***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 — Exercise training reduces the symptoms of chronic heart failure . Which exercise intensity yields maximal beneficial adaptations is controversial . Furthermore , the incidence of chronic heart failure increases with advanced age ; it has been reported that 88 % and 49 % of patients with a first diagnosis of chronic heart failure are > 65 and > 80 years old , respectively . Despite this , most previous studies have excluded patients with an age > 70 years . Our objective was to compare training programs with moderate versus high exercise intensity with regard to variables associated with cardiovascular function and prognosis in patients with postinfa rct ion heart failure . Methods and Results — Twenty-seven patients with stable postinfa rct ion heart failure who were undergoing optimal medical treatment , including & bgr;-blockers and angiotensin-converting enzyme inhibitors ( aged 75.5±11.1 years ; left ventricular [ LV ] ejection fraction 29 % ; & OV0312;o2peak 13 mL · kg−1 · min−1 ) were r and omized to either moderate continuous training ( 70 % of highest measured heart rate , ie , peak heart rate ) or aerobic interval training ( 95 % of peak heart rate ) 3 times per week for 12 weeks or to a control group that received st and ard advice regarding physical activity . & OV0312;o2peak increased more with aerobic interval training than moderate continuous training ( 46 % versus 14 % , P<0.001 ) and was associated with reverse LV remodeling . LV end-diastolic and end-systolic volumes declined with aerobic interval training only , by 18 % and 25 % , respectively ; LV ejection fraction increased 35 % , and pro-brain natriuretic peptide decreased 40 % . Improvement in brachial artery flow-mediated dilation ( endothelial function ) was greater with aerobic interval training , and mitochondrial function in lateral vastus muscle increased with aerobic interval training only . The MacNew global score for quality of life in cardiovascular disease increased in both exercise groups . No changes occurred in the control group . Conclusions — Exercise intensity was an important factor for reversing LV remodeling and improving aerobic capacity , endothelial function , and quality of life in patients with postinfa rct ion heart failure . These findings may have important implication s for exercise training in rehabilitation programs and future studies Background High-intensity interval training ( HIT ) as exercise therapy is gradually implemented in cardiac rehabilitation as the cardiovascular benefits from exercise is intensity dependent . However , in previous studies , HIT has been performed with strict supervision . The aim of the study was to assess the feasibility and effectiveness of different modes of HIT in cardiac rehabilitation . Design a r and omized clinical study . Methods Ninety participants with coronary artery disease ( 80 men/10 women , mean age 57 ± 8 years ) were r and omly assigned to one of three exercise modes : group exercise ( GE ) , treadmill exercise ( TE ) , or home-based exercise ( HE ) . HIT was performed twice a week for 12 weeks with an exercise intensity of 85–95 % of peak heart rate . The primary outcome measure was change in peak oxygen uptake ( peak VO2 ) . Results Eighty-three participants ( 92 % ) completed the intervention without any severe adverse events . Peak VO2 increased from 34.7 ± 7.3 to 39.0 ± 8.0 ml/kg/min , 32.7 ± 6.5 to 36.0 ± 6.2 ml/kg/min , and 34.4 ± 4.8 to 37.2 ± 5.2 ml/kg/min in TE , GE , and HE , respectively . Mean group difference for TE vs. HE was 1.6 ml/kg/min ( 95 % confidence interval , CI , 0.7 to 3.1 , p = 0.02 ) , TE vs. GE 1.1 ml/kg/min ( 95 % CI−0.5 to 2.5 , p = 0.27 ) , and GE vs. HE 0.6 ml/kg/min ( 95 % CI −1.0 to 2.1 , p = 1 ) . However , on-treatment analysis showed no significant difference between groups . Conclusion HIT was efficiently performed in three setting s of cardiac rehabilitation , with respect to target exercise intensity , exercise attendance , and increase in peak VO2 . Exercise mode was not essential for exercise capacity Background : Small studies have suggested that high-intensity interval training ( HIIT ) is superior to moderate continuous training ( MCT ) in reversing cardiac remodeling and increasing aerobic capacity in patients with heart failure with reduced ejection fraction . The present multicenter trial compared 12 weeks of supervised interventions of HIIT , MCT , or a recommendation of regular exercise ( RRE ) . Methods : Two hundred sixty-one patients with left ventricular ejection fraction ⩽35 % and New York Heart Association class II to III were r and omly assigned to HIIT at 90 % to 95 % of maximal heart rate , MCT at 60 % to 70 % of maximal heart rate , or RRE . Thereafter , patients were encouraged to continue exercising on their own . Clinical assessment s were performed at baseline , after the intervention , and at follow-up after 52 weeks . Primary end point was a between-group comparison of change in left ventricular end-diastolic diameter from baseline to 12 weeks . Results : Groups did not differ in age ( median , 60 years ) , sex ( 19 % women ) , ischemic pathogenesis ( 59 % ) , or medication . Change in left ventricular end-diastolic diameter from baseline to 12 weeks was not different between HIIT and MCT ( P=0.45 ) ; left ventricular end-diastolic diameter changes compared with RRE were −2.8 mm ( −5.2 to −0.4 mm ; P=0.02 ) in HIIT and −1.2 mm ( −3.6 to 1.2 mm ; P=0.34 ) in MCT . There was also no difference between HIIT and MCT in peak oxygen uptake ( P=0.70 ) , but both were superior to RRE . However , none of these changes was maintained at follow-up after 52 weeks . Serious adverse events were not statistically different during supervised intervention or at follow-up at 52 weeks ( HIIT , 39 % ; MCT , 25 % ; RRE , 34 % ; P=0.16 ) . Training records showed that 51 % of patients exercised below prescribed target during supervised HIIT and 80 % above target in MCT . Conclusions : HIIT was not superior to MCT in changing left ventricular remodeling or aerobic capacity , and its feasibility remains unresolved in patients with heart failure . Clinical Trial Registration : URL : http://www . clinical trials.gov . Unique identifier : NCT00917046 There is a paucity of methods for improving the affective experience of exercise . We tested a novel method based on discoveries about the relation between exercise intensity and pleasure , and lessons from behavioral economics . We examined the effect of reversing the slope of pleasure during exercise from negative to positive on pleasure and enjoyment , remembered pleasure , and forecasted pleasure .  Forty-six adults were r and omly assigned to a 15-min bout of recumbent cycling of either increasing intensity ( 0 - 120 % of watts corresponding to the ventilatory threshold ) or decreasing intensity ( 120 - 0 % ) . Ramping intensity down , thereby eliciting a positive slope of pleasure during exercise , improved postexercise pleasure and enjoyment , remembered pleasure , and forecasted pleasure . The slope of pleasure accounted for 35 - 46 % of the variance in remembered and forecasted pleasure from 15 min to 7 days postexercise . Ramping intensity down makes it possible to combine exposure to vigorous and moderate intensities with a pleasant affective experience To examine the risk of primary cardiac arrest during vigorous exercise , we interviewed the wives of 133 men without known prior heart disease who had had primary cardiac arrest . Cases were classified according to their activity at the time of cardiac arrest and the amount of their habitual vigorous activity . From interviews with wives of a r and om sample of healthy men , we estimated the amount of time members of the community spent in vigorous activity . Among men with low levels of habitual activity , the relative risk of cardiac arrest during exercise compared with that at other times was 56 ( 95 per cent confidence limits , 23 to 131 ) . The risk during exercise  among men at the highest level of habitual activity was also elevated , but only by a factor of 5 ( 95 per cent confidence limits , 2 to 14 ) . However , among the habitually vigorous men , the overall risk of cardiac arrest -- i.e . , during and not during vigorous activity -- was only 40 per cent that of the sedentary men ( 95 per cent confidence limits , 0.23 to 0.67 ) . Although the risk of primary cardiac arrest is transiently increased during vigorous exercise , habitual vigorous exercise is associated with an overall decreased risk of primary cardiac arrest Background Increased aerobic exercise capacity appears to reduce both all-cause mortality and cardiovascular disease mortality .  Physical exercise to improve peak oxygen uptake ( VO2peak ) is thus strongly recommended , however evidence regarding the most efficient training intensity for patients with coronary artery disease ( CAD ) is still lacking . The purpose of this r and omized study was therefore to assess the effects of high intensity aerobic interval exercise compared to moderate intensity exercise , representing the same total training load , for increasing VO2peak in stable CAD- patients . Methods Twenty-one stable CAD- patients were r and omized to supervised treadmill walking at either high intensity ( 80–90 % of VO2peak ) or moderate intensity ( 50–60 % of VO2peak ) three times a week for 10 weeks . Results After training VO2peak increased by 17.9 % ( P = 0.012 ) in the high intensity group and 7.9 % ( P = 0.038 ) in the