Ever since those sane Romans, we have known that exercise is good for body and mind. But it has only recently become clear just how good for the brain vigorous exercise is. It not only cheers you up: it helps you think.
A new international review of 106 studies on fitness and health in children found far more than the physical benefits doctors were expecting. It concluded that improvements in cardiorespiratory fitness have short- term and long-term positive effects on depression, anxiety, mood status and self-esteem in young people, and are also associated with a higher academic performance. So it is all the more sad that two British studies, released at the same time as the research review, show how dramatically short of exercise children are.
Monitoring actual levels of physical activity by using portable recording devices, both studies find that only 2.5 per cent of our school-age children achieve the current (very modest) recommended hour a day. Worse still, these studies show that children's activity levels have been drastically overestimated, with true levels likely to be about six times lower than official government data, which relies on information supplied by parents.
While this has implications for obesity and disease, a new crop of medical studies shows that it also has important implica-tions for children's academic achievement and neurological development.
A study at Michigan State University randomly assigned 214 11-year-old pupils to PE for one term, while their degree of activity (moderate or vigorous) outside school was also measured. Then the pupils' academic performance was assessed using grades from four core academic classes and standardised test scores. Pupils who took part in more vigorous physical activities at least three times a week - including organised sports such as football or rugby, or non-organised after-school activities such as skateboarding - did about 10 per cent better in core classes such as maths, science, English and social studies. The difference between vigorous aerobic activity and moderate activity is heart rate. Moderate activities, such as walking, don't get the heart rate up or make you breathe as hard as running and swimming do.
The researchers added: "Increased physical activity during the day may increase alertness and reduce boredom, which may lead to increased attention span and concentration. increased self-esteem, which would improve classroom behaviour as well as performance."
A new, large-scale study by the US Centers for Disease Control and Prevention confirms on a national level what some smaller, localised studies have concluded. Researchers tracked the reading and maths skills of more than 5,000 pupils between five and 10 as shown on a series of standardised tests.
They discovered that girls who attended the highest levels of PE (70 to 300 minutes a week), scored consistently higher on the tests than those who did under 35 minutes a week.
Though they found no significant change in academic achievement for boys, they speculated that a higher level of physical activity might be needed to yield the same result because boys are usually more active than girls.
Some of the explanations for these findings may lie in the specific, positive associations between physical activity and cognitive function that are being identified, particularly for executive function. Executive function influences a child's ability to understand when to apply knowledge, effectively plan, update working memory, shift from one mental set to another and inhibit impulsive behaviour. Improvements in any of these may boost academic performance.
Paediatric researchers at the US National Institute of Diabetes and Digestive and Kidney Diseases believe the same thing may happen in children as in animals. Research on animals shows that exercise, particularly regular exercise, stimulates the growth of blood vessels and neurons in the brain. The researchers randomly assigned children aged seven to 11 to one of three "training doses": one third only learnt about healthy nutrition and the benefits of physical activity, one-third also exercised 20 minutes after school and another third exercised for 40 minutes. Children played running games, with hula hoops and skipping ropes, raising their heart rates to 79 per cent of the maximum, considered to be vigorous.
Functional Magnetic Resonance Imaging (fMRI) - specialised brain scans - revealed a direct, positive relationship between the level of physical activity and level of frontal-lobe brain activity (blood flow), an important area for executive function. Furthermore, these brain changes corresponded directly with improvements in standardised tests assessing their decision-making processes and achievement in maths.
So now there's a further incentive to ensure children spend at least an hour a day doing moderate to vigorous physical activity. (And remember: vigorous is much better then moderate). No school should worry that exercise will reduce grades by displacing classroom time. All schools, in conjunction with parents, can devise ways of increasing physical activity, formally and informally, in and out of school time.
Dr Aric Sigman is a fellow of the Royal Society of Medicine, a member of The Institute of Biology and associate fellow of the British Psychological Society
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