Hemiparesis is a common motor impairment following stroke that leads to disability. The goal of stroke-related physical rehabilitation is to reduce the severity of motor-related disability in hopes that improved motor capacity (i.e. what one can do) will generalize to improved motor performance (i.e. what one actually does) in everyday activities. Recent studies have demonstrated that motor capacity and motor performance are distinct domains of motor function, but few have objectively measured motor performance. Furthermore, even though many studies have demonstrated that motor capacity is only moderately associated with motor performance, few studies have examined other factors that might influence motor performance. The purpose of this dissertation was to characterize motor performance, and potential modifying factors of motor performance, in nondisabled adults and adults with chronic stroke, and to develop and validate a novel, accelerometry-derived assessment methodology to quantify motor performance.
Using wrist-worn accelerometry, we characterized duration of upper limb (UL) activity that occurred in everyday environments (i.e. real-world activity) as an index of motor performance. We also characterized several potential modifying factors of UL activity [i.e. self-reported time spent in sedentary activity, cognitive impairment, depressive symptomatology, number of comorbidities, living arrangement, age, motor capacity, pre-stroke hand dominance, and Activities of Daily Living (ADLs) status]. Increased self-reported time spent in sedentary activity was associated with decreased UL activity in nondisabled adults. Decreased motor capacity and dependence in ADLs were associated with decreased UL activity in adults with chronic stroke. These results identify potential factors that could be targeted during rehabilitation in patient populations. Additionally, duration of UL activity obtained from nondisabled adults could be used as a referent value for setting outcome goals for patients with UL impairment.
We also developed and validated a novel, accelerometry-based methodology to quantify real-world bilateral UL activity. This methodology was first validated in a laboratory setting in nondisabled adults. We derived two accelerometry-based metrics to quantify intensity of bilateral UL activity and contribution of each UL to activity. The accelerometry-derived metrics distinguished between high- and low-intensity UL activity, and between UL activities that were completed using both ULs versus one UL. The accelerometry-derived metrics were also strongly correlated with secondary measures (i.e. convergent validity was established).
Having established the validity of the accelerometry-based methodology, we characterized real-world bilateral UL activity during a “typical” day in nondisabled adults and adults with chronic stroke. We demonstrated that duration and intensity of UL activity were lower in adults with stroke than in nondisabled adults, and that UL activity was more lateralized (i.e. unaffected UL activity exceeded affected UL activity) in adults with stroke. We also demonstrated that motor capacity and motor performance were not associated in a subset of adults with stroke.
Taken together, our results suggest that motor capacity and motor performance are distinct domains of motor function that should be assessed separately. Furthermore, factors other than motor capacity should be identified and targeted during rehabilitation to improve motor performance above that which can be obtained by improvement in motor capacity alone.