Application and Reliability of Accelerometer-Based Arm Use Intensities in the Free-Living Environment for Manual Wheelchair Users and Able-Bodied Individuals

Abstract

Arm use in manual wheelchair (MWC) users is characterized by a combination of overuse and a sedentary lifestyle. This study aimed to describe the percentage of daily time MWC users and able-bodied individuals spend in each arm use intensity level utilizing accelerometers. Arm use intensity levels of the upper arms were defined as stationary, low, mid, and high from the signal magnitude area (SMA) of the segment accelerations based on in-lab MWC activities performed by eight MWC users. Accelerometry data were collected in the free-living environments from forty MWC users and 40 sex- and age-matched able-bodied individuals. The SMA intensity levels were applied to the free-living data and the percentage of time spent in each level was calculated. The SMA intensity levels were defined as, stationary: ≤0.67 g, low: 0.671–3.27 g, mid: 3.27–5.87 g, and high: >5.871 g. The dominant arm of both MWC users and able-bodied individuals was stationary for most of the day and less than one percent of the day was spent in high intensity arm activities. Increased MWC user age correlated with increased stationary arm time (R = 0.368, p = 0.019). Five and eight days of data are needed from MWC users and able-bodied individuals, respectively, to achieve reliable representation of their daily arm use intensities.

Development and evaluation of the ARM algorithm: A novel approach to quantify musculoskeletal disorder risk factors in manual wheelchair users in the real world

“…Additionally, MWC users were excluded if they had health complications that would inhibit their ability to participate in the larger longitudinal study such as stage IV pressure injuries, extensive comorbidities, or severe pain. Detailed inclusion criteria are described elsewhere [ 12 ].…”

“…Additionally, participants were asked to perform a functional calibration at the beginning of data collection [ 8 ]. Our established method was used to calculate the humeral elevation angle [ 8 , 12 ]. In summary, a sensor fusion method (Kalman filter) was employed to estimate IMU orientation from linear acceleration and angular velocity [ 21 ].…”

“…Inertial measurement units (IMUs), which contain an accelerometer, gyroscope, and magnetometer, can be worn in the free-living environment to continuously capture arm use across a large majority of the day. IMUs have previously been used to quantify wheelchair propulsion behaviors and daily arm use in MWC users [7][8][9][10][11][12]. In a recent study [13], inspired by ergonomics literature [14], we defined risk and recovery metrics to assess arm use in MWC users in the free-living environment.…”

Inertial Measurement Unit–Derived Ergonomic Metrics for Assessing Arm Use in Manual Wheelchair Users With Spinal Cord Injury: A Preliminary Report

“…Additionally, participants were asked to perform a functional calibration at the beginning of each day and after re-donning the sensors. 11 , 17 Participants in both cohorts were asked to wear the IMUs during their typical daily routines and not to alter these routines for the sake of the study. The able-bodied cohort did not use wheelchairs or simulate living with an SCI in any way.…”

“… 15 , 16 An SMA threshold (SMA = 0.67 g) to detect static (SMA ≤ 0.67 g) and dynamic periods was calculated as part of a previous study and has been applied to the data in the current study. 17 , 18 To calculate the humeral elevation angles, the functional calibration was used to align the inertial reference frame with the anatomical axes. The angles between the long axes of the body segments and vertical were defined as the humeral elevation and thorax deviation angles.…”