Quantifying Real-World Upper-Limb Activity in Nondisabled Adults and Adults with Chronic Stroke

Background. Motor capability is commonly assessed inside the clinic, but motor performance in real-world settings (ie, outside of the clinic) is seldom assessed because measurement tools are lacking. Objective. To quantify real-world bilateral upper-limb (UL) activity in nondisabled adults and adults with stroke using a recently developed accelerometry-based methodology. Methods. Nondisabled adults (n = 74) and adults with chronic stroke (n = 48) wore accelerometers on both wrists for 25 to 26 hours. Motor capability was assessed using the Action Research Arm Test (ARAT). Accelerometry-derived variables were calculated to quantify intensity of bilateral UL activity (ie, bilateral magnitude) and the contribution of both ULs to activity (magnitude ratio) for each second of activity. Density plots were used to examine each second of bilateral UL activity throughout the day. Results. Nondisabled adults demonstrated equivalent use of dominant and nondominant ULs, indicated by symmetrical density plots and a median magnitude ratio of -0.1 (interquartile range [IQR] = 0.3), where a value of 0 indicates equal activity between ULs. Bilateral UL activity intensity was lower (P <.001) and more lateralized in adults with stroke, as indicated by asymmetrical density plots and a lower median magnitude ratio (-2.2; IQR = 6.2, P <.001). Density plots were similar between many stroke participants who had different ARAT scores, indicating that real-world bilateral UL activity was similar despite different motor capabilities. Conclusions. Quantification and visualization of real-world bilateral UL activity can be accomplished using this novel accelerometry-based methodology and complements results obtained from clinical tests of function when assessing recovery of UL activity following neurological injury.