Association between Objectively Determined Physical Activity Levels and Body Composition in 6-8-Year-Old Children from a Black South African Population: BC-IT Study

Physical inactivity in children is a global pandemic in parallel with increasing obesity prevalence. However, studies assessing the association between physical activity (PA) and body composition (BC) report conflicting findings, possibly because of the different methodologies across studies, with objective methods promising reliable results. This study determines the association between objectively determined PA levels and BC in 6–8-year-old children from a black South African population. Ninety-three children aged 6–8 years, who formed part of a larger study on BC using the deuterium dilution method (DDM), were included. Height and weight were measured according to the standard procedures, and body mass index z-score was calculated. Fatness was determined by DDM. An accelerometer was used to measure PA levels. Regression models were performed to determine the relationship between PA and BC. Approximately 23% of the children did not meet the recommended PA guidelines and 27% were overfat. After adjustments were made, more time spent in vigorous PA was significantly associated with lower fat mass (β = −0.25, p = 0.01, 95%CI: −11.08; −1.20) and fat mass % (β = −0.20, p = 0.04, 95%CI: −12.63; −0.18). Participation in high PA, especially of high intensity, was associated with reduced adiposity in children. Behavioural changes such as increasing high intensity PA is strongly recommended for reducing adiposity.

Longitudinal relationships between changes in body composition and changes in selected metabolic risk factors (abdominal obesity and blood pressure) among South African adolescents

BACKGROUND

Incidence of childhood high blood pressure (BP) is increasing worldwide. This study examined the longitudinal relationship between changes in body composition (i.e. body mass index (BMI), waist circumference (WC) and percentage body fat) and selected metabolic risk factors (abdominal obesity and BP) among adolescents from the Tlokwe municipality in the North West Province of South Africa.

METHOD

One hundred and eight-six adolescents (81 boys and 105 girls) aged 14 to 16 years participated in the study. Body composition was measured following the International Society of the Advancement of Kinanthropometry standard procedures. BMI, abdominal obesity using WC measurement, and resting BP were determined. Analysis of variance (ANOVA) for repeated measures was calculated to determine changes in anthropometric measures and body composition as well as changes in BP. Additionally, Univariate analysis of variance with repeated measures and participants as a random sample was applied. Diastolic BP (DBP) and systolic BP (SBP) were used as dependent variables and sex, age, BMI, WC, and waist-to-height ratio as independent variables.

RESULTS

Significant changes were found for stature, BMI, body mass, WC, SBP, and DBP. BMI for the total group was significant and positively related to abdominal obesity in 2012 (r = 0.55; p < 0.01) and in 2013 (r = 0.77; p < 0.01) and to SBP (r = 0.26; p < 0.05) in 2012 and (r = 0.17; p = 0.43) in 2013. BMI among the boys was significantly and positively related to abdominal obesity in 2012 (r = 0.83; p < 0.01) and 2013 (r = 0.91; p < 0.01). For the girls, BMI was significantly and positively related to abdominal obesity (r = 0.49; p < 0.01) and to SBP (r = 0.32; p = 0.05) in 2012. Boys with a higher WC in 2012 had significantly increased DBP (p < 0.05). Boys measured in 2012 with greater WC and BMI show a significant increase in SBP.

CONCLUSIONS

BMI was positively related to BP and abdominal obesity over time. Relatively high BMI and abdominal obesity significantly increased the likelihood of elevated BP over time, especially in boys. BMI was a predictor of abdominal obesity in boys, while in girls, BMI was a predictor of both abdominal obesity and SBP. In view of the future health implications of both abdominal obesity and elevated BP, urgent strategic interventions programs aimed at increasing physical activity and advocating for well-balanced dietary practices as well as importance of keeping normal blood pressure among South African adolescents are needed.

The Exercise, Arterial Modulation and Nutrition in Youth South Africa Study (ExAMIN Youth SA)

