In a study published in the Journal of School Health (Garcia et al. 1995), researchers examined the gender and developmental differences in exercise-related beliefs and exercise behaviors of 286 racially diverse youth, exploring factors that predicted exercise. Compared with males, females reported less prior and current exercise, lower self-esteem, poorer health status, and lower exercise self-schema, or perception of themselves as athletic. Further, 8^th grade girls compared with 5^th and 6^th grade girls reported less social support for exercise and fewer exercise role models, directly opposite to what was found for boys.

Another study (Trost et al. 1996) looked at the gender and exercise relationship of 334 5^th grade students in rural South Carolina in regard to their after-school physical activity. Boys reported significantly greater participation in vigorous (6 METS or higher) and moderate to vigorous exercise (at least 4 METS). Relative to girls, boys demonstrated significantly higher levels of physical fitness, greater self-efficacy in overcoming barriers to physical activity, and higher levels of participation in community sports and physical activity organizations. Specifically, boys scored significantly higher that girls on self-efficacy (overcoming barriers), suggesting that boys were more physically active than girls because they were more confident in their ability to overcome traditional barriers to physical activity such as time constraints, feelings of fatigue, poor weather, and homework obligations. This information may be important in planning exercise intervention strategies for girls. Researchers concluded that low levels of physical activity appear to be particularly prevalent in preadolescent and adolescent girls.

Studies and observations indicate that girls become much less active than boys as they grow older. In fact, girls between the ages of 14 and 16 are the most inactive compared with children of all ages. This lack of activity in girls is reflected in fitness test scores reported by the Cooper Institute for Aerobics Research. At the age of 7, 86% of girls passed the 1-mile run test and 57% the upper-body strength test. By the age of 15 only 49% were able to pass the 1-mile run and even worse, only 27% passed the upper-body strength test (Cooper 1999).