The Effects Of Enhanced Exercise And Vitamin D Supplement Combined With Calcium On Muscle Strength, Fracture And Life Quality Of Postmenopausal Women In Dongcheng District Of Beijing

Background and purpose:Osteoporosis is a kind of bone disease characterized by decreased bone strength leading to an increased fracture risk. The prevalence of postmenopausal osteoporosis is higher owing to lower peak bone and decline of estrogen in postmenopausal women. It is suggested that vitamin D inadequacy is related to decline of muscular strength, higher risk of falling and fracture, and reduced life quality in postmenopausal women. However, whether vitamin D supplementation can improve muscular strength and life quality and lower the occurrence of fracture is still controversial. Related researches, especially the large sample of prospective study is rather insufficient in Chinese population. Moreover, the community-based prospective intervention study in China is still lacking. Therefore, we designed a two-year community-based prospective randomized controlled trial in postmenopausal women with a high risk of osteoporosis in Dongcheng district of Beijing. The primary aim is to observe the effects of enhancing exercise and calcium supplements combined with different vitamin D preparations on muscular strength, fracture occurrence and life quality, in order to develop an economical and effective population-based intervention mode on osteoporosis.Methods:614 postmenopausal women selected from communities in Dongcheng district of Beijing through a survey questionnaires about risk factors of osteoporotic fractures, aged between 45 and 81, were eventually enrolled in the study. The general conditions, lifestyle, osteoporosis-related conditions, past illnesses and treatments, menstrual and obstetrical history, and family history were all recorded through a questionnaire. The study population was randomized to four groups including group A (control group),B (enhanced exercise of Tai chi), C(calcium 600mg/d and vitamin D 800IU/d), and D(calcium 600mg/d and 1,25(OH)2D 0.25μg/d). The time of stand test and grip strength were tested at baseline, one year and two years after intervention respectively. Life quality was assessed by SF-36, occurrence of falling and fracture was also recorded during the follow-up. Serum bone turnover markers and 25OHD levels were measured at baseline and two years after intervention. SPSS 16.0 was used for statistical analysis.Results:1.Baseline:(1)The prevalence of 25OHD<50nmol/1 was approximately 92.6% in the study population. (2) It is revealed by regression analysis that serum 25OHD level was not associated with either muscle strength(standing test and grip strength) or life quality(SF-36) after controlling for confounding factors(P>0.05).2. Two years after intervention:(1) Both muscle strength and part of SF-36 scales decreased significantly in the control group. Serum PINP increased significantly in the two-year follow-up, while β-CTX remained at baseline. (2) In group B, standing test, grip strength and most of SF-36 scales did not change dramatically in the two-year follow-up compared to baseline. In terms of bone turnover markers, total PINP increased significantly (54.9±21.0vs.61.0±20.4, P=0.005)while serum β-CTX decreased evidently (0.43±0.18vs.0.39±0.17, P=0.024) two years after intervention.(3)In group C, left grip strength improved significantly one year after intervention (22.18±4.34vs.22.73±4.53, P=0.043).while grip strength at the end of 2nd year did not change compared with baseline. The SF-36 scales of life quality were stable during the two-year follow-up. Furthermore, total PINP increased significantly (52.2±19.0vs.57.3±21.4, P=0.016) whileβ-CTX remained unchanged at the end of 2nd year of intervention compared to those at baseline.(4)In group D, muscle strength did not change both in 12 month and 24 month after intervention. Life quality did not improve either, and even decreased partly in the process. Serum β-CTX decreased significantly (0.40±0.17vs.0.36±0.18, P=0.011) and PINP did not change compared with baseline two years after intervention.(5)Serum 25OHD increased significantly in all groups at the end of 2nd year compared to baseline. Group C and D increased more dramatically compared to the other two groups.Conclusion:In the present study:1. Both muscle strength and life quality decreased significantly with age in postmenopausal women.2. Enhanced exercise could not improve muscle strength and life quality dramatically.Regarding bone turnover markers, it may promote bone formation and inhibit bone resorption.3. Calcium supplement combined with vitamin D of 800IU/d cannot dramatically improve life quality. It may enhance muscle strength in postmenopausal women in the short run, while long-term effect still needs further observation. In addition, it may promote bone formation.4. Calcium supplement combined with active vitamin D did not have a beneficial effect on muscular strength and life quality in the study. And it may inhibit bone resorption.5.Long-term ordinary vitamin D supplementation 800IU/d or active vitamin D supplementation 0.25μg/d could improve vitamin D deficiency significantly.