Purpose: The goal of the MEDEX-OP trial was to compare the effectiveness of a high-in-tensity resistance and impact training (HiRIT) program to a low intensity, Pilates-based exercise program (marketed under the name Buff Bones®, BB), alone or in combination with antiresorptive medication, on indices of bone strength and fracture risk (aBMD, cortical, trabecular and total BMC and vBMD, cortical thickness, functional performance, body composition, anthropometrics).

Methods: Otherwise healthy postmenopausal women with low bone mass (T-score <= -1.0) who were on or off stable doses (>= 12 months) of antiresorptive medication were recruited. One hundred and fifteen women (63.6 +/- 0.7 years; FN T-score -1.8 +/- 0.1) were randomly allocated to twice-weekly, 40-min, supervised HiRIT (5 sets of 5 repetitions at > 80% 1 RM) or BB, stratified by medication intake, resulting in four groups: HiRIT (n = 42), BB (n = 44), HiRIT-med (n = 15), BB-med (n = 14). Analyses of variance were performed (data presented as mean +/- SE). To increase the sample size and statistical power, the groups on and off medication were combined (e.g. HiRIT plus HiRIT-med). For spine and hip outcomes, the influence of medication intake on exercise efficacy was explored through subgroup analyses.

Results: HiRIT but not BB improved aBMD at the lumbar spine (1.9 +/- 0.4% versus 0.1 +/- 0.4%, p < 0.001) as well as trabecular and total BMC and vBMD at the proximal femur. Both HiRIT and BB increased thickness at the medial cortex of the femoral neck (2.4 +/- 0.9%, p = 0.040; and 1.8 +/- 0.8%, p = 0.037). Results from subgroup analyses suggest antiresorptive medication may enhance exercise efficacy at the proximal fe-mur. Both programs improved functional performance but HiRIT effects were larger for leg and back muscle strength and the five times sit-to-stand test (p < 0.05). In addition, HiRIT in-creased stature whereas BB did not (0.2 +/- 0.1 cm versus -0.0 +/- 0.1 cm, p = 0.004). There was a positive relationship between maximum weight lifted and changes in spine BMD and muscle strength in the HiRIT groups. Both programs were well tolerated (7 adverse events: HiRIT 3; BB 4) and exercise compliance was good (82.4 +/- 1.3%).

Conclusion: High-intensity resistance and impact training improved indices of bone strength and fracture risk more than Buff Bones®. Combining osteoporosis medication with HiRIT may enhance effects on bone at the hip but more trials are needed to fully test the interaction.

Disclosures: Melanie Kistler-Fischbacher, None