***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: To overcome the problem of altered breathing strategy during resistive ventilatory muscle training ( VMT ) , we used a single-orifice inspiratory resistance together with a target feedback device ( TFD ) in patients with chronic obstructive pulmonary disease ( COPD ) . In a preliminary study ( study A ) , we showed that the resistance plus TFD was effective in controlling breathing strategy . We subsequently used the resistor plus TFD in a 5-wk study ( study B ) of VMT in 17 COPD patients who were r and omized into high-intensity ( HI ) and low-intensity ( LI ) training groups . Compared with the LI group , the HI group showed significant increases in static maximal inspiratory pressure ( 21.3 vs. 5.0 cmH2O ) , maximal sustained ventilatory capacity ( MSVC , 3.2 vs -0.1 l/min , sustained maximal mouth pressure ( 12.1 vs. 0.6 cmH2O ) , mean mouth pressure ( 6.9 vs. 3.9 cmH2O ) , peak inspiratory flow rate ( 12.3 vs. 4.0 l/min ) , and maximal sustained work rate ( 12.2 vs. 4.2 cmH2O.l-1.min-1 ) . We conclude that targeted VMT with control of breathing strategy improves both ventilatory muscle strength and endurance There is very little information about the effect of inspiratory muscle training on inspiratory flow ( V'I ) and thus on power output ( PO ) in patients with chronic obstructive pulmonary disease ( COPD ) . In this study we aim ed to evaluate the changes induced by training on the determinants of PO .  Thirty one patients with severe COPD were r and omly divided into : Group 1 , trained with 30 % maximal inspiratory pressure ( PI , max ) ; Group 2 , with 10 % PI , max ; and Group 3 also trained with 30 % PI , max , but the breathing pattern was evaluated while performing the training manoeuvres along inspiratory muscle training ( IMT ) . All groups used a threshold device for 10 weeks . The PO for each of the loads during an incremental threshold test was evaluated prior to and after training . Maximal PO ( POmax ) increased in all groups , but the increment was higher in groups trained with 30 % PI , max ( p<0.005 ) , mainly due to an increase in V'I. Group 3 showed a progressive increase in V'I ( p<0.001 ) during the training manoeuvres in spite of an increase in load along IMT . In addition , the load after IMT was overcome with a shorter inspiratory time ( tI ) ( p<0.02 ) , a smaller tI/total duration of the respiratory cycle ( t(tot ) ) , ( p<0.001 ) with no change in tidal volume or t(tot ) . The increment in POmax in this group correlated with the V'I generated while training ( r=0.85 ; p<0.0001 ) . We conclude that in patients with chronic obstructive pulmonary disease , the use of an intermediate threshold load for training improves power output mainly by increasing inspiratory flow , an effect consistent with an increase in shortening velocity of inspiratory muscles We investigated the relationship between the sensation of breathlessness and progressively higher resistive inspiratory loadings in nine normal subjects ( 31 + /- 17 yr ; forced expiratory volume in one second ( FEV1 ) = 105 + /- 9 % of predicted ) and in eighteen chronic obstructive pulmonary disease ( COPD ) patients ( 63 + /- 7 yr ; FEV1 = 43 + /- 17 % of predicted ) . The sensation of breathlessness correlated with mouth pressure both in normals ( r = 0.94 ) and in COPD patients ( r = 0.95 ) , with a steeper slope in patients . On this basis we studied the effect of inspiratory muscle training on the sensation of breathlessness in sixteen COPD patients ( 63 + /- 8 yr ; FEV1 = 52 + /- 19 % of predicted ) . After a baseline assessment of lung function , MIP ( maximal inspiratory pressure ) , inspiratory muscle endurance and the sensation of breathlessness ( Borg scale ) at different inspiratory loads , the patients were divided into two groups : the first was trained by means of resistive breathing , the second used a placebo device . At the end of the training , MIP increased more in the trained group ( 56 + /- 10 to 69 + /- 15 cmH2O ; p less than 0.001 ) than in the placebo group ( 50 + /- 17 to 56 + /- 22 cmH2O ; p = NS ) . The Borg score fell significantly at all the considered inspiratory loads in trained patients , but not in the placebo group . We conclude that the training with inspiratory resistances decreased the sensation of breathlessness via an increase in inspiratory muscle strength and endurance The effect of inspiratory muscle training ( IMT ) on exercise capacity in patients with chronic airflow limitation ( CAL ) has been debated . The present study was planned to further investigate the effects of IMT on exercise performance . Twenty patients ( aged 62+/-1 yrs ; forced expiratory volume in one second/forced vital capacity ( FEV1/FVC ) 36+/-2 % ) were trained 30 min daily for 6 days a week during 10 weeks , with either 30 % ( Group 1 ) or 10 % ( Group 2 ) of peak maximal inspiratory pressure ( PI , max ) as a training load . Exercise performance was evaluated by the