RT Journal Article SR Electronic T1 Investigating context-specific sedentary behaviours and cardiometabolic health in college-based young adults (CONTEXT-SB): a protocol for a longitudinal observational study JF BMJ Open JO BMJ Open FD British Medical Journal Publishing Group SP e096116 DO 10.1136/bmjopen-2024-096116 VO 14 IS 12 A1 Diana, Jake Christopher A1 Chauntry, Aiden James A1 Cowley, Emma A1 Paterson, Craig A1 Struder, Jeb F A1 Pagan-Lassalle, Patricia A1 Meyer, Michelle L A1 Lin, Feng-Chang A1 Moore, Justin B A1 Hanson, Erik D A1 Stoner, Lee YR 2024 UL http://bmjopen.bmj.com/content/14/12/e096116.abstract AB Background Sedentary behaviour (SB) is detrimental to cardiometabolic disease (CMD) risk, which can begin in young adulthood. To devise effective SB-CMD interventions in young adults, it is important to understand which context-specific SB (CS-SB) are most detrimental for CMD risk, the lifestyle behaviours that cluster with CS-SBs and the socioecological predictors of CS-SB.Methods and analysis This longitudinal observational study will recruit 500 college-aged (18–24 years) individuals. Two laboratory visits will occur, spaced 12 months apart, where a novel composite CMD risk score (eg, arterial stiffness, metabolic and inflammatory biomarkers, heart rate variability and body fat distribution) will be calculated, and questionnaires to measure lifestyle behaviours and levels of the socioecological model will be administered. After each laboratory visit, total SB (activPAL) and CS-SB (television, transportation, academic/occupational, leisure computer, ‘other’; ecological momentary assessment) will be measured across 7 days.Ethics and dissemination This study has received full ethical approval, and participants provide written informed consent. Our hypothesis is that certain CS-SB will show stronger associations with CMD risk, compared with total sedentary behaviour (T-SB), even after accounting for coexisting lifestyle behaviours. We also expect a range of intra-individual, inter-individual and physical environmental socioecological factors will predict CS-SB. Findings addressing both the primary and any secondary research aims will be submitted for publication in a high-impact peer-reviewed journal.