human
***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: OBJECTIVE : To assess the acute metabolic and cardiovascular responses to walking exercise at an intensity corresponding to the heart rate of claudication pain onset and to investigate the effects of a 12-week walking training program at this intensity on walking capacity . METHODS : Twenty-nine patients with intermittent claudication were r and omly allocated to the  walking training  ( n = 17 ) or control ( CO , n = 12 ) group . The walking training group performed an acute exercise session comprising 15 × 2-min bouts of walking at the heart rate of claudication pain onset , with 2-min interpolated rest intervals . The claudication symptoms and cardiovascular and metabolic responses were evaluated . Walking training was then performed at the same intensity twice each week for 12 weeks , while the control group engaged in twice weekly stretching classes  . The claudication onset distance and total walking distance were evaluated before and after the interventions . Brazilian Registry Clinical Trials : RBR-7M3D8W . RESULTS : During the acute exercise session , the heart rate was maintained within tight limits . The exercise intensity was above the anaerobic threshold and > 80 % of the heart rate peak and VO2peak . After the exercise training period , the walking exercise group ( n = 13 ) showed increased claudication onset distance ( 309±153 vs. 413±201 m ) and total walking distance ( 784±182 vs. 1,100±236 m ) compared to the control group ( n = 12 ) ( p<0.05 ) . CONCLUSION : Walking exercise prescribed at the heart rate of claudication pain onset enables patients with intermittent claudication to exercise with tolerable levels of pain and improves walking performance This study examined whether a training intervention likely to elicit adaptations in the leg could result in reduced leg pain and increased whole body physical capacity .  Twenty-seven peripheral arterial disease ( PAD ) patients were r and omized to either an individual leg plantar flexion training group ( TG ) training 4 × 4 min intervals at 80 % of maximal work rate three times per week for 8 weeks or a control group . The TG significantly increased plantar flexion peak oxygen uptake and power output by 23.5 and 43.9 % , respectively . Treadmill peak oxygen uptake ( VO2peak ) significantly increased 12.3 % in the TG and was associated with a significant increased time to exhaustion of 20.0 % when treadmill walking . Eleven of 14 patients no longer reported leg pain limitations at VO2peak . No differences in cardiac output measured at VO2peak , or walking economy were observed . Plantar flexion training was effective in increasing VO2peak and walking performance , and may be a useful strategy in treatment of PAD In a vascular rehabilitation program , 28 % of our frail elderly patients are unable to be tested with traditional progressive exercise protocol s at program entry due to the high ( 2.0 miles/h or 3.2 km/h ) initial treadmill speeds . The purpose of this investigation was to compare a new progressive treadmill protocol which has a reduced initial speed ( 1.0 mile/h or 1.6 km/h ) to an established protocol performed at 2.0 miles/h ( 3.2 km/h ) to determine the comparability and reproducibility of the new protocol . Eleven patients with arterial claudication performed three symptom-limited exercise tests in r and om order . Two tests used the new protocol while the remaining trial used the established protocol .  Claudication pain was measured using a 5-point scale . Oxygen consumption , heart rate , minute ventilation , respiratory exchange ratio and blood pressure at peak exercise were similar among the three trials . There were strong intra-class correlations for peak oxygen consumption ( r = 0.97 ) , onset of claudication ( r = 0.96 ) and maximum walking time ( r = 0.98 ) between the two trials using the new protocol . There was also a significant correlation between the new protocol and the established protocol for peak oxygen consumption ( r = 0.90 ) and maximum walking time ( r = 0.89 ) . The new progressive treadmill protocol represents a valid , reliable protocol for patients with arterial claudication . This protocol may be useful for testing patients with a low functional capacity so that clinical ly appropriate exercise prescriptions can be established and the efficacy of treatments can be determined BACKGROUND This prospect i ve , r and omized controlled clinical trial determined whether an optimal exercise program length exists to efficaciously change claudication onset time ( COT ) and peak walking time ( PWT ) in patients with peripheral artery disease and claudication . METHODS The study r and omized 142 patients to supervised exercise ( n = 106 ) or a usual care control group ( n = 36 ) , with 80 completing the exercise program and 27 completing the control intervention .  