average life expectancy has increased owing to continued economic growth and advancements 
 in medical science and technology , and , as such , the elderly population is increasing 
 rapidly . according to a recent report , elderly individuals are less likely to receive 
 medical treatment as they age , when their income is lower , and if they are female1 , and the burden of medical costs is 
 increasing accordingly . in particular , because prevalence of metabolic syndrome is higher in those aged over 60 
 than in other age groups , it has been of clinical interest . in those with metabolic 
 syndrome , risk of cardiovascular disease is increased by more than 2-fold , while risk of 
 diabetes is increased by more than 10-fold2 , 3 . increasing prevalence of metabolic syndrome in older individuals has been reported to be 
 closely related to low physical activity in the elderly4 . among various risk factors for metabolic syndrome , high blood 
 pressure has been found to be most significant , followed by abdominal obesity . thus , in 
 order to decrease prevalence of metabolic syndrome , factors that can decrease blood pressure 
 and abdominal obesity should be investigated5 . exercise  a factor influencing metabolic syndrome that can be regulated  is essential for 
 maintaining health , recovering health from chronic disease , and maintaining independence in 
 the elderly , and is reported to have positive physical , psychologic , and social 
 influences6 . in a previous study 
 regarding tai chi in middle - aged women , risk factors for metabolic syndrome decreased while 
 health - related quality of life improved7 . similarly , in a pilot study investigating tai chi in 11 middle - aged subjects with metabolic 
 syndrome , waist circumference and blood pressure showed significant improvement compared 
 with baseline values8 . therefore , the present study aimed to determine the effects of tai chi in the elderly , who 
 show high prevalence of metabolic syndrome , and to investigate whether tai chi can be used 
 actively in a clinical setting . this study used a nonequivalent control group pretest - posttest quasi - experimental design . the sample size necessary for t - tests was calculated as 36 subjects in each group according 
 to g * power analysis conducted with an effect size of 0.67 , significance level of 0.05 , and 
 power of 0.80 , based on the results of a previous study9 . in the present study , 68 elderly individuals residing in j city were divided into 2 groups : 
 36 in the experimental group , who received tai chi training for 6 weeks , and 36 in the 
 control group , who did not receive tai chi training . however , 2 subjects in each group 
 withdrew , resulting in 34 subjects in each group . subjects were aged over 65 , had not exercised regularly during the last 
 6 months , had no health problems preventing them from exercising , and could perform physical 
 activities independently . subjects received an explanation regarding the purpose and methods 
 of the study prior to participation and provided written informed consent according to the 
 principles of the declaration of helsinki . the intervention used in this study was yang style 24-form tai - chi , which was conducted for 
 60 minutes per session , 5 sessions per week , for a total of 6 weeks . in each session , 
 subjects in the experimental group conducted 10 minutes of warm - up exercises , 45 minutes of 
 tai chi , and 5 minutes of cool - down exercises . similar to the experimental group , the 
 control group performed 10 minutes of warm - up exercises and 5 minutes of cool - down exercises 
 in each session , 5 times per week , for a total of 6 weeks . the content validity of the 
 program was verified by a medical specialist , nursing professor with experience conducting 
 exercise - related research , and exercise therapist . the intervention was conducted at our 
 organization s auditorium from 14:00 pm to 15:00 pm . mean waist circumference was determined after measuring twice using a tape 
 ( dritz ) , while blood pressure was measured using an automated sphygmomanometer ( model 
 bpbio330 , meditec ) on the subject s right arm after relaxing for 20 minutes . data were 
 collected between december 2 , 2013 , and february 24 , 2014 . after collecting data from the 
 control group for 6 weeks homogeneity 
 between the experimental and control groups was tested using  and t - tests . t 
 and paired t - tests were performed to determine differences in waist circumference and blood 
 pressure between groups . subjects mean age was 72.4  3.8  years and 71.2  5.1  years in the experimental and 
 control groups , respectively . because there were no significant differences between groups in age , gender , marital 
 status , educational level , religion , income , or exercise status , the groups were found to be 
 homogeneous ( table 1table 1.subjects general characteristicscharacteristicexperimental group ( n = 34)control group ( n = 34)age ( yrs)72.4  3.871.2  5.1gendermale11 ( 32.4)10 ( 29.4)female23 ( 67.6)24 ( 70.5)marital statusmarried23 ( 67.6)26 ( 76.5)other11 ( 32.4)8 ( 23.5)educational levelno school5 ( 14.7)4 ( 11.8)elementary school20 ( 58.8)20 ( 58.8)middle school5 ( 14.7)5 ( 14.7)high school4 ( 11.8)4 ( 11.8)college0 ( 0)1 ( 2.9)religionbuddhist13 ( 38.2)11 ( 32.4)christian6 ( 17.6)6 ( 17.6)catholic8 ( 23.5)5 ( 14.7)other1 ( 2.9)2 ( 5.9)no religion6 ( 17.6)10 ( 29.4)income , 10,000 won50 4 ( 11.8)9 ( 26.5)>5015 ( 44.1)14 ( 41.2)100 15 ( 44.1)10 ( 29.4)200 0 ( 0)1 ( 2.9)exerciseyes11 ( 32.4)9 ( 26.5)no23 ( 67.6)25 ( 73.5)data are presented as mean  sd or n ( % ) , as appropriate . ) . data are presented as mean  sd or n ( % ) , as appropriate . moreover , before the intervention , there were no significant differences between groups in 
