***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 Heart rate recovery ( HRR1 ) immediately after exercise reflects parasympathetic activity , which is markedly attenuated in chronic heart failure ( CHF ) patients . The aim of our study was to examine both continuous and interval exercise training effects on HRR1 in these patients . Design The population study consisted of 29 stable CHF patients that participated at a rehabilitation program of 36 sessions , three times per week . Of the 29 patients , 24 completed the program . Patients were r and omly assigned to interval { n = 10 [ 100 % peak work rate ( WRp ) for 30 s , alternating with rest for 30 s ] } and to continuous training [ n = 14 ( 50%WRp ) ] . Methods All patients performed a symptom-limited cardiopulmonary exercise test on a cycle ergometer before and after the completion of the program . Measurements included peak oxygen uptake ( VO2p ) , anaerobic threshold ( AT ) , WRp , first degree slope of VO2 during the first minute of recovery ( VO2/t-slope ) , chronotropic response [ % chronotropic reserve ( CR ) = ( peak HR - resting HR ) × 100/(220 - age - resting HR ) ] , HRR1 ( HR difference from peak exercise to one minute after ) . Results After the completion of the rehabilitation program there was a significant increase of WRp , VO2p , AT and VO2/t-slope ( by 30 % , P=0.01 ; 6 % , P=0.01 ; 10 % , P=0.02 ; and 27 % , P=0.03 respectively for continuous training and by 21 % , P≤0.05 ; 8 % , P=0.01 ; 6 % , P = NS ; and 48 % , P=0.02 respectively for interval training ) . However , only patients exercised under the continuous training regime had a significant increase in HRR1 ( 15.0±9.0 to 24.0±12bpm ; P=0.02 ) and CR ( 57±19 to 72±21 % , P=0.02 ) , in contrast with those assigned to interval training ( HRR1 : 21 ± 11 to 21 ± 8 bpm ; P = NS and CR : 57 ± 18 to 59 ± 21 % , P = NS ) . Conclusions Both continuous and interval exercise training program improves exercise capacity  in CHF patients . However , continuous rather than interval exercise training improves early HRR1 , a marker of parasympathetic activity , suggesting a greater contribution to the autonomic nervous system AIMS Diastolic dysfunction ( DD ) was identified as a predictor of adverse prognosis in heart failure with reduced ejection fraction ( HFREF ) . It is , however , unknown if DD is improved by exercise training , which is known to induce reverse remodelling , and if the training effect is attenuated in elderly HFREF patients . We therefore assessed DD in a cohort of referent controls ( RCs ) and HFREF patients and studied the response of DD to endurance exercise in two age groups ( ≤55 years and ≥65 years ) . METHODS AND RESULTS Sixty RC ( 30 ≤ 55 years , mean age 50 ± 5 years ; 30 ≥ 65 years , 72 ± 4 years ) and 60 HFREF patients ( 30 ≤ 55 years , 46 ± 5 years ; 30 ≥ 65 years , 72 ± 5 years , EF 28 ± 5 % ) were r and omized to 4 weeks of supervised endurance training or to a control group . Exercise training was effective in reducing LV isovolumetric relaxation time by 29 % in young and by 26 % in old HFREF patients ( P < 0.05 for both ) . As assessed by tissue Doppler , septal E ' increased by 37 % in young and by 39 % among old HFREF patients ( P < 0.005 for both ) result ing in a significant decrease in the E/E ' ratio from 13 ± 1 to 10 ± 1 in young and 14 ± 1 to 11 ± 1 in old HFREF patients ( P < 0.05 for both ) . Serum levels of N-terminal pro brain natriuretic peptide were significantly reduced after endurance training in HFREF patients of all ages . CONCLUSION In HFREF , diastolic function is significantly impaired in all age groups  . Endurance training is highly effective in improving left ventricular diastolic function in HFREF patients regardless of age . This study is registered at Clinical Trials.gov ( number : NCT00176319 ) Background Optimal timing of cardiac transplantation in ambulatory patients with severe left ventricular dysfunction is often difficult . To determine