A new study suggests that recreational physical activity during the teenage years may play a protective role in breast health by influencing breast tissue composition and reducing biological markers linked to stress.
Researchers found that teenage girls who regularly took part in leisure-time physical activities such as sports, dance, or gym workouts had lower water content in their breast tissue — a marker associated with lower breast density — along with reduced levels of stress-related biomarkers. Lower breast density has previously been linked to a reduced risk of breast cancer.
The findings, published in Breast Cancer Research, highlight adolescence as a critical window for breast development and suggest that lifestyle habits formed during this period could have long-term health implications.
The study involved around 200 adolescent girls who reported how many hours they spent on recreational physical activity during the week before the survey. Participants also provided blood and urine samples and underwent breast tissue assessments. More than half of the girls — 51 percent — reported no physical activity in the previous week, pointing to low activity levels among adolescents.
Girls who engaged in more than two hours of organised recreational physical activity in a week showed significantly lower breast water content compared with those who reported no activity. Importantly, this association was independent of body fat levels. These girls also had lower urinary levels of 15-F2t-isoprostane, a biomarker linked to oxidative stress.
While previous research has consistently shown that physically active adult women face a lower risk of breast cancer, the biological mechanisms behind this connection have not been well understood. This study is among the first to link recreational physical activity in adolescence to changes in breast tissue composition and stress-related biological markers.
Researchers caution that longer-term studies are needed to determine how these early biological changes may influence breast cancer risk later in life. However, they say the findings strengthen the case for encouraging physical activity early in development.
With breast cancer rates rising among younger women and physical inactivity remaining common among adolescents, the study underscores the potential public health importance of promoting regular recreational exercise during the teenage years.