Margaret I. Damare, Lauren C. Bates-Fraser, Emma S. Cowley, Erik Hanson, FACSM, Lee Stoner, FACSM. University of North Carolina at Chapel Hill, Chapel Hill, NC.

BACKGROUND: Middle-aged and older adults reportedly engage in high amounts of prolonged sedentary behavior (SB, ≤1.5 METs in seated/reclined posture). Prolonged SB is associated with increased arterial stiffness (AS), a measure of cardiovascular disease (CVD) risk. Current U.S. recommendations for SB interruption are broad, and limited to the adage “sit less, move more.” Thus, the proposed study aims to identify a suitable (feasible and effective) modality (walking or pedaling) for SB interruption in adults ≥45 years at risk for CVD. METHODS: The proposed randomized controlled cross-over trial will recruit 20 participants (male and female ≥45) with ≥2 CVD risk factors. Participants will complete three experimental lab visits, an exit interview, and an ecological momentary assessment (EMA). Each experimental condition will include 2.5 hrs sitting with (WALK, PEDAL) or without (CON) interruptions. During experimental visits, sitting will be interrupted at the midpoint of each hour with 5 mins of standing, and at the end of each hour with 5 mins of walking or pedaling (under-desk elliptical). The primary outcome of the study will be global (carotid-femoral, brachial-femoral, femoral-ankle) pulse wave velocity. Compared to segmental measures of PWV, global-PWV allows for more comprehensive evaluation of impacts that prolonged SB and proposed interruptions may have on CVD risk. The aim will be tested using a time (PRE, POST) by condition (CON, WALK, PEDAL) mixed effects model. ANTICIPATED RESULTS: Findings from this study will identify whether one or both modalities (walking and/or pedaling) effectively mitigate the increase in AS associated with prolonged sitting. Participant feedback (exit interview) and real-time movement behavior (EMA) will provide qualitative information to facilitate development of population-specific recommendations for SB interruption in adults at high risk for CVD.

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