***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: Background R and omized controlled trials ( RCT ) are required to test relationships between physical activity and cognition in children , but these must be informed by exploratory studies . This study aim ed to inform future RCT by : conducting practical utility and reliability studies to identify appropriate cognitive outcome measures ; piloting an RCT of a 10 week physical education ( PE ) intervention which involved 2 hours per week of aerobically intense PE compared to 2 hours of st and ard PE ( control ) . Methods 64 healthy children ( mean age 6.2 yrs SD 0.3 ; 33 boys ) recruited from 6 primary schools . Outcome measures were the Cambridge Neuropsychological Test Battery ( CANTAB ) , the Attention Network Test ( ANT ) , the Cognitive Assessment System ( CAS ) and the short form of the Connor 's Parent Rating Scale ( CPRS : S ) . Physical activity was measured habitually and during PE sessions using the Actigraph accelerometer . Results Test- retest intraclass correlations from CANTAB Spatial Span ( r 0.51 ) and Spatial Working Memory Errors ( 0.59 ) and ANT Reaction Time ( 0.37 ) and ANT Accuracy ( 0.60 ) were significant , but low . Physical activity was significantly higher during intervention vs. control PE sessions ( p < 0.0001 ) . There were no significant differences between intervention and control group changes in CAS scores . Differences between intervention and control groups favoring the intervention were observed for CANTAB Spatial Span , CANTAB Spatial Working Memory Errors , and ANT Accuracy . Conclusions The present study has identified practical and age-appropriate cognitive and behavioral outcome measures for future RCT , and identified that schools are willing to increase PE time . Trial registration numberIS RCT N70853932 ( http://www.controlled-trials.com BACKGROUND Few scientific studies have examined movement-based embodied contemplative practice s such as yoga and their effects on cognition . The purpose of this r and omized controlled trial was to examine the effects of an 8-week Hatha yoga intervention on executive function measures of task switching and working memory capacity . METHODS Community-dwelling older adults ( N = 118 ; mean age = 62.0 ) were r and omized to one of two groups : a Hatha yoga intervention or a stretching-strengthening control . Both groups participated in hour-long exercise classes 3 × /week over the 8-week study period . All participants completed established tests of executive function including the task switching paradigm , n-back and running memory span at baseline and follow-up . RESULTS Analysis of covariances showed significantly shorter reaction times on the mixed and repeat task switching trials ( partial η(2 ) = .04 , p < .05 ) for the Hatha yoga group . Higher accuracy was recorded on the single trials ( partial η(2 ) = .05 , p < .05 ) , the 2-back condition of the n-back ( partial η(2 ) = .08 , p < .001 ) , and partial recall scores ( partial η(2 ) = .06 , p < .01 ) of running span task . CONCLUSIONS Following 8 weeks of yoga practice , participants in the yoga intervention group showed significantly improved performance on the executive function measures of working memory capacity and efficiency of mental set shifting and flexibility compared with their stretching-strengthening counterparts . Although the underlying mechanisms need to be investigated , these results dem and larger systematic trials to thoroughly examine effects of yoga on executive function as well as across other domains of cognition , and its potential to maintain or improve cognitive functioning in the aging process CONTEXT Many observational studies have shown that physical activity reduces the risk of cognitive decline ; however , evidence from r and omized trials is lacking . OBJECTIVE To determine whether physical activity reduces the rate of cognitive decline among older adults at risk . DESIGN AND SETTING R and omized controlled trial of a 24-week physical activity intervention conducted between 2004 and 2007 in metropolitan Perth , Western Australia . Assessors of cognitive function were blinded to group membership . PARTICIPANTS We recruited volunteers who reported memory problems but did not meet criteria for dementia . Three hundred eleven individuals aged 50 years or older were screened for eligibility , 89 were not eligible , and 52 refused to participate . A total of 170 participants were r and omized and 138 participants completed the 18-month assessment . INTERVENTION Participants were r and omly allocated to an education and usual care group or to a 24-week home-based program of physical activity . MAIN OUTCOME MEASURE Change in Alzheimer Disease Assessment Scale-Cognitive Subscale ( ADAS-Cog ) scores ( possible range , 0 - 70 ) over 18 months . RESULTS In an intent-to-treat analysis , participants in the intervention group improved 