Comparison of leg dominance and fatigue state on lower extremity kinematics during cutting manoeuvres in male soccer players

Soccer is one of the most popular sports played in South Africa and around the world. Soccer is a high intensity, semi-contact sport which is associated with an increased prevalence of injuries, especially to the lower extremities. Central and neuromuscular fatigue is believed to cause changes to kinetic and kinematic patterns of soccer players which may increase the risk for injuries, specifically related to the anterior cruciate ligament (ACL). To investigate the effects of fatigue on knee joint kinematics during the stance phase of a cutting manoeuvre of the dominant and non-dominant legs. A quantitative approach, more specifically, an experimental study design was adopte and a quasi-experimental study design was selected. A ‘within-participants post-test only design’ was used, which is also known as a ‘repeated measures design’ because all participants were ‘repeatedly’ measured under each experimental condition. Due to the non-randomization of the quasi-experimental design, non-probability sampling was utilized to sample the population group for the proposed study. A total of 13 male soccer players volunteered for the study. The participants had the following characteristics (mean ± SD): age 22.15 ± 2.77 years; height 169.64 ± 5.75 cm and weight 64.60 ± 7.04 kg. Non-significant differences within hip joint kinematics were observed between the dominant and non-dominant legs in a non-fatigued state in all three planes of motion (F = 0.61, p = 0.55). Similar kinematic characteristics were observed for the knee joint (F = 1.25, p = 0.48) and the ankle joint (F = 3.33, p = 0.64). Non-significant differences were also observed during the fatigued state in all three planes of motion for the hip joints (F = 8.98, p = 0.72), knee joints (F = 5.21, p = 0.41) and ankle joints (F = 0.21, p = 0.12). Peak vertical forces were however significantly different between the fatigued state compared to the non-fatigued state during the cutting manoeuvre (F = 23.51, p = 0.035), thereby indicating that neuromuscular fatigue may influence landing forces on impact during a directional change. The effect of leg dominance did not have a statistically significant impact on any kinematic measures as well as the interactions between fatigue and non-fatigue trials were also not observed for any of the kinematic parameters. Several initial contact and peak stance–phase lower limb-joint rotations were influenced by fatigue during the execution of the sub-maximal 60° cutting manoeuvre. The main effect of fatigue produced an increase in knee internal rotation and hip abduction and a decrease in peak knee abduction angles compared to non-fatigue, but they were not statistically significant. Significant differences were found between dominant and non-dominant legs as well as between fatigue and non-fatigue with ankle pronation (p=0.007) and ankle external rotation (p=0.033). Knee abduction angle during cutting (p=0.061) also showed an effect even though not statistically significant. The purpose was to examine the combined effects of leg dominance and fatigue on lower-limb biomechanics during a sub-maximal 60° cutting manoeuvre. The conclusion of the present study related to limb dominance was that no statistically significant differences were evident for any of the dependent variables (limb dominance; fatigue state) related to the independent variables (i.e. joint [hip, knee, ankle], contact time, ground reaction however, between-subject fatigue variations that is large enough could negatively impact the biomechanical data comparisons. Future research should target specific locations of fatigue within a general fatigue paradigm and develop standardized tasks to achieve this

Evaluation of a Physical Activity and Multi-Micronutrient Intervention on Cognitive and Academic Performance in South African Primary Schoolchildren

Executive functions (EFs) are essential for optimal academic development. Appropriate nutrition and physical activity (PA) have been shown to facilitate optimal cognitive development. Therefore, this study examined whether a 12-week school-based PA and multi-micronutrient supplementation (MMNS) intervention would improve cognitive and academic performance. A cluster-randomized controlled trial (RCT) was conducted. Children from four schools located in a peri-urban area of South Africa were randomly assigned to (i) PA + MMNS, (ii) PA + placebo, (iii) MMNS or (iv) placebo. Information processing and inhibitory control were measured with a computerized Flanker task. End-of-year results provided insight into academic achievement. Anthropometric measures were used to determine nutritional status. Data were analyzed with linear mixed-models, adjusting for baseline scores, school classes and age; 932 children (458 girls (49.1 completed baseline and post-intervention assessments. Cognitive performance improved among all four groups, with no significant group x time effects. For academic achievement, there was no significant interaction effect between the combined intervention group and placebo. We encourage future studies in this neglected area in order to determine the most optimal design of school-based nutrition and PA programs to enhance overall cognitive performance

Association of accelerometry-based and self-reported physical activity with cardiovascular risk in South African children

