with the increase of lifestyle - related diseases and the aging of society , the number of 
 patients with peripheral arterial disease ( pad ) is also increasing1 .
pad is a systemic arteriosclerotic disease that can lead to 
 critical limb ischemia ( cli ) associated with rest pain and wound when aggravated .
it is 
 reported by tascii ( trance - atlantic inter - society consensus ii ) that 30% of the patients 
 with cli have to amputate limbs and 25% of them die within one year from the onset2 , indicating that cli has an extremely poor 
 prognosis .
arteriosclerosis is associated with the progression of pad . increasing the amount of 
 physical activity
is reported to play an important role for the prevention of progression 
 and improvement of arteriosclerosis3 .
once 
 affected with cli , patients will have to suffer from pain , wound , or amputation and 
 consequently their walking ability might decrease , leading to a remarkable decrease of 
 physical activity .
however , no study has ever shown the properties of physical activity of 
 cli to date , and therefore the effect of the amount of physical activity on the patients 
 quality of life ( qol ) remains unclear .
the purpose of this study was to evaluate the amount of physical activity of the patients 
 with cli consecutively in order to clarify the properties of physical activity of cli and to 
 examine the relationship between the amount of physical activity and adl ( activity of daily 
 living ) or qol of the patients with cli .
among the patients who were admitted to our kasukabe chuo general hospital for the 
 treatment of wounds caused by cli during april to december in 2015 and became able to make 
 an ambulatory visit to our foot care outpatient department , a total of 21 patients agreed to 
 participate in the study and signed the informed consent .
of them , 12 patients who were 
 eligible for the 2 months of consecutive evaluation of the amount of physical activity were 
 enrolled in the study ( men : 11 ; woman : 1 ; mean age : 64.4 [ range : 4480 ] ) ( table 1table 1.patient clinical characteristicsage [ years ; mean ( range)]64.4 ( 4480)male [ n ( % ) ] 11 ( 91.7%)amputation region [ n ( % ) ] no amputation ( with ulcer)2 ( 16.7%)toe amputation2 ( 16.7%)metatarsal bone amputation5 ( 41.7%)lower leg amputation3 ( 25.0%)bilateral lesions / unilateral lesions ( n)7/5comorbidity and arteriosclerosis risk 
 factor [ n ( % ) ] diabetes merits10 ( 83.3%)hypertension10 ( 83.3%)cardiac diseases11 ( 91.7%)dyslipidemia 6 ( 50.0%)hemodialysis7 ( 58.3%)current smoking 9 ( 75.0%)maximum skin perfusion pressuredorsum ( mmhg ) 59.1 ( 2989)sole ( mmhg)60.6 ( 3099)maximum strength of the knee - extension ( kgf ) 30.3 ( 17.060.3)weight bearing index ( % ) 46.7 ( 23.066.0)sf-8pcs ( physical component summary ) 35.0 ( 29.452.8)mcs ( mental component summary ) 46.7 ( 23.066.0)sf-8 : medical outcomes study 8-item short - form health survey ) .
sf-8 : medical outcomes study 8-item short - form health survey all the patients were asked to walk wearing prosthetics .
exclusion criteria were defined as 
 patients who ( 1 ) were unable to walk outdoors and required nursing care in daily life , ( 2 ) 
 were unable to respond to the questionnaire , ( 3 ) had difficulty to wear prosthetics on their 
 own , or ( 4 ) got wounded during the study . a pedometer with an accelerometer ( mediwalk , terumo , japan )
was used for the 
 measurement of the amount of physical activity , and the number of steps walked was used as 
 the index of the amount of physical activity .
patients were asked to wear the pedometer all 
 day except during bathing and sleeping .
the number of steps walked during the 2 months was 
 recorded and was confirmed on an outpatient basis once every two months .
dedicated software 
 ( nfc reader / writer ) was used to download the data of the steps from the pedometer and to 
 confirm it .
participants were asked to lead a regular life and no instruction was given as 
 to the number of steps .
sf-8 , a profile - based comprehensive scale , was used for the analysis of qol . for the 
 numerical calculation ,
the sf-8 scoring program ( excel version ) was used , with 50 pts 
 defined as the national standard value ( based on the 2007 national standard value ) , to 
 calculate the point based on the national standard value . as for the other research items , factors such as age , gender , body mass index ( bmi ) , 
 possession status of risk factors of comorbidity and arteriosclerosis , disease history , and 
 treatment course
in addition , skin perfusion pressure ( spp ) as the blood flow 
 of the lower limb artery was evaluated by using a laser doppler ( sensilase pad3000 , kaneka 
 medix , osaka , japan ) at the time of the first outpatient visit . regarding the lower limb 
 muscle strength ,
the maximum voluntary isokinetic knee extension muscle strength was 
 measured using hand - held dynamometer ( -tasf-1 , anima , japan ) . for knee extensor strength 
 measurements ,
subjects were asked to sit on a chair with knee flexion at 90 degrees and to 
 push against the dynamometer pad as much as possible for 5 seconds .
