Seven trials (n=561) comprising five randomised controlled trials (RCTs, n=464) and two controlled clinical trials (n=97) were included. The methodological quality was low for three RCTs and one controlled clinical trial that assessed postmenopausal women. None of these trials reported details of randomisation, blinding or allocation concealment. Only one trial sufficiently described details of dropouts and withdrawals. Methodological quality was moderate for two RCTs and one controlled clinical trial that assessed elderly subjects. Two trials described methods of randomisation. One trial reported blinding of assessor together with allocation concealment. Two RCTs reported sufficient details of withdrawals and drop-outs.
Meta-analysis of studies that evaluated the effect of tai chi on bone mineral density change at the spine in comparison with no treatment found no statistically significant effects (weighted mean difference 0.02, 95% confidence interval: -0.02 to 0.06, p=0.31; three RCTs). There was no evidence of statistical heterogeneity.
One RCT (n=132) found that tai chi was superior to control for loss of bone mineral density compared to a sedentary lifestyle. Two RCTs (n=21 and 22) found no differences between tai chi and exercise or calcium supplements for bone mineral density. One controlled clinical trial (n=4) found significant effects of tai chi on serum osteocalcin, pyridinoline and deoxypyridinoline compared to baseline (data not reported).
Elderly participants aged over 65 years:
There were no statistically significant differences for one RCT (n=180) that compared tai chi with resistance training and no treatment for total hip bone mineral density in women and in men. There was no evidence of differences between groups for total bone mineral density of the spine in both genders. One RCT (n=28) found statistically significant differences in favour of tai chi in comparison with resistance training on bone metabolism for alkaline phosphatase at six weeks (p<0.05) and parathyroid hormone concentration at 12 weeks (p<0.05). One controlled clinical trial (n=57) reported that tai chi significantly improved total bone mineral density (site not reported, p<0.05) and reduced fracture rate (p<0.01) in institutionalised elderly participants.