0.26 points ( 95 % confidence interval , -0.89 to 0.54 ) and those in the usual care group deteriorated 1.04 points ( 95 % confidence interval , 0.32 to 1.82 ) on the ADAS-Cog at the end of the intervention . The absolute difference of the outcome measure between the intervention and control groups was -1.3 points ( 95 % confidence interval,-2.38 to -0.22 ) at the end of the intervention . At 18 months , participants in the intervention group improved 0.73 points ( 95 % confidence interval , -1.27 to 0.03 ) on the ADAS-Cog , and those in the usual care group improved 0.04 points ( 95 % confidence interval , -0.46 to 0.88 ) . Word list delayed recall and Clinical Dementia Rating sum of boxes improved modestly as well , whereas word list total immediate recall , digit symbol coding , verbal fluency , Beck depression score , and Medical Outcomes 36-Item Short-Form physical and mental component summaries did not change significantly . CONCLUSIONS In this study of adults with subjective memory impairment , a 6-month program of physical activity provided a modest improvement in cognition over an 18-month follow-up period . TRIAL REGISTRATION anzctr.org.au Identifier : ACTRN12605000136606 The effects of acute aerobic exercise on cognitive functions in humans have been the subject of much investigation ; however , these studies are limited by several factors , including a lack of r and omized controlled design s , focus on only a single cognitive function , and testing during or shortly after exercise . Using a r and omized controlled design , the present study asked how a single bout of aerobic exercise affects a range of frontal- and medial temporal lobe-dependent cognitive functions and how long these effects last . We r and omly assigned 85 subjects to either a vigorous intensity acute aerobic exercise group or a video watching control group .  All subjects completed a battery of cognitive tasks both before and 30 , 60 , 90 , or 120 min after the intervention . This battery included the  Hopkins Verbal Learning Test-Revised , the Modified Benton Visual Retention Test , the Stroop Color and Word Test , the Symbol Digit Modalities Test , the Digit Span Test , the Trail Making Test , and the Controlled Oral Word Association Test . Based on these measures , composite scores were formed to independently assess prefrontal cortex- and hippocampal-dependent cognition . A three-way mixed Analysis of Variance was used to determine whether differences existed between groups in the change in cognitive function from pre- to post-intervention testing . Acute exercise improved prefrontal cortex- but not hippocampal-dependent functioning , with no differences found between delay groups . Vigorous acute aerobic exercise has beneficial effects on prefrontal cortex-dependent cognition and these effects can last for up to 2 hr after exercise Strength training has been reported as a potentially useful exercise to improve psychological aspects in the elderly , but its effects remain controversial . This study investigated the effectiveness of strength training conducted twice a week for 12 weeks for improving health-related quality of life ( HRQOL ) and executive cognitive function . The study was a single-blind r and omized controlled trial with assessment s before and after intervention . HRQOL and executive function were assessed using the SF-36 Health Status Survey and a computerized neuro-cognitive assessment using task-switch reaction time trials , respectively . Subjects comprised 119 participants > or = 65 years old , r and omized to either strength training ( n=65 ) or health education classes ( controls , n=54 ) . The strength training program was design ed to strengthen the large muscle groups most important for functional activities and to improve balance . The effects of the intervention on the eight dimensions of the SF-36 in the control and training groups were analyzed . Only the mental health scale of the SF-36 was significantly improved for the training group compared with controls after 12 weeks . Task-switch reaction time and correct response rate remained unchanged . Short-term strength training might have modest positive effects on HRQOL , although this training period may not be sufficient to affect executive function in relatively healthy older people Objective Unblinded outcome assessment can lead to biased estimates of treatment effect in r and omised trials . We review ed published trials to assess how often blinded assessment is used , and whether its use varies according to the type of outcome or assessor . Design and setting A review of parallel group , individually r and omised phase III trials published in four general medical journals ( BMJ , Journal of the American Medical Association , The Lancet , and New Engl and Journal of Medicine ) in 2010 . Main outcome measures Whether assessment of the primary outcome was blinded , and