Background: The impact of a sedentary and unhealthy lifestyle on cardiovascular health is well-documented, however the current obesity and hypertension trends among children is concerning. The ExAMIN Youth SA study aims to investigate the impact of lifestyle behaviors (physical fitness/activity, dietary intake and psychosocial factors) involved in early vascular aging among South African children. Methods: This study is an analytical, multidisciplinary, observational cohort study in a school-based setting. We aim to phenotype a cohort of ~1,000 primary school children (black and white boys and girls between ages 5-9 years) based on current clinical childhood conditions including hypertension and obesity. The primary phenotype is large artery stiffness and retinal microvascular diameters, both biomarkers of early vascular aging. The risk factors and mediators of early vascular aging and also responsible for the clinical conditions include physical inactivity, unhealthy diet, and life stress. Additionally, urinalysis and salivary analyses will be performed to identify biomarkers related to the pathophysiology of early vascular aging. Discussion: In line with the growing prevalence of obesity and hypertension responsible for the development of early vascular aging from childhood to adulthood, this study will address the critical areas in which we observe unfavorable arterial modulation related to dietary behaviors, physical inactivity, and early life stress. Implementation of novel biological markers may further contribute to our understanding of early cardiovascular adaptations in childhood, and aid in the development of primary prevention programs. Trial registration: The study was retrospectively registered on ClinicalTrials.gov on 15 August 2019 (NCT04056377).

Relationship between obesity and blood pressure among employees in the Vhembe district municipality of Limpopo Province, South Africa

OBJECTIVE

The aim of this study was to investigate the relationship between obesity and blood pressure among employees of the Vhembe district municipality of Limpopo province.

METHODS

A cross-sectional study was conducted among 452 local government employees (207 males, 245 females) aged 24-65 years. Body mass index (BMI), blood pressure (BP) and waist circumference (WC) measurements, and waist-to-height ratio (WHtR) were assessed. Data were analysed using Statistical Package for Social Sciences (SPSS) statistics, version 21.

RESULTS

The results showed that 27% of the participants were classified as overweight and 34% as obese, with females being more overweight and obese (29 and 48%, respectively) compared to males (24 and 17%, respectively). Twenty-five per cent of the participants were hypertensive, with females (27%) showing a higher prevalence compared to males (22%). Based on BMI categories, the obese group (35%) had a higher prevalence of hypertension in contrast to groups that were of normal weight (18%) and overweight (22%). The results also showed that systolic blood pressure (SBP) was positively (p ≤ 0.05) correlated with BMI (r = 0.15), WC (r = 0.26) and WHtR (r = 0.29) in the normal and overweight groups (WC, r = 0.23 and WHtR, r = 0.26), and WHtR correlated with SBP (r = 0.26) and diastolic blood pressure (DBP) (r = 0.19).

CONCLUSIONS

The study showed a high prevalence of overweight, obesity and hypertension, with females more affected than their male counterparts. BMI, WC and WHtR were positively correlated with SBP in the normal and overweight groups, with WHtR positively correlated with both SBP and DBP in the overweight group. Therefore, it is recommended that intervention regimes designed to address obesity and hypertension should consider risk awareness for cardiovascular diseases, impaired quality of life and productivity among local government employees.

The challenges of underweight and overweight in South African children: are we winning or losing the battle? A systematic review

Underweight and overweight are adverse effects of malnutrition and both are associated with negative health consequences in children and adolescents. In South Africa, the burden of economic and social disparity coexists with malnutrition in children. The purpose of this study was to review available South Africa studies regarding the comprehensive summary of prevalence of underweight and overweight and evaluates government policies in addressing undernutrition and overnutrition in South African children and adolescents. We searched subject-specific electronic bibliographic databases of observational studies published on malnutrition, undernutrition, overnutrition, underweight and overweight in South African boys and girls from birth to 20 years of age in studies published on or after 1990. A total of sixteen cross-sectional, three longitudinal studies and one report met the criteria for inclusion in this review. Descriptive data synthesis revealed the small number of longitudinal studies highlights the dearth of research in tracking undernutrition and overnutrition in South African children. In this review, 0.7%-66% of underweight was reported among children in rural areas compared to a 3.1%-32.4% of overweight in urban areas. All studies reported a higher rate of underweight in boys than girls who were significantly more likely to have higher body fat. The data indicated that both underweight and overweight were positively related with health-related physical activity and psychological health problems such as low activity, low fitness, low self-image and self-esteem. Numerous recommendations were made in the reviewed studies, however effective strategic programs in eradicating both underweight and overweight are minimal. It is evident from the reviewed studies that the burden of underweight and overweight are still a problem in South African children. The most highly affected by underweight are rural children, while children in urban areas in transition are faced with burden of overweight. There is little evidence to suggest that government strategic programs are effective in addressing underweight and overweight in South African children. Based on these findings, sustainable school-based feeding schemes and physical education programmes are needed for optimal benefits in children and adolescents.

The association between dyslipidemia and anthropometric indicators in black and white adolescents residing in Tlokwe Municipality, North-West Province, South Africa: the PAHL study

BACKGROUND

The dyslipidemia associated with excess weight is a risk for cardiovascular disease. Worldwide and in South Africa adolescent obesity has been reported.

