RESUMO
We investigated the effects of estrogen therapy (ET) associated with low-intensity and high-frequency mechanical vibration (MV) on bone tissue in osteopenic female mice. Fifty 3-month-old female Swiss mice were ovariectomized (OVX) or sham-operated, and distributed after 4â months into the following groups, with 10 animals per group: Sham; Control, OVXâ +â vehicle solution; MV, OVXâ +â MV; ET, OVXâ +â 17ß-estradiol; and MVâ +â ET, OVXâ +â MV and 17ß-estradiol. Both vehicle solution and 17ß-estradiol (10â µgâ kg-1â day-1 ) were injected subcutaneously 7â days per week, and vibration (0.6â g, 60â Hz) was delivered 30â min per day, 5â days per week. Bone mineral density (BMD) and body composition were evaluated by densitometry at baseline and after 60â days of treatment when the animals were euthanized, and their femurs underwent histomorphometric and histochemical analyses. The Control group showed increased weight and fat percentage, while the ET and MVâ +â ET groups showed increased lean mass but decreased fat percentage. At the end of the treatment period, the BMD decreased in Control, remained constant in Sham and MV, and increased in ET and MVâ +â ET. The MVâ +â ET group showed the greatest bone volume compared with Sham (129%), Control (350%), MV (304%) and ET (14%). No differences occurred in cortical thickness. The Control group showed the highest content of mature collagen fibers, while the MVâ +â ET group showed the highest content of immature collagen fibers. In conclusion, ET plus MV was effective in improving bone quality in osteopenic female mice, and this improvement is associated with specific changes in trabecular but not cortical bone.
Assuntos
Doenças Ósseas Metabólicas , Estradiol/farmacologia , Vibração , Animais , Densidade Óssea/efeitos dos fármacos , Osso e Ossos/efeitos dos fármacos , Feminino , Camundongos , Estimulação Física/métodosRESUMO
OBJECTIVE: In this longitudinal, paired-control study, we developed special vibration platforms to evaluate the effects of low-intensity vibration on neuromuscular function and functional capacity in osteopenic postmenopausal women. METHODS: Women in the platform group (PG; nâ=â62) stood still and barefoot on the platform for 20 minutes, 5 times a week for 12 months. Each platform vibrated with a frequency of 60âHz, intensity of 0.6g, and amplitude of less than 1âmm. Women in the control group (CG; nâ=â60) were followed up and instructed not to modify their physical activity during the study. Every 3 months all volunteers were invited to a visit to check for any change in their lifestyle. Assessments were performed at baseline and at 12 months, and included isometric muscle strength in the hip flexors and back extensors, right handgrip strength, dynamic upper limb strength (arm curl test), upper trunk flexibility (reach test [RT]), mobility (timed up and go test), and static balance (unipedal stance test). Statistical analyses were performed using the intention-to-treat strategy. RESULTS: Both groups were similar for all variables at baseline. At the end of intervention, the PG was significantly better than CG in all parameters but in the RT. When compared with baseline, after 12 months of vibration the PG presented statistically significant improvements in isometric and dynamic muscle strength in the hip flexors (+36.7%), back extensors (+36.5%), handgrip strength (+4.4%), arm curl test (+22.8%), RT (+9.9%), unipedal stance test (+6.8%), and timed up and go test (-9.2%), whereas the CG showed no significant differences during the same period of time. As such, there were no side effects related to the study procedures during the 12 months of intervention. CONCLUSIONS: Low-intensity vibration improved balance, motility, and muscle strength in the upper and lower limbs in postmenopausal women.