***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Tai Chi , a moving meditation , is examined for its efficacy in post-stressor recovery . Forty-eight male and 48 female Tai Chi practitioners were r and omly assigned to four treatment groups : Tai Chi , brisk walking , mediation and neutral reading . Mental arithmetic and other difficult tests were chosen as mental challenges , and a stressful film was used to produce emotional disturbance . Tai Chi and the other treatments were applied after these stressors . After all treatments , the salivary cortisol level dropped significantly , and the mood states were also improved . In general the stress-reduction effect of Tai Chi characterized moderate physical exercise . Heart rate , blood pressure , and urinary catecholamine changes for Tai Chi were found to be similar to those for walking at a speed of 6 km/hr . Although Tai Chi appeared to be superior to neutral reading in the reduction of state anxiety and the enhancement of vigour , this effect could be partially accounted for by the subjects ' high expectations about gains from Tai Chi . Approaches controlling for expectancy level are recommended for further assessment Objective To determine the effect of Tai Chi on oxidative stress in a population of elderly Mexican subjects . Design It was carried out a quasi-experimental study with a sample of 55 healthy subjects r and omly divided into two age-matched groups : ( i ) a  control group with 23 subjects and ( ii ) an experimental group with 32 subjects . The experimental group received daily training in Tai Chi for 50 min . Measurements It was measured before and after 6-month of exercise period : thiobarbituric acid reactive substances ( TBARS ) , total antioxidant status ( TAS ) , superoxide dismutase ( SOD ) , and glutathione peroxidase ( GPx ) . Results It was found that the experimental group exhibited a statistically significant decrease in glucose levels , total cholesterol , low-density lipoprotein cholesterol ( LDLC ) , and systolic blood pressure , as well as an increase in SOD and GPx activity and TAS compared with the control group ( p < 0.05 ) . Conclusions Our findings suggest that the daily practice of Tai Chi is useful for reducing OxS in healthy older adults This study was design ed to determine whether a 6-month Tai Chi exercise program can improve self-reported physical functioning limitations among healthy , physically inactive older individuals . Ninety-four community residents ages 65 to 96 ( M age = 72.8 years , SD = 5.1 ) volunteered to participate in the study . Participants were r and omly assigned to either a 6-month experimental ( Tai Chi ) group ( n = 49 ) , which exercised twice per week for 60 min , or a wait-list control group ( n = 45 ) . A 6-item self-report physical functioning scale , assessing the extent of behavioral dysfunction caused by health problems , was used to evaluate change in physical functioning limitations as a result of Tai Chi intervention . Results indicated that compared to the control group , participants in the Tai Chi group experienced significant improvements in all aspects of physical functioning over the course of the 6-month intervention . Overall , the experimental group had 65 % improvement across all 6 functional status measures ranging from daily activities such as walking and lifting to moderate-vigorous activities such as running . It was concluded that the 6-month Tai Chi exercise program was effective for improving functional status in healthy , physically inactive older adults . A self-paced and self-controlled activity such as Tai Chi has the potential to be an effective , low-cost means of improving functional status in older persons OBJECTIVE To evaluate the effects of two exercise approaches , Tai Chi ( TC ) and computerized balance training ( BT ) , on specified primary outcomes ( biomedical , functional , and psychosocial indicators of frailty ) and secondary outcomes ( occurrence of falls ) . DESIGN The Atlanta FICSIT ( Frailty and Injuries : Cooperative Studies of Intervention Techniques ) , a prospect i ve , r and omized , controlled clinical trial with three arms ( TC , BT , and education [ ED ] . Intervention length was 15 weeks , with primary outcomes measured before and after intervention and at 4-month follow-up . Falls were monitored continuously throughout the study . SETTING Persons aged 70 and older living in the community . PARTICIPANTS A total of 200 participants , 162 women and 38 men ; mean age was 76.2 . MEASUREMENTS Biomedical ( strength , flexibility , cardiovascular endurance , body composition ) , functional ( IADL ) , and psychosocial well-being ( CES-D scale , fear of falling question naire , self-perception of present and future health , mastery