Because the study has not yet sponsorship.

Osteoporosis has become a worldwide concern an a matter of public health as osteoporosis is a major contributing factor associated with insufficiency fracture of the spine, wrist and proximal femur, and as a result, can diminish quality of life as well as increase direct and indirect healthcare costs.

The pathophysiology of osteoporosis is based on two main factors; low bone mass and age associated architectural changes within the bone, high impact exercise in childhood can improve the peak bone mass and bone architecture. The evidence suggests that bone adaptation to increased load is optimal in early puberty (Tanner stages I and II) since around 30% of total body adult bone mass is accrued during this period.

However, the optimal exercise program for increasing peak bone mineral content is still unclear. Therefore, the aim of this study is to assess if 15 minutes of high-impact exercise three times per week improve areal bone mineral density assessed by DXA of pre pubertal girls after a ten-month regimen compared to low-impact exercise. This information could highly impact the development of public health policies directed to pre pubertal girls.

Inclusion Criteria:

• Girls between ages 8 to 10
• Tanner I

Exclusion Criteria:

• Precocious menarche (within the selected timeframe)
• Chronic disorders or medications known to affect bone metabolism or musculoskeletal function.
• Body Mass Index 30 or higher
• Regular vigorous physical activity (training more than 8 hours per week)