The burden of non-communicable diseases is increasing, with risk factors emerging early in life. Physical activity reduces cardiovascular risk, but limited evidence exists for children from lower-income countries and mostly relies on self-reported methods that might be inaccurate and biased. We aimed to compare self-reported and accelerometer-measured physical activity in relation to cardiovascular risk markers in children from underserved communities in South Africa. We analysed cross-sectional data from 594 children aged 8 to 13. Physical activity was measured via accelerometry and the Physical Activity Questionnaire for Older Children (PAQ-C). Correlation analyses and linear regression models examined the relationship between accelerometer-measured and self-reported physical activity and their association with cardiovascular risk markers (body mass index, blood pressure, blood lipid profile and glycated haemoglobin). Results show a positive but weak correlation between PAQ-C scores and accelerometer-measured moderate-to-vigorous physical activity (MVPA). MVPA was inversely associated with body mass index, whilst sedentary behaviour correlated positively with lipid levels. PAQ-C scores were inversely associated with systolic blood pressure. The comparison of self-reported and accelerometer-measured physical activity in children from Gqeberha, South Africa, revealed inconsistencies in their correlation and association with cardiovascular risk markers. Accelerometry provided a more accurate cardiovascular risk estimation than PAQ-C, although associations were weak. Further, longitudinal studies should investigate the predictive power of both methodologies. These findings inform researchers and public health practitioners in the choice of method for physical activity appraisal beyond practical considerations, especially when combined with cardiovascular risk and in lower-income settings. Significance: We explore two widely used methods to assess physical activity levels in children. By comparing both methods, we expose inconsistencies in their correlation and association with cardiovascular risk markers. These data can guide researchers and public health practitioners in the use of one method beyond practical considerations. Whilst this work focuses on children from marginalised areas of South Africa, the issues explored are of relevance to other lower-income settings. Open data set: https://doi.org/10.5281/zenodo.721714

Physical Activity, Sedentary Behaviour, Weight Status, and Body Composition among South African Primary Schoolchildren

Background:; Over the past decades, childhood overweight has increased in many African countries. We examined the relationship between sedentary behaviour, moderate-to-vigorous physical activity (MVPA), and body composition in South African primary schoolchildren living in peri-urban settings.; Methods:; MVPA was measured via 7-day accelerometry and body composition via bioelectrical impedance analysis in 1090 learners (49.2% girls, M; age; = 8.3 ± 1.4 years). The relationships between MVPA and sedentary behaviour with the various body composition indicators (body fat and fat-free mass [total, truncal, arms, and legs], bone mass, muscle mass, and body water) were tested with mixed linear regressions.; Results:; The prevalence of overweight and obesity was 9.8% and 6.6%, respectively; 77.1% of the children engaged in ≥60 min of MVPA/day. Girls were more likely to be overweight/obese, to accumulate less than 60 min of MVPA/day, and had significantly higher relative body fat than boys (; p; s < 0.001). Lower MVPA was associated with a higher likelihood of being overweight/obese, higher relative body fat, and lower relative fat-free mass, bone mass, muscle mass, and body water (; p; s < 0.001). For lower sedentary behaviour, the associations with body composition pointed in the opposite direction.; Conclusions:; In this South African setting, girls are a particularly relevant target group for future physical activity interventions to prevent overweight/obesity-related non-communicable diseases in later life

Associations Between Household Socioeconomic Status, Car Ownership, Physical Activity, and Cardiorespiratory Fitness in South African Primary Schoolchildren Living in Marginalized Communities

Little is known whether physical activity (PA)-promoting environments are equally accessible to children with divergent socioeconomic status (SES) in low-/middle-income countries. The authors, therefore, examined whether South African children from poorer versus wealthier families living in marginalized communities differed in moderate to vigorous PA and cardiorespiratory fitness. We also tested associations between family car ownership and PA/cardiorespiratory fitness.; Parents/guardians of 908 children (49% girls, mean age = 8.3 [1.4] y) completed a survey on household SES. PA was assessed via 7-day accelerometry, parental and child self-reports, and cardiorespiratory fitness with the 20-m shuttle run test.; Based on accelerometry, most children met current moderate to vigorous PA recommendations (≥60 min/d). About 73% of the children did not engage in structured physical education lessons. Whereas children of the lowest SES quintile accumulated higher levels of device-based moderate to vigorous PA, peers from the highest SES quintile engaged in more sedentary behaviors, but self-reported higher engagement in sports, dance, and moving games after school. Families' car ownership was associated with higher parent/self-reported leisure-time PA.; A deeper understanding is needed about why wealthier children are more sedentary, but simultaneously engage in more leisure-time PA. The fact that access to structural physical education is denied to most children is critical and needs to be addressed

Mixed intervention effects and long-term changes in physical activity and cardiovascular outcomes among children at risk of cardiovascular diseases

