Physical Inactivity As a Risk Factor for Cardiovascular Disease in Communities Undergoing Rural to Urban Transition: the THUSA Study

Background: Coronary heart disease (CHD) remains uncommon among South African blacks. Habitual physical activity contributes to the low prevalence of CHD in this population. The aim of this study was to determine the physical activity levels of black South Africans in the North West Province and to assess the relationship between physical activity and the prevalence of risk factors for cardiovascular disease in a cross-sectional study.

Subjects And Methods: Apparently healthy volunteers (n = 946) were recruited from randomly selected sites in the North West Province, South Africa. Measurements were made in community halls. Demographic data, anthropometric measurements and physical activity were determined. Blood pressures were measured, blood was drawn and serum and plasma samples were prepared. Biochemical variables were determined using standardised methodology.

Results: Men were significantly more active than women, with mean physical activity index (PAI) scores of 3.66 +/- 1.78 and 2.75 +/- 1.04 respectively (P = 0.0001). Subjects in the deep rural areas were more inactive than more urbanized subjects. With multivariate tests in men, no statistically significant differences in CHD risk could be found with increasing physical activity, except for fasting insulin, which was significantly lower in the moderately active group than in the inactive group. In women, the most active group had a significantly higher mean high-density lipoprotein (HDL)-cholesterol concentration than the most inactive group and also a significantly lower mean triglyceride concentration. The most active group of women also had a significantly higher mean fasting serum glucose than the less active group. Among both men and women, inactive overweight subjects had the highest mean systolic blood pressure, total serum cholesterol and low-density lipoprotein (LDL)-cholesterol.

Conclusions: In men, only fasting serum insulin was significantly associated with physical inactivity, but in woman, a number of cardiovascular disease risk factors were significantly associated with physical inactivity especially in overweight subjects.