These soccer-loving Somali students are doing what health experts want all teenagers to do every day: exercising “moderately to vigorously.”
Mohamed Abdiwahab/AFP/via Getty Images
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Mohamed Abdiwahab/AFP/via Getty Images
The World Health Organization recommends that teens spend at least an hour a day getting enough exercise to break a sweat — a brisk walk or a more intense soccer game. Much research suggests that this level of activity is crucial for supporting growth in body and mind.
But new global data suggests that only a small minority of children and adolescents benefit. In fact, one in four people report not getting 60 minutes of moderate to vigorous exercise. any day of the week, according to a new study In The Lancet Global Health. Girls, as well as adolescent girls in middle- and low-income countries, reported even lower levels of exercise.
“The results are disappointing, because one of the main findings is that the trend over the last 15 years is stable,” says Fiona Bull, head of the physical activity unit at the World Health Organization, co-author of the study. “This data calls us to rethink what we are doing. Business as usual will not change these trends.”
Changing habits in adolescence could have a lifelong impact, said Solveig Cunninghamglobal health researcher at Emory University. “As a teenager, if your benchmark is zero days of physical activity, that will be your benchmark as an adult.”
What 3 million teenagers revealed
So how can researchers tell if teens are sweating – or not? It’s tricky. Researchers would love to be able to strap smartwatches to children to get detailed data, but that would be expensive. The second best strategy is to ask a basic question: How many days in the last week were you active for at least 60 minutes?
The report draws on survey data publishing a version of this question among more than 3 million adolescents from 140 countries over the past 15 years. Only about 14% of children worldwide report getting an hour of exercise per day. Globally, the average teenager reports fewer than three such days per week, the study found.
According to the study, children in low- and middle-income countries tend to be less active than their counterparts in wealthier Western countries. There is no single explanation for this trend, but a few probable causes stand out.
“Physical activity is about opportunity,” says Andrea Ramirez Varelaepidemiologist at the University of Texas Health Science Center at Houston. In many low-income countries, she says the environment – where they live, go to school and play – often restricts opportunities to be active. The study didn’t eliminate the urban-rural divide, but some research suggests that rural teens in low-income countries are moving more, she said, often out of necessity. In increasingly populated urban areas, activity is less.
Many cities aren’t designed to be walkable, Varela says. In Latin America, where she does most of her research, “many parents think it’s not safe to let their children walk from place to place on their own,” she says — much less go out and play independently. In some urban centers, air pollution can also make outdoor activities unhealthy.
Screens can also play a role. After school, “children and adolescents, when they arrive home, start watching television, they are in front of a screen,” explains Valrela. “Because this digital world is so engaging, they’re going to stay sedentary the rest of the day.”
Cultural barriers
The report also reveals a stubborn gender gap.
Girls were less active than boys in almost all countries. Nearly 30% don’t exercise at all during the week, compared to 22% of boys. Only 11% of girls were active daily, compared to 17% of boys. And the weekly average of girls’ active days was lower (2.4 versus 3).
“It’s very concerning to see this gender difference so early,” says Bull, noting that the difference often persists into adulthood.
Different standards regarding what is appropriate for girls are often the cause of this discrepancy.
“In many places, when girls reach puberty, there are taboos about engaging in physical activity,” says Cunningham. Take the example of India, where Cunningham focused much of his research. “Mothers or grandmothers will say, ‘Well, you know, we don’t want girls spending a lot of time outside. Their skin might get darker. That might have negative implications on their ability to marry.’
Cunningham notes that girls are active in other, often less intense, ways. “In South Asia, as well as in the United States, a significant portion of girls’ active time is spent on household chores,” she says. “If the boys are playing outside and the girls are inside sweeping, they are both active, but it’s not the same thing.”
What would make them move?
Improving these trends won’t be easy, experts tell NPR. Redesigning cities to be more walkable, for example, takes many years and substantial investment. Many experts see schools as a practical place to start. “To make progress, we need to focus on the environments in which children and adolescents spend most of their time,” says Varela.
In fact, data suggests that countries where adolescents engage in more physical exercise tend to schedule more structured sports periods during or after the school day. Implementing such programs in other countries could help close the gap, Varela believes, especially if it is done in a way that makes the sport accessible and affordable.
Such efforts will require sustained attention from policymakers, Varela believes, who face pressure from all sorts of competing interests. But she says it’s worth it.
“Failing to address the problem at this stage of life will perpetuate it into adulthood,” she says, where the costs to society, in terms of poor physical and mental health, will only increase.
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