Prevalence and Determinants of Undernutrition in Schoolchildren in the Kilombero District, South-Eastern Tanzania.

Childhood undernutrition is a major issue in low- and middle-income countries, affecting the health, well-being, and educational outcomes of schoolchildren. This study aimed to assess the prevalence and associated factors of stunting, wasting, and underweight among schoolchildren in peri-urban areas in the south-eastern part of Tanzania. A cross-sectional study was conducted involving 930 children aged 6-12 years from four primary schools from July to August 2019. The WHO Anthro Survey Analyzer was employed to estimate the prevalence of stunting, wasting, and underweight, while logistic regression analyses examined sociodemographic background, malaria infection, anaemia, anthropometric measures, and dietary diversity score as potential factors. The prevalence of stunting, wasting, underweight, overweight, and obesity was 11.8%, 4.3%, 3.9%, 11.1%, and 2.0%, respectively. Overall, 1.5% of the children had malaria, as determined by rapid diagnostic tests, and 0.4% had severe anaemia. Univariate analysis indicated higher odds of undernutrition among children aged 9-12 compared to their younger peers. Stunting was more common among children with low and medium dietary diversity. Anaemia was found in 11.2% of schoolchildren, and severe anaemia was associated with wasting. Multivariate analysis revealed that age and low dietary diversity were significantly associated with undernutrition. These findings emphasise the need for school-based health and nutrition programmes targeting children beyond the age of 5 to improve their nutritional status and mitigate potential adverse effects on health, cognition, and academic achievement. Regular assessment of the nutritional status of schoolchildren is warranted.

Randomized Trial to Improve Body Composition and Micronutrient Status Among South African Children.

INTRODUCTION: Physical activity (PA) promotion combined with multimicronutrient supplementation (MMNS) among school-age children may reduce fat mass accrual and increase muscle mass through different mechanisms and so benefit child health. This study determined the efficacy of combined interventions on body composition among South African schoolchildren and determined if micronutrients mediate these effects. STUDY DESIGN: Longitudinal cluster randomized controlled trial of children followed from 2019 to 2021. Statistical analyses carried from 2022 to 2023. SETTING/PARTICIPANTS: A total of 1,304 children 6-12 years of age recruited from public schools in Gqeberha, South Africa. INTERVENTION: Children were randomized by classes to either: (a) a physical activity group (PA); (b) a MMNS group; (c) a physical activity + multimicronutrient supplementation group (PA + MMNS); and (d) a placebo control group. MAIN OUTCOME MEASURES: Trajectories of overall and truncal fat free mass (FFM) and fat mass (FM) estimates in modeled at 9 and 21 months using latent growth curve models (LGCM). Changes in micronutrient concentrations at 9 months from baseline. RESULTS: An increased FFM trajectory was found among children in the MMNS arm at 9 months (Beta 0.16, 95% CI = 0.12, 0.31). The PA and MMNS arms both had positive indirect effects on this trajectory at 9 months (Beta 0.66, 95% CI = 0.44, 0.88 and Beta 0.32 95% CI = 0.1 0.5, respectively) and similarly at 21 months when mediated by zinc concentration changes. A reduced FM trajectory was found among children in the PA promotion arm at 9 months when using this collection point as the referent intercept. This arm was inversely associated with the FM trajectory at 9 months when mediated by zinc changes. CONCLUSIONS: PA and MMNS promotion in school-based interventions directly contributed to reductions in FM and increased FFM among South African children and indirectly through changes in micronutrient status. TRIAL REGISTRATION: ISRCTN, ISRCTN29534081. Registered on August 9, 2018 Institutional review board: Ethikkommission Nordwest- und Zentralschweiz" (EKNZ, project number: Req-2018-00608). Date of approval: 2018.

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

BACKGROUND/AIM: School-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. METHODS: This 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. RESULTS: We 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 < .001). When considering type and intensity of infection, a positive association of A. lumbricoides infection and MVPA was found. In contrast, light T. trichiura-infected children had significantly lower grip strength scores compared to non and heavily-infected children. VO2max and MVPA were positively associated with light T. trichiura infection. No significant association between the clustered CVD risk score and infection with any STH species was evident. CONCLUSIONS: STH-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.

