the main purpose of a rehabilitation program after lower extremity bypass surgery in 
 patients with peripheral arterial disease ( pad ) is the early reacquisition of skills in 
 activities of daily living ( adl ) by improving walking ability . a multicenter study1 reported that patients who underwent 
 uneventful lower extremity bypass surgery started walking on postoperative day ( pod)2 and were discharged home on pod16.9 . an aggressive 
 postoperative rehabilitation is important to improve a patient s walking performance 
 considering the recent trend of shortening the length of hospital stay . however , some 
 patients show a very low physical activity ( pa ) level , spending most of their time in bed , 
 despite the improvement in their walking ability by revascularization . patients with symptomatic pad have a lower pa level than non - pad patients because of their 
 limited walking capacity2,3,4 . it has been shown 
 that a low pa level is a significant risk factor for progression of pad , loss of physical 
 function , and occurrence of cardiovascular disease ( cvd)5 , 6 . thus , rehabilitation 
 programs should focus not only on improving walking ability but also on increasing daily pa 
 levels to prevent future adverse cardiovascular events . however , in patients who have 
 undergone lower extremity bypass surgery , the association between perioperative pa level and 
 long - term prognosis has not been investigated . this study aimed to evaluate preoperative - to - postoperative changes in pa levels of pad 
 patients who underwent lower extremity bypass surgery and to examine the effect of these 
 changes with long - term clinical outcomes . a total of 13 patients ( 16 limbs ; 11 males and 2 females ; fontaine stage 2 ) who underwent 
 lower extremity bypass surgery for pad between february 2010 and november 2010 were included 
 in this study . the mean age of the male participants was 73  years ( range , 6581  years ) . patient characteristics are described in table 1table 1.baseline characteristics of patients with peripheral arterial disease ( n = 
 13)baseline characteristicsn ( % ) demographic factorsmale11 ( 84.6)mean age at study inclusion , mean ( range ) years73 ( 6581)body mass index , mean  sd22.7  3.1medical history at bypass surgeryangina pectoris5 ( 38.5)myocardial infarction2 ( 15.3)tia and/or stroke5 ( 38.5)ankle brachial pressure index0.53  0.23diabetes mellitus8 ( 61.4)hypertension13 ( 100)hyperlipidemia10 ( 76.9)smoking11 ( 84.6)trial bypassaortobifemoral1 ( 7.7)iliofemoral2 ( 15.4)femoropopliteal ( above the knee ) 7 ( 53.8)femoropopliteal ( below the knee)2 ( 15.4)popliteal - popliteal ( from above to below the knee)1 ( 7.7)tia : transient ischemic attack . tia : transient ischemic attack the pa level of the patients was measured objectively and continuously with a triaxial 
 accelerometer ( active style pro . daily pa ( metabolic equivalents [ mets]-hours / day ) was defined as the total amount of 
 mets - hours , calculated using bi - link - analysis software ( omron healthcare ) , which calculates 
 the intensity of pa ( represented by mets ) as a 1-minute value . measurement began at least 2 
 days prior to the surgery and continued until the day of discharge , except on the day of 
 surgery . walking ability was evaluated by measuring the maximum walking distance ( mwd ) and via the 
 walking impairment questionnaire ( wiq ) . the self - efficacy for physical activity ( sepa ) test 
 was also used for subjective estimation of self - efficacy . wiq and sepa questionnaires were used to measure parameters 
 preoperatively and at discharge , respectively . there were no target pa levels to attain , and 
 the patients were not provided with any guidance by the medical staff to increase their pa 
 level during hospitalization . the rehabilitation program was initiated at pod1 and gradually advanced , unless there were 
 reports of perioperative complications or subjective symptoms such as oppressive pain . once 
 independent walking was established , the patients visited the rehabilitation center and 
 started a supervised exercise program , which consisted of a 60-minute session including a 
