Adolescent girls and young women are less likely to engage in heart-rate raising recreational activities than their male peers, and when they do keep at it for shorter periods of time, research has revealed.
Current guidelines in the UK and US recommend that children and teens undertake at least an hour of moderate or vigorous physical activity a day, with adults advised to aim for 150 minutes a week.
However, a study from the US has found that more than 20% of adolescent girls and 12% of boys do no sports or recreational physical activity in a week, with just under 30% of men and almost 40% of women, aged 18-29, saying the same.
Dr Charlene Wong, co-author of the research from Duke University in North Carolina, said the research could help to direct public health interventions, noting that the study suggests the focus should be on females, young adults and those from minority and low-income backgrounds.
“Our black female young adults were the least likely to say they did any physical activity and those who did were active for the shortest amount of time,” she said.
Writing in the journal Jama Pediatrics, Wong and colleagues describe how they pooled and analysed data from an annual nationwide health survey in the US, encompassing the years 2007 to 2016, focusing on responses from 9,472 individuals aged between 12 and 29.
The survey, carried out through interviews, asked participants questions about their levels of physical activity relating to sports or recreational pursuits.
While almost 88% of boys aged between 12 and 17 reported some moderate or vigorous exercise in a week, the figure fell to just under 73% for males aged 18 to 24, and to just below 71% for those aged 25 to 29. For females the proportion fell from just over 78% of adolescents to just over 61% for both of the older age groups.
For those who did get their blood pumping, the amount of time spent exercising also fell with age, from just over 71 minutes a day for adolescent boys to just over 50 minutes for those aged 25 to 29. For girls, it fell from 56 minutes to just over 39 minutes a day respectively.
White adolescent boys were the most likely to say they exercised in a week, with black males aged 18-24 reporting the longest duration of physical activity a day.
Once factors including weight, education and income were taken into account, the team found race was linked to whether females reported any physical activity: in general, a larger proportion of white females said they exercised than black or Hispanic participants. The trend was less clear for males.
Higher income was linked to reporting physical activity for females regardless of age, but the same only held true for adolescent boys and not young men, while young adults with a college education were more likely to report any exercise across both sexes. Weight had little impact on whether participants reported exercising.
While it is not clear what is behind the trends, the authors say multiple factors might be at play including issues around body image, social norms for exercise being different between the sexes, less scheduled activity after leaving school and growing pressures of working life.
But the study had limitations, including that activity such as walking to work was not included, it was not considered whether participants had children, or were pregnant, and the authors admit that self-reported data can lead to an over-estimation of activity.
Dr Gavin Sandercock, an expert in child activity and fitness from the University of Essex who was not involved in the study, said the findings mirror certain trends seen in the UK, including that females exercise less than males and that physical activity drops across both sexes with age.
While he noted there are already some campaigns aimed at encouraging girls and women to exercise, including This Girl Can, he said it was also important to help individuals of both sexes from lower income groups to become physically active.
“We know that if you get children more active, as well as getting more physically healthy, they get happier and their educational attainment improves,” he said.
Joan Duda, professor of sport and exercise psychology at the University of Birmingham, said offering a choice of activities and cultivating a sense of empowerment is key: “We need to do more to promote participation in physical activity in the case of adolescent females, and males, not just taking it up or giving a particular activity ‘a go’ but also how to sustain quality engagement,” she said.