PURPOSE: The goal of the MEDEX-OP trial was to compare the effectiveness of a high intensity resistance and impact training (HiRIT) program to a Pilates-based exercise program (Buff Bones®, BB), alone or in combination with antiresorptive bone medications, on indices of fracture risk (bone mineral density [BMD], body composition, muscle strength, functional performance).

METHODS: Otherwise healthy postmenopausal women with low bone mass (T-score ≤ -1.0), screened for conditions known to influence bone and muscle health, who were on or off stable doses (≥ 12 months) of antiresorptive medication were recruited. One hundred and fifteen women (63.6 ± 0.7 years; BMI 25.5 kg/m2; 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 covariance, adjusted for baseline age, were performed (data presented as mean ± SE).

RESULTS: HiRIT but not BB improved lumbar spine BMD (1.9 ± 0.4% versus -0.6 ± 0.4%, p < 0.005), trochanteric BMD (2.9 ± 0.7 versus -0.6 ± 0.6, p = 0.002) and stature (0.2 ± 0.1 cm versus -0.0 ± 0.1 cm, p = 0.004). HiRIT-med improved BMD more than HiRIT alone at the femoral neck (4.9 ± 1.3% versus -0.0 ± 0.7%, p = 0.008) and total hip (2.2 ± 0.7% versus -0.5 ± 0.4%, p = 0.007). HiRIT and BB both improved muscle strength and functional performance but HiRIT effects were greater for isometric back muscle strength (31.8 ± 3.2% versus 14.4 ± 3.1%, p < 0.005) and five times sit-to-stand test (-11.8 ± 1.8% versus -3.8 ± 1.8%, p = 0.002). 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 bone mass, muscle strength, functional performance and stature while Pilates-based exercise only improved functional performance. Combining osteoporosis medication with HiRIT may enhance effects on bone at the hip but more trials are needed to fully test the interaction.