By Jeanne Nichols, Ph.D., FACSM
Once thought of as a disease of “little old ladies,” osteoporosis is now considered by many researchers as a pediatric disorder that manifests itself in old age. Peak bone mass and strength, which girls achieve in their 20s, predicts future fracture risk. In other words, the greater the bone mass and strength at the time girls reach their peak, the lower their chance of sustaining an osteoporotic fracture as they grow older. Research has also shown that the rate at which we accrue bone mineral is highest during late childhood and early adolescence. This is why it is critical to promote bone-healthy behaviors in children and teens.
Studies comparing athletes from different sports have shown the highest bone mineral density values in athletes participating in sports associated with high impact forces, such as in gymnastics, volleyball, and basketball, and in sports that require variable loads, or “odd-impact” loads to the skeleton, such as in soccer, tennis, and European handball. In addition to impact loading from jumping and sprinting activities, bone also adapts favorably to high joint reaction forces from vigorous muscular contractions, such as in weightlifting or resistance training. These types of activities should be considered when planning exercise programs for children and teens.
In addition to the type of exercise to optimize bone mass and strength, several randomized, controlled exercise interventions have also provided insight into the frequency and duration of exercise needed to build bone in young girls. Although an exact exercise prescription for bone health is not known, knowledge gained from these intervention studies can help practitioners plan community exercise programs to promote bone health in children and teens.
Several elementary school-based programs in which jumping and running games were added to physical education classes for approximately 10-30 minutes three days per week during the school year have shown significantly greater gains in bone mineral at the hip and lumbar spine in pre- and early pubescent girls compared to girls who participated in regular P.E. activities 1-3. From these studies we can conclude that brief sessions of vigorous impact exercise three days per week can promote bone health throughout the developmental years. Young girls need to learn and practice these bone-healthy behaviors to optimize their bone mass and strength in adulthood and decrease their risk of osteoporosis in old age.
Additional information on bone health:
ACSM’s Position Stand on Physical Activity and Bone Health
National Osteoporosis Foundation
1. Fuchs, R. K., J. J. Bauer, and C. M. Snow. Jumping improves hip and lumbar spine bone mass in prepubescent children: a randomized controlled trial. J Bone Miner Res. 16:148-156, 2001.
2. MacKelvie, K. J., K. M. Khan, M. A. Petit, P. A. Janssen, and H. A. McKay. A school-based exercise intervention elicits substantial bone health benefits: a 2-year randomized controlled trial in girls. Pediatrics. 112:e447, 2003.
3. McKay, H. A., M. A. Petit, R. W. Schutz, J. C. Prior, S. I. Barr, and K. M. Khan. Augmented trochanteric bone mineral density after modified physical education classes: a randomized school-based exercise intervention study in prepubescent and early pubescent children. J Pediatr. 136:156-162, 2000.