Abstract
Purpose: :
Lack of physical activity (PA) is a well-known risk factor for cardiovascular diseases. Recently, it has been shown that time in sedentary behaviors has deleterious associations with biomarkers of cardio-metabolic health. This study examines the associations of PA and television (TV) viewing time with retinal vascular caliber and explores the differences in this association in 4 racial groups (White, Black, Hispanic and Chinese).
Methods: :
6176 adults aged 45 to 84 years from six U.S. communities were evaluated in the Multi-Ethnic Study of Atherosclerosis, a population-based cross-sectional study. Retinal vascular calibers were measured from digital retinal photographs using a computer-assisted method and summarized into Central Retinal Artery and Vein Equivalents (CRAE and CRVE). Typical weekly time and frequency of intentional PA and TV viewing were assessed using a modified Typical Week Physical Activity Survey.
Results: :
Those in the lowest two quartiles of intentional (MET-mins/week) PA had a wider retinal venular caliber (3.32 µm: p<0.001; and, 1.7 µm: p<0.05 wider respectively) compared to those in the highest quartile of intentional PA; these differences remained significant (p<0.05) after adjustment for age, gender, race, education, smoking, diabetes, hypertension, body mass index, triglycerides, C-Reactive Protein and TV viewing time in all ethnic groups except Blacks. Similar multi-variate analyses showed that those in the highest quartile of TV viewing time had a wider retinal venular caliber (2.21 µm: p<0.05 wider) compared to those in the lowest quartile; this association remained significant (p<0.05), in Whites only following adjustment.
Conclusions: :
Our results show an association of lack of PA and greater TV viewing time with wider retinal venules, independent of other cardiovascular risk factors. Further longitudinal studies are needed to confirm these associations and explore ethnic differences