Cardiorespiratory Fitness and Light-Intensity Physical Activity Are Independently Associated with Reduced Cardiovascular Disease Risk in Urban Black South African Women: A Cross-Sectional Study

Background: Low levels of physical activity, poor cardiorespiratory fitness, and a sedentary lifestyle have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D). Few studies have examined their independent associations in an urban black sub-Saharan African population. Objectives: To examine the independent associations of physical activity, cardiorespiratory fitness, and sedentary time on body composition and cardiometabolic risk factors for CVD and T2D in black South African women. Materials and Methods: A subsample (n = 76; 18–45 years) was recruited, as part of a cross-sectional study. Accelerometry, cardiorespiratory fitness, body composition, insulin sensitivity, serum lipids, and blood pressure were measured. Results: Light- but not moderate- to vigorous intensity physical activity was inversely associated with trunk fat mass (r = −0.25, P = 0.03). Sedentary time was associated with triglyceride (TG) (r = 0.36, P = 0.01) and TG/HDL-C (r = 0.34, P = 0.04), and these relationships were independent of body fat. Cardiorespiratory fitness was inversely associated with body fat % (r = −0.34, P = 0.02), central fat mass (r = −0.31, P = 0.03), visceral adipose tissue (VAT, r = −0.47, P < 0.01), and insulin resistance (HOMA-IR; r = −0.41, P = 0.01). The association between cardiorespiratory fitness and HOMA-IR was independent of body fat and physical activity, but not VAT. Cardiorespiratory fitness was inversely associated with sedentary time (r = −0.31, P = 0.03), but not with any of the physical activity variables (P > 0.05). Conclusion: Both physical activity and cardiorespiratory fitness were associated with reduced total and central fat mass, VAT, and reduced cardiometabolic risk for CVD and T2D. Longitudinal studies are required to confirm whether the promotion of increasing light physical activity, while reducing sedentary time and increasing cardiorespiratory fitness, reduces the risk for obesity, CVD and T2D.