The exercise program consisted of intermittent walking to nearly maximal claudication pain 3 days per week . COT and PWT were the primary outcomes obtained from a treadmill exercise test at baseline and bimonthly during the study . RESULTS After exercise , changes in COT ( P < .001 ) and PWT ( P < .001 ) were consistently greater than changes after the control intervention . In the exercise program , COT and PWT increased from baseline to month 2 ( P < .05 ) and from months 2 to 4 ( P < .05 ) but did not significantly change from months 4 to 6 ( P > .05 ) . When changes were expressed per mile walked during the first 2 months , middle 2 months , and final 2 months of exercise , COT and PWT only increased during the first 2 months ( P < .05 ) . CONCLUSIONS Exercise-mediated gains in COT and PWT occur rapidly within the first 2 months of exercise rehabilitation and are maintained with further training . The clinical significance is that a relatively short 2-month exercise program may be preferred to a longer program to treat claudication because adherence is higher , costs associated with personnel and use of facilities are lower per patient , and more patients can be trained for a given amount of personnel time and re source utilization 1 . The activities of  phosphofructokinase ( PFK ) , citrate synthetase ( CS ) , lactate dehydrogenase ( LDH ) , 3-hydroxyacyl-CoA dehydrogenase ( ACDH ) and cytochrome-c oxidase(Cyt-ox ) in the calf muscle tissue were compared in subjects with intermittent claudication ( n = 38 ) and controls ( n = 20 ) . The activities of CS , ACDH and Cyt-ox were increased and the activity of Cytox was positively correlated to the maximal walking distance ( MWD ) in the patients . 2 . Thirty-three patients with intermittent claudication were r and omized to three treatment groups : ( 1 ) operative surgery , ( 2 ) operative surgery supplemented with physical training and ( 3 ) physical training alone . Before and after 6 - 12 months of treatment , symptom-free walking distance ( SFWD ) , MWD , ankle-brachial blood pressure quotient ( ankle index ) , maximal plethysmographic calf blood flow ( MPBF ) and the activities of PFK , CS , LDH , ACDH and Cyt-ox were measured . 3 . SFWD and MWD increased in all three groups . Ankle index and MPBF increased in groups 1 and 2 , but were unchanged in group 3 . The activities of Cyt-ox and CS decreased with operation , but the activity of Cyt-ox was further augmented with training in group 3 . Overall , the change in ankle index explained 80 - 90 % of the variability in walking performance . In a separate analysis , the increased activity of Cyt-ox in group 3 was positively correlated to , and explained 31 % of the variability in , the improvement in SFWD . 4 . These findings indicate that both physical activity and a reduced calf blood flow are necessary conditions for the enzymatic adaptation to take place . A causal relationship between metabolic adaptation in the muscle tissue and walking performance is suggested . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND In patients with intermittent claudication , a supervised walking exercise program increases peak exercise performance and community-based functional status .  Patients with peripheral arterial disease also have muscle weakness in the affected extremity that may contribute to the walking impairment . However , the potential benefits of training modalities other than walking exercise , such as strength training , have not been critically evaluated in this patient population . The present study tested the hypothesis that a strength training program would be as effective as treadmill walking exercise and that combinations of strengthening and walking exercise would be more effective than either alone in improving exercise performance . METHODS AND RESULTS Twenty-nine patients with disabling claudication were r and omized to 12 weeks of supervised walking exercise on a treadmill ( 3 h/wk at a work intensity sufficient to produce claudication ) , strength training ( 3 h/wk of resistive training of five muscle groups of each leg ) , or a nonexercising control group . Grade d treadmill testing was performed to maximally tolerated claudication pain to define changes in peak exercise performance . After 12 weeks , patients in the treadmill training program had a 74 + /- 58 % increase in peak walking time as well as improvements in peak oxygen consumption ( VO2 ) and the onset of claudication pain . Patients in the strength-trained group had a 36 + /- 48 % increase in peak walking time but no change in peak VO2 or claudication onset time . Control subjects had no changes in any of these measures over the 