A recent article published in JAMA Pediatrics highlights a study conducted with the intention of identifying physical activity levels of adolescents and young adults in the United States, and more specifically, breaking down and examining the activity levels by sex, income, and race/ethnicity. The findings indicate that overall, females participated in less physical activity than males, and that minority racial/ethnic groups and individuals with lower incomes were typically less physically active. 
The study itself was conducted from 2007 to 2016 with self-reported physical activity information collected from 9,472 adolescent and young adult participants: 4,771 males and 4,701 females. The average age of the participants was 20.6.  The study found that among teenagers between ages 12 and 17, around 88% of the males reported being physically active, compared to about 78% of females. However, between the ages 18 and 24, these rates drop to 73% for males, and only about 62% for females, indicating that after high school, fewer women participate in physical activity. This disparity is even greater among minority groups. For example, among female participants aged 18 to 24, around 71% of white women reported participating in any moderate or vigorous physical activity, compared to only 45% of black women. When looking at the data with regards to income, about 80% of women in the highest income bracket remained physically active after age 17, compared to between 45% to 55% of women below the poverty line. 
Researchers have considered reasons for these disparities and how to address them. An adolescent medicine specialist from Harvard University, Dr. Holly Gooding, was not involved in the study, but believes that socialization norms may contribute, as teen girl socialization is not often centered around physical activities, unlike with boys. She also points out that schools and communities that serve minority populations often have fewer resources such as athletic fields or safe spaces to participate in physical activity outside of school. Dr. Charlene Wong, one of the authors of the study also cited the increased use of mobile devices as contributing to decreased physical activity for all groups. Dr. Wong suggests that this study has demonstrated where to aim for improvements in physical activity in young people, and that it may be helpful to use programs in schools to develop healthy physical activity habits, especially among women, that can be carried into adulthood. 
 Armstrong, S., Wong, C.A., Perrin, E., Page, S., Sibley, L., & Skinner, A. Association of Physical Activity With Income, Race/Ethnicity, and Sex Among Adolescents and Young Adults in the United States: Findings From the National Health and Nutrition Examination Survey, 2007-2016. JAMA Pediatrics, 2018;172(8):732-740. doi:10.1001/jamapediatrics.2018.1273.