cardiovascular disease ( cvd ) is a major contributor to the global burden of diseases1 , 2 . in 
 addition , cvd ( heart failure and stroke , etc . ) often causes disuse muscle atrophy in the 
 acute and subacute phase , which increases the likelihood of wheelchair or bedridden state in 
 the chronic phase3,4,5 .
consequently , the 
 progression of muscle atrophy in lower extremity function may render a high need for medical 
 and nursing care .
the short physical performance battery ( sppb)a brief performance battery based on a timed 
 short distance walk , repeated chair stands , and a set of balance tests  is a validated 
 assessment tool for measuring lower extremity function that is widely used in both clinical 
 and research settings6 , 7 .
the popularity of this instrument stems , in part , from its relative 
 ease of use , perceived potential for implementation in clinical practice , and good 
 association with physical activity levels and general walking disability in a variety of 
 patients or older adults .
it has also been found to predict mortality , hospitalization rate , 
 and a variety of comorbid disease conditions7 .
although the sppb is an effective assessment tool for lower 
 extremity function , it is unclear the sppb can be used to evaluate mobility capability for 
 cardiovascular disease patients including inpatients and outpatients .
previous studies 
 demonstrated that gait speed was associated with survival in older adults and which was 
 faster with healthy older adults than outpatients , which was faster than inpatients8 , 9 . 

thus , the purpose of this study was to examine two hypotheses : that the sppb would be higher 
 with healthy older adults than outpatients , which was higher than inpatients ; and that the 
 sppb can be validated assessment tool for strength tests and lower extremity morphological 
 evaluation in middle - aged and older adult cardiovascular disease patients .
thirty - six middle - aged and older adults , aged 49 to 89  years , with cardiovascular diseases 
 [ outpatients ( out - pt ) and inpatients ( in - pt ) ] and healthy subjects ( ctrl ) volunteered to 
 participate in the study and were selected according to the exclusion criteria ( history of 
 anemia , cerebrovascular disease and arthroscopic joint surgery ) .
in addition , volunteers who 
 suffered from a chronic disease such as severe orthopedic disorders , peripheral vascular 
 disease , or cognitive dysfunction were excluded from the study .
all participants had 
 undergone complete chemistry and hematologic evaluation and were informed of the risks 
 associated with involvement in the study and signed an informed consent document before 
 participation .
all participants were recruited through study notices in area and oral 
 communications in the university hospital .
the principles of the world medical association 
 declaration of helsinki and the american college of sports medicine guidelines for use of 
 human subjects were adopted in this study .
analyses of ultrasound images and all measurements data were performed by 
 the same author , who was blinded to the group assignments .
the author has been specialized 
 in the research of exercise physiology by use of ultrasound images , strength tests and lower 
 extremity morphological evaluation more than 15  years .
the 
 tests were performed in the following sequence : a ) standing balance tests , b ) gait test , and 
 c ) chair stand test .
the standing balance portion requires participants to maintain , for 10 
 seconds each , stances with their feet placed side by side , semi - tandem , and in tandem .
the gait test measured the time needed to 
 walk 4  m at a typical pace .
the chair stand required participants to rise from a steel 
 chair , 0.40  m height and 0.30  m depth , with their arms across their chest , five times . 

categorical scores , range : 04 , for both the gait and the chair stand tests were based on 
 timed quartiles established previously in a large population .
individuals who were unable to 
 complete either the 4  m gait task or the 5 repetitions chair stand test received a score of 
 0 .
the sum of the three components comprised the final sppb score , with a possible range 
 from 0 to 12 .
maximum voluntary isometric contraction ( mvic ) of the handgrip was determined using a 
 factory - calibrated hand dynamometer ( tkk 5401 , takei scientific instruments co. , ltd . , 

all subjects were instructed to maintain an upright standing position , arms 
 at their side , holding the dynamometer in the right hand with the arm at a right angle and 
 the elbow held at the side of the body .
the size of the dynamometer handle was set so that 
 it felt comfortable to the subject while squeezing the grip .
each subject underwent 2 
 trials , and the best value of 2 trials was used for analysis .
mvic of the knee extensors was determined using a digital handheld dynamometer ( tas mt-1 , 
 anima co. , ltd . ,
the 
 dynamometer pad is 55  55  mm , and its front side is curved to fit the shape of the area of 
 the extremity to be measured .
subjects were seated in a hard chair with their knees flexed 
 90 and their arms on their thighs .
the dynamometer was placed perpendicular to the leg just 
 above the malleoli . during all tests ,
the dynamometer was kept stable by the examiner using 
 both hands and the subject s leg was fixed by a belt to keep the knee flexed at 90. 
 subjects were told to push against the dynamometer by attempting to straighten their leg . 