distance walked in 6 min ( 6MWD ) and by changes in oxygen consumption ( V'O2 ) and minute ventilation ( V'E ) during a progressive exercise test . Changes in PI , max and dyspnoea were also measured . Results showed a significant increment in peak PI , max in both groups , whereas dyspnoea and 6MWD improved only in Group 1 ( p<0.05 and p<0.01 , respectively ) . No increment in maximal workload or in peak V'O2 was observed in either group . Patients in Group 1 , however , showed a reduction in V'E and V'O2 for the same exercise . A correlation between changes in V'E and V'O2 during a workload of 75 kpm x min(-1 ) was observed in Group 1 ( r=0.92 ; p<0.001 ) . We conclude that inspiratory muscle training using a load of 30 % peak maximal inspiratory pressure , improves dyspnoea , increases walking capacity and reduces the metabolic cost of exercise Twenty-one patients with severe chronic irreversible airflow obstruction ( FEV1 consistently less than 1.2 l ) were allocated r and omly to one of two training programmes design ed to reduce respiratory disability or a placebo training control group . Daily structured physical exercise , twice daily inspiratory muscle training by resistive breathing , or daily placebo training were undertaken for 10 weeks , and the effects on lung function , exercise capacity , respiratory symptoms and psychological state compared . Maximal work achieved on a progressive bicycle exercise test was significantly increased in all groups ( 36 % , 23 % and 34 % respectively ) and global improvement in mood also occurred . There was no significant change in respiratory symptom score , static lung function tests or 12 min walking distance . Neither form of active treatment showed superiority over placebo training BACKGROUND AND PURPOSE Previous studies have provided little information about the comparative efficacy of treatment with pressure threshold and targeted resistive inspiratory muscle training devices . This study compared the efficacy of these two types of inspiratory muscle training ( IMT ) devices on inspiratory muscle function , exercise capacity , and quality of life in patients with chronic obstructive pulmonary disease ( COPD ) . METHODS Forty two patients with moderate to severe COPD were r and omly assigned to either a control group , a group receiving pressure threshold inspiratory muscle training , or a group receiving targeted resistive inspiratory muscle training . The training intensity was 50 % of patients ' maximal inspiratory pressure ( MIP ) . Home-based training comprised two 15-minute sessions a day , 5 days a week for 8 weeks . Inspiratory muscle function measurement included MIP and inspiratory muscle endurance . RESULTS Thirty patients completed the program , 10 from each group . Twelve patients were excluded because of changes in pharmacological regimen or admission to the hospital ( n = 5 ) , study withdrawal ( n = 4 ) , or poor compliance with the training program ( n = 3 ) . After training , a significant increase in endurance time was found for the threshold group and targeted resistive group ( 4.4 + /- 3.2 min and 3.0 + /- 2.9 min , respectively , both p < 0.05 vs control ) , with no significant difference between the 2 training groups . The 6-minute walking distance also increased significantly in both training groups ( p < 0.05 ) . CONCLUSIONS Targeted resistive IMT with a controlled training load has a similar efficacy to the more popularly used pressure threshold IMT and can be incorporated in the treatment of COPD patients . The targeted resistance device offers a less expensive and easily used treatment choice Twenty-eight patients with stable chronic obstructive pulmonary disease ( COPD ) undertook a training program with a simple respiratory apparatus for 15 min three times daily for 6 weeks . Fourteen patients were allocated to an inspiratory resistance training program  and 14 to a control group .  In all subjects the median FEV1 was 0.72 and the median FEV1/FVC was 39 % . There was no difference in FEV1 or FEV1/FVC between the control and the test groups . In both groups of patients FEV1 FVC and the corresponding values during inspiration , FIV1 and FIVC , as well as MVV , were found unchanged following the training period . Inspiratory resistance tolerance increased in both groups but no significant difference in the improvement could be observed between the two groups . Both groups also showed a similar increase , 23 ( 76 - 10 ) % , in stair-climbing ability . There was no correlation between increases in inspiratory load tolerance and stair-climbing ability . It is suggested that both inspiratory load tolerance and work ability can be improved in COPD patients , but that inspiratory resistance training does not contribute to these improvements The present study was aim ed at evaluating the effects of a specific inspiratory muscle training protocol on the structure of inspiratory muscles in patients with chronic obstructive pulmonary disease . Fourteen