Abstract
Background: Individuals with end-stage knee osteoarthritis (OA) walk at a lower intensity (ie, slower step cadence) contributing to worse physical function. Previous literature reports daily step counts and sedentary time, with little information regarding stepping bouts or cadence. Determining relationships between daily higher stepping cadence duration and clinical outcomes can move the field toward optimal daily stepping prescription.Objective: To quantify daily physical activity patterns of individuals with end stage knee OA and determine the contribution of high stepping cadence to explain functional capacity variability.Design: Cross-sectional analysis.Setting: Veterans Administration medical center.Participants: U.S. military veterans (n = 104; age: 67.1 years [7.2]; mean [SD]; male [89.3%]) with end-stage knee OA were enrolled.Intervention: Not applicable.Main outcome measure: Functional capacity (6-Minute Walk Test [6MWT]). Physical activity (activPAL wearable sensor; cadence and time sitting, standing, and stepping), pain (Western Ontario and McMaster Universities Osteoarthritis Index-pain subscale) sociodemographic variables, and comorbidities (body mass index and Functional Comorbidity Index) are the main explanatory variables.Results: Participants' wake time was mainly sitting (11.0 h/day) in >= 60-minute bouts (29.7% +/- 12.7 of sitting time). Standing (3.4 hours/day) and stepping (1.4 h/day) primarily occurred in 0-5 minute bouts (standing: 87.7% +/- 14.4 of standing time, stepping: 98.7% +/- 12.7 of stepping time) and stepping cadence was predominantly incidental (1-19 spm; 52.9% +/- 9.6 of total stepping time). Backward elimination model results indicated shorter medium-to-brisk cadence bout duration, older age, and higher pain significantly explained shorter 6MWT distance (R-Adj(2)=0.24, p < .01).Conclusions: Individuals with knee OA spend most of their waking hours sitting, while standing and stepping occurs in short bouts at very low stepping cadence. Decreased time in high stepping cadence is associated with lower functional capacity. Future studies should explore if increasing the daily time spent in higher step cadence can improve functional capacity in this population.