For boys, puberty means growth spurts that could help them rebound the basketball better or take advantage of longer strides to steal bases or win races. For girls, puberty can have the opposite effect, making them self-conscious and bringing on doubt that could lead to them abandoning sports altogether.
The latter was the focus of a recent study in the U.K. which was published in The Journal of Adolescent Health. The study concluded that puberty -- particularly breast development -- is a leading factor in why only 12 percent of the country's teenage girls reach physical activity guidelines.
The study used a large sample size, quizzing 2,089 girls on breast development, whether it hinders their enthusiasm for participating in sports, and whether they felt fully educated about their bodies.
Andria Castillo, a 17-year-old high school junior, told the New York Times she was "painfully self-conscious" about her breast size when she was around 11 years old. During taekwondo classes, she said, she "would look in the big mirror and try to find ways to cover [herself] up and hide" because she felt she was developing more slowly than girls her age.
Eventually, she told her dad she wanted to quit taekwondo.
Castillo noted that a friend of hers had the same problem for the opposite reason. That friend, who was active in sports, suddenly stopped participating in athletics after her breasts developed rapidly.
“She eventually stopped going to gym altogether,” Castillo said. “Instead, she just went to a classroom and did her homework.”
The study, titled "The Influence of the Breast on Sport and Exercise Participation in School Girls in the United Kingdom," confirmed researchers' suspicions about one of the main reasons teenage girls quit sports.
“We make assumptions about what we think we know, so it’s important to be able to say that as cup size increases, physical activity decreases for a lot of girls,” Dr. Sharonda Alston Taylor, an assistant professor of pediatrics at Baylor College of Medicine in Texas, told the Times.
The study found that 73 percent of girls said they had concerns related to their breasts when it came to playing sports, and 38 percent cited concerns about their breasts bouncing as a major reason why they stopped participating in sports. Another 34 percent told researchers they don't like changing clothes in locker rooms where other girls can see them.
The study's authors said school and health officials can combat the anxiety -- and get girls to return to sports or avoid quitting them altogether -- through education programs. That can include everything from instructing girls on the use of sports bras, to helping them navigate the "overwhelming and confusing" task of selecting appropriate bras. Most of the girls who completed the research survey said they would be most comfortable learning from a female teacher, without boys present.
Some experts said segregating gym classes and sports by gender could help alleviate most of the problems. Kimberly Burdette, a doctoral candidate in psychology at Loyola University Chicago, was not a participant in the research, but she studies the psychological factors that could cause people to shy away from exercise.
“It’s hard to be in the zone, focusing on athletic movement, on what your body can do, if you’re thinking about what others think your body looks like,” she told the Times. “I like programming that is for girls only, where a girl can try a sport, regardless of her ability, without the male gaze.”
But others, like University of Colorado psychology professor Elizabeth A. Daniels, said it's not just about playing sports with members of the opposite gender. Girls can also say harsh and derisive things about each other.
“I’m not sure the concern or embarrassment is always just about boys,” she told the Times. “So do we change the structure of the gym class or address respectful behavior?”