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- Background A limited number of studies have researched the associations between conventional cardiovascular disease (CVD) risk factors and arterial stiffness in children. Objectives To explore the associations between specific conventional CVD risk factors and arterial stiffness in black South African (SA) children. Methods This cross-sectional study included 59 children (male:17; female:42). The mean age (and associated standard deviation) of the participants was 11.15 (1.40) years. Conventional CVD risk factors included body mass index (BMI), waist circumference (WC), hip circumference, systolic blood pressure (SBP), resting heart rate (RHR), peak oxygen consumption (VO2peak) and physical activity. Pearson’s correlation was used to measure associations between arterial stiffness, expressed as the stiffness index (SI), and CVD risk factors. Hierarchical multiple regression analysis adjusting for age was performed to identify associations between the independent variables (VO2peak, SBP, BMI, physical activity, RHR and WC) and the dependent variable (SI). Results Arterial stiffness was found to be significantly positively correlated with age (r=0.52; p=0.03) and significantly negatively correlated with VO2 peak (r= –0.53; p=0.03) in male participants. Following regression analysis, the association with age (r2=0.27; p=0.03) and SI remained significantly independent. When means were combined across the two gender groups, age (r=0.27; p=0.04) and RHR (r=0.26; p=0.05) were found to be significantly positively correlated with SI. Following regression analysis, both age (r2=0.07; p=0.04) and RHR (r2=0.15; p=0.02) remained significantly independently associated with SI. Conclusion Age and RHR appear to be strong predictors of arterial stiffness in black SA children.
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- Background Obesity is currently one of the most dominating diseases affecting younger adults in South Africa. This is commonly caused by a poor lifestyle, which may lead to an increased risk of non-communicable diseases. Objectives The aim of the study was to examine if a six-week concurrent resistance and aerobic training program could elicit body composition and cardiorespiratory changes in rural black college women. Methods Forty sedentary black females (aged 18 - 25 years) were randomly assigned to a combined resistance and aerobic training (COM) group (n = 20) or a control group (n = 20). The COM group participated in four times weekly aerobic and resistance training. Aerobic training consisted of 30 minutes a session (week 1 - 3: cycling for 3 minutes at 60% heart rate reserve (HRR), followed by 2 minutes at 50% HRR; week 4 - 6: 3 minutes at 70% HRR, followed by 2 minutes at 60% HRR). Resistance training consisted of participants training at 50% of their one-repetition maximum (1-RM) for week 1 - 3, doing 3 sets of 15 repetitions; for week 4 - 6 at 60% 1-RM, doing 3 sets of 15 repetitions. Results Following the intervention, the COM group significantly (P ≤ 0.05) decreased their body fat percentage when compared to the control group (P = 0.006; d = 0.9), while no significant changes were observed in waist-to-hip ratio (P = 0.223) and cardiorespiratory endurance (P = 0.260) in either group. Conclusions Although body composition (especially waist circumference and body fat percentage) and cardiorespiratory fitness are recommended as the main targets of physical activity programs aimed at preventing CVD in college students, this study demonstrated that a six-week concurrent program improved body fat percentage, and not WHR and cardiorespiratory fitness, in sedentary rural college-aged females. Further, these findings suggest that one method of program design does not fit all populations and that exercise prescription should be targeted and not generalized.
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