Objective: Risk factors for chronic diseases such as insufficient physical activity (PA), overweight or hypertension are getting more predominant among children. While school-based interventions are promising preventive strategies, evidence of their long-term effectiveness, especially among vulnerable populations is scarce. KaziKidz is a physical education intervention that promotes healthy and active lifestyles among children from low-income communities (https://www.kazibantu.org/kazikidz/). We aim at assessing the short- and long-term effects of KaziKidz on cardiovascular risk factors in high-risk children from disadvantaged communities. Methods: The intervention was tested in a cluster-randomized controlled trial between January and October 2019 in eight primary schools in South Africa. Children with adverse cardiovascular profiles were defined as presenting at least one risk factor for (1) overweight, (2) elevated blood pressure, (3) glycaemia, and/or (4) cholesterolemia. After their identification, high-risk children were re-assessed 2-years post-intervention. Study outcomes include accelerometry-measured PA (MVPA), body-mass-index (BMI), mean arterial pressure (MAP), glucose (HbA1c), and lipid levels (TC/HDL). We conducted mixed regression analyses to assess intervention effects by cardiovascular risk profile, and Wilcoxon signed-rank tests to evaluate longitudinal changes in the high-risk subpopulation. Results: A significant intervention effect on MVPA during school hours was found for physically inactive children (B: 1.71, 95% CI: 0.14 - 3.35, p-value: 0.008), and among active (B: 1.80, 95% CI: -0.22 - 3.82, p-value: 0.035) and inactive (B: 2.03, 95% CI: 0.58 - 3.42, p-value: < 0.001) girls. In contrast, the intervention lowered HbA1c (B: -0.26, 95% CI: -0.52 - -0.01, p-value: 0.037) and TC/HDL (B: -0.11, 95% CI: 0.18 - -0.05, p-value: 0.002) only in children with normal glucose or lipid values, respectively. The intervention effects were not maintained in at-risk children at follow-up. A decline was observed in MVPA from 53.29 to 41.90 min/day (z = -1.95, p = 0.05, r = 0.26), and an increase in BMI-for-age (z = -0.34, p = 0.737, r = 0.03), MAP (z = -5.18, p < 0.001, r = 0.42), HbA1c (z = -1.63, p = 0.104, r = 0.25) and TC/HDL (z = -1.61, p = 0.11, r = 0.21). Conclusion: We conclude that schools are key settings to promote PA and improve health; however, because the intervention effects were not maintained in children at risk of non-communicable diseases (NCDs), structural changes that ensure effective interventions reach disadvantaged populations are necessary to achieve sustainable impact. Funding: Swiss National Science Foundation (SNSF)

How are academic achievement and inhibitory control associated with physical fitness, soil-transmitted helminth infections, food insecurity and stunting among South African primary schoolchildren?

Cardiovascular fitness has been associated with both executive function and academic achievement in multiple cohort studies including children and adolescents. However, research is scarce among children from low- and middle-income countries. Hence, this paper focuses on South African primary schoolchildren living in marginalized areas and examines if academic achievement and inhibitory control can be explained by children's age, socioeconomic status, soil-transmitted helminth infections, food insecurity, stunting, grip strength, and cardiorespiratory fitness.; The sample of this cross-sectional study consisted of 1277 children (48% girls, mean age: 8.3 years). Data were assessed via questionnaires, stool samples, anthropometric measurements, 20 m shuttle run test, grip strength test, Flanker task, and school grades. Data were analysed with mixed linear regression models with random intercepts for school classes, separately for boys and girls.; Higher socioeconomic status was most closely associated with academic achievement among boys (p < 0.05), whereas higher levels of cardiorespiratory fitness and not being stunted explained most variance in academic achievement in girls (p < 0.05). Higher age turned out to be associated with better performance in the Flanker task (p < 0.01). Additionally, in boys, higher grip strength was associated with better information processing and inhibitory control of attention (p < 0.01), whereas in girls, higher cardiorespiratory fitness levels were positively associated with these cognitive abilities (p < 0.05).; Academic performance has been shown to be compromised in schoolchildren living in marginalised areas, compared to schoolchildren in less disadvantaged parts of South Africa. The present study suggests that cardiorespiratory fitness and grip strength are two potentially modifiable factors that are associated with children's academic achievement and cognitive performance, and that should be targeted in future school-based interventions

Practice Change Needed for the Identification of Pediatric Hypertension in Marginalized Populations: An Example From South Africa