"What If Others Think I Look Like " The Moderating Role of Social Physique Anxiety and Sex in the Relationship between Physical Activity and Life Satisfaction in Swiss Adolescents.

BACKGROUND: Physical activity has been shown to have a positive effect on life satisfaction in adolescents. Despite these benefits, physical activity levels constantly drop during adolescence, suggesting potential interfering factors in this link. Since worries about physical appearance are an important issue at this age, this study aims to examine the relationship between physical activity and life satisfaction in adolescents and explores possible moderating effects of social physique anxiety and sex. METHODS: We used data from a longitudinal study with N = 864 vocational students (mean age = 17.87 years, range: 16-25, 43% female) from Switzerland. To test our hypotheses, we used multiple hierarchical regression analyses as well as simple slope analyses. RESULTS: We did not find a significant direct effect of physical activity on life satisfaction. However, we found a significant two-way interaction between physical activity and social physique anxiety. An additional significant three-way interaction occurred, indicating that a positive effect of physical activity on life satisfaction holds only for female adolescents with low social physique anxiety levels. CONCLUSIONS: This study highlights the importance of developing a healthy relationship with one's body to fully benefit from physical activity, especially for female adolescents. Taken together, these results reveal important considerations for physical activity educators.

Dietary diversity in primary schoolchildren of south-central Côte d'Ivoire and risk factors for non-communicable diseases.

BACKGROUND: A balanced nutrition is important for children's physical and cognitive development; yet, remains a challenge in many parts of low- and middle-income countries (LMICs). Early detection of nutritional deficiency and metabolic syndrome in school-aged children is necessary to prevent non-communicable diseases (NCDs) in later life. This study aimed at obtaining baseline data on health, nutritional status, and metabolic markers of NCDs among primary schoolchildren in Côte d'Ivoire. METHODS: A cross-sectional survey was conducted among 620 children from 8 public primary schools located in the south-central part of Côte d'Ivoire. Underweight and overweight were defined as a body mass index (BMI; kg/m2) < 5th and 85th up to 95th percentile for sex and age, respectively. Dietary diversity of children was calculated based on a 24-hour recall conducted with the primary caretaker according to the guideline of Food and Agriculture Organization. Anaemia, malaria, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and blood glucose levels (HbA1c) were assessed, using capillary blood samples. Logistic models were performed to identify risk factors associated with overweight, HDL-C, LDL-C, and HbA1c. RESULTS: Among the 620 children (330 girls, 290 boys; Mage 8.0 (± 1.7) years), 530 children attended school in a semi-urban and 90 in a rural area. Around 60% of children had a medium dietary diversity score (DDS). Children in peri-urban areas consumed more cereals (80.2% vs. 63.3%, p < 0.05). Most children were normal weight (n = 496), whereas 3.9% of children classified as prediabetic, 5% were underweight, and 15% overweight. LDL-C and HDL-C levels of children were associated with age, high DDS, and moderate anaemia. A significant association was found between prediabetes and malaria infection, as well as medium and high DDS. Overweight was associated with malaria infection and moderate anaemia. CONCLUSION: Overweight, prediabetes, low HDL-C, malaria, and anaemia are the main concerns of children's health in Taabo. Our findings highlight interactions between infectious diseases, particularly malaria, and NCD risk factors. Monitoring NCD risk and infectious disease comorbidity in LMIC paediatric populations simultaneously is essential to better understand the dual diseases burden and apply early prevention measures.

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, Mage = 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 (ps < 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 (ps < 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.

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%), Mage (mean age) = 8.42 ± 1.94 years) completed baseline and post-intervention assessments. Cognitive performance improved among all four groups, with no significant group × 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.

Is grip strength linked to body composition and cardiovascular risk markers in primary schoolchildren? Cross-sectional data from three African countries.

