An Evaluation of Select Physical Activity Exercise Classes (PEX) on Bone Mineral Density: 697 Board #13 June 1, 3: 30 PM - 5: 00 PM.

PURPOSE: To assess the efficacy of structured physical activity classes on bone mineral density (BMD). METHODS: Thirty-nine women ages 18-35 y who were either enrolled in a yoga class (n=14), cardio-kickboxing class (n=13), or no physical activity class (control; n=12) voluntarily consented to participate. Dual-energy x-ray absorptiometry (DEXA) scans of the hip, spine, and total body were measured just before commencement and just after completion of the semester-long classes. Likewise, blood samples were drawn preand post-semester for measurement of osteocalcin, and dietary and physical activity questionnaires were also completed. RESULTS: Neither yoga nor cardio-kickboxing affected BMD at any of the measured sites. Osteocalcin concentration increased from preto post-semester measures (pre = 12.15 ng/mL, post = 41.15 ng/mL; P < 0.001), but groups were not different (P = 0.314). CONCLUSIONS: Based on these data, 12 weeks of yoga and cardio-kickboxing physical activity classes were insufficient to induce bone mineral density changes. However, osteoblast activity was likely elevated as reflected by increased blood osteocalcin concentrations over time, thereby indicating stimulation of the bone formation process.