12-week period . After the first 12 weeks , patients in the initial walking exercise group continued for 12 more weeks of supervised treadmill training . This result ed in an additional 49 + /- 53 % increase in peak walking time ( total of 128 + /- 99 % increase over the 24 weeks ) . After the initial 12 weeks , patients in the strength-trained group began 12 weeks of supervised treadmill training , and patients in the control group participated in a 12-week combined program of strengthening and treadmill walking exercise . The combined strength and treadmill training program and treadmill training after 12 weeks of strength training result ed in increases in peak exercise performance similar to those observed with 12 weeks of treadmill training alone . CONCLUSIONS A supervised treadmill walking exercise program is an effective means to improve exercise performance in patients with intermittent claudication , with continued improvement over 24 weeks of training . In contrast , 12 weeks of strength training was less effective than 12 weeks of supervised treadmill walking exercise . Finally , strength training , whether sequential or concomitant , did not augment the response to a walking exercise program Background Few medical therapies improve lower extremity functioning in people with lower extremity peripheral artery disease ( PAD ) . Among people with PAD , we studied whether a group-mediated cognitive behavioral intervention promoting home-based unsupervised exercise prevented mobility loss and improved functional performance compared to control . Methods and Results One hundred ninety-four PAD participants were r and omized . During months 1 to 6 , the intervention group met weekly with other PAD participants and a facilitator . Group support and self-regulatory skills were used to help participants adhere to walking exercise . Ninety-percent of exercise was conducted at or near home . The control group attended weekly lectures . During months 6 to 12 , each group received telephone contact only . Primary outcomes have been reported . Here we compare changes in exploratory outcomes of mobility loss ( the inability to climb a flight of stairs or walk one-quarter mile without assistance ) , walking velocity , and the Short Physical Performance Battery . Compared to controls , fewer participants r and omized to the intervention experienced mobility loss at 6-month follow-up : 6.3 % versus 26.5 % , P=0.002 , odds ratio=0.19 ( 95 % CI=0.06 to 0.58 ) and at 12-month follow-up : 5.2 % versus 18.5 % , P=0.029 , odds ratio=0.24 ( 95 % CI=0.06 to 0.97 ) . The intervention improved fast-paced 4-m walking velocity at 6-month follow-up ( P=0.005 ) and the Short Physical Performance Battery at 12-month follow-up ( P=0.027 ) , compared to controls . Conclusions In exploratory analyses , a group-mediated cognitive behavioral intervention promoting unsupervised walking exercise prevented mobility loss and improved functioning at 6- and 12-month follow-up in PAD patients . Clinical Trial Registration URL : http:// clinical trials.gov . Unique identifier : NCT00693940 PURPOSE A pilot study was conducted to test the feasibility of supervised treadmill exercise training to improve functioning in study participants with peripheral arterial disease who did not have classical symptoms of intermittent claudication . METHODS For this study , 32 men and women with peripheral arterial disease but no symptoms of claudication were r and omized to exercise training or usual care .  The intervention was a 12-week supervised treadmill walking program . Outcomes included 6-minute walk distance , maximum treadmill walking distance , and 4-meter walking velocity . Participant-reported community walking ability was measured with the Walking Impairment Question naire ( WIQ ) . Inflammatory blood factor levels also were measured . RESULTS Altogether , 25 participants who completed follow-up testing were included in intention-to-treat analyses . Of 24 participants ( 58 % ) r and omized to exercise , 14 completed the entire exercise training program . The participants r and omized to the intervention showed greater improvement in their WIQ walking speed score than the control subjects ( P = .05 ) . The participants r and omized to the intervention showed improvements in their 6-minute walk distance ( 1 
    Output:
    
agent
Data showed improvements secondary to exercise in ' physical function ' and ' general health ' .
The other domains - ' role physical ' , ' bodily pain ' , ' vitality ' , ' social ' , ' role emotional ' , and ' mental health ' - did not show improvement at six months .
Although results showed significant heterogeneity between trials , population s and outcomes were comparable overall , with findings relevant to the claudicant population .