OBJECTIVES: Muscular strength represents a specific component of health-related fitness. Hand grip strength (HGS) is used as an indicator for musculoskeletal fitness in children. HGS can also be used as a marker of cardiometabolic risk, but most available HGS data are derived from Western high-income countries. Therefore, this study examines whether HGS is associated with body composition and markers of cardiovascular risk in children from three sub-Saharan African countries. DESIGN: Cross-sectional study. SETTING: Public primary schools (grade 1-4) in Taabo (Côte d'Ivoire), Gqeberha (South Africa) and Ifakara (Tanzania). PARTICIPANTS: Data from 467 children from Côte d'Ivoire (210 boys, 257 girls), 864 children from South Africa (429 boys, 435 girls) and 695 children from Tanzania (334 boys, 361 girls) were analysed. PRIMARY AND SECONDARY OUTCOME MEASURES: Body composition (assessed via bioelectrical impedance analysis) was the primary outcome. Cardiovascular risk markers were considered as secondary outcome. Blood pressure was measured with an oscillometric monitor, and blood markers (cholesterol, triglycerides, glycated haemoglobin) via Afinion point-of-care testing. HGS (independent variable) was assessed with a hydraulic hand dynamometer. Inferential statistics are based on mixed linear regressions and analyses of covariance. RESULTS: Across all study sites, higher HGS was associated with lower body fat, higher muscle mass and higher fat-free mass (p<0.001, 3.9%-10.0% explained variance), both in boys and girls. No consistent association was found between HGS and cardiovascular risk markers. CONCLUSIONS: HGS assessment is popular due to its simplicity, feasibility, practical utility and high reliability of measurements. This is one of the first HGS studies with children from sub-Saharan Africa. There is a great need for further studies to examine whether our findings can be replicated, to develop reference values for African children, to establish links to other health outcomes, and to explore whether HGS is associated with later development of cardiovascular risk markers. TRIAL REGISTRATION NUMBER: ISRCTN29534081.

Understanding Sleep-Wake Behavior in Late Chronotype Adolescents: The Role of Circadian Phase, Sleep Timing, and Sleep Propensity.

Background: Adolescents with a late chronotype are at greater risk for mood disorders, risk-taking behaviors, school absenteeism, and lower academic achievement. As there are multiple causes for late chronotype, the field lacks studies on the relationship between mood, circadian phase, and phase angle of entrainment in late chronotype adolescents. Three objectives guide this explorative study: (1) to describe sleep, circadian phase, and phase angle of entrainment in late chronotype adolescents, (2) to explore how different levels of lateness are associated with sleep quality, sleep propensity, and mood, and (3) to investigate the influence of circadian phase on bedtime choice and sleep duration. Methods: Baseline data from 19 male adolescents (M = 16.4 ± 1.0 yrs), who were part of a larger intervention trial, were analyzed. Chronotype was measured with the Munich Chronotype Questionnaire, circadian timing via dim light melatonin onset (DLMO), and sleep habits with a 7-day sleep log. Further questionnaires assessed daytime sleepiness, sleep quality, and mood. Evening sleepiness and sustained attention were used as a proxy for evening sleep propensity. Results: On school nights, sleep duration averaged 7.78 h (±1.65), and 9.00 h (±1.42) on weekend nights. Mean DLMO was observed at 23.13 h (± 1.65), with a weekend phase angle of entrainment of 2.48 h. Regression fittings revealed a tendency for shorter phase angles with delayed DLMOs. Further analysis with chronotype subgroups revealed that this was only true for light and moderate late types, whereas extreme late types showed wide phase angles. Even though daytime sleepiness and sleep duration did not differ between subgroups, mood and sleep quality declined as lateness increased. Extreme late chronotypes experienced higher evening sleepiness, while slight late chronotypes showed higher evening attention. Chronotype but not DLMO predicted bedtime on school- and particularly weekend-nights. Conclusions: Our findings suggest that with increasing lateness, the likelihood of experiencing poor sleep quality and mood disorders increases. As DLMO did not predict bedtime, our data indicate that the factors contributing to a late chronotype are versatile and complex, particularly for extreme late types. Further studies involving a larger and gender-balanced sample are needed to confirm findings.