index , perceived quality of sleep , and intrusiveness ) variables . RESULTS Grip strength declined in all groups , and lower extremity range of motion showed limited but statistically significant changes . Lowered blood pressure before and after a 12-minute walk was seen following TC participation . Fear of falling responses and intrusiveness responses were reduced after the TC intervention compared with the ED group ( P = .046 and P = .058 , respectively ) . After adjusting for fall risk factors , TC was found to reduce the risk of multiple falls by 47.5 % . CONCLUSIONS A moderate TC intervention can impact favorably on defined biomedical and psychosocial indices of frailty . This intervention can also have favorable effects upon the occurrence of falls .  Tai Chi warrants further study as an exercise treatment to improve the health of older people BACKGROUND Patients with Parkinson 's disease have substantially impaired balance , leading to diminished functional ability and an increased risk of falling . Although exercise is routinely encouraged by health care providers , few programs have been proven effective . METHODS We conducted a r and omized , controlled trial to determine whether a tailored tai chi program could improve postural control in patients with idiopathic Parkinson 's disease . We r and omly assigned 195 patients with stage 1 to 4 disease on the Hoehn and Yahr staging scale ( which ranges from 1 to 5 , with higher stages indicating more severe disease ) to one of three groups : tai chi , resistance training , or stretching . The patients participated in 60-minute exercise sessions twice weekly for 24 weeks . The primary outcomes were changes from baseline in the limits-of-stability test ( maximum excursion and directional control ; range , 0 to 100 % ) . Secondary outcomes included measures of gait and strength , scores on functional-reach and timed up- and -go tests , motor scores on the Unified Parkinson 's Disease Rating Scale , and number of falls . RESULTS The tai chi group performed consistently better than the resistance-training and stretching groups in maximum excursion ( between-group difference in the change from baseline , 5.55 percentage points ; 95 % confidence interval [ CI ] , 1.12 to 9.97 ; and 11.98 percentage points ; 95 % CI , 7.21 to 16.74 , respectively ) and in directional control ( 10.45 percentage points ; 95 % CI , 3.89 to 17.00 ; and 11.38 percentage points ; 95 % CI , 5.50 to 17.27 , respectively ) . The tai chi group also performed better than the stretching group in all secondary outcomes and outperformed the resistance-training group in stride length and functional reach .  Tai chi lowered the incidence of falls as compared with stretching but not as compared with resistance training . The effects of tai chi training were maintained at 3 months after the intervention . No serious adverse events were observed . CONCLUSIONS Tai chi training appears to reduce balance impairments in patients with mild-to-moderate Parkinson 's disease , with additional benefits of improved functional capacity and reduced falls . ( Funded by the National Institute of Neurological Disorders and Stroke ; Clinical Trials.gov number , NCT00611481 . ) Background Post-menopausal osteopenic women are at increased risk for skeletal fractures . Current osteopenia treatment guidelines include exercise , however , optimal exercise regimens for attenuating bone mineral density ( BMD ) loss , or for addressing other fracture-related risk factors ( e.g. poor balance , decreased muscle strength ) are not well-defined . Tai Chi is an increasingly popular weight bearing mind-body exercise that has been reported to positively impact BMD dynamics and improve postural control , however , current evidence is inconclusive . This study will determine the effectiveness of Tai Chi in reducing rates of bone turnover in post-menopausal osteopenic women , compared with st and ard care , and will preliminarily explore biomechanical processes that might inform how Tai Chi impacts BMD and associated fracture risks . Methods / Design A total of 86 post-menopausal women , aged 45 - 70y , T-score of the hip and /or spine -1.0 and -2.5 , have been recruited from primary care clinics of a large healthcare system based in Boston . They have been r and omized to a group-based 9-month Tai Chi program plus st and ard care or to st and ard care only . A unique aspect of this trial is its pragmatic design , which allows participants r and omized to Tai Chi  to choose from a pre-screened list of community-based Tai Chi programs . Interviewers masked to participants ' treatment group assess outcomes at baseline and 3 and 9 months after r and omization . Primary outcomes are serum markers of bone resorption ( C-terminal