Researcher(s)
- Matt Librizzi, Exercise Science, University of Delaware
Faculty Mentor(s)
- Daniel White, Physical Therapy, University of Delaware
Abstract
Introduction: Excessive sedentary behavior often leads to increased knee pain and functional limitation in adults with knee osteoarthritis (OA). Interventions to reduce sedentary behavior may improve knee pain and physical function. Previous studies investigating sedentary behavior lacked a standardized definition, using various criteria like sitting or low energy expenditure, which make comparisons difficult. To address this, we developed the Posture and Physical Activity Index (POPAI) to detect the standardized definition of sedentary behavior. This study aims to validate the POPAI to detect sedentary behavior.
Methods: We recruited 23 participants with knee OA. Participants wore two activity monitors, on the waist and thigh, and were video recorded performing seven activities including: one seated and resting, two seated and active, one standing and resting, two standing and active, and one walking. Each activity lasted three minutes with a one-minute seated rest in between. The POPAI uses body position and energy expenditure from the activity monitors to determine if the participant is performing sedentary behavior, standardized as sitting or lying and <1.5 METs energy expenditure. The POPAI was compared to the graded criterion video using sensitivity and specificity.
Results: 23 participants with knee OA were included (Age 61±10.9 years, 69.5% female, BMI 27.7±4.1 kg/m2, Average Duration of Symptoms 11.6 ± 9.03 years, Bilateral knee OA 61%). To detect sedentary behavior, the POPAI had a sensitivity of 72%, specificity of 96%, and accuracy of 87%. The POPAI’s positive predictive value was 90%, and the negative predictive value was 86%.
Conclusion: These data demonstrate the POPAI is a valid tool for detecting sedentary behavior and can be used when researching sedentary behavior in adults with knee OA.