Pre- and early-teen girls who are engaged in moderate to high impact sports such as gymnastics basketball or football are more likely to have better bone mass structure and strength a study has found. The Swedish study evaluated whether extra physical education classes would have an impact on bone parameters in growing children and measured the impact of school-based exercise on tibia cortical bone mass distribution. A total of 170 children (72 girls and 98 boys) were provided with 200 minutes of physical education per week and three other schools (44 girls and 47 boys) continued with the standard 60