Young boys seem to reap many more fitness benefits from joining an extracurricular soccer team than from standard gym classes, new research indicates.

Spanish researchers found that 8-year-olds who played soccer for at least 3 hours each week for 3 years had stronger bones, more lean mass, and could run faster than boys who opted instead for 45-minute gym classes twice per week.

These findings suggest that mandatory physical education classes alone are not enough to encourage bone growth and other healthy changes in pre-pubertal boys, one of the study’s authors told Reuters Health.

“Children should do more exercise and also they should likely perform other kinds of exercise,” such as soccer, said Dr. Jose A. Lopez Calbet of the Universidad de Las Palmas de Gran Canaria in the Canary Islands.

“Parents must look for a kind of sport that their children like and encourage them to practice three or more times a week,” he added.

This recommendation is particularly relevant right before puberty, Calbet said, when children’s bodies are preparing to add on significant amounts of bone mass.

He noted that these results likely apply to girls as well as boys, but further research is needed.

To investigate what amount of exercise young boys need before puberty, Calbet and his colleagues followed 17 young soccer players and 11 boys just enrolled in gym class for 3 years, noting how their bodies changed. Boys were an average of between 8 and 9 years old.

The investigators found that soccer players had significantly higher bone density by the end of the study period than boys taking gym class.

Furthermore, while soccer players’ percentage of body fat did not change, other boys experienced an increase in body fat over the three-year period. Soccer players also developed more lean body mass.

Soccer players could also sprint faster than other boys, the authors report in the journal Medicine & Science in Sports & Exercise.

This study “shows clearly that soccer participation stimulates bone acquisition in prepubertal children,” they write.

“It is important that children exercise regularly before the start of the pubertal spurt in growth,” Calbet concluded.

SOURCE: Medicine & Science in Sports & Exercise, October 2004.