High- quality evidence shows that exercise programmes provided important benefit compared with placebo or usual care in improving both pain-free and maximum walking distance in people with leg pain from IC who were considered to be fit for exercise intervention .
Exercise did not improve ABI , and we found no evidence of an effect of exercise on amputation or mortality .
Exercise may improve quality of life when compared with placebo or usual care .
***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: OBJECTIVE : To assess the acute metabolic and cardiovascular responses to walking exercise at an intensity corresponding to the heart rate of claudication pain onset and to investigate the effects of a 12-week walking training program at this intensity on walking capacity . METHODS : Twenty-nine patients with intermittent claudication were r and omly allocated to the  walking training  ( n = 17 ) or control ( CO , n = 12 ) group . The walking training group performed an acute exercise session comprising 15 × 2-min bouts of walking at the heart rate of claudication pain onset , with 2-min interpolated rest intervals . The claudication symptoms and cardiovascular and metabolic responses were evaluated . Walking training was then performed at the same intensity twice each week for 12 weeks , while the control group engaged in twice weekly stretching classes  . The claudication onset distance and total walking distance were evaluated before and after the interventions . Brazilian Registry Clinical Trials : RBR-7M3D8W . RESULTS : During the acute exercise session , the heart rate was maintained within tight limits . The exercise intensity was above the anaerobic threshold and > 80 % of the heart rate peak and VO2peak . After the exercise training period , the walking exercise group ( n = 13 ) showed increased claudication onset distance ( 309±153 vs. 413±201 m ) and total walking distance ( 784±182 vs. 1,100±236 m ) compared to the control group ( n = 12 ) ( p<0.05 ) . CONCLUSION : Walking exercise prescribed at the heart rate of claudication pain onset enables patients with intermittent claudication to exercise with tolerable levels of pain and improves walking performance This study examined whether a training intervention likely to elicit adaptations in the leg could result in reduced leg pain and increased whole body physical capacity .  Twenty-seven peripheral arterial disease ( PAD ) patients were r and omized to either an individual leg plantar flexion training group ( TG ) training 4 × 4 min intervals at 80 % of maximal work rate three times per week for 8 weeks or a control group . The TG significantly increased plantar flexion peak oxygen uptake and power output by 23.5 and 43.9 % , respectively . Treadmill peak oxygen uptake ( VO2peak ) significantly increased 12.3 % in the TG and was associated with a significant increased time to exhaustion of 20.0 % when treadmill walking . Eleven of 14 patients no longer reported leg pain limitations at VO2peak . No differences in cardiac output measured at VO2peak , or walking economy were observed . Plantar flexion training was effective in increasing VO2peak and walking performance , and may be a useful strategy in treatment of PAD In a vascular rehabilitation program , 28 % of our frail elderly patients are unable to be tested with traditional progressive exercise protocol s at program entry due to the high ( 2.0 miles/h or 3.2 km/h ) initial treadmill speeds . The purpose of this investigation was to compare a new progressive treadmill protocol which has a reduced initial speed ( 1.0 mile/h or 1.6 km/h ) to an established protocol performed at 2.0 miles/h ( 3.2 km/h ) to determine the comparability and reproducibility of the new protocol . Eleven patients with arterial claudication performed three symptom-limited exercise tests in r and om order . Two tests used the new protocol while the remaining trial used the established protocol .  Claudication pain was measured using a 5-point scale . Oxygen consumption , heart rate , minute ventilation , respiratory exchange ratio and blood pressure at peak exercise were similar among the three trials . There were strong intra-class correlations for peak oxygen consumption ( r = 0.97 ) , onset of claudication ( r = 0.96 ) and maximum walking time ( r = 0.98 ) between the two trials using the new protocol . There was also a significant correlation between the new protocol and the established protocol for peak oxygen consumption ( r = 0.90 ) and maximum walking time ( r = 0.89 ) . The new progressive treadmill protocol represents a valid , reliable protocol for patients with arterial claudication . This protocol may be useful for testing patients with a low functional capacity so that clinical ly appropriate exercise prescriptions can be established and the efficacy of treatments can be determined BACKGROUND This prospect i ve , r and omized controlled clinical trial determined whether an optimal exercise program length exists to efficaciously change claudication onset time ( COT ) and peak walking time ( PWT ) in patients with peripheral artery disease and claudication . METHODS The study r and omized 142 patients to supervised exercise ( n = 106 ) or a usual care control group ( n = 36 ) , with 80 completing the exercise program and 27 completing the control intervention .  