Effects of weight training time on bone mineral density of patients with secondary osteoporosis after hemiplegia

The aim of the study was to investigate the effects of weight training time on bone mineral density (BMD) of patients with secondary osteoporosis after hemiplegia. A total of 129 hemiplegic patients with stroke, 75 males and 54 females, aged 50–75 years, were recruited in this study. Male patients were randomly divided into 3 groups (25 cases each) receiving 30 min (group M30), 60 min (group M60), or 90 min (group M90) daily upright bed weight training. Female patients were similarly randomly allocated into groups F30, F60 and F90 (18 cases each) with daily upright bed weight training for 30, 60 and 90 min, respectively. After 3 months of training, BMD at anteroposterior lumbar spine (L1-L4) and ipsilateral femoral neck were examined by dual-energy X-ray absorptiometry. Compared to pre-treatment, no statistical difference in BMD was found after 3 months in males who underwent daily 30-min weight training (group M30). By contrast, a significant increase in BMD was seen at lumbar and femoral neck in groups M60 and M90 after 3 months (all p<0.05). By pair-wise comparison, we found that BMD at lumbar and at femoral neck was significantly higher in groups M60 vs. M30 and in groups M90 vs. M60 (all p<0.05). For female subjects, daily 90-min weight training significantly increased BMD at lumbar and at femoral neck in group F90 (both p<0.05), but daily 30- or 60-min weight training did not produce similar improvement after 3 months. By pair-wise comparison, we found a significantly higher BMD at lumbar and at femoral neck in groups F90 vs. F60 after 3 months of treatment (both p<0.05). In conclusion, in order to stimulate BMD and reverse osteoporosis in patients with secondary osteoporosis after hemiplegia, daily weight training for minimum 60 and 90 min was needed for males and females, respectively.