Exercise and Children: Better Brain Health, Less Obesity, Less Stress

Physically active young people can do better in school and improve their self-expression, self-confidence and social interaction compared with more sedentary children (WHO 2017). Indeed, two studies published in 2017 underscore the value of children getting plenty of exercise.

Let’s take a quick look at this research.

Study 1. Fitness and Academic Achievement

Kao, S-C., et al. 2017. Muscular and aerobic fitness, working memory, and academic achievement in children. Medicine & Science in Sports & Exercise, 49 (3), 500–508.

Experimental Approach

Historically, most studies on physical activity in youth have focused on the cognitive benefits of cardiovascular exercise, with improvements in cognitive control attracting particular interest as an outcome of such activity. Kao et al. (2017) explain cognitive control as a set of mental processes that manage goal-directed behavior. One of those processes, working memory, temporarily manages and stores information central to academic achievement.

Research findings have demonstrated that cardiorespiratory exercise contributes to working memory performance in preadolescent boys and girls, according to Kao and colleagues. However, they note that initial evidence has emerged to show that muscular fitness can also improve working memory and academic achievement. Thus, their own study aimed to determine and compare the effects of muscular fitness and cardiorespiratory exercise on working memory and academic achievement in youth.

Participants

The study worked with 44 boys and 35 girls (aged 9–11), following conventional informed-consent procedures for children. Participants were free of neurological disease and attention deficit disorder. All of them underwent a screening to make sure they could complete the study’s planned exercises. None of the children were involved in an individualized education program. A trained academic gave each of them the Kaufman Brief Intelligence Test—an individually administered test of verbal and nonverbal intelligence—to estimate their intelligence quotient (IQ).

Aerobic Fitness Assessment

A graded treadmill test determined maximal aerobic fitness. Speed remained constant (3.0 miles per hour), while grade increased 2.5% every 2 minutes until volitional exhaustion. After a 30-minute break, the researchers assessed muscular fitness.

Muscular Fitness Assessment

After instruction on proper form, the young participants did a battery of submaximal muscular fitness exercises, including lunge, front squat, pushup, bent-over row, shoulder press, calf raise and curl-up. Exercises used body weight or a dual-grip medicine ball (2.7–8.1 kilograms).

Once the researchers had determined the appropriate loading weight and felt confident the children knew proper exercise form, participants completed as many repetitions (with correct form) as possible in 30 seconds. To normalize potential differences in results due to body size, Kao et al. calculated strength by using muscular fitness indices that took body weight into account.

Cognition and Academic Achievement

The researchers used a child-friendly n-back (in this case, 2-back) task that has become a standard assessment for measuring working memory. This was a continuous-performance task. The children were presented with a sequence of stimuli and asked to indicate whenever the current stimulus matched the one from two steps earlier in the sequence.

Academic achievement was based on standardized mathematics and reading tests.

Results

The study results suggest a link between higher levels of aerobic/muscular
fitness and greater task-condition performance of working memory. Findings showed that muscular fitness may make unique contributions to working memory independent of aerobic fitness. On the other hand, greater aerobic fitness proved to be associated with better performance in algebra.

Recent research has shown that, during muscle contractions, skeletal muscle releases specialized immune cells (cytokines and peptides) that may uniquely affect brain metabolism and function; Kao and colleagues hypothesize that this influence may be more pronounced in people with greater muscular fitness. The researchers note that some health benefits of resistance training—reduced insulin resistance, improved metabolic control and decreased adiposity—have also been associated with enhanced working memory.

Take-Home Message

The well-known life-improving benefits of cardiorespiratory and muscular fitness also apply to children’s cognitive health. This study shows that for youth to gain optimal cognitive benefits from exercise, professionals should design programs that include aerobic and muscular fitness components.

Study 2: Fitness, Stress and Body Composition

Gerber, M., et al. 2017. Fitness, stress, and body composition in primary schoolchildren. Medicine & Science in Sports & Exercise, 49 (3), 581–87.

Experimental Approach

Research has demonstrated that children with obesity have an increased risk of developing hypertension, insulin resistance, endothelial dysfunction, nonalcoholic fatty liver disease, orthopedic disorders and chronic pain. Though findings on the underlying causes of childhood obesity are inconclusive, Gerber et al. (2017) noted that physical inactivity and psychological stress may be contributing factors. Thus, they wanted to determine whether physical activity and fitness positively affect the relationships between measures of psychosocial stress and obesity.

Participants

The study worked with 325 first-grade children (51% girls, 49% boys; median age 7.3 years) from public primary schools in Switzerland, following international informed-
consent guidelines.

Assessments

Parental questionnaires and reports helped the researchers assess stressors (peers, family, life events and school) and vigorous physical activity participation. To estimate maximal aerobic power, the scientists had the children do a standard 20-meter shuttle-run test, which involves running back and forth on a set course. The test began with a running speed of 5.0 mph and then increased 0.3 mph every minute at a constant pace, set by an audio signal. The test ended when the child was unable to continue the constant pace (going back and forth on the 20-meter run). The completed number of stages was used to estimate maximal aerobic consumption.

Obesity-related measures were body mass index (BMI), sum of skinfolds and waist circumference.

Results

Gerber et al. found that “children experiencing elevated school-related stress had lower body mass index, body fat, and waist circumferences if they had high fitness and physical activity levels, as compared with their less active and fit peers.”

Importantly, the study authors highlight current research showing a strong correlation between childhood obesity and adult obesity. Thus, successful adult obesity prevention may need to begin with childhood physical activity programs, which can then continue into the young-adult and adult years.

Gerber and associates also note that physically active children have a slightly lower stress-hormone response (i.e., cortisol, adrenaline, noradrenaline) to psychological stressors, according to research on Finnish children (Martikainen et al. 2013).

Take-Home Message

Young children should be encouraged to remain physically active in order to reduce excess weight and obesity. This may help them combat adult obesity and better manage psychological life stressors.

Inspirational Thoughts and Action Plan

Fitness professionals have a unique and valuable leadership opportunity to help children learn movement and behavioral skills needed to engage in lifelong physical activity. At facilities where you train, encourage more youth to try walking and bicycling to combat sedentary behavior. Expand the horizons for youth involvement to include aerobic and muscular fitness training, sports programs and healthy recreational activities. Expand your role in promoting physical activity for our nation’s young people. You can make a difference. Go for it!