The exercise program consisted of intermittent walking to nearly maximal claudication pain 3 days per week . COT and PWT were the primary outcomes obtained from a treadmill exercise test at baseline and bimonthly during the study . RESULTS After exercise , changes in COT ( P < .001 ) and PWT ( P < .001 ) were consistently greater than changes after the control intervention . In the exercise program , COT and PWT increased from baseline to month 2 ( P < .05 ) and from months 2 to 4 ( P < .05 ) but did not significantly change from months 4 to 6 ( P > .05 ) . When changes were expressed per mile walked during the first 2 months , middle 2 months , and final 2 months of exercise , COT and PWT only increased during the first 2 months ( P < .05 ) . CONCLUSIONS Exercise-mediated gains in COT and PWT occur rapidly within the first 2 months of exercise rehabilitation and are maintained with further training . The clinical significance is that a relatively short 2-month exercise program may be preferred to a longer program to treat claudication because adherence is higher , costs associated with personnel and use of facilities are lower per patient , and more patients can be trained for a given amount of personnel time and re source utilization 1 . The activities of  phosphofructokinase ( PFK ) , citrate synthetase ( CS ) , lactate dehydrogenase ( LDH ) , 3-hydroxyacyl-CoA dehydrogenase ( ACDH ) and cytochrome-c oxidase(Cyt-ox ) in the calf muscle tissue were compared in subjects with intermittent claudication ( n = 38 ) and controls ( n = 20 ) . The activities of CS , ACDH and Cyt-ox were increased and the activity of Cytox was positively correlated to the maximal walking distance ( MWD ) in the patients . 2 . Thirty-three patients with intermittent claudication were r and omized to three treatment groups : ( 1 ) operative surgery , ( 2 ) operative surgery supplemented with physical training and ( 3 ) physical training alone . Before and after 6 - 12 months of treatment , symptom-free walking distance ( SFWD ) , MWD , ankle-brachial blood pressure quotient ( ankle index ) , maximal plethysmographic calf blood flow ( MPBF ) and the activities of PFK , CS , LDH , ACDH and Cyt-ox were measured . 3 . SFWD and MWD increased in all three groups . Ankle index and MPBF increased in groups 1 and 2 , but were unchanged in group 3 . The activities of Cyt-ox and CS decreased with operation , but the activity of Cyt-ox was further augmented with training in group 3 . Overall , the change in ankle index explained 80 - 90 % of the variability in walking performance . In a separate analysis , the increased activity of Cyt-ox in group 3 was positively correlated to , and explained 31 % of the variability in , the improvement in SFWD . 4 . These findings indicate that both physical activity and a reduced calf blood flow are necessary conditions for the enzymatic adaptation to take place . A causal relationship between metabolic adaptation in the muscle tissue and walking performance is suggested . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND In patients with intermittent claudication , a supervised walking exercise program increases peak exercise performance and community-based functional status .  Patients with peripheral arterial disease also have muscle weakness in the affected extremity that may contribute to the walking impairment . However , the potential benefits of training modalities other than walking exercise , such as strength training , have not been critically evaluated in this patient population . The present study tested the hypothesis that a strength training program would be as effective as treadmill walking exercise and that combinations of strengthening and walking exercise would be more effective than either alone in improving exercise performance . METHODS AND RESULTS Twenty-nine patients with disabling claudication were r and omized to 12 weeks of supervised walking exercise on a treadmill ( 3 h/wk at a work intensity sufficient to produce claudication ) , strength training ( 3 h/wk of resistive training of five muscle groups of each leg ) , or a nonexercising control group . Grade d treadmill testing was performed to maximally tolerated claudication pain to define changes