• DXA - at baseline and 9 months
  
• Nutrient Intake Interview - at baseline, 3, 9 and 12 months
  
• Physical Activity Recall - at baseline, 3, 9 and 12 months
  
• Strength/Fitness measures - at baseline, 3, 9 and 12 months
  

In recent years, osteoporosis has become a major public health problem in the United States. Osteoporosis can best be prevented by optimizing bone mineral gain and reducing bone loss. Because the rate of bone development reaches its peak during adolescence, fostering bone health in childhood is of critical importance. Although there have been many studies of exercise and nutritional factors that influence bone mass in adults, few randomized, prospective studies have been conducted in children. This study will determine whether parent training is effective in increasing children's calcium intake, strength, and frequency of aerobic exercise.

Families will be randomly assigned to either the physical activity and nutrition intervention group or to the injury prevention control group. Families in both groups will undergo training during 9 weekly classes. The intervention training will emphasize health topics, principles of behavior, and contingency management techniques. Post-training coaching procedures will be provided periodically for 9 months. Coaching procedures will assist parents with problem solving and help them refine and maintain parenting skills. All families will be assessed prior to training and at Months 3, 9, and 12. Outcome measures will include 24-hour recall estimates of change in diet and change in physical activity. Total bone calcium, bone density, body composition, and skeletal age will also be assessed.