whether measurement of peak oxygen consumption ( Vo2 ) during maximal exercise testing can be used to identify patients in whom transplantation can be safely deferred , we prospect ively performed exercise testing on all ambulatory patients referred for transplant between October 1986 and December 1989 . Methods and Results Patients were assigned into one of three groups on the basis of exercise data : Group 1 ( n = 35 ) comprised patients accepted for transplant ( Vo2<14 ml/kg/min ) ; group 2 ( n = 52 ) comprised patients considered too well for transplant ( Vo2 > 14 ml/kg/min ) ; and group 3 ( n = 27 ) comprised patients with low Vo2 rejected for transplant due to noncardiac problems . All three groups were comparable in New York Heart Association functional class , ejection fraction , and cardiac index ( p = NS ) . Pulmonary capillary wedge pressure was significantly lower in group 2 than in either group 1 or 3 ( p<0.05 ) , although there was wide overlap . Patients with preserved exercise capacity ( group 2 ) had cumulative 1- and 2-year survival rates of 94 % and 84 % , which are equal to survival levels after transplantation . In contrast , patients rejected for transplant ( group 3 ) had survival rates of only 47 % at 1 year and 32 % at 2 years , whereas patients awaiting transplantation ( group 1 ) had a survival rate of 790 % at 1 year ( both ( p < 0.005 versus patients with Vo2 > 14 ml/kg/min ) . All deaths in group 2 were sudden . By univariate and multivariate analyses , peak Vo2 was the best predictor of survival , with only pulmonary capillary wedge pressure providing additional prognostic information . Conclusions .These data suggest that cardiac transplantation can be safely deferred in ambulatory patients with severe left ventricular dysfunction and peak exercise Vo2 of more than 14 ml/min/kg . ( Circulation 1991;83:778–786 BACKGROUND Exercise testing with ventilatory expired gas analysis has proven to be a valuable tool for assessing patients with heart failure ( HF ) . Peak oxygen consumption ( peak VO2 ) continues to be considered the gold st and ard for assessing prognosis in HF . The minute ventilation -- carbon dioxide production relationship ( VE/VCO2 slope ) has recently demonstrated prognostic significance in patients with HF , and in some studies , it has outperformed peak VO2 . METHODS Two hundred thirteen subjects , in whom HF was diagnosed , underwent exercise testing between April 1 , 1993 , and October 19 , 2001 . The ability of peak VO2 and VE/VCO2 slope to predict cardiac-related mortality and hospitalization was examined . RESULTS Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictors of cardiac-related mortality and hospitalization ( P < .01 ) . Multivariate analysis revealed that peak VO2 added additional value to the VE/VCO(2 ) slope in predicting cardiac-related hospitalization , but not cardiac mortality . The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be significantly better than peak VO2 in predicting cardiac-related mortality ( P < .05 ) . Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization ( 0.77 vs 0.73 ) , the difference was not statistically significant ( P = .14 ) . CONCLUSIONS These results add to the present body of knowledge supporting the use of cardiopulmonary exercise testing in HF . Consideration should be given to revising clinical guidelines to reflect the prognostic importance of the VE/VCO2 slope in addition to peak VO2 Background : Capacity to exercise may not be fully restored in patients with heart failure even in the long term after ventricular assist device ( VAD ) implantation . The benefits of exercise training in patients with VAD are unknown . Design and methods : Fifteen patients , aged 38.3 ± 15.9 years , bridged to heart transplantation with left ventricular assist device or biventricular assist device were r and omized at a ratio of 2 : 1 to a  training group  ( TG , n = 10 ) or a control group ( n = 5 ) , 6.3 ± 4 months after implantation . Both the groups were advised to walk 30–45 min/day . TG also underwent moderate-intensity aerobic exercise using a bike or treadmill for 45 min , three to five times a week , combined with high-intensity inspiratory muscle training using a computer- design ed software to respiratory exhaustion , two to three times a week for 10 weeks . The patients were tested using cardiopulmonary exercise testing , 6-min walk test , spirometry and electronic pressure manometer for inspiratory muscle strength ( Pimax ) and endurance ( sustained Pimax ) measurement . Quality of life was assessed with the Minnesota Living with Heart Failure question naire . Results : TG improved peak oxygen consumption ( 19.3 ± 4.5 vs. 16.8 ± 3.7 ml/kg per min , P = 0.008 ) and VO2 at ventilatory threshold ( 15.1 ± 4.2 vs. 12 ± 5.6 ml/kg per min , P = 0.01 ) , whereas the ventilation/carbon dioxide slope decreased ( 35.9 ± 5.6 vs. 40 ± 6.5 , P = 0.009 ) . The 6-min walk test distance increased ( 527 ± 76 vs. 462 ± 88 m , P = 0.005 ) and quality of life was improved ( 38.2 ± 11.6 vs. 48.9 ± 12.8 , P = 0.005 ) , as well as Pimax ( 131.8 ± 33 vs. 95.5 ± 28cmH2O , P = 0.005 ) , sustained Pimax ( 484 ± 195 vs. 340 ± 193cmH2O/s/10 3 , P = 0.005 ) , and inspiratoty lung capacity ( 2.4 ± 0.9 vs. 1.7 ± 0.7 L , P = 0.008 ) were improved . No significant changes were noted in the control group . Conclusion : Our findings indicate that exercise training may improve the functional status of VAD recipients  even at a later period after implantation and thus , may have additional importance in cases of destination therapy AIMS This study was design ed to evaluate the effects of combined endurance/resistance training on NT-proBNP levels in patients with chronic heart failure ( CHF ) . The safety of resistive weight training for patients with CHF is question ed . Possible detrimental effects include an increase in ventricular diastolic pressure and secondary unfavourable remodelling . Circulating levels of the N-terminal fragment of brain natriuretic peptide ( NT-proBNP ) reflect left ventricular diastolic wall stress and are strongly related to mortality and treatment success in CHF . METHODS AND RESULTS In this study , 27 consecutive patients with stable CHF and left ventricular ejection fraction ( LVEF ) < 35 % were enrolled in a 4 months non-r and omized combined endurance/resistance training programme .  Blood sampling for measurement of NT-proBNP , functional assessment , cardiopulmonary exercise testing , echocardiography and radionuclide angiography  were performed at entry and after 4 months . After 4 months , exercise training caused a significant reduction in circulating concentrations of NT-proBNP ( 2124+/-397 pg/ml before , 1635+/-304 pg/ml after training , p=0.046 , interaction ) , whereas no changes were observed in an untrained heart failure control group . NYHA functional class ( p=0.02 , interaction ) , maximal ( peak VO2 : p=0.035 , interaction ; maximal workload : p<0.00001 , interaction ) and submaximal ( workload at anaerobic threshold : p=0.001 , interaction ; rate-pressure product at anaerobic threshold : p=0.001 , interaction ) exercise parameters as well as work efficiency ( Wattmax/VO2peak : p=0.0001 , interaction ) were significantly improved . In addition , a decrease in left ventricular end-systolic diameter was observed in the trained heart failure group ( p=0.016 ) . CONCLUSION Four months of combined endurance/resistance training significantly reduced circulating levels of NT-proBNP in patients with CHF , without evidence of adverse remodelling . Exercise training might offer additional non-pharmacological modulation of the activated neurohormonal pathways in the setting of CHF OBJECTIVES The aim 
    Output:
    
Aerobic exercise may be effective at improving NTproBNP and the VE/VCO2 slope in systolic HF patients , but these effects are limited to a specific HF population meeting specific inclusion criterion in a limited number of studies .