strength by 35%, while the other group increased elbow flexor strength by 13.4%. Brain scans taken before and after the study showed greater and more focused activity in the prefrontal cortex, suggesting the strength gains resulted from improvements in the subjects’ brains’ ability to signal the target muscle.6

Strong evidence exists to support the claim that higher levels of physical activity and fitness are correlated with increased learning capacity and cognitive ability. Evidence of the mind’s ability to create physical strength gains lends credence to the converse relationship as well. Further evidence of this association would have to show that higher levels of mental stimulation and intelligence are correlated with increased physical capabilities. The research done by the Cleveland Clinic Foundation appears to satisfy this requirement, since a certain level of cognitive ability is required to achieve the requisite mental focus and concomitant strength gains; however, a demonstration that more intelligent subjects achieve greater physical improvements would go farther to substantiate this claim. Nevertheless, the studies presented here lend significant support to the complementary relationship between fitness and intelligence.


  1. Raine, Lauren B., et al. “The Influence of Childhood Aerobic Fitness on Learning and Memory.” Plos One. 11 Sept. 2013. Online. 29 Nov. 2013.
  2. Kaplan, Karen. “Physical Fitness boost brainpower in kids, study finds.” Los Angeles Times. 11 Sept. 2013. Online. 29 Nov. 2013.,0,6326552.story#axzz2nrpOEGui.
  3. Sifferlin, Alexandra. “Study: More Active Teens Get Higher Test Scores.” 22 Oct. 2013. Online. 29 Nov. 2013.
  4. Annals of Behavioral of Medicine, August 2001. Cited in “The Human Brain.” The Franklin Institute. Online. 29 Nov. 2013.
  5. Journal of Applied Psychology, October 2000. Cited in “The Human Brain.” The Franklin Institute. Online. 29 Nov. 2013.
  6. Society for Neuroscience, Annual Meeting, November 11, 2001. Cited in “The Human Brain.” The Franklin Institute. Online. 29 Nov. 2013.