isokinetic knee extensor 
 strength was measured 2 times on each side , and the highest value for the right and left 
 legs was used as the knee extensor muscle strength . the weight bearing index ( wbi )
sf-8 and the knee extensor muscle strength were assessed every month from the time of the 
 first outpatient visit .
all the research items were examined retrospectively using medical records and classified 
 into the following groups such as the without toe - amputation group , the toe amputation 
 ( including multiple toes amputation ) group , the metatarsal bone amputation group , and the 
 lower leg amputation group in order to compare the number of steps walked with qol in each 
 group in addition to the overall target characteristics .
( ibm , tokyo , japan ) was used for the 
 statistical analysis , and an unpaired t - test and a correlation analysis was performed . with 
 the use of a two - sided test , a p value of 0.05 was defined as statistically significant .
all the 
 patients gave their informed consent after being orally informed regarding the purpose , 
 methods , interests , and risks of this study .
of the 12 target patients , 2 were classified into the without toe - amputation ( with ulcer ) 
 group , 2 into the toe amputation group , 5 into the metatarsal bone amputation group , 3 into 
 the lower leg amputation group , and 7 had wound in both legs .
the patients with toe 
 amputation wore a shoe - type orthosis , and those with metatarsal bone amputation wore a foot 
 prosthesis and a shoe - type orthosis , and those with lower leg amputation wore a tsb ( total 
 surface bearing ) type orthosis .
the research results of risk factors of comorbidity and 
 arteriosclerosis revealed that 10 patients ( 83.3% ) had diabetes , another 10 patients ( 83.3% ) 
 had hypertension , 11 patients ( 91.7% ) had cardiovascular disease , 6 patients ( 50.0% ) had 
 dyslipidemia , 7 patients ( 58.3% ) had maintenance hemodialysis , and 9 patients ( 75.0% ) had a 
 smoking habit .
average maximum spp , average maximum strength of the knee - extension , average 
 weight bearing index and sf-8 score were shown in table 
 1 .
the average number of daily steps walked of all the patients during the measurement period 
 was 2,323 steps ( range : 4046,505 ) . compared between patients with bilateral lesions ( n=7 ) 
 and those with unilateral lesions ( n=5 ) , the average number of steps walked of the patients 
 with bilateral lesions was 2,979  238 steps and that of the those with unilateral lesions 
 was 1,403  1,198 steps , showing no significant difference .
there was no clear tendency in 
 the number of amputation site - specific steps walked .
there was also no obvious correlation 
 between the number of steps walked and age as well as the maximum strength of the 
 knee - extension muscle , the maximum spp of the sole and the dorsum , and qol scores ( table 2table 2.univariate correlations between in - average steps and age , maximum skin perfusion 
 pressure , maximum strength of the knee - extension , weight bearing index , and 
 health - related qolrelated factorsrage0.403maximum skin perfusion pressuredorsum 0.312 sole0.399 maximum strength of the knee - extension0.329 weight bearing index0.361sf-8pcs ( physical component summary ) 0.370 mcs ( mental component summary ) 0.164 sf-8 : medical outcomes study 8-item short - form health survey ) .
sf-8 : medical outcomes study 8-item short - form health survey the followings were the specific qol assessments ; pf ( physical function ) : 41.5 ( 41.516.7 ) , 
 rp ( role physical ) : 54.1 ( 52.427.9 ) , bp ( bodily pain ) : 46 ( 60.438.2 ) , gh ( general health ) : 
 50.3 ( 50.335.9 ) , vt ( vitality ) : 53.7 ( 53.746.8 ) , sf ( social functioning ) : 45.6 
 ( 52.830.9 ) , re ( role emotional ) : 54.2(54.235.6 ) , and mh ( mental health ) : 44.9 ( 53.938.5 ) . 