 warm - up phase , 20 minutes of treadmill walking , and a cool - down phase . the exercise 
 intensity was gradually increased according to the tasc ii recommendation7 , with a maximum grade of 12% if patients 
 achieved a walking speed of 2.4  km / h . based on the postoperative change in their pa levels , patients were classified into 2 
 groups : an active group ( n = 6 ) , who showed an increase in pa postsurgery , and an inactive 
 group ( n = 7 ) , who showed a decrease in pa postsurgery . in addition , the occurrence of adverse events such as bypass graft 
 occlusion , cvd events , and cardiovascular intervention for a new lesion was compared between 
 the 2 groups . this study was approved by the ethics committee of the sakakibara heart institute of 
 okayama ( approval no . differences in baseline patient characteristics were evaluated with 2-tailed t tests for 
 continuous variables and 2  2  tests for categorical variables . paired t tests the occurrence of adverse 
 events within 24 months after the surgery was evaluated using kaplan - meier curves , and the 
 log - rank test was used to assess the association of in - hospital pa level with subsequent 
 cardiovascular events . there were no hospital deaths or major postoperative complications during the course of the 
 study . the mean length of hospitalization after bypass surgery was 13.7  3.9 days , and all 
 patients were discharged home from the hospital without a transfer to a rehabilitation 
 facility . the ankle - brachial pressure indexes were significantly improved from 0.53  0.23 
 preoperatively to 0.90  0.18 at discharge ( p < 0.001 ) . as a result , the walking ability 
 of the patients improved significantly , with the mwd improving from 265.8  173.6  m to 744.6 
  440.5  m ( p < 0.001 ) and the wiq score improving from 120.1  60.9 to 259.6  87.0 ( p < 0.001 ) . the sepa score showed improvement from 38.5  17.6 to 50.1  17.2 ( p < 
 0.05 ) . these results demonstrate that the walking performance and self - efficacy of these 
 patients improved significantly with surgical revascularization . in terms of pa level , the number of steps the patients were able to walk daily improved 
 significantly , from 1,713.1  1,261.5 steps preoperatively to 2,692.4  1,967.1 steps at 
 discharge ( p < 0.05 ) . however , the actual pa level ( represented by a mean daily 
 mets - hours ) did not increase after surgery ( 23.0  4.4 mets - hours / day preoperatively and 
 22.3  4.3 mets - hours / day at discharge ) . these results suggest that the improved walking 
 ability after lower extremity bypass surgery was not necessary associated with increased 
 in - hospital pa level in some patients ( table 
 2table 2.preoperative and postoperative resultspreoperationpostoperationankle brachial pressure index0.53  0.230.90  0.18**maximum walking distance ( m)265.8  173.6744.6  440.5**walking impairment questionnaire120.1  60.9259.6  87.0**self - efficacy for physical activity38.5  17.650.1  17.2*daily walking steps ( step)1,713.1  1,261.52,692.4  1967.1*pa ( mets - hours / day)23.0  4.422.3  4.3*p<0.05 , * * p<0.01 ) . to clarify the association between perioperative pa level and patient prognosis after 
 bypass surgery , patients were classified into 2 groups based on the 
 preoperative - to - postoperative change in pa levels as follows : an active group ( n = 6 ) , whose 
 daily pa level ( mets - hours / day ) at discharge was higher than that at the preoperative level 
 ( rate of change , 117.5  9.1% ) , and an inactive group ( n = 7 ) , whose daily pa level was 
 lower ( 82.9  11.8% ) than that at the preoperative level . the baseline characteristics of 
 the patients are shown in table 3table 3.characteristics of the active and inactive groupsbaseline characteristicsactive ( n = 6)inactive ( n = 7)n ( % ) n ( % ) demographic factorsmale6 ( 100)5 ( 71.4)age at study inclusion , mean ( range ) years73 ( 6781)73 ( 6580)medical history at bypass surgeryangina pectoris3 ( 50)2 ( 28.6)myocardial infarction1 ( 16.7)1 ( 14.3)tia and/or stroke4 ( 66.7)1 ( 14.3)diabetes mellitus4 ( 66.7)4 ( 57.1)hypertension6 ( 100)7 ( 100)hyperlipidemia5 ( 83.3)5 ( 71.4)smoking6 ( 100)5 ( 71.4)trial bypassaortobifemoral1 ( 16.7)0 ( 0)iliofemoral1 ( 16.7)1 ( 14.3)femoropopliteal ( above the knee)3 ( 50)4 ( 57.1)femoropopliteal ( below the knee)0 ( 0)2 ( 28.6)popliteal - popliteal ( from above to below the knee)1 ( 16.7)0 ( 0)ankle brachial pressure indexpreoperation0.50  0.190.46  0.22postoperation0.88 the pa level at discharge was significantly higher in the active group ( 25.1 