 waist circumference , systolic blood pressure ( sbp ) , or diastolic blood pressure ( dbp ) ( table 2table 2.dependent variables between groupsvariableexperimental group ( n = 34)control group ( n = 34)waist circumference ( cm)82.6  6.183.2  6.6systolic blood pressure ( mmhg)149.3  19.6143.8  22.8diastolic blood pressure ( mmhg ) 88.1  16.6 86.6  17.1data are presented as mean  sd . ) . after the intervention , waist circumference decreased by 1.8  cm in the 
 experimental group and increased by 0.2  cm in the control group ; change in waist 
 circumference showed a significant difference between groups ( p=0.001 ) ( table 3table 3.dependent variables before and after the intervention between groupsvariablebeforeafterwaist circumference ( cm)experimental group82.6  6.1 80.8  6.0**control group83.2  6.683.4  6.6systolic blood pressure ( mmhg)experimental group149.3  19.6 132.7  15.6**control group143.8  22.8144.7  20.5diastolic blood pressure ( mmhg)experimental group 88.1  16.6 78.0  11.4**control group 86.6  17.1 87.5  13.9data are presented as mean  sd , * * p<0.01 ) . data are presented as mean  sd , * * p<0.01 sbp decreased by 16.6 mmhg in the experimental group and increased by 0.8 mmhg in the 
 control group ; change in sbp showed a significant difference between groups ( p=0.001 ) ( table 3 ) . dbp decreased by 10.1 mmhg in the experimental group and increased by 0.9 mmhg in the 
 control group ; change in dbp showed a significant difference between groups ( p=0.001 ) ( table 3 ) . tai chi conducted in elderly individuals decreased the risk factors for metabolic syndrome , 
 thus , showing positive effects . change in waist circumference before and after the 
 intervention showed a significant difference between the experimental and control groups . this finding is consistent with a previous study10 reporting a significant difference in waist circumference after 24 
 weeks of exercise , and with another study9 
 reporting an increase in oxygen consumption of 16.1% in the tai chi exercise group and a 
 decrease of 1.8% in the control group after 1  year of yang style tai chi exercise . regarding bp in the experimental group , before the tai chi intervention , values for sbp and 
 dbp were higher than normal . after the intervention , however , sbp and dbp measured within 
 normal ranges . on the contrary , in the control group , values for sbp and dbp were higher 
 than normal both before and after the intervention . these results are similar to a previous 
 study5 showing that high bp contributed 
 to prevalence of metabolic syndrome in middle - aged and elderly individuals living in one 
 region . our findings also agree with another study7 in which 12 weeks of tai chi exercise conducted in middle - aged women 
 with metabolic syndrome exerted significant effects on decreasing certain risk factors for 
 metabolic syndrome ( dbp , waist circumference ) in the experimental group compared with the 
 control group . in the present study in which the intervention was conducted for a relatively short period 
 of time ( 6 weeks ) , significant differences in dependent variables , including waist 
 circumference and bp , may have occurred because the exercise was conducted frequently ( 5 
 times per week ) . we applied tai chi exercise 5 times per week for a total of 6 weeks in 
 elderly men and women and observed significant decreases in waist circumference and bp in 
 the experimental group . thus , regular tai chi training has a positive impact on decreasing the risk factors for 
 metabolic syndrome in the elderly . the findings of this study suggest the need for further research to identify the effects on 
 body mass index and blood - related indicators in the elderly .
[ purpose ] the purpose of this study was to investigate the effects of tai chi on waist 
 circumference and blood pressure in the elderly . 
 the present study used a nonequivalent 
 control group pretest - posttest design . 
 [ subjects and methods ] sixty - eight elderly 
 individuals residing in j city were divided into 2 groups : 34 in the experimental group , 
 who received tai chi training for 6 weeks , and 34 in the control group , who did not 
 receive tai chi training . 
 simplified yang style 24-form tai chi was used as the 
 intervention , which was conducted for 60 minutes per session , 5 sessions per week , for a 
 total of 6 weeks . in each session , subjects in the experimental group conducted 10 minutes 
 of warm - up exercises , 45 minutes of tai chi , and 5 minutes of cool - down exercises . 
 waist 
 circumference and blood pressure were measured before and after the 6-week intervention . 
 [ results ] waist circumference and blood pressure decreased significantly after the 6-week 
 intervention in the experimental group compared with the control group . [ conclusion ] tai 
 chi can be used as an effective intervention to improve waist circumference and blood 
 pressure in the elderly .