each subject was 
 given 2 trials with an interval of at least 2  min between the trials .
percent body fat and fat - free mass were measured using leg - to - leg bioelectrical impedance 
 analysis ( reactance technology , inner scan , tanita , tokyo , japan ) .
the measurements were 
 carried out while the subjects stood with their elbows extended and relaxed .
after thigh and lower leg length measurements using anatomic landmarks , all measurement 
 sites were marked with a marker pen and then mid - thigh , at 50% between the lateral condyle 
 of the femur and the greater trochanter , and lower - leg , at 30% proximal between the lateral 
 malleolus of the fibula and the lateral condyle of the tibia , girths and were measured using 
 a tape measure on the right side of the body12 .
ultrasound evaluation of muscle thickness ( mth ) was performed by 
 using a real - time linear electronic scanner with a 10.0-mhz scanning head ( 5.5  cm length 
 probe , prosound c3cv , hitachi aloka system , tokyo , japan ) .
the scanning head was coated with 
 a water - soluble transmission gel to provide acoustic contact without depressing the dermal 
 surface .
the subcutaneous adipose tissue - muscle interface and the muscle - bone interface were 
 identified from the ultrasonic image .
the perpendicular distance from the adipose 
 tissue - muscle interface to the muscle - bone interface was considered to represent mth . 

briefly , the measurements were carried out while the subjects stood with their elbows 
 extended and relaxed12 .
all data were 
 analyzed using jmp software v.12.0 for mac ( sas institute inc .
pearson 
 product correlations of tandem , or chair stand , or gait or total sppb scores and variable 
 factors were also statistically quantified .
when the data were not normally distributed , 
 non - parametric statistical analysis , wilcoxon signed rank test , was used to identify 
 differences in in - pt vs. out - pt vs. ctrl groups .
a stepwise multiple - regression analysis 
 ( method of increasing and decreasing the variables , criterion was set at p<0.05 ) was 
 performed to develop a prediction equation for sppb scores using age , height , weight , bmi , 
 % bf , systolic and diastolic blood pressures , resting heart rate , handgrip , knee extension , 
 fat free - mass , mid - thigh and lower - leg girths , and anterior mid - thigh , posterior mid - thigh , 
 and posterior lower - leg mths as independent variables .
consequently , the predicted 
 variables , coefficients and intercept coefficients were automatically picked out by the jmp 
 software .
the sample size was estimated from 
 a priori power analysis to detect the correlation ( power of 0.80 , an  of 0.05 , two - tailed , 
 and =0.5 ) with the reference13 . 

