Physical activity and inflammation among young adults in the African-PREDICT study: Comparison of three self-report and objective physical activity measures

We examined cross-sectional associations between physical activity and inflammatory markers among 1202 ethnically diverse South African young adults. Global Physical Activity Questionnaire (GPAQ), Godin Leisure-Time Exercise Questionnaire (GLTEQ) and combined heart rate and accelerometry device (ActiHeart) data were used. Participant blood samples were analysed for C-reactive protein (CRP), Interleukin-6 (IL-6) and Tumor necrosis factor (TNF-α). Associations between physical activity and inflammatory variables were calculated using regression models adjusted for age, sex, ethnicity, socioeconomic status, smoking, alcohol, body mass index and sedentary behaviour. Participants' mean age was 24.5 years (±3.1 years); 52% were female; 50% had black ethnicity; 52% were tertiary educated. Over three quarters (77%) met GPAQ guidelines and 68% were GLTEQ 'Active'. GLTEQ 'active' category participants had lower CRP and IL-6 levels compared to those in the inactive category. Those meeting the WHO GPAQ guidelines had lower CRP levels than those who did not. There was a positive association between meeting guidelines and IL-6 levels, and higher AEE was associated with higher CRP, IL-6 and TNF-α levels. Associations between physical activity and inflammation among young adults varied depending on the measure used, possibly reflecting the different ability of the three measures to distinguish different types and intensities of physical activity.