OBJECTIVES

To determine the association between dyslipidemia and anthropometric indices in black and white adolescents.

METHODS

The study involved 129 black and 69 white adolescents aged 12 to 16 years. Data collected included height, weight, waist circumference (WC) and skinfolds, blood pressure and blood for glucose, insulin, total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (Trig) and C - reactive protein (CRP).

RESULTS

WC correlated negatively with HDL in both blacks (p=0.042) and whites (p=0.008) and in whites it correlated positively with LDL (p=0.006); TC/HDL (p=<0.001) and LDL/HDL ratio (p<0.0001). WC/Hgt correlated negatively with HDL (p=0.028) and positively with LDL/HDL (p=0.026 and p<0.0001) in both races. In whites positive correlations were between WC/Hgt and TC (p=0.049); LDL (p=0.003) and TC/HDL (p<0.0001). BAZ correlated positively with TC/HDL ratio (p=0.004) and LDL/HDL ratio (p=0.002). The most common abnormalities were HDL and LDL.

CONCLUSION

Whites exhibited more associations between dyslipidemia and anthropometric indicators as compared to Blacks, suggesting that there might be differences in the lipid metabolism or even susceptibility to risk factors in adolescents.

The relationship between body composition and physical fitness in 14 year old adolescents residing within the Tlokwe local municipality, South Africa: the PAHL study

Background

Little is known about the relationship between body composition and physical fitness in 14 year-old high school adolescents of South Africa. Baseline data from a longitudinal study on physical activity and health (PAHLS) may provide valuable information for future studies, hence to inform public health policy makers. The objectives of this study are to determine the prevalence of underweight, normal weight and overweight among adolescents aged 14 years in the Tlokwe Local Municipality of the North West Province of South Africa, and to assess the association between physical fitness and body composition separately for boys and girls, adjusted for race and locality.

Methods

Body weight, height and triceps, and subscapular skinfolds of 256 adolescents (100 boys and 156 girls) aged 14 years were measured, and percentage body fat and body mass index (BMI) were calculated. BMI was used to determine underweight, normal weight and overweight based on the standard criterion. Physical fitness was assessed by standing broad jump, bent arm hang and sit-ups according to the EUROFIT fitness standard procedures. Multinomial logistic regression analyses stratified for gender and adjusted for race (black or white), and the locality (urban or township) of the schools were used to analyze the data.

Results

In the total group 35.9% were underweight and 13.7% overweight. Boys were more underweight (44%) than girls (30.7%). The prevalence of overweight was 8% in boys and 17.3% in girls. BMI was strongly (p = 0.01) related with percentage body fat. Strong and significant positive associations between physical fitness and BMI for the underweight girls with high physical fitness scores (OR, 10.69 [95%CI: 2.81-40.73], and overweight girls with high physical fitness scores (OR, 0.11 [95%CI: 0.03-0.50]) were found. Non-significant weaker positive relationship between physical fitness and BMI for the underweight boys with high physical fitness scores (OR, 1.80 [95%CI: 0.63-5.09]), and the overweight boys with high physical fitness scores (OR, 0.18 [95%CI: 0.02-1.78]) were found.

Conclusion

Both underweight and overweight among boys and girls in Tlokwe Local Municipality exist, and their effects on physical fitness performances were also noticed. As such, strategic physical activity, interventions or follow-up studies recognizing this relationship particularly in the overweight adolescents are needed. In addition, authorities in health and education departments dealing with adolescents should make use of this evidence base information in policies development.

Development and tracking of body mass index from preschool age into adolescence in rural South African children: Ellisras Longitudinal Growth and Health Study