Impact of a school-based health intervention program on body composition among South African primary schoolchildren: results from the KaziAfya cluster-randomized controlled trial.

BACKGROUND: The prevalence of overweight and obesity is increasing among African children potentially predisposing them to greater obesity and non-communicable diseases (NCDs) in adulthood. This risk may be higher among growth-impaired children who may have greater fat mass. Therefore, we examined the effects of school-based physical activity (PA) promotion and multi-micronutrient supplementation (MMNS) on body composition among South African children enrolled in a longitudinal school-based randomized controlled trial. METHODS: Children were cluster-randomized by class to one of four groups: (a) a physical activity group (PA), (b) a multi-micronutrient supplementation group (MMNS), (c) a physical activity + multi-micronutrient supplementation group (PA + MMNS), and (d) control group, and were being followed for 3 years. Linear random effects regression models with random intercepts for school classes tested the associations of each intervention arm with overall fat mass (FM), fat-free mass (FFM), truncal fat mass (TrFM), and truncal fat-free mass (TrFFM) at 9 months (T2) for boys and girls. These differences were then explored among children who differed in height velocity (HV). RESULTS: A total of 1304 children (614 girls, 667 boys) in twelve clusters were assessed at baseline and after 9 months follow-up (T2). At baseline, approximately 15% of children were classified as overweight or obese while approximately 38% of children were classified as mildly stunted or moderately/severely stunted. Among girls, promotion of PA was associated with reduced FM and TrFM at T2 while MMNS was associated with increased FFM. Children with reduced HV in the PA arm had reduced FM while children in the MMNS arm with lower HV had increased FM compared to children in the control arm. Similarly, children with lower HV in the MM and PA groups had reduced TrFM compared to children in the control arm. CONCLUSIONS: Our study suggests that the promotion of school-based physical activity programs and micronutrient supplementation can reduce childhood adiposity and so reduce the risk of obesity and chronic diseases later in adulthood. TRIAL REGISTRATION: ISRCTN, ISRCTN29534081 . Registered on August 9, 2018. The trial was designed, analyzed, and interpreted based on the CONSORT protocol (Additional file 1: CONSORT checklist for randomized trial).

Low-intensity scheduled morning exercise for adolescents with a late chronotype: a novel treatment to advance circadian phase?

Study Objectives: During adolescence, an interplay between biological and environmental factors leads to constrained sleep duration and timing. The high prevalence of sleep deprivation during this developmental period is a public health concern, given the value of restorative sleep for mental, emotional, and physical health. One of the primary contributing factors is the normative delay of the circadian rhythm. Therefore, the present study aimed to evaluate the effect of a gradually advanced morning exercise schedule (30 min shift each day) completed for 45 min on 5 consecutive mornings, on the circadian phase and daytime functioning of adolescents with a late chronotype, compared with a sedentary control group. Methods: A total of 18 physically inactive male adolescents aged 15-18 years spent 6 nights at the sleep laboratory. The morning procedure included either 45 min walking on a treadmill or sedentary activities in dim light. Saliva dim light melatonin onset, evening sleepiness, and daytime functioning were assessed during the first and last night of laboratory attendance. Results: The morning exercise group had a significantly advanced (earlier) circadian phase (27.5 min ± 32.0), while sedentary activity resulted in a phase delay (-34.3 min ± 53.2). Morning exercise also led to higher evening sleepiness in the earlier hours of the night, but not at bedtime. Mood measures improved slightly in both study conditions. Conclusions: These findings highlight the phase-advancing effect of low-intensity morning exercise among this population. Future studies are needed to test the transference of these laboratory findings to adolescents' real life.

Moderate-to-Vigorous Physical Activity Is Associated With Cardiorespiratory Fitness Among Primary Schoolchildren Living in Côte d'Ivoire, South Africa, and Tanzania.

