We aimed to estimate the associations between substituting 30-min/day of walking or moderate-to-vigorous physical activity (MVPA) for 30 min/day of sitting and cardiovascular risk factors in a South Asian population free of cardiovascular disease. We collected information regarding sitting and physical activity from a representative sample of 6991 participants aged 20 years and above from New Delhi, India and Karachi, Pakistan enrolled in 2010-2011 in the Center for cArdio-metabolic Risk Reduction in South Asia study using the International Physical Activity Questionnaire (short form). We conducted isotemporal substitution analyses using multivariable linear regression models to examine the cross-sectional associations between substituting MVPA and walking for sitting with cardiovascular risk factors. Substituting 30 min/day of MVPA for 30 min/day of sitting was associated with 0.08 mmHg lower diastolic blood pressure (β = -0.08 [- 0.15, - 0.0003]) and 0.13 mg/dl higher high-density lipoprotein cholesterol (β = 0.13 [0.04, 0.22]). Substituting 30 min/day of walking for 30 min/day of sitting was associated with 0.08 kg/m2 lower body mass index (β = -0.08 [- 0.15, - 0.02]), and 0.25 cm lower waist circumference (β = -0.25 [- 0.39, - 0.11]). In conclusion, substituting time engaged in more-active pursuits for time engaged in less-active pursuits was associated with modest but favorable cardiovascular risk factor improvements among South Asians.
Keywords: Cardiovascular risk factor; Isotemporal substitution models; Physical activity; Sitting; South Asia.