the physical characteristics and clinical data are shown in table 1table 
 1.the physical characteristics and clinical 
 datain - pt out - pt ctrl 
 male ( n)777female 
 ( n)555age ( years)71.8 ( 11.6)70.3 ( 8.1)70.0 
 ( 6.7)height ( cm)160 ( 14)162 ( 10)164 ( 9)weight ( kg)59.8 ( 14.0)60.9 ( 10.0)58.9 
 ( 7.1)body mass index 
 ( kg / m)23.6 ( 6.5)23.3 ( 3.0)22.0 
 ( 1.4)% body fat30.1 ( 17.5)24.0 ( 7.6)23.1 ( 6.4)systolic bp ( mmhg)113 ( 24)133 ( 19)137 ( 19 ) 
 diastolic bp 
 ( mmhg)64 ( 14 ) 71 ( 11 ) 82 ( 12 ) 
 resting heart rate 
 ( bpm ) 79 ( 12 ) 71 ( 12 ) 73 ( 8)bnp  ( pg / m1)177 ( 170 ) * 62 ( 46)-hospital admission ( within 
 10  years)number 2.9 ( 2.2 ) 2.0 
 ( 1.9)0duration ( days)49.3 ( 53.5)23.1 ( 24.2 ) 0specific diseases ( n)vascular diseases360ischemic 
 heart diseases 6 100valvular diseases030congestive heart failure710hypertension690others 
 320 data are 
 given as mean ( standard deviation ) .
there were no significant differences among 
 three conditions in physical characteristics except for systolic and diastolic blood 
 pressures .
total sppb scores , strength tests , and morphological assessments were greater in 
 the ctrl and the out - pt groups compared with the in - pt group ( table 2table 
 2.short physical performance battery ( sppb ) , strength tests , 
 and morphological assessmentsin - ptout - ptctrl sppb ( raw 
 data)side - by - side 
 stand ( sec)10.0 ( 0.0)10.0 ( 0.0)10.0 
 ( 0.0)semi - tandem stand ( sec)10.0 ( 0.0)10.0 
 ( 0.0)10.0 ( 0.0)tandem stand ( sec ) 7.1 
 ( 3.6)8.3 ( 3.1)10.0 ( 0.0 ) gait test ( sec/4 m ) 5.4 ( 3.2 ) 3.8 ( 0.6 ) * 3.4 
 ( 0.3 ) chair stand test 
 ( sec/5rep)16.0 ( 5.0)10.0 ( 1.7 ) * * 7.4 ( 1.7 ) # # , 
   sppb scoreside - by - side stand 1.0 ( 0.0 ) 1.0 ( 0.0 ) 
 1.0 ( 0.0)semi - tandem stand   1.0 ( 0.0 ) 
 1.0 ( 0.0 ) 1.0 ( 0.0)tandem stand 1.3 ( 0.8 ) 1.6 ( 0.8 ) 
 2.0 ( 0.0 ) gait test 3.5 ( 1.0 ) 
 3.9 ( 0.3 ) 4.0 ( 0.0)chair stand test 2.2 ( 1.3 ) 3.7 ( 0.5 ) 
 * * 4.0 ( 0.0 ) total sppb   9.0 
 ( 2.4 ) 11.2 ( 1.0 ) * 12.0 ( 0.0 ) strength testhandgrip  ( kg)24.1 ( 9.8)28.6 ( 8.6)29.3 
 ( 7.2)knee extension  ( kg)19.7 ( 9.9)34.9 ( 10.3 ) 
 * * 37.4 ( 6.3 ) morphological assessmentfat free - mass ( kg)40.9 ( 11.4)46.2 ( 8.4)43.5 ( 10.2)mid - thigh girth ( cm)43.8 ( 8.1)46.3 ( 3.3)45.0 
 ( 6.2)lower - leg girth ( cm)33.1 ( 5.2)35.3 
 ( 2.4)34.2 ( 4.1)anterior mid - thigh mth ( cm)3.13 
 ( 0.89 ) 4.28 ( 0.74 ) * * 4.34 ( 0.60 ) posterior mid - thigh mth ( cm)5.06 ( 0.78 ) 
 6.05 ( 0.51 ) * * 5.55 ( 0.81 ) posterior lower - leg mth ( cm)5.59 
 ( 0.82 ) 6.52 ( 0.61 ) * * 6.46 ( 0.50 ) 
 n=36 .
mth : muscle thickness . * * p<0.01 , * p<0.05 , in - pt vs. 
 out - pt .
pearson s correlation coefficients between sppb 
 scores and variable factors are shown in table 
 3table 3.pearsons 
 correlation coefficients between sppb scores and variable 
 factorspearson s correlationtandemchair 
 standgait total sppb scores strength testhandgrip0.432 
 * * 0.527 * * 0.523 * * 0.562 * * knee extension0.382 
 * 0.717 * * 0.491 * * 0.690 * * morphological assessmentfat 
 free - mass0.369 * 0.386 * 0.429 * * 0.366 * mid - thigh girth0.2330.548 * * 0.364 * 0.464 * * lower - leg girth0.2640.598 * * 0.409 * 0.436 * * anterior mid - thigh mth0.463 * * 0.802 * * 0.569 
 * * 0.759 * * posterior mid - thigh mth0.488 
 * * 0.472 * * 0.465 * * 0.563 * * posterior lower - leg mth0.437 * * 0.670 * * 0.583 * * 0.655 
 * * n=36 .
mth : muscle thickness . * * p<0.01 , * p<0.05 , in - pt vs. 
 out - pt .
mth : muscle thickness . * * p<0.01 , 
 * p<0.05 to predict tandem stand , the predicted age and posterior mid - thigh muscle thickness were 
 calculated ( tandem stand=1.80  posterior mid - thigh muscle thickness  0.10  age + 5.43 ) 
 ( n=36 , r=0.331 , p<0.05 ) . to predict chair stand , the predicted fat free - mass , 
 knee extension and anterior mid - thigh muscle thickness were calculated ( chair stand=0.21  
 fat - free mass  3.21  anterior mid - thigh muscle thickness  0.25  knee extension mvic + 
 22.34 ] ( r=0.776 , p<0.01 ) . to predict gait test ,
the predicted posterior 
 lower - leg muscle thickness was only calculated ( gait test= 1.51  posterior lower - leg 
 muscle thickness + 13.59 ) ( r=0.340 , p<0.01 ) .
to predict total sppb scores , 
 the predicted knee extension and anterior mid - thigh muscle thickness were calculated ( total 
 sppb scores=0.05  knee extension mvic + 1.15 anterior mid - thigh muscle thickness + 4.60 ) 
 ( r=0.630 , p<0.05 ) .
the main findings of this study were as follows . first , total sppb scores were greater with 
 ctrl group than out - pt group , which was higher than in - pt group .
second , knee extension 
 strength and anterior mid - thigh muscle thickness can predict total sppb scores in 
 middle - aged and older adult cardiovascular disease patients . the sppb assessment
was established as a disability evaluation for older adults , healthy 
 elderly and some disability conditions6 , 14,15,16 .
a previous study reported that impaired 
 mobility was reflected by a total sppb score of less than 1014 .
in addition , total sppb scores of 46 were 4.2 to 4.9 times more 
 likely to have disability in the activities of daily living or mobility - related disability 
 at 4  years . on the other hand ,
those with total sppb scores of 79 were 1.6 to 1.8 times 
 more likely to become disabled17 . in this 
 study ,
the average of total sppb scores in in - pt group was 9.0 and scores of 46 were only 
 in 2 patients .
however , a stepwise 
 multiple - regression analysis could be applied to the predictor knee extension and anterior 
 mid - thigh muscle thickness to predict total sppb scores .
these results suggested that the 
 total sppb scores could be evaluated by the strength tests and morphological assessment in 
 knee extensor muscles for middle - aged and older adult cardiovascular disease patients , even 
 if severely impaired mobility patients were very few within the group . in this study ,
the scores in side - by - side , semi - tandem stand and gait test were similar 
 among the three groups .
in contrast , the chair stand test ( 4 out of 12 score ) makes up a 
 large part of total sppb scores compared with tandem stand ( 2 out of 12 score ) , suggesting 
 that the differences of total sppb scores were mainly dependent on the chair stand test .
it 
 is well known that knee extension muscle size and strength play an important role in the 
 chair stand performance for older adults18 , 19 . additionally , knee extension muscle size 
 and strength were higher correlation coefficients with chair stand test , compared with 
 balance and gait tests in this study .
thus , it appears that the total sppb scores were 
 largely affected by muscle strength and size of the quadriceps femoris .
the limitation of this study was very difficult to evaluate the function and morphological 
 assessment within the same hospital admission for in - pt group or the same hospital visit for 
 the out - pt group .
the sppb is an effective tool as the strength tests and lower extremity 
 morphological evaluation for middle - aged and older adult cardiovascular disease patients . 