Background: Physical inactivity and low cardiorespiratory fitness (CRF) are independent cardiovascular risk factors among children, but have rarely been investigated concurrently in sub-Saharan Africa. The purpose of this study was to compare physical activity (PA) and CRF of primary schoolchildren living in Côte d'Ivoire (CI), South Africa (ZA), and Tanzania (TZ), to test sex- and age-related differences, and to examine whether PA and CRF are associated with each other. Methods: Baseline data from an ongoing cluster-randomized controlled trial were used, including 499 children from CI (Taabo, 49% girls, M = 8.0 ± 1.6 years), 1,074 children from ZA (Gqeberha, 49% girls, M = 8.3 ± 1.4 years), and 593 children from TZ (Ifakara, 51% girls, M = 9.4 ± 1.7 years). PA was assessed by accelerometry and CRF by a 20 m shuttle-run test. The data were analyzed using multi-/univariate analyses of variance and mixed linear models. Results: Most children met recommendations put forward by the World Health Organization for moderate-to-vigorous PA (MVPA) and achieved high CRF scores. In CI, 89.6% of the children met MVPA recommendations (boys: 91.7%, girls: 87.4%), whereas this rate was 76.9% in ZA (boys: 91.0%, girls: 62.4%), and 93.8% in TZ (boys: 95.5%, girls: 92.0%). Children from TZ had the highest CRF and MVPA levels, followed by children from CI and ZA. Boys had higher MVPA levels than girls, whereas girls engaged in more sedentary behavior. Sex differences were strongest in ZA. Sedentary behavior and MVPA were higher among older schoolchildren compared to their younger peers. Higher MVPA, but not sedentary behavior, was associated with better CRF. Conclusions: In all three settings, higher levels of MVPA were associated with higher CRF scores. Nevertheless, children living in the most urbanized setting (such as observed in ZA) were physically less active and had lower CRF than peers living in more rural areas (such as observed in CI and TZ). Particularly for girls, urbanization might increase the risk for insufficient MVPA, which may have negative effects on their CRF, thus negatively influencing health and well-being at later age.

Associations of Growth Impairment and Body Composition among South African School-Aged Children Enrolled in the KaziAfya Project.

(1) Background: Early childhood malnutrition may result in increased fat mass (FM) among school-aged children in low- and middle-income countries (LMICs). We explored whether South African children with shorter stature have greater overall and abdominal FM compared to normal stature children. (2) Methods: Baseline assessments of body composition and weight were determined among school-aged children enrolled in a randomized controlled trial in Port Elizabeth, South Africa, using bioelectrical impedance analysis. Multiple linear regression models tested associations of children's height and degree of stunting with FM, fat free mass (FFM), truncal fat mass (TrFM), and truncal fat free mass (TrFFM) overall and by sex. (3) Results: A total of 1287 children (619 girls, 668 boys) were assessed at baseline. Reduced child height was associated with higher FM and lower FFM and TrFFM, but these associations were reversed with increases in height. Girls classified as mildly or moderately/severely stunted had higher FM and TrFM but lower FFM and TrFFM, while no association was found for boys. (4) Conclusions: Our study suggests that efforts to reduce the non-communicable disease burden in LMICs should target growth-impaired children who may have greater overall FM and greater abdominal FM.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Prevalence of Stunting and Relationship between Stunting and Associated Risk Factors with Academic Achievement and Cognitive Function: A Cross-Sectional Study with South African Primary School Children.

Childhood stunting can have negative long-term consequences on cognitive development, academic achievement, and economic productivity later in life. We determined the prevalence of stunting and examined whether stunting and associated risk factors (low dietary diversity, insufficient hemoglobin, food insecurity, and soil-transmitted helminth (STH) infections) are associated with academic achievement and cognitive function among South African children living in marginalized communities. A cross-sectional sample of 1277 children (aged 5-12 years) was analyzed. Stunting was defined according to 2007 WHO growth references. Cognitive functioning was measured with the computerized Flanker task and academic performance via school grades. Blood and stool samples were collected to obtain hemoglobin level and STH infection. Dietary diversity was assessed by a food frequency questionnaire. Associations were examined via mixed linear regression (with school class as a random intercept). Nine percent of the children were stunted (95% CI: 7.6-10.8%). Low dietary diversity (ß = 0.13, p = 0.004), food insecurity (ß = -0.12, p = 0.034), and stunting (ß = -0.13, p = 0.031) were associated with poorer end of the year results among girls. No such associations were found among boys. No significant associations were found for socioeconomic status and hemoglobin levels. The prevalence of stunting and STH infections were low in the present sample. Risk factors seem differently associated with girls' and boys' academic achievement. Promoting nutrition may help to promote academic achievement among girls living in low- and middle-income countries.

