the accelerometer is a useful measurement tool for monitoring physical activity , especially 
 the upper extremity activities of patients with stroke1 . unlike previous assessment tools for upper - limb function after 
 stroke
, accelerometers can also assess level of performance of activities of daily living , 
 as well as capacity ( the ability to perform some action)2 .
thus , accelerometers allow objective measurement of upper - limb 
 activity during daily living as well as in clinical practice3 .
a previous study found that accelerometry of daily arm activity was 
 significantly related to the mal - aou scale , an upper - limb assessment tool which takes the 
 form of a semistructured interview4 .
an 
 accelerometer was also used in a study assessing the reliability of log-14 for upper limb 
 measurement5 .
however , subjects in these 
 studies wore the accelerometer for more than one day , making it difficult to evaluate 
 upper - limb movement of specific activities .
the action research arm test ( arat ) is a tool 
 that assesses the abilities of grasp , grip , pinch and performance of gross movements after 
 stroke6 .
it is a highly reliable and 
 validated measurement tool for the evaluation of upper limb motor impairment7 .
the arat is used to measure specific upper 
 limb movements including fine and gross movements8 , and a comparison between the accelerometer and arat would determine 
 whether the accelerometer is a useful tool for monitoring specific upper limb activities . 

accordingly , the purpose of this study was to investigate the sensitivity of an 
 accelerometer in measuring upper extremity activities .
fifteen subjects were recruited from rehabilitation hospitals in won - ju , korea for this 
 study .
the inclusion criteria were : a diagnosis of stroke with hemiparesis , no severe 
 deficits in cognitive function ( mini mental state examination ( mmse ) score > 22 ) and the 
 absence of orthopedic upper limb limitations .
we obtained written informed consent using the 
 form approved by the yonsei university wonju institutional review board from all research 
 subjects before beginning the study .
the accelerometer used in this study was a fitmeter developed by fit dot life corporation 
 of korea in 2010 .
the fitmeter is small ( 35  mm  35  mm  13 mm ) and light ( 13.7 g ) ; thus , 
 it is easy and convenient to attach to a specific body part .
the frequency of measurement 
 and sensitivity of the fitmeter are from 1/32 to 30 seconds and 2 to 8 g , respectively9 . for this study ,
the fitmeter was set at 
 1/32 seconds and 2 g to measure slower activities and fine motor movements .
the arat assesses motor function of the upper limbs after stroke , as well as the amount of 
 movement possible in stroke recovery stages .
the arat uses a wooden box and different sizes 
 of blocks and other objects .
the arat consists of 19 test items including those that involve 
 grasp ( 6 ) , grip ( 4 ) , pinch ( 6 ) and gross movement ( 3 ) actions .
the highest possible arat 
 score is 57 , based on a four - point scale that rates the quality of movement over 60 seconds 
 as follows : 0 = no movement , 1 = partial movement , 2 = movement performed slower than normal 
 ( 560 seconds ) , 3 = movement performed normally ( in less than 5 seconds ) .
the test takes 
 515 minutes to complete , depending on the subject s symptoms10 .
the inter - rater and test - retest reliabilities for stroke patients 
 were 0.99 and 0.98 , respectively indicating high reliabilities11 .
subjects wore 
 accelerometers embedded within wrist bands on both wrists and performed the arat items . 

subjects were required to place both arms on the desk before and after performing the arat 
 in order to clarify the start and end point of the test .
the mann - whitney 
 test was used to compare median differences in arat and acceleration scores between the 
 affected and non - affected sides .
spearman s rank correlation coefficient was calculated to 
 test the significance of relationships between acceleration and arat variables .
table 1table 1.subject characteristics at baseline ( n=15)characteristicgender , m / f ( total)9/6 , 15age ( yrs)67.3  9.9affected side , l / r , ( total)7/8 , 15time since stroke onset ( y)3.1  2.3values expressed as mean  sd or n. shows the demographic characteristics of the study subjects . the study 
 included nine males and six females with a mean age of 67.3  9.9  years .
there was a significant difference in the median score between the affected and non - affected 
 sides both the arat and accelerometer results .
the arat scores were higher on the 
 non - affected side ( p<0.05 ) , while upper limb activity was higher on the affected side 
 ( p<0.05 ) ( table 2table 2.median differences in arat and acceleration scores between the affected and 
 non - affected sidesaffected sidenon - affected sidearat42.8 ( 11.1)57 ( 0)accelerometer74488.3 ( 51778.1)35963.1 ( 11240.5)values are mean ( sd ) , p<0.05 ) .
the correlation coefficient between arat and accelerometer results indicates 
 that the results were not significantly correlated ( table 3table 3.correlation between arat and the accelerometerarat ( affected side)accelerometer ( affected side)0.24accelerometer ( non - affected side)0.91 ) .
values expressed as mean  sd or n. values are mean ( sd ) , p<0.05
previous accelerometer studies primarily measured physical activity over several days12 . in contrast , this study was performed in 
 a clinical setting and measured and compared upper extremity movements of specific 
 activities performed using the paretic and non - paretic hands .
the accelerometer results 
 indicated there is a significant difference between the affected and unaffected upper 
 extremities , and this was confirmed by the arat .
this outcome was not 
 consistent with previous studies comparing accelerometer recordings and the results of the 
 motor activity log and the actual amount of use test1 .
first , because we did not consider the timing of arat 
 activities , there are data errors associated with the amount of upper limb movement as 
 measured by the accelerometer . in addition , differences in quantitative and qualitative data 
 of the accelerometer and arat affected the correlation coefficients .
however , the results of 
 this study indicate that the accelerometer is a sensitive tool for measuring upper limb 
 activity .
future studies should use an accelerometer to measure specific activities in a 
 clinical setting .
 [ purpose ] this study investigated the sensitivity of an accelerometer in a comparison 
 with the action research arm test ( arat ) . [ subjects ] fifteen stroke patients participated 
 in this study . [ methods ] subjects wore accelerometers on both wrists and performed the 
 arat items . 
 we then compared the data measured by the accelerometer with that of the arat . 
 
 [ results ] arat scores were higher on the non - affected side than the affected side , while 
 the amount of upper extremity movement was higher on the affected side . 
 the correlation 
 coefficients for the two tools were not significantly different . 
 [ conclusion ] our findings 
 indicate that an accelerometer is a useful and sensitive instrument for clinically 
 measuring the upper extremity activity of patients with stroke . 