in addition , pcs ( physical component summary ) and mcs ( mental component summary ) were 43.2 
 ( 45.426.8 ) and 48.6 ( 52.745.2 ) , respectively .
pf , bp , sf , and mh was lower than the 
 national standard value ( 50 pts ) , and both pcs and mcs were also lower than the 
 standard .
cli patients with rest pain and wound are likely to lose walking ability and adl 
 ability2 . walking ability
is considered 
 to be associated with the knee extension muscle strength4 . in this study , we calculated the knee extension muscle strength 
 using wbi .
reported that wbi 40% is considered as an ambulatory level and 
 that wbi 60% is considered necessary to lead a normal daily life5 .
the maximum wbi of the cli patients in this study was 46.7% 
 ( 2366% ) on average , while 3 out of 12 of them did not reach the ambulant level in the knee 
 extension muscle strength and 11 out of 12 of them did not reach the necessary level in 
 their daily life .
mcdermott et al.6 
 reported that even pad patients without wound were likely to show a significantly low value 
 of the lower limb extension muscle strength . in our study , too , cli patients were found to 
 have a remarkable decrease in the knee extension muscle strength .
this is the first study that used the number of steps walked to show whether or not the 
 amount of physical activity of the patients with cli was lower than the standard . the 
 average number of steps walked of the patients with cli was about 2,300 steps in this study . 

this was remarkably low compared with healthy individuals of the same age and patients with 
 diabetic foot7 , 8 .
the patients with cli are forced to limit walking in order to 
 reduce the burden on the wound , relieving of the lower limb is required .
furthermore , health - related qol was 
 evaluated by using sf-8 and it was revealed that pf ( physical function ) , bp ( bodily pain ) , 
 sf ( social functioning ) , and mh ( mental health ) were lower than the national standard value 
 of 50 points .
there are some studies reporting the relationship between the lower - limb muscle strength 
 and the amount of physical activity9 , 10 . in our study , however , no significant 
 association was observed between the average number of steps walked and the lower - limb 
 muscle strength among cli patients .
moreover , it is generally considered that the amount of 
 physical activity and health - related qol are strongly correlated with each other11 and that the higher the sense of 
 well - being , the more they are involved in physical activity12 , but no correlation was observed between the number of steps walked 
 and health - related qol in our study .
patients with cli need non - weight bearing exercise 
 during the treatment of wound to reduce the burden to the wounded area , which consequently 
 imposes restrictions on their walking .
in addition to these restrictions during the 
 treatment of the wounded area , the physical activity of the patients with cli is affected by 
 various factors such as age , amputation sites , and complications , which may be the reason 
 why no direct correlation was found .
the fact that health - related qol did not show any 
 correlation with a single index was considered as reflecting the various obstacle images of 
 patients with cli . as ferrucci et
al.13 reported that 
 patients with high physical activity were likely to have lower mortality and lower risk of 
 adl , the amount of physical activity is important from the viewpoint of healthy life 
 expectancy . during the 2 months of study period , some of the patients who experienced 
 recurrence of wound that was probably caused by walking were lost to follow - up . as is 
 reported
, 30% of the patients with cli will have to have amputation within one year9 , so the management of the risk of recurrence 
 is also necessary .
therefore , providing guidance to simply increase the amount of physical 
 activity is not enough .
it remains unknown whether improvement of the amount of physical 
 activity of patients with cli is associated with life prognosis .
strict supervision to 
 maintain the amount of physical activity is necessary while taking appropriate care of 
 wound .
first it is a japanese single center study with 
 a limited number of patients .
further studies with larger numbers of subjects are obviously 
 needed to confirm these findings .
the majority of our sample was male , so it is possible 
 that our study findings would have differed if more females were included in our sample . 

confirmation of the findings of the current study in other populations will be needed . in 
 our study
we were unable to elucidate to what extent the amount of physical activity poses 
 an influence on the patient s prognosis .
further study by longitudinal observations is 
 required to fully understand the clinical significance of the amount of physical 
 activity .
 [ purpose ] the purpose of this study was to evaluate the amount of physical activity of 
 the patients with critical limb ischemia consecutively in order to clarify the 
 characteristics of physical activity of critical limb ischemia . 
 [ subjects and methods ] 
 twelve patients who were eligible for the 2 months of consecutive evaluation of the amount 
 of physical activity were enrolled in the study ( men : 11 ; woman : 1 ; mean age : 64.4 [ range : 
 4480 ] ) . 
 a pedometer with an accelerometer was used for the measurement of the number of 
 steps walked as an index of the amount of physical activity . 
 participants were asked to 
 lead a regular life and no instruction was given as to the number of steps . 
 [ results ] the 
 average number of daily steps walked was 2,323 steps ( range : 4046,505 ) . 
 there was no 
 clear tendency in the number of amputation site - specific steps walked . 
 there was also no 
 correlation between the number of steps walked and age as well as the maximum strength of 
 the knee - extension muscle , skin perfusion pressure of the sole and the dorsum , and qol 
 scores . 
 [ conclusion ] the number of steps walked of the patients with critical limb 
 ischemia was remarkably low and no significant association with health - related qol . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION
Conflict of interest