The purpose of this observational prospective cohort study was to investigate the development and tracking of body mass index (BMI) of Ellisras rural children from preschool age into late adolescence from the Ellisras Longitudinal Growth and Health Study. Heights and weights of children were measured according to the standard procedures recommended by the International Society for the Advancement of Kinanthropometry twice a year from 1996 to 2003. In total, 2,225 children--550 preschool and 1,675 primary school--aged 3-10 years (birth cohorts 1993 to 1986) were enrolled at baseline in 1996 and followed through out the eight-year periodic surveys. In 2003, 1,771 children--489 preschool and 1,282 primary school--were still in the study. The prevalence of overweight was significantly higher among girls (range 1.6-15.5%) compared to boys (range 0.3-4.9%) from age 9.1 years to 14.9 years. The prevalence of thinness (severe, moderate, and mild) ranged from 7.1% to 53.7% for preschool children and from 8.0% to 47.6% for primary school children. Both preschool and primary school children showed a significant association between the first measurements of BMI and the subsequent measurement which ranged from B=0.2 (95% confidence interval [CI] 0.1-0.4) to B=0.8 (95% CI 0.6-0.9) for preschool and B=0.2 (95% CI 0.1-0.3) to B=0.7 (95% CI 0.6-0.8) for primary children. A significant tracking of BMI during 4-12 years of life was more consistent for preschool children (B=0.6 (95% CI 0.6-0.7) and for primary school children (B=0.6 (95% CI 0.5-0.6). Investigation of nutritional intake and physical activity patterns will shed light on how healthy these children are and their lifestyle.

Habitual physical activity and body composition of black township adolescents residing in the North West Province, South Africa

Objective

It is known that stunting and obesity affect a large proportion of children in the world, and these can be affected by the physical activity levels of the children. In the present study, we evaluated the association between physical activity, physical development and body composition in black adolescent children.

Design

Cross-sectional study.

Setting

Black township schools in the North West Province, South Africa.

Methods

Three-hundred and thirteen grade 8 children were included in the Physical Activity in Youth study. Anthropometric measurements, body composition measures and maturity level as assessed by Tanner stages were determined in these children. In addition, Previous Day Physical Activity Recall questionnaires were administered on the children to record the various activities they undertake daily.

Results

The demographic characteristics of the children showed a high level of homogeneity. A high prevalence of stunting (16.3%) was observed in the children, which was higher in boys than in girls (21.6 vs. 12.3%). Also prevalent was overweight/obesity (8.6%), but this was higher in girls than in boys (13.4 vs. 1.6%). The children also showed a reduction in levels of physical activity with advancement in maturity; furthermore, boys showed a more central form of fat deposition whilst girls showed more gynoid deposition.

Conclusions

The study revealed that physical activity plays a role in determining body composition, and further indicated that physical activity is associated with favourable body composition measures. Children who were more active were likely to have less fat deposits.

Body composition and physical fitness of undernourished South African rural primary school children

OBJECTIVE

The purpose of this study was to determine the relationships between the body composition characteristics, body mass index (BMI), sum of skinfolds (SSF), % body fat (%BF), fat-free mass (FFM) and waist-to-hip ratio (WHR), and nine physical fitness items in undernourished rural primary school children in Ellisras, South Africa.

DESIGN

A cross-sectional study.

SETTING

The study consisted of 462 boys and 393 girls who were aged 7-14 y.

MEASUREMENTS

Five body composition measures were assessed: BMI, SSF, %BF, FFM and WHR. Nine physical fitness test items were assessed: standing long jump, bent arm hang, sit-ups, 10 x 5 m shuttle run, 50 m sprint, 1600 m run, flamingo balance, sit and reach, plate tapping.

RESULTS

BMI was highly correlated with FFM (r = 0.7, P < 0.001). In line with findings from Western countries, regression coefficients (B) showed that children with higher BMI or SSF performed worse in bent arm hang (girls, B = -0.84, P < 0.001, and B = -0.06, P = 0.02, respectively) and in 1600m run (B = 6.68, P < 0.001). BMI was significantly associated with flamingo balance (B = 0.26, P = 0.04). WHR was positively associated with bent arm hang (B = 9.37, P = 0.03), and inversely with sit and reach (B = -7.48, P = 0.01). In contrast, significant relationships were found between BMI and standing long jump (B = 0.74, P = 0.04), sit and reach (B = 0.51, P < 0.001), flamingo balance (B = 0.26, P = 0.04) and plate tapping (B = -19, P = 0.01). SSF was significantly associated with sit and reach (B = 0.04, P = 0.03). Significant inverse associations were found between FFM and bent arm hang (girls, B = -0.06, P = 0.05), 1600 m run (girls, B = -2.33, P = 0.003) and 50 m run (boys, B = -0.11, P = 0.006). FFM was significantly associated with standing long jump (boys, B = 0.99, P < 0.001; girls, B = 0.73, P < 0.001), flamingo balance (B = 0.17, P < 0.001), and with sit and reach (boys, B = 0.59, P = 0.03).

CONCLUSION

In the present study in undernourished children, body composition was significantly related to physical fitness, but not always in the expected direction. It is therefore important to note that in this population, BMI should not be interpreted as a measure of fatness/overweight, but rather as an indicator of muscle mass.