Application and Reliability of Arm Use Intensities in the Free-Living Environment for Manual Wheelchair Users

Abstract

AbstractArm use in individuals with spinal cord injury who use manual wheelchairs (MWC) is complex, characterized by a combination of overuse and a sedentary lifestyle. This study aimed to calculate arm use intensity levels for MWC users, describe the percentage of daily wear time MWC users and able-bodied individuals spend in each arm use intensity level, and test the reliabilities of the measurements for both MWC users and able-bodied individuals.MWC users wore two inertial measurement units (IMUs) on their bilateral upper arms while performing six MWC-based activities in-lab. Video data were recorded and each second was coded as active or stationary. Acceleration-based signal magnitude area (SMA) ranges were defined for stationary, low, mid, and high arm use intensity levels. IMU data were also collected in the free-living environments for MWC users and able-bodied individuals for four days (3 weekdays and 1 weekend day). The SMA levels were applied to the free-living data from the dominant arm and the percentage of time spent in each level was calculated. The required number of days to achieve moderate, good, and excellent reliabilities was calculated.Eight adult MWC users with SCI participated in the in-lab data collection and SMA arm use intensity levels were defined as, stationary: ⩽ 0.67g, low: 0.671 – 3.27g, mid: 3.271 – 5.87, and high: > 5.871. Six MWC users and 15 able-bodied individuals completed the free-living data collection. The dominant arm of both MWC users and able-bodied individuals was stationary for the majority of the day. The reliability analysis indicated that at least five and eight days of data are needed from MWC users and able-bodied individuals, respectively, to achieve reliable representation of their overall daily arm use intensities throughout a week.Future research is needed to understand the recovery time associated with stationary arm use and if it differs between MWC users and matched able-bodied individuals. At least five days of data should be collected when utilizing these methods for MWC users. The methods presented here will contribute to understanding the mechanisms which cause increased shoulder pain and pathology for MWC users.