Structural equation modeling of the relationship of bone mineral density and its risk factors in Japanese women

Effects of high-intensity swimming training on the bones of ovariectomized rats

[Purpose]

This study was performed to assess the effects of high-intensity intermittent swimming training(HIT) on bone in ovariectomized rats.

[Methods]

Six-week-old female Sprague-Dawley rats were randomly assigned to either sham operation or bilateral ovariectomy. After surgery, they were divided into the following four groups: 1) sham-operated sedentary (S), 2) sham-operated exercise training (SE), 3) OVX sedentary (O), 4) OVX exercise training (OE) 5) OVX given 17β-estradiol (OE2) and 6) OVX exercise training and given 17β-estradiol (OEE). SE, OE and OEE rats were used extremely high-intensity swim exercise. The rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 5, the next 9, and the last 5 days, respectively. Between exercise bouts, a 10-s pause was allowed. HIT was originally designed as an exercise method; a method that very quickly induces an increase in the maximum oxygen intake (Tabata I et al., 1996). OEE and OE2 rats were subcutaneously injected ethanol with 25μg/kg body weight 17β-estradiol 3 times per week.

[Results]

Bone strength, bone mineral density and trabecular bone parameters were measured after a 8-weeks experimental period. Bone strength was significantly higher in the SE, OE, OE2 and OEE group compared with the O group. BV/TV was significant increase in the SE, OE groups compared with the O group. BMD showed no difference in the OE group compared with the O group.

[Conclusion]

This study demonstrate some beneficial effects of postmenopausal osteoporosis of high-intensity intermittent swimming training on bone structure and strength.

Factors influencing the pharmacological management of osteoporosis after fragility fracture: results from the Ontario Osteoporosis Strategy's fracture clinic screening program

Potential mediating factors in the pathway to initiation of osteoporosis treatment following a fragility fracture were evaluated. Patients' perceived need for treatment, mediated by their perception of bone density test results, was central to treatment initiation. Interventions focusing on patients' perceptions of need and test results may improve treatment rates.

INTRODUCTION

We tested a hypothesized pathway to osteoporosis (OP) pharmacotherapy initiation in fragility fracture patients. We hypothesized that bone mineral density (BMD) testing is strongly associated with treatment initiation and perception of BMD test results would inform patients' perceived need for treatment, which would mediate the effect between BMD testing and treatment initiation.

METHODS

A longitudinal cohort study followed patients, ≥50 years of age, screened for fragility fracture in 31 fracture clinics in Ontario, Canada who had no prior diagnosis of or treatment for OP. At screening, OP risk factors, baseline-patient perception of OP risk, OP knowledge, and perceived benefits of medication were reported by patients. Patients were followed up within 6 months of fracture to determine BMD testing and prescription of and adherence to first-line OP pharmacotherapy. Structural equation modeling tested the hypothesized pathway. Significance and magnitude of the coefficients and indicators of overall model fit were used to test our model.

RESULTS

The direct path from BMD testing to OP treatment initiation was non-significant. The pathway to treatment initiation was mediated by patients' perception of their need, which was influenced by their self-reported BMD results. Baseline fracture risk factors, knowledge of OP, and perceived benefits of treatment-predicted patient-perceived need for treatment at follow-up and initiation of OP treatment.

CONCLUSIONS

Patient perceptions were central factors in the path to initiation of OP pharmacotherapy. Interventions to facilitate accurate patient perceptions of BMD test results and OP risk status could prove helpful in improving OP treatment initiation.