THURSDAY, Feb. 15, 2024 (Health Day News) — Schools that want little girls to get plenty of exercise might want to rethink their dress code.

A University of Cambridge study of more than 1 million kids in 135 countries found that in countries where most students wear school uniforms, fewer kids get the 60 minutes a day of physical activity recommended by the World Health Organization (WHO). 

And regardless of schools’ uniform policies, fewer girls than boys are hitting the benchmark in the early grades, the study found.

Researchers noted there was already evidence that little girls aren’t always comfortable participating in active play when they’re wearing skirts or dresses. 

While the new study doesn’t prove that uniforms limit kids’ activity, researchers called on schools to consider whether specific uniform designs might encourage or restrict opportunities to be active during the day.

“Schools often prefer to use uniforms for various reasons,” said study leader Mairead Ryan, of the University of Cambridge. “We are not trying to suggest a blanket ban on them, but to present new evidence to support decision-making.”

Previous, smaller studies have also suggested that uniforms may be a barrier to physical activity.

The WHO recommends young people get an average of 60 minutes a day of moderate-intensity physical activity. The difference in percentage of boys and girls meeting the guideline across all countries was, on average, 7.6 percentage points, researchers found.

The study analyzed data on the physical activity levels of nearly 1.1 million 5- to 17-year-olds. In more than 75% of countries surveyed, a majority of schools required uniforms. And in those countries, participation in physical activity lagged. 

Where uniforms were the norm, a median 16% of kids were getting the recommended level of activity (meaning half got more, half less). Where uniforms were less common, this rose to 19.5%. 

Across all ages, boys were 1.5 times more likely to hit the mark than girls. But, researchers showed, the gap widened from 5.5 percentage points in the primary grades in non-uniform countries to 9.8 percentage points in countries were most schools required uniforms.

The findings were published Feb. 14 in the Journal of Sport and Health Science.

Researchers said this dovetails with other evidence suggesting girls are more self-conscious about being active when wearing uniforms.

“Girls might feel less confident about doing things like cartwheels and tumbles in the playground, or riding a bike on a windy day, if they are wearing a skirt or dress,” said senior study author Esther van Sluijs, an MRC investigator at Cambridge.

“Social norms and expectations tend to influence what they feel they can do in these clothes,” she added in a Cambridge news release. “Unfortunately, when it comes to promoting physical health, that’s a problem.”

Researchers said there is ample evidence now to investigate whether there is a cause-and-effect relationship between uniforms and inactivity. 

“Regular physical activity helps support multiple physical, mental and well-being needs, as well as academic outcomes,” Ryan said. “We now need more information to build on these findings, considering factors like how long students wear their uniforms after school, whether this varies depending on their background, and how broader gendered clothing norms may impact their activity.”

More information

The group Girls Uniform Agenda has more about school uniforms and physical activity

SOURCE: University of Cambridge, news release, Feb. 14, 2024