whether this differed according to outcome or assessor type . Results We identified 258 eligible trials . Of these , 106 ( 41 % ) were reported as double-blind , and 152 ( 59 % ) as partially or fully open-label ( that is , they included some groups who were unblinded , such as patients , those delivering the intervention , or those in charge of medical care ) . Of the 152 open trials , 125 required outcome assessment . Of these 125 trials , only 26 % stated that outcome assessment was blinded ; 51 % gave no information on whether assessment was blinded or not . Furthermore , 18 % of trials did not state who performed the assessment . The choice of outcome type ( e.g. instrument measured , rated , or naturally occurring event ) did not appear to influence whether blinded assessment was performed ( range 24 - 32 % for the most common outcome types ) . However , the choice of outcome assessor did influence blinding ; independent assessors were blinded much more frequently ( 71 % ) than participant ( 5 % ) or physician ( 24 % ) assessors . Despite this , open trials did not use independent assessors any more frequently than double-blind trials ( 17 % vs. 18 % respectively ) . Conclusions Blinding of outcome assessors is infrequently used and poorly reported . Increased use of independent assessors could increase the frequency of blinded assessment The aims of this study were to examine the effects of aerobic exercise on measures of executive performance and their relationships with changes in cardiorespiratory fitness , cardiac vagal control ( heart rate variability ) and psychological variables . Thirty-six sedentary seniors aged 60 - 75 years were r and omly assigned to a swimming and aquaerobics program or a stretching program two times a week for 21 weeks . Executive functions ( inhibition , updating of working memory and cognitive flexibility ) and cardiorespiratory fitness ( estimated VO2max ) were assessed at the start , after 10 weeks of program and at the end of the program . Resting HRV and measures of psychological outcomes ( depression , self-efficacy , decisional balance ) were obtained at the start and at the end of the program . Participants of both groups significantly improved their VO2max level , their psychological state and their performance for the 2-back task . Only the participants in the aquaerobics group significantly improved their vagally-mediated HRV and their performance for the Stroop test and the verbal running-span test at the end of the program . Only improvements in cardiac vagal control and in inhibition were shown to be functionally related . These results are discussed in line with the model of neurovisceral integration Background Systematic review s ( SRs ) can help decision makers interpret the deluge of published biomedical literature . However , a SR may be of limited use if the methods used to conduct the SR are flawed , and reporting of the SR is incomplete . To our knowledge , since 2004 there has been no cross-sectional study of the prevalence , focus , and completeness of reporting of SRs across different specialties . Therefore , the aim of our study was to investigate the epidemiological and reporting characteristics of a more recent cross-section of SRs . Methods and Findings We search ed MEDLINE to identify potentially eligible SRs indexed during the month of February 2014 . Citations were screened using prespecified eligibility criteria . Epidemiological and reporting characteristics of a r and om sample of 300 SRs were extracted by one review er , with a 10 % sample extracted in duplicate . We compared characteristics of Cochrane versus non-Cochrane review s , and the 2014 sample of SRs versus a 2004 sample of SRs . We identified 682 SRs , suggesting that more than 8,000 SRs are being indexed in MEDLINE annually , corresponding to a 3-fold increase over the last decade . The majority of SRs addressed a therapeutic question and were conducted by authors based in China , the UK , or the US ; they included a median of 15 studies involving 2,072 participants .  Meta- analysis was performed in 63 % of SRs , mostly using st and ard pairwise methods . Study risk of bias/ quality assessment was performed in 70 % of SRs but was rarely incorporated into the analysis ( 16 % ) . Few SRs ( 7 % ) search ed sources of unpublished data , and the risk of publication bias was considered in less than half of SRs . Reporting quality was highly variable ; at least a third of SRs did not report use of a SR protocol , eligibility criteria relating to publication 
    Output:
    
Meta- analysis of chronic PA revealed a significant , small effect size while analysis of acute PA revealed a non-significant , trivial result .
Age and intensity were significant moderators while allocation concealment , blinding , and intervention length were not .
Conclusions Chronic PA can significantly improve WMP while acute PA can not .