cross linking telopeptide of type I collagen ) , bone formation ( osteocalcin ) , and BMD of the lumbar spine and proximal femur ( dual-energy X-ray absorptiometry ) . Secondary outcomes include health-related quality -of-life , exercise behavior , and psychological well-being . In addition , kinetic and kinematic characterization of gait , st and ing , and rising from a chair are assessed in subset of participants ( n = 16 ) to explore the feasibility of modeling skeletal mechanical loads and postural control as mediators of fracture risk . Discussion Results of this study will provide preliminary evidence regarding the value of Tai Chi as an intervention for decreasing fracture risk in osteopenic women . They will also inform the feasibility , value and potential limitations related to the use of pragmatic design s for the study of Tai Chi and related mind-body exercise . If the results are positive , this will help focus future , more in-depth , research on the most promising potential mechanisms of action identified by this study .Trial registration This trial is registered in Clinical Trials.gov , with the ID number of NCT01039012 BACKGROUND AND PURPOSE African Americans suffer disproportionately higher cardiovascular disease mortality rates than do whites . Psychosocial stress influences the development and progression of atherosclerosis . Carotid intima-media thickness ( IMT ) is a valid surrogate measure for coronary atherosclerosis , is a predictor of coronary outcomes and stroke , and is associated with psychosocial stress factors . Stress reduction with the Transcendental Meditation ( TM ) program decreases coronary heart disease risk factors and cardiovascular mortality in African Americans . B-mode ultrasound is useful for the noninvasive evaluation of carotid atherosclerosis . METHODS This r and omized controlled clinical trial evaluated the effects of the TM program on carotid IMT in hypertensive African American men and women , aged > 20 years , over a 6- to 9-month period . From the initially enrolled 138 volunteers , 60 subjects completed pretest and posttest carotid IMT data . The assigned interventions were either the TM program or a health education group . By use of B-mode ultrasound , mean maximum IMT from 6 carotid segments was used to determine pretest and posttest IMT values . Regression analysis and ANCOVA were performed . RESULTS Age and pretest IMT were found to be predictors of posttest IMT values and were used as covariates . The TM group showed a significant decrease of -0.098 mm ( 95 % CI -0 . 198 to 0.003 mm ) compared with an increase of 0.054 mm ( 95 % CI -0.05 to 0.158 mm ) in the control group ( P=0.038 , 2-tailed ) . CONCLUSIONS Stress reduction with the TM program is associated with reduced carotid atherosclerosis compared with health education in hypertensive African Americans . Further research with this stress-reduction technique is warranted to confirm these preliminary findings OBJECTIVE To determine the effect on balance and strength of 3 months of intensive balance and /or weight training followed by 6 months of low intensity Tai Chi training for maintenance of gains . DESIGN R and omized control intervention . Four groups in 2 x 2 design : Control , Balance , Strength , Balance + Strength , using blinded testers . SETTING Exercise and balance laboratory at University of Connecticut Health Center . PARTICIPANTS Subjects were 110 healthy community dwellers ( mean age 80 ) who were free of dementia , neurological disease , and serious cardiovascular or musculoskeletal conditions . INTERVENTIONS Short-term training ( 3 months ) occurred 3 times/week ( 45 minutes Balance and Strength , 90 minutes Balance + Strength ) . Balance training included equilibrium control exercises of firm and foam surfaces and center-of-pressure biofeedback . Strengthening consisted of lower extremity weight-lifting . All subjects than received long-term group Tai Chi instruction ( 6 months , 1 hour , 1 time/week ) . MEASUREMENTS Losses of balance during Sensory Organization Testing ( LOB ) , single stance time ( SST ) , voluntary limits of stability ( FBOS ) , summed isokinetic torque of eight lower extremity movements ( ISOK ) , and usual gait velocity ( GVU ) . RESULTS AND CONCLUSIONS Balance training meaningfully improved all balance measures by restoring performance to a level analogous to an individual 3 to 10 years younger : LOB = -2.0 + /- 0.3 ( adjusted paired differences , P < .005 ANOVA ) ; SST = 7.0 + / 
    Output:
    
Due to the limited evidence available currently no conclusions can be drawn as to the effectiveness of tai chi on CVD risk factors .
There was some suggestion of beneficial effects of tai chi on CVD risk factors but this was not consistent across all studies .