###### Abstract
The repeated practice of upper limb movements directly related to daily activities--an intervention known as high-repetition task-specific training--is highly effective in improving upper limb motor function poststroke [6; 10; 11; 12]. However, providing sufficient high-repetition task training dosage in IRFs remains a challenge; previous studies have shown that patients in IRFs engage in an average of only 8 to 44 min per day of task specific upper limb training [13], with some accounts of as few as 4 min per session [14]. Although no guidelines exist for an optimal dosage of high-repetition task-training poststroke, whether patients are truly receiving \"high repetition\" is also disputable, with some studies estimating as few as 23-32 repetitions on average in a session [14]. In any event, the average dosage of upper limb training that patients receive in IRFs is unlikely to be sufficient to achieve meaningful improvements in upper limb function [14]. Another key motivation for addressing upper limb impairments early in recovery is the prevention of learned non-use, wherein stroke survivors avoid using their more involved (MI) upper limb and enter a deleterious cycle of worsening function [15; 16]. This phenomenon, which is distinct from impaired motor function, is particularly concerning for patients who retain residual motor capacity of the MI upper limb after a stroke but risk losing it due to learned non-use. Several factors may contribute to learned non-use, such as hemi-spatial neglect, a sense of urgency to complete a task using the less involved (LI) limb instead, or low motivation to use the MI limb (e.g., if the non-dominant side is affected by stroke). The current state-of-the-art approach to preventing learned non-use is constraint induced movement therapy (CIMT), which is an interventional program that uses elements of high-repetition task-training of the MI upper limb while also constraining the LI side. The program involves 6 h of training per day across 2 weeks under the guidance of a trained clinician [17]. CIMT has shown clinically meaningful improvements in MI upper limb function that can persist long after intervention [18]. However, widespread adoption of CIMT in clinical practice has been limited by the intensive time demands it places on clinicians [19]. Given the increasing pressure on healthcare resources and clinician time [20; 21], increasing total therapy time in IRFs to include more supervised upper limb intervention is highly improbable. Likewise, allotting a greater percentage of existing therapy time on upper limb recovery would come at the expense of other important interventions. There is a pressing need for interventions that engage the MI upper limb early in recovery while also minimizing clinician oversight. A viable alternate solution would be to leverage each patient's downtime between therapy sessions to participate in upper limb task practice. Sedentary behavior among stroke survivors is a known concern in IRFs; stroke survivors have been reported to spend up to 74% on average participating in sedentary activities like lying in bed or sitting in a chair watching television [22]. Capitalizing on this underutilized downtime would serve to both limit sedentary behavior and to engage the patient in meaningful upper limb task practice. Such interventions could reasonably be implemented without disrupting the established clinician workflow of scheduled therapy sessions if the intervention requires little to no clinician oversight. Wearable technology is increasingly recognized as a potentially effective means by which to deliver interventions in environments with limited clinical resources. The implementation of rehabilitative wearable technology into daily life is a realistic prospect, especially given the widespread use of motion sensor technology in commonly owned devices like cellphones and fitness watches. In quite simple applications, wearable motion sensor technology can provide information on the quantity and quality of upper limb movement post stroke [23,24].