ABSTRACTObjectiveNeck circumference is a simple anthropometric measurement that may be linked to chronic diseases, physical activity, and muscle strength. We sought to verify the association of moderate and vigorous physical activity levels and relative muscle strength with neck circumference in a community in southern Brazil.MethodsWe cross-sectionally analyzed data from 2,488 participants (51% women), aged 20-79 years old from the Study of Health in Pomerode (SHIP-Brazil) conducted in Pomerode, Santa Catarina, Brazil. Increased neck circumference was defined with cutoff points of >39cm for men and >35cm for women. The independent variables were the level of moderate and vigorous physical activity using the short International Physical Activity Questionnaire, and relative muscle strength using the handgrip test and body mass. Univariate and multiple Poisson regression models were used to determine the association between variables (p≤0.05).ResultsThe prevalence of increased neck circumference was 48.2% (60.4% in men, 39.6% in women) and was associated with low relative muscle strength (PR=1.26, 95%CI: 1.17-1.35) in men, insufficient moderate and vigorous physical activity levels (PR=1.23, 95%CI: 1.14-1.32), and relative muscle strength (PR=1.73, 95%CI: 1.61-1.87) in women. After adjusting for covariates, no significant associations were observed between insufficient moderate and vigorous physical activity levels in men (PR=1.02, 95%CI: 0.95-1.07).ConclusionIncreased neck circumference seems to be an important predictor of low moderate and vigorous physical activity and relative strength loss in adults, and more pronounced in women.