Tri-axial accelerometer analysis techniques for evaluating functional use of the extremities

Abstract

Activity monitors provide an objective mechanism for evaluating patient function. It is unclear what similarities or unique information may be yielded using different analyses. Fifteen patients scheduled to undergo shoulder arthroplasty and fifteen matched control subjects wore tri-axial accelerometer activity monitors bilaterally at the lower (wrist) and upper (biceps) arm for 3 days. Measures of central tendency, variance, sample entropy, and asymmetry were calculated. A novel technique to evaluate time distribution of activity intensity was also performed. Within both groups there was a difference in central tendency and variance when comparing dominant and non-dominant limbs for both the lower (Controls: Mean Activity, P < 0.001; Max Activity, P < 0.001; Patients: Mean Activity, P = 0.044; Max Activity, P = 0.009) and upper (Controls: Mean Activity, P < 0.001; Max Activity, P = 0.046; Patients: Mean Activity, P = 0.002; Max Activity, P = 0.049) arm. Within group differences were also present for lower arm entropy in both groups (Controls, P < 0.001; Patients P = 0.041), and at the upper arm for patients (P = 0.003). There were differences between groups for the asymmetry index for both the lower (P = 0.033) and upper arm (P = 0.005), and maximum activity level of the lower arm (P = 0.05). Between group differences were present for time distribution of activity intensity, as the involved upper arm of patients was inactive for a greater time than controls (P = 0.013). These results highlight unique information provided by multiple analysis methods, and include a novel approach of evaluating the distribution of time spent across variable intensity activities.

Identifying physical activity type in manual wheelchair users with spinal cord injury by means of accelerometers

“…; patter length = 2). 24 Finally, we computed the cross-correlation between the three orthogonal axes (that is, x-y, y-z and x-z cross-correlations). 25 The total number of variables was 59 for each accelerometer (that is, 14 variables for the four axes and three variables for the correlation between axes).…”

Novel approaches to objectively assess shoulder function

“…A novel technique to evaluate activity over the course of the day included the use of activity bins. 7 The bins were created to calculate the amount of time patients were inactive, and the time spent performing activities categorized as low and high intensity. Inactive limb use time was calculated as a percentage of the total wear time: inactivity < 110 m/s 2 /epoch.…”

“…Inactive limb use time was calculated as a percentage of the total wear time: inactivity < 110 m/s 2 /epoch. 6 A within-subject normalization method was performed wherein the epoch data was divided into low and high activity bins based on the percentage of the maximum activity (MA) count determined from a control group 7 : Low activity : 110 m/s 2 /minute epoch ≤ Activity ≤ 33% of MA High activity : Activity > 33% of MA where 33% of MA is greater than 110 m/s 2 in a segment that experiences accelerations above 0.01 m/s 2 . The epochs in each bin were summed to determine the percentage of each day spent at the different activity levels, and the total percent time spent in each bin was averaged across days for analysis.…”

Effects of mirror feedback during balanced exercise performance in the old people with mild cognitive impairment

“…Mirror exercise has been utilized to provide feedback to the exerciser oneself for improving neurological function with balanced usage between the left and right sides of the body. In this study, one of the most commonly practiced exercise regime, lateral raises, were conducted by body upper limbs in a synchronized fashion with and without the mirror feedback during exercises (Hurd et al, 2013;Lang et al, 2017). Performance was assessed by comparing synchronized motion between the left and right limbs by angle (°) for the positional comparison and angular acceleration (°/sec 2 ) for the motion comparison.…”