One hundred and twenty-five healthy children ( 58 boys , 67 girls ) , aged 10-11 years old ( 10.8 0.4 years ) , who were self-assessed as belonging to Tanner stages I and II , were randomly divided into two experimental groups , a strength training group ( 19 boys , 22 girls ) and an endurance training group ( 21 boys , 24 girls ) that would train twice a week for 8 weeks , as well as a control group ( 18 boys , 21 girls ; no training program ) .