  3.8 mets - hours / day ) than in the inactive group ( 19.9  3.2 mets - hours / day , p < 0.05 ) . the number of steps that the patients were able to walk daily at discharge was also 
 significantly higher in the active group ( 3,884.5  1,783.0 steps ) than in the inactive 
 group ( 1,670.6  1,565.3 steps , p < 0.05 ) . furthermore , in the active group , both values 
 increased significantly after surgery ( p < 0.05 ) , whereas no significant improvements 
 were seen in the inactive group . the wiq score at discharge was significantly higher in the 
 active group than in the inactive group ( 313.2  43.3 and 213.7  90.9 , respectively ; p < 
 0.05 ) , whereas no significant differences were noted in the mwd or sepa scores . there were 
 no significant differences in the rate of preoperative - to - postoperative changes in the mwd , 
 wiq , and sepa scores between groups ( table 
 4table 4.rate of preoperative - to - postoperative changes in walking ability and 
 self - efficacyactive groupinactive groupmaximum walking distance ( m)392.44404.05296.34120.20walking impairment questionnaire267.95185.24244.1380.05self - efficacy for physical activity236.59233.83137.1286.79 ) . tia : transient ischemic attack in terms of long - term outcomes ( within 24 months after surgery ) , adverse cardiovascular 
 events occurred in 16.7% of the patients in the active group ( 1 percutaneous transluminal 
 angioplasty ) , whereas adverse cardiovascular events occurred in 71.4% of the patients in the 
 inactive group ( 3 graft occlusions , 1 percutaneous coronary intervention , and 1 congestive 
 heart failure ; p = 0.08 : fig . 1fig . in the present study , we evaluated the preoperative - to - postoperative changes in pa level of 
 patients who underwent lower extremity bypass surgery and the effect of these changes on 
 long - term clinical outcomes . the walking ability ( based on mwd and wiq scores ) and 
 self - efficacy ( based on sepa score ) of the patients improved significantly after surgery . lundgren et al.8 reported that the walking 
 ability of patients improved after surgical revascularization secondary to improvement in 
 lower leg blood flow and ankle blood pressure . a randomized trial involving pad patients 
 with intermittent claudication showed that supervised exercise rehabilitation further 
 improved walking ability after revascularization8 . thus , our aggressive rehabilitation program , including supervised 
 exercise therapy , might have enhanced the effect of surgical revascularization . the 
 self - efficacy of pad patients has been demonstrated to be related to walking ability9 . the improvement in sepa scores in this 
 study is attributable to the improvement in patients walking ability after surgical 
 revascularization . however , despite an improved walking ability , pa levels did not improve postoperatively in 
 approximately half of the patients . sieminski et al.4 compared the pa levels of patients with and without pad by using an 
 accelerometer and found that the pad patients had significantly lower pa levels than the 
 non - pad patients ( 357 and 616  kcal / day , respectively ) . mcdermott et al.2 reported that a higher rate of pad patients ( 15% ) showed 
 physical inactivity in low - intensity activities such as casual walking or strolling compared 
 with non - pad patients ( 5% ) , suggesting that the low pa level in pad patients was 
 attributable to the inactivity of the relatively low - intensity activities . furthermore , pad 
 patients are less likely to develop regular exercise habits compared with non - pad 
 individuals2,3,4 . in this study , improved 
 walking capacity with supervised exercise did not result in an improvement in total pa in 
 the inactive group , probably because the patients continued to be inactive even after 
