## 1 Introduction  
Early activity post-stroke reduces secondary complications, reduces hospital length of stay [1], improves long-term functional outcomes [2, 3], and possibly builds self-efficacy toward self-management [4]. Early post-stroke activity refers to any out-of-bed activity, including supported sitting, transfers, standing, and walking, performed within 24-48 h post-stroke [5, 6]. Clinical practice guidelines (CPG) recommend that mobilization should be frequent, short, and occur daily [5]. Engaging individuals in early activity post-stroke depends on the routines in the acute hospital setting because this is where patients' care typically starts. Regardless of variability in hospitalization duration and setting, acute hospital settings are expected to implement treatment protocols that enable and facilitate out-of-bed activities in the early post-stroke period. In-hospital physical activity may be viewed in a broader context, regardless of medical diagnosis. This topic has been recognized as having great importance due to the negative effects of low mobilization on many health and function domains [7,8] and since a growing body of evidence suggests that engaging in progressive activity promotes post-operative recovery and prevents adverse events during acute illness [9,10]. Despite this, recent systematic reviews have revealed that the inpatient population (e.g., surgical, medical, or intensive care) spends approximately 90% to 100% of their hospital stay lying in bed or sitting and, in most cases, performs less than 1000 steps [11,12]. The most common tools for monitoring activity in people post-stroke are a behavioral mapping, which is based on structured observation of the patient, and accelerometry [13]. Observation methodology provides rich information, although the capacity to capture activity patterns throughout the entire day is limited because it requires the physical presence of an observer. Alternatively, accelerometry allows continuous measurement of activity and quantification of body posture and activities. Several studies established the face validity of accelerometry in people post-stroke. Body position and mobility in people post-stroke have been monitored primarily during the sub-acute and chronic phases. Studies conducted in an acute hospital setting showed that, broadly speaking, patients were inactive [11,12,14,15,16]. Patients in the first- and second weeks post-stroke stayed in their room more than 80% of the active daytime (8:00-17:00), they remained in bed 50% of the time, and remained in supported sitting for 4-28% of the time. Only 2-17% of the time was spent on upright activities that included walking and standing [14,15,16], although walking involved less than 100 steps [17]. An exception was a study that showed that patients in the acute stroke unit were active 45% of the day [18], demonstrating that this designated setting enables a higher level of activity. These empirical findings indicate a gap between the established importance of early and frequent activity and clinical practice. A comprehensive description of the activity of patients post-stroke in an acute hospital setting, which includes the distribution and duration of activity periods over the entire length of the day, the duration of activity periods, and the change in activity over time, may shed light on specific factors that hinder higher levels of activity in such settings for post-stroke patients (e.g., specific times during the day in which activity is very low). The goal of the current study was to characterize stroke patients' activity patterns using accelerometers in an acute hospital inpatient setting and to analyze the recorded activity with respect to meaningful clinical contextual and non-contextual factors, e.g., comparing work shifts (morning and evening) and testing associations with patients' clinical status.