Study On Exercise Intervention Pattern And The Relationship Between Physical Activity And Onset Of Postmenopausal Osteoporosis

ObjectivePostmenopausal osteoporosis(PMO),which affects up to half of the older women in most countries, increases the susceptibility and fragility fractures, mortality and debility in postmenopausal women. Since there is no effective cure for established osteoporosis, the prevention should be specially emphasized. Many different types of exercise intervention programs have been studied for their effect on BMD in postmenopausal women, including walking, strength training, and combining together the both. However, up to now, no study has been evolved to investigate the association between habitual activities and BMD or to approach a dose-response relationship between the level of habitual physical activity and BMD in postmenopausal women. Futhermore, the association between physical exercise and BMD in postmenopausal women is controversial. The controversy is still existence on how to constitute the best form of exercise to improve bone mineral density and decrease bone loss in postmenopausal women.The purpose, therefore, of this article is to report the results of this study by to parts: (1) Investigating the relationship of habitual physical activity and onset of osteoporosis in Chinese postmenopausal women; (2) Determining the effect of a well- designed combined with aerobic, resistance, and extension exercise program on BMD in this population.MethodsIn the hospital-based case-control study comprising 67 cases and 67 controls(average 56.5±8.3 years ), who were recruited in the same hospital during Feb 2007 to Feb 2008, free of metabolic diseases or medication affecting bone metabolism, an interviewer-administered questionnaire was utilized to retrospectively assess physical activity. The long version of the International Physical Activity Questionnaire (IPAQ,Chinese version) was used to define the level of PA. This instrument evaluates the frequency and duration of activities performed during transportation, at work, at home or in leisure- over the course of recent one year. Women were classified as physically inactive, physically active, and physically vigorously active. Bone mineral density at the lumbar spine was assessed by dual-energy X-ray absorptiometry (DXA). Chi-square test was utilized to compare differences between cases and controls. Conditional logistic regression was utilized to estimate odds ratios and 95% confidence intervals as well as to control the effects of PA and BMD.In the exercise intervention study, the population comprised 45 postmenopausal women, who exercised over 12months (exercise group), and 36 women who served as a nontraining control group. The subjects were screened for diseases and drugs known to adversely affect bone mineral density. A well- designed combined with aerobic, resistance, and extension exercise pragram was used. Two group training sessions per week and 3 home training sessions per week were performed in the EG. Exercisers performed progressive step on the floor and from steps (4 inch) a minimum of 3 days per week at 50 to 200 jumps per session. Resistance training intensities were initially set at 60% of the one repetition maximum for the bench press and leg press and at a weight that could be lifted comfortably for 12-20 repetitions for the other exercises for the first 2 weeks of training. Following a warm-up, two sets of 8-10 repetitions were performed on each of the following exercises: bench press, shoulder press, biceps curl, back extension, as well as knee flexion, knee extension, and leg press. Physical fitness was determined by maximum strength and cardiovascular performance. Bone mineral density of the hip, and lumbar spine was measured at baseline and 12 months using dual x-ray absorptiometry (DXA).Strength was assessed for bench-press,squat, and waist-curl exercises at baseline and after the 3, 6 month exercise program.Means and standard deviations (X±SD) were used to describe continuous variables. We examined the relationships among exercise-induced changes in fitness and fatness with BMD. The rate of BMD change was analyzed by linear regression. ResultsThe cases and the controls were indifferent for age, occupation, and education level, etc(P>0.05). PA in total and transportation, leisure-time was different between the cases and the controls(P< 0.01). PA in occupational, housework did not show significant difference between the cases and controls(P>0.05). Walking, health-enhanced dance, climbing the floor, are effective ways for postmenopausal to prevent PMO. After adjustment for the use of hormone replacement therapy(HRT), histories of physical exercise both at present and teenager, body mass index(BMI), the association between the PA in total and in transportation and onset of PMO risk remain significant(P<0.05). Physically active in total and in transportation significantly decreased risk of PMO (adjusted OR=0.301, 95% CI: 0.102-0.887; OR=0.05, CI: 0.007-0.406, respectively). After adjusting for confounding variables in a stepwise regression analysis, significant relationships with PMO no longer be detected for PA in leisure-time.Thirty-six out of 45 persons in the exercise group and thirty-six controls completed the exercise inervention. The subjects in the exercise (N=36) and control (N=36) groups did not differ significantly in age, height, weight, body mass index, menopausal years, years on hormone replacement therapy, and risk factors (smoking status, alcohol, coffee, and cola consumption). Average compliance was 82% for the whole exercise group at month 12. All the subjects decreased in bone mineral density, however, the rate of bone loss was lower in the exercise group than the control. Exercise groups had a significantly greater increase in strength and a greater decrease in pain score compared with nonexercise groups after the intervention. Exercise increased aerobic and strength fitness. Maximum isometric strength significantly (p < 0.001) increased in the EG. Thus, the study demonstrated that multipurpose high-intensity exercise programs significantly affect relevant menopausal bone loss. ConclusionPhysical activity may play a role in BMD levels in postmenopausal women. These findings indicate that physical activity in transition and the total can be likely to decrease PMO risk in Chinese women. In order to combat the increasing incidence of osteoporosis, keeping physically active, especially in transition and the total should be emphasized. Walking is feasible and can be incorporated into everyday life. One of the potential interventions for increasing and/or maintaining vertebral bone mineral density (BMD) in postmenopausal women is exercise, a low-cost, nonpharmacologic intervention that is available to most individuals. General purpose exercise programs with special emphasis on bone density can significantly improve strength and endurance and reduce bone loss, back pain, in osteopenic women in their critical early postmenopausal years.