The association between physical activity, blood pressure and renin in black African teachers : the SABPA study

Abstract

Objectives: The aim of this study was to determine associations between physical activity (PA), blood pressure (BP) and renin in urban black Africans. Methods: The study sample included 137 urban African males (N=68) and females (N=69) (aged 41.53 ± 8.13 and 44.16 ± 7.37 years, respectively), from the North West Province, South Africa. Anthropometric measurements, ambulatory blood pressure and energy expenditure were determined. Actical® accelerometers were used to determine energy expenditure (METS) over a 24 hour period. Fasting blood samples were used to determine fasting blood glucose, serum cotinine (COT), gamma–glutamyl transferase (GGT) and plasma renin. Results: A greater percentage (64%) of African males were hypertensive compared to African females (33.33%). SBP (p<0.001) and DBP (p<0.001) were significantly higher in males than females. Female subjects were more obese (32.00±7.75 kg/m2) whereas males demonstrated an overweight status (27.28±5.86kg/m2). Male subjects displayed overall higher lifestyle risks (BP, smoking, alcohol consumption, HIV–status) than females. Multivariate regression analyses demonstrated an inverse relationship between BP and renin in both males and females, but no associations existed between renin and physical inactivity. Conclusion: PA appeared not to buffer elevated blood pressure in this specific African sample, as no significant associations supported this hypothesis. The results confirm that black Africans display lower renin levels associated with elevated blood pressure. Furthermore, low renin and physical inactivity was not related to indicate elevated BP through elevated SNS activity.