 revascularization and , as a consequence , their pa level did not increase outside the 
 rehabilitation center . despite the similarities in the baseline characteristics and walking ability of the 
 patients in the 2 groups , late adverse cardiovascular events occurred in 71.4% of patients 
 in the inactive group within 24 months after surgery ( graft occlusion , 42.9% ; percutaneous 
 coronary intervention for progress of coronary artery lesion , 14.3% ; rehospitalization for 
 congestive heart failure , 14.3% ) , whereas the incidence of cvd in the active group was only 
 16.7% . considering the fact that physical inactivity is a risk factor for progression of 
 arteriosclerosis , the patients who did not show improvement in in - hospital pa levels even 
 after revascularization may be more likely to experience late adverse cardiovascular events 
 because they may not change their sedentary lifestyle despite the improvement in their 
 walking ability . generally , pa is considered to be effective for controlling risk factors like diabetes 
 mellitus10 , 11 . furthermore , several studies have demonstrated the relationship 
 between physical inactivity and adverse cardiovascular events . depressive symptoms in pad 
 patients are associated with adverse events , and this association is partially explained by 
 physical inactivity in these patients , who exercise only a few times in a month12 . another study showed the association 
 between pa level and inflammatory biomarkers , which are risk factors for adverse 
 cardiovascular events13 . in addition , 
 garg et al.6 reported that pad patients 
 with higher daily pa levels have lower rates of mortality and adverse cardiovascular events 
 than those with lower pa levels . in contrast , low - intensity physical activities such as 
 recreational activities have been shown to decrease the risk of adverse cardiovascular 
 events , which are strongly related to mortality in pad patients14 . in conclusion , the higher level of in - hospital pa after lower extremity bypass surgery was 
 associated with a better long - term prognosis in our study . post - bypass surgery 
 rehabilitation programs should aim at improving the daily pa level and walking ability of 
 pad patients for the prevention of cvd . it is unknown 
 whether patients who showed a high pa level during hospitalization continue to be active 
 after discharge . therefore , a long - term assessment of pa in the home setting is necessary 
 for a more precise analysis of the association between perioperative pa and patient 
 prognosis after lower extremity bypass surgery for pad . furthermore , the number of patients 
 in this study was small and the follow - up period was relatively short . in the future , a 
 clinical trial may be needed to determine whether interventions that increase in - hospital pa 
 levels reduce the occurrence of long - term adverse cardiovascular events in patients with 
 pad .
[ purpose ] this study aimed to evaluate the effect of in - hospital physical activity on 
 patient prognosis after lower extremity bypass surgery for peripheral arterial disease . 
 [ subjects and methods ] a total of 13 patients ( 16 limbs ; 11 males and 2 females ; mean age 
 [ standard deviation ] , 72.8 [ 5.9 ] years ) who underwent lower extremity bypass surgery for 
 fontaine stage 2 peripheral arterial disease were included in this study and assigned to 
 either an active group ( n = 6 ) to perform increased physical activity after surgery or an 
 inactive group ( n = 7 ) to perform decreased physical activity after surgery . 
 daily 
 in - hospital physical activity levels were measured continuously with a triaxial 
 accelerometer . 
 the occurrence of adverse cardiovascular events within a 2  year follow - up 
 period was compared between groups . [ results ] at discharge 
 , the patients in the active 
 group were able to walk more steps daily than those in the inactive group . 
 the incidence 
 of adverse events was 16.7% in the active group and 71.4% in the inactive group . 
 [ conclusion ] a higher in - hospital physical activity level was associated with a better 
 long - term prognosis after lower extremity bypass surgery in patients with peripheral 
 arterial disease .