in peak exercise performance . After 12 weeks , patients in the treadmill training program had a 74 + /- 58 % increase in peak walking time as well as improvements in peak oxygen consumption ( VO2 ) and the onset of claudication pain . Patients in the strength-trained group had a 36 + /- 48 % increase in peak walking time but no change in peak VO2 or claudication onset time . Control subjects had no changes in any of these measures over the 12-week period . After the first 12 weeks , patients in the initial walking exercise group continued for 12 more weeks of supervised treadmill training . This result ed in an additional 49 + /- 53 % increase in peak walking time ( total of 128 + /- 99 % increase over the 24 weeks ) . After the initial 12 weeks , patients in the strength-trained group began 12 weeks of supervised treadmill training , and patients in the control group participated in a 12-week combined program of strengthening and treadmill walking exercise . The combined strength and treadmill training program and treadmill training after 12 weeks of strength training result ed in increases in peak exercise performance similar to those observed with 12 weeks of treadmill training alone . CONCLUSIONS A supervised treadmill walking exercise program is an effective means to improve exercise performance in patients with intermittent claudication , with continued improvement over 24 weeks of training . In contrast , 12 weeks of strength training was less effective than 12 weeks of supervised treadmill walking exercise . Finally , strength training , whether sequential or concomitant , did not augment the response to a walking exercise program Background Few medical therapies improve lower extremity functioning in people with lower extremity peripheral artery disease ( PAD ) . Among people with PAD , we studied whether a group-mediated cognitive behavioral intervention promoting home-based unsupervised exercise prevented mobility loss and improved functional performance compared to control . Methods and Results One hundred ninety-four PAD participants were r and omized . During months 1 to 6 , the intervention group met weekly with other PAD participants and a facilitator . Group support and self-regulatory skills were used to help participants adhere to walking exercise . Ninety-percent of exercise was conducted at or near home . The control group attended weekly lectures . During months 6 to 12 , each group received telephone contact only . Primary outcomes have been reported . Here we compare changes in exploratory outcomes of mobility loss ( the inability to climb a flight of stairs or walk one-quarter mile without assistance ) , walking velocity , and the Short Physical Performance Battery . Compared to controls , fewer participants r and omized to the intervention experienced mobility loss at 6-month follow-up : 6.3 % versus 26.5 % , P=0.002 , odds ratio=0.19 ( 95 % CI=0.06 to 0.58 ) and at 12-month follow-up : 5.2 % versus 18.5 % , P=0.029 , odds ratio=0.24 ( 95 % CI=0.06 to 0.97 ) . The intervention improved fast-paced 4-m walking velocity at 6-month follow-up ( P=0.005 ) and the Short Physical Performance Battery at 12-month follow-up ( P=0.027 ) , compared to controls . Conclusions In exploratory analyses , a group-mediated cognitive behavioral intervention promoting unsupervised walking exercise prevented mobility loss and improved functioning at 6- and 12-month follow-up in PAD patients . Clinical Trial Registration URL : http:// clinical trials.gov . Unique identifier : NCT00693940 PURPOSE A pilot study was conducted to test the feasibility of supervised treadmill exercise training to improve functioning in study participants with peripheral arterial disease who did not have classical symptoms of intermittent claudication . METHODS For this study , 32 men and women with peripheral arterial disease but no symptoms of claudication were r and omized to exercise training or usual care .  The intervention was a 12-week supervised treadmill walking program . Outcomes included 6-minute walk distance , maximum treadmill walking distance , and 4-meter walking velocity . Participant-reported community walking ability was measured with the Walking Impairment Question naire ( WIQ ) . Inflammatory blood factor levels also were measured . RESULTS Altogether , 25 participants who completed follow-up testing were included in intention-to-treat analyses . Of 24 participants ( 58 % ) r and omized to exercise , 14 completed the entire exercise training program . The participants r and omized to the intervention showed greater improvement in their WIQ walking speed score than the control subjects ( P = .05 ) . The participants r and omized to the intervention showed improvements in their 6-minute walk distance ( 1 
    Output:
    