***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: OBJECTIVES To evaluate and compare the effectiveness and cost-effectiveness of a leisure centre-based exercise programme , an instructor-led walking programme and advice-only in patients referred for exercise by their GPs . DESIGN A single-centre , parallel-group , r and omised controlled trial , consisting of three arms , with the primary comparison at 6 months . SETTING Assessment s were carried out at Copthall Leisure Centre in Barnet , an outer London borough , and exercise programmes conducted there and at three other leisure centres and a variety of locations suitable for supervised walking throughout the borough . PARTICIPANTS Participants were aged between 40 and 74 years , not currently physically active and with at least one cardiovascular risk factor . INTERVENTIONS The 943 patients who agreed to participate in the trial were assessed in cohorts and r and omised to one of the following three arms : a 10-week programme of supervised exercise classes , two to three times a week in a local leisure centre ; a 10-week instructor-led walking programme , two to three times a week ; an advice-only control group who received tailored advice and information on physical activity including information on local exercise facilities . After 6 months the control group were rer and omised to one of the other trial arms . Assessment s took place before r and omisation , at 10 weeks ( in a r and om 50 % sub sample of participants ) , 6 months and 1 year in the leisure centre and walking arms . The control participants were similarly assessed up to 6 months and then reassessed at the same intervals as those initially r and omised to the leisure centre and walking groups . MAIN OUTCOME MEASURES The primary outcome measures were changes in self-reported exercise behaviour , blood pressure , total cholesterol and lipid subfractions . Secondary outcomes included changes in anthropometry , cardiorespiratory fitness , flexibility , strength and power , self-reported lifestyle behaviour , general and psychological health status , quality of life and health service usage . The costs of providing and making use of the service were quantified for economic evaluation . RESULTS There was a net increase in the proportion of participants achieving at least 150 minutes per week of at least moderate activity in the sport/leisure and walking categories in all three study groups : at 6 months , the net increases were 13.8 % in the leisure centre group , 11.1 % in the walking group and 7.5 % in the advice-only group . There were significant reductions in systolic and diastolic blood pressure in all groups at each assessment point compared with baseline . There were also significant and sustained improvements in cardiorespiratory fitness and leg extensor power , and small reductions in total and low-density lipoprotein cholesterol in all groups , but there were no consistent differences between the groups for any parameter over time . All three groups showed improvement in anxiety and mental well-being scores 6 months after the beginning of the trial . Leisure centre and walking groups maintained this improvement at 1 year . There were no differences between groups . Costs to the participants amounted to pound 100 for the leisure centre scheme and pound 84 for the walking scheme , while provider costs were pound 186 and pound 92 , respectively . Changes in overall Short Form 36 scores were small and advice only appeared the most cost-effective intervention . CONCLUSIONS The results of this trial suggest that referral for tailored advice , supported by written material s , including details of locally available facilities , supplemented by detailed assessment s may be effective in increasing physical activity . The inclusion of supervised exercise classes or walks as a formal component of the scheme may not be more effective than the provision of information about their availability . On cost-effectiveness grounds , assessment and advice alone from an exercise specialist may be appropriate to initiate action in the first instance . Subsidised schemes may be best concentrated on patients at higher absolute risk , or with specific conditions for which particular programmes may be beneficial . Walking appears to be as effective as leisure centre classes and is cheaper . Efforts should be directed towards maintenance of increased activity , with proven measures such as telephone support . Further research should include an up date d meta- analysis of published exercise interventions using the st and ardised mean difference approach Objective : In the general population , attention is reliably enhanced after exposure to certain physical environments , particularly natural environments . This study examined the impacts of environments on attention in children with ADHD . Method : In this within subjects design , each participant experienced each of three treatments ( environments ) in single blind controlled trials . Seventeen children 7 to12 years old professionally diagnosed with ADHD experienced each of three environments — a city park and two other well-kept urban setting s — via individually guided 20-minute walks . Environments were experienced 1 week apart , with r and omized assignment to treatment order . After each walk , concentration was measured using Digit Span Backwards . Results : Children with ADHD  concentrated better after the walk in the park than after the downtown walk ( p = .0229 ) or the neighborhood walk ( p = .0072 ) . Effect sizes were substantial ( Cohen 's d = .52 and .77 , respectively ) and comparable to those reported for recent formulations of methylpheni date . Conclusion : Twenty minutes in a park setting was sufficient to elevate attention performance relative to the same amount of time in other setting s. These findings indicate that environments can enhance attention not only in the general population but also in ADHD population s. “ Doses of nature ” might serve as a safe , inexpensive , widely accessible new tool in the tool kit for managing ADHD symptoms . ( J. of Att . Dis . 2009 ; 12(5 ) 402 - 409 OBJECTIVES This study examined the association between access to quality urban green space and levels of physical activity . STUDY DESIGN A cross-sectional examination of the relationship between access to quality urban green space and level of recreational physical activity in 4950 middle-aged ( 40 - 70 years ) respondents from the European Prospect i ve Investigation into Cancer and Nutrition ( EPIC ) , who resided in Norwich , UK . METHODS Using geographic information systems ( GIS ) , three measures of access to open green space were calculated based on distance only , distance and size of green space and distance , size and quality of green space . Multiple regression models were used to determine the relationship between the three indicators of access to open green space and level of recreational physical activity . RESULTS There was no evidence of clear relationships between recreational activity and access to green spaces . Non-significant associations were apparent for all variables , and there was no evidence of a clear trend in regression coefficients across quartiles of access for either the distance , size adjusted , and quality and size-adjusted models . Furthermore , the neighbourhood measures of access to green spaces showed non-significant associations with recreational physical activity . CONCLUSIONS Access to urban green spaces does not appear to be associated with population levels of recreational physical activity in our sample of middle-aged adults 
    Output:
    
Based on these data , a meta- analysis provided some evidence of a positive benefit of a walk or run in a natural environment in comparison to a synthetic environment .
There was also some support for greater attention after exposure to a natural environment but not after adjusting effect sizes for pretest differences .
Meta- analysis of data on blood pressure and cortisol concentrations found less evidence of a consistent difference between environments across studies .