patients ( males , FEV1 , 24 + /- 7 % predicted ) were r and omized to either inspiratory muscle or sham training groups . Supervised breathing using a threshold inspiratory device was performed 30 minutes per day , five times a week , for 5 consecutive weeks . The inspiratory training group was subjected to inspiratory loading equivalent to 40 to 50 % of their maximal inspiratory pressure . Biopsies from external intercostal muscles and vastus lateralis ( control muscle ) were taken before and after the training period . Muscle sample s were processed for morphometric analyses using monoclonal antibodies against myosin heavy chain isoforms I and II . Increases in both the strength and endurance of the inspiratory muscles were observed in the inspiratory training group . This improvement was associated with increases in the proportion of type I fibers ( by approximately 38 % , p < 0.05 ) and in the size of type II fibers ( by approximately 21 % , p < 0.05 ) in the external intercostal muscles . No changes were observed in the control muscle . The study demonstrates that inspiratory training induces a specific functional improvement of the inspiratory muscles and adaptive changes in the structure of external intercostal muscles A quantitative systematic review , or meta- analysis , uses statistical methods to combine the results of multiple studies . Meta-analyses have been done for systematic review s of therapeutic trials , diagnostic test evaluations , and epidemiologic studies . Although the statistical methods involved may at first appear to be mathematically complex , their purpose is simple : They are trying to answer four basic questions . Are the results of the different studies similar ? To the extent that they are similar , what is the best overall estimate ? How precise and robust is this estimate ? Finally , can dissimilarities be explained ? This article provides some guidance in underst and ing the key technical aspects of the quantitative approach to these questions . We have avoided using equations and statistical notations ; interested readers will find implementations of the described methods in the listed references . We focus here on the quantitative synthesis of reports of r and omized , controlled , therapeutic trials because far more meta-analyses on therapeutic studies than on other types of studies have been published . For practical reasons , we present a stepwise description of the tasks that are performed when statistical methods are used to combine data . These tasks are 1 ) deciding whether to combine data and defining what to combine , 2 ) evaluating the statistical heterogeneity of the data , 3 ) estimating a common effect , 4 ) exploring and explaining heterogeneity , 5 ) assessing the potential for bias , and 6 ) presenting the results . Deciding Whether To Combine Data and Defining What To Combine By the time one performs a quantitative synthesis , certain decisions should already have been made about the formulation of the question and the selection of included studies . These topics were discussed in two previous articles in this series [ 1 , 2 ] . Statistical tests can not compensate for lack of common sense , clinical acumen , and biological plausibility in the design of the protocol of a meta- analysis . Thus , a reader of a systematic review should always address these issues before evaluating the statistical methods that have been used and the results that have been generated . Combining poor- quality data , overly biased data , or data that do not make sense can easily produce unreliable results . The data to be combined in a meta- analysis are usually either binary or continuous . Binary data involve a yes/no categorization ( for example , death or survival ) . Continuous data take a range of values ( for example , change in diastolic blood pressure after antihypertensive treatment , measured in mm Hg ) . When one is comparing groups of patients , binary data can be summarized by using several measures of treatment effect that were discussed earlier in this series [ 3 ] . These measures include the risk ratio ; the odds ratio ; the risk difference ; and , when study duration is important , the incidence rate . Another useful clinical measure , the number needed to treat ( N 
    Output:
    
Results indicate that targeted resistive or threshold IMT was associated with significant improvements in some outcomes of inspiratory muscle strength ( PI(max ) ( cm H2O ) ) and endurance ( Inspiratory Threshold Loading ( kPa ) ) , exercise capacity ( Borg Scale for Respiratory Effort ( modified Borg scale ) , Work Rate maximum ( Watts ) ) , and dyspnea ( Transition Dyspnea Index ) , whereas IMT without a target or not using threshold training did not show improvement in these variables .
There was no conclusive evidence regarding quality of life measures .
IMT is effective for adults with COPD when using threshold or targeted devices that control or provide a target for training intensity