Abstract P119: Isotemporal Substitution Modeling of Daily Physical Activity Intensity and Cardiometabolic Diseases Among South Asians: The Centre for Cardiometabolic Risk Reduction in South-Asia (CARRS) Study
Authors: Wei Jingkai , Anjana Ranjit Mohan , Kowalski Alysse , Goenka Shifalika , Shivashankar Roopa , Kadir Masood , Prabhakaran Dorairaj , Tandon Nikhil , Lobelo Felipe , Narayan KM Venkat , Ali Mohammed K 
Published: March 2022

Objective:
Several studies have shown that engaging in moderate-to-vigorous physical activity (MVPA) and avoiding prolonged sedentary time leads to beneficial effects on cardiometabolic disease risk. However, the associations between physical activity (PA) intensity and cardiometabolic risk have not been examined in population-based studies in South Asian populations.

Hypothesis:
We hypothesize that substituting sedentary time for MVPA will be associated with reduced cardiometabolic risks in South Asians.

Methods:
Cross-sectional data of 6,428 participants aged from 30 to 59 years (53.2% female) from New Delhi, India and Karachi, Pakistan that were enrolled in the CARRS Cohort study in 2010-11 were analyzed. We used the International Physical Activity Questionnaire (IPAQ, short form) culturally adapted to South Asian context, to classify respondent’s activities as sedentary, light activity (walking), and MVPA. We examined associations between time spent at different PA intensities and cardiometabolic diseases (defined as heart disease (including heart attack, angina and heart failure), stroke or Type 2 diabetes). Relevant risk factors (body weight, HDL-C and HbA1c) were examined using isotemporal substitution models, which drops one of three PA intensities and adjusts for total time of PA and covariates (i.e. outcome=PA 1+ PA 2 + total time for PA + covariates). Linear regression models were used to examine the associations between different PA intensities with risk factors of cardiometabolic diseases, and logistic regression models were used to examine the association between different types of PA intensities and prevalence of cardiometabolic diseases, adjusted for age, sex, sleep duration, status of depression, hypertension, hyperlipidemia and chronic kidney disease.

Results:
Isotemporal substitution models showed that replacing 1-hour/day sedentary time with a similar amount of MVPA at the population level was associated with 0.35 kilograms lower in body weight (95% CI: -0.50, -0.20, p<0.0001), 0.02% lower in HbA1c (95% CI: -0.04, -0. 003, p=0.02) and 0.20 mg/dl higher level in HDL-C (95% CI: 0.08, 0.32, p=0.003). Replacing 1-hour sedentary time with a similar amount of MVPA was associated with a lower prevalence of cardio-metabolic diseases (POR=0.95, 95% CI=0.91 to 0.98, p=0.01), while replacing 1-hour MVPA with an amount of sedentary time was associated with a higher prevalence of cardiometabolic diseases (POR=1.06, 95% CI=1.02 to 1.10, p=0.01).

Conclusion:
Substituting sedentary time with MVPA was associated with favorable cardiometabolic health, while time spent sedentary may be detrimental to cardiometabolic health among young and middle-aged South Asians. Future intervetions aiming at promoting increases in MVPA and reductions in sedentary time may show benefits in terms of preventing cardiometabolic diseases in South Asia.