Introduction: Hypertension in children has increased globally over the past 20 years; yet, little is known about this issue among disadvantaged communities from low- and middle-income countries. Age-, sex-, and height-adjusted normative tables are the "gold" standard for the diagnosis and estimation of pediatric hypertension worldwide, but it is unclear whether the use of international standards is appropriate for all contexts. The purpose of this study was to evaluate and compare different international references to identify hypertension among South African school-aged children from disadvantaged communities. Methods: Blood pressure, weight, and height were measured in a cohort of 897 children aged 8-16 years from eight peri-urban schools in the Eastern Cape of South Africa. Cross-sectional prevalence of hypertension was calculated according to American, German, and global normative tables, as well as pseudo-normative data from the own study population. Isolated systolic hypertension and body mass index (BMI) were considered markers for cardiovascular disease. Multinomial logistic regression was used to compare the likelihood of blood pressure categorization with increasing BMI levels. Results: Hypertension prevalence ranged from 11.4% with the pseudo-normative study tables to 28.8% based on the German reference. Global guidelines showed the highest agreement both among international standards (92.5% with American guidelines) and with the study reference (72.5%). While the global and the American references presented higher systolic over diastolic hypertension rates (23.6 vs. 10.6% and 24.2 vs. 14.7%, respectively), the American guidelines predicted the highest increased risk for hypertension stage 2 [odds ratio, 1.72 (95% confidence interval: 1.43-2.07)] with raising levels of BMI. Conclusion: Our results support the heterogeneity of blood pressure estimates found in the South African literature, and highlight the underrepresentation of African children in international guidelines. We call for caution in the use of international standards in different contexts and advocate for the development of normative tables that are representative of the South African pediatric population necessary to ensure an accurate identification of hypertension both from the clinical and epidemiological perspective

Associations between soil-transmitted helminth infections and physical activity, physical fitness, and cardiovascular disease risk in primary schoolchildren from Gqeberha, South Africa.

Background/aimSchool-aged children in low- and middle-income countries carry the highest burden of intestinal helminth infections, such as soil-transmitted helminths (STH). STH infections have been associated with negative consequences for child physical and cognitive development and wellbeing. With the epidemiological transition and rise in cardiovascular disease (CVD), studies have shown that helminth infections may influence glucose metabolism by preventing obesity. Thus, the aim of this study was to determine the association of STH infections in schoolchildren from Gqeberha, focusing on physical activity, physical fitness, and clustered CVD risk score.MethodsThis cross-sectional study involved 680 schoolchildren (356 girls and 324 boys; mean age 8.19 years, SD±1.4) from disadvantaged communities in Gqeberha (formerly, Port Elizabeth), South Africa. Stool samples were collected and examined for STH infections using the Kato-Katz method. Physical activity (accelerometer) and physical fitness (grip strength, 20 m shuttle run) were measured using standard procedures. Furthermore, anthropometry, blood pressure, as well as glycated haemoglobin and lipid profile from capillary blood samples were assessed. We employed one-way ANOVAs to identify the associations of STH infections in terms of species and infection intensity with physical activity, physical fitness, and clustered CVD risk score.ResultsWe found a low STH infection prevalence (7.2%) in our study, with participants infected with at least one intestinal helminth species. In comparison to their non-infected peers, children infected with STH had lower mean grip strength scores, but higher mean VO2max estimation and higher levels of MVPA (p ConclusionsSTH-infected children had lower grip strength scores than their non-infected peers, yet, achieved higher VO2max and MVPA scores. Our study highlights that the type and intensity of STH infection is relevant in understanding the disease burden of STH infections on children's health. The findings of our study must be interpreted cautiously due to the low infection rate, and more research is needed in samples with higher prevalence rates or case-control designs

Physical Activity, Cardiorespiratory Fitness and Clustered Cardiovascular Risk in South African Primary Schoolchildren from Disadvantaged Communities: A Cross-Sectional Study

The coexistence of multiple cardiovascular risk factors has been reported in school-aged children from the age of nine years, but most evidence stems from high-income countries. This cross-sectional study aimed at describing the cardiovascular health risk, physical activity (PA) behavior and cardiorespiratory fitness (CRF) levels of South African primary schoolchildren, and at examining the associations between PA/CRF and a composite measure of cardiovascular risk. Cross-sectional data from 832 primary schoolchildren (grade 1-4) were analyzed. Total cholesterol/HDL ratio, triglycerides, systolic/diastolic blood pressure, body fat, and glycated hemoglobin were assessed as cardiovascular risk markers. Data were analyzed via mixed linear regressions and analyses of covariance. Overall, 24.2% of the participants did not meet current PA standards. Higher CRF/PA were associated with lower body fat and lower clustered cardiovascular risk (; p; < 0.05). When categorizing children into CRF/PA quartiles, a lower clustered cardiovascular risk gradient was found in children with higher CRF (; p; < 0.05) or PA (; p; < 0.05). Our data shows that higher CRF/PA is associated with lower clustered cardiovascular risk already from a young age. Given that clustered cardiovascular risk present during childhood can track into adulthood, we advocate for PA participation and a healthy weight from a young age onwards