notably , high knee extensor muscle strength and quadriceps femoris muscle thickness are 
 positively associated with high sppb scores .
 [ purpose ] to examine if the sppb is higher with healthy subjects than outpatients , which 
 was higher than inpatients and if the sppb can be validated assessment tool for strength 
 tests and lower extremity morphological evaluation in cardiovascular disease patients . 
 
 [ subjects and methods ] twenty - four middle aged and older adults with cardiovascular 
 disease were recruited from inpatient and outpatient facilities and assigned to separate 
 experimental groups . 
 twelve age - matched healthy volunteers were assigned to a control 
 group . 
 sppb test was used to assess balance and functional motilities . 
 the test outcomes 
 were compared with level of care ( inpatient vs. outpatient ) , physical characteristics , 
 strength and lower extremity morphology . 
 [ results ] total sppb scores , strength tests ( knee 
 extensor muscle strength ) , and lower extremity morphological evaluation ( muscle thickness 
 of anterior and posterior mid - thigh and posterior lower - leg ) were greater in healthy 
 subjects and outpatients groups compared with inpatients . 
 to predict total short physical 
 performance battery scores , the predicted knee extension and anterior mid - thigh muscle 
 thickness were calculated . 
 [ conclusion ] the sppb is an effective tool as the strength 
 tests and lower extremity morphological evaluation for middle - aged and older adult 
 cardiovascular disease patients . 
 notably , high knee extensor muscle strength and 
 quadriceps femoris muscle thickness are positively associated with high sppb scores . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION
Conflicts of interest