moderate intensity group . The training-induced adaptation was significantly higher in the high intensity group ( P = 0.011 ) . Conclusions High intensity aerobic interval exercise is superior to moderate exercise for increasing VO2peak in stable CAD- patients . As VO2peak seems to reflect a continuum between health and cardiovascular disease and death , the present data may be useful in design ing effective training programmes for improved health in the future BACKGROUND Exercise-based cardiac rehabilitation is considered an important adjunct treatment and secondary prevention measure in patients with coronary artery disease ( CAD ) . However , the issues of training modality and exercise intensity for CAD patients remain controversial . OBJECTIVE Main aim of the present study is to test the hypothesis that aerobic interval training ( AIT ) yields a larger gain in peak aerobic capacity ( peakVO2 ) compared to a similar training programme of moderate continuous training ( MCT ) in CAD patients . STUDY DESIGN In this multicentre study stable CAD patients with left ventricular ejection fraction>40 % will be r and omized after recent myocardial infa rct ion or revascularization ( PCI or CABG ) to a supervised 12-week programme of three weekly sessions of either AIT ( 85 - 90 % of peak oxygen uptake [ peakVO2 ] , 90 - 95 % of peak heart rate ) or MCT ( 60 - 70 % of peakVO2 , 65 - 75 % of peak heart rate ) . The primary endpoint of the study is the change of peakVO2 after 12 weeks training . Secondary endpoints include safety , changes in peripheral endothelial vascular function , the evolution of traditional cardiovascular risk factors , quality of life and the number and function of circulating endothelial progenitor cells as well as endothelial microparticles . Possible differences in terms of long-term adherence to prescribed exercise regimens will be assessed by regular physical activity question naires , accelerometry and re assessment of peakVO2 12 months after r and omization . A total number of 200 patients will be r and omized in a 1:1 manner ( significance level of 0.05 and statistical power of 0.90 ) . Enrolment started December 2010 ; last enrolment is expected for February 2013 BACKGROUND Exercise-based cardiac rehabilitation increases peak oxygen uptake ( peak VO₂ ) , which is an important predictor of mortality in cardiac patients . However , it remains unclear which exercise characteristics are most effective for improving peak VO₂ in coronary artery disease ( CAD ) patients . Proof of concept papers comparing Aerobic Interval Training ( AIT ) and Moderate Continuous Training ( MCT ) were conducted in small sample sizes and findings were inconsistent and heterogeneous . Therefore , we aim ed to compare the effects of AIT and Aerobic Continuous Training ( ACT ) on peak VO₂ , peripheral endothelial function , cardiovascular risk factors , quality of life and safety , in a large multicentre study . METHODS Two-hundred CAD patients ( LVEF > 40 % , 90 % men , mean age 58.4 ± 9.1 years ) were r and omized to a supervised 12-week cardiac rehabilitation programme of three weekly sessions of either AIT ( 90 - 95 % of peak heart rate ( HR ) ) or ACT ( 70 - 75 % of peak HR ) on a bicycle . Primary outcome was peak VO₂ ; secondary outcomes were peripheral endothelial function , cardiovascular risk factors , quality of life and safety . RESULTS Peak VO₂ ( ml/kg/min ) increased significantly in both groups ( AIT 22.7 ± 17.6 % versus ACT 20.3 ± 15.3 % ; p-time 
    Output:
    
However , the novelty of this study is to be found in a subgroup analysis based on whether the exercise protocol s were or were not isocaloric .
These results suggest that not the intensity nor the modality but the total EE of the exercise programmes determines the improvement in exercise capacity after training .
This concords with a recent meta- analysis by Kraal et al. , who showed that session duration , programme length and training intensity were all related to the improvement in exercise capacity , but found no independent effect of any of these training characteristics after correction for total EE in patients with CAD .
As such , one could conclude that HIIT offers a time-efficient alternative for MCT as it requires less time ( approximately 30 minutes/week ) to be spent exercising while providing similar health benefits compared to MCT .
As a result , HIIT can overcome one of the most frequently cited barriers to physical activity , which is lack of time .
Nevertheless , these results also imply that one can achieve the same gains with less strain : i.e. if we spend enough minutes exercising at moderate intensity we obtain the same improvements , which , from an adherence perspective , might be as important as saving 30 minutes per week