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.

Effects of school-based physical activity and multi-micronutrient supplementation intervention on growth, health and well-being of schoolchildren in three African countries: the KaziAfya cluster randomised controlled trial protocol with a 2 × 2 factorial design.

BACKGROUND: In low- and middle-income countries, infectious diseases remain a key public health issue. Additionally, non-communicable diseases are a rapidly growing public health problem that impose a considerable burden on population health. One way to address this dual disease burden, is to incorporate (lifestyle) health promotion measures within the education sector. In the planned study, we will (i) assess and compare physical activity, physical fitness, micronutrient status, body composition, infections with soil-transmitted helminths, Schistosoma mansoni, malaria, inflammatory and cardiovascular health risk markers, cognitive function, health-related quality of life, and sleep in schoolchildren in Côte d'Ivoire, South Africa and Tanzania. We will (ii) determine the bi- and multivariate associations between these variables and (iii) examine the effects of a school-based health intervention that consists of physical activity, multi-micronutrient supplementation, or both. METHODS: Assuming that no interaction occurs between the two interventions (physical activity and multi-micronutrient supplementation), the study is designed as a cluster-randomised, placebo-controlled trial with a 2 × 2 factorial design. Data will be obtained at three time points: at baseline and at 9 months and 21 months after the baseline assessment. In each country, 1320 primary schoolchildren from grades 1-4 will be recruited. In each school, classes will be randomly assigned to one of four interventions: (i) physical activity; (ii) multi-micronutrient supplementation; (iii) physical activity plus multi-micronutrient supplementation; and (iv) no intervention, which will serve as the control. A placebo product will be given to all children who do not receive multi-micronutrient supplementation. After obtaining written informed consent from the parents/guardians, the children will be subjected to anthropometric, clinical, parasitological and physiological assessments. Additionally, fitness tests will be performed, and children will be invited to wear an accelerometer device for 7 days to objectively assess their physical activity. Children infected with S. mansoni and soil-transmitted helminths will receive deworming drugs according to national policies. Health and nutrition education will be provided to the whole study population independently of the study arm allocation. DISCUSSION: The study builds on the experience and lessons of a previous study conducted in South Africa. It involves three African countries with different social-ecological contexts to investigate whether results are generalisable across the continent. TRIAL REGISTRATION: The study was registered on August 9, 2018, with ISRCTN. https://doi.org/10.1186/ISRCTN29534081.

Adolescents' personal beliefs about sufficient physical activity are more closely related to sleep and psychological functioning than self-reported physical activity: A prospective study.

BACKGROUND: Preliminary evidence among adults suggests that the ways in which individuals think about their physical activity (PA) behavior is more closely associated with their well-being than self-reported PA. This study therefore aimed to examine whether and how self-reported PA and personal beliefs about sufficient PA are associated with sleep and psychological functioning in a sample of Swiss adolescents, using both cross-sectional and prospective data. METHODS: An overall sample of 864 vocational students (368 girls, 17.98 ±â€¯1.36 years, mean ±â€¯SD) was followed prospectively over a 10-month period. At each measurement occasion, participants filled in a series of self-report questionnaires to assess their PA levels, their personal beliefs about whether or not they engage in sufficient PA, sleep (insomnia symptoms, sleep quality, sleep-onset latency, and number of awakenings), and psychological functioning (depressive symptoms, quality of life, perceived stress, and mental toughness). RESULTS: Adolescents who believe that they are sufficiently physically active to maintain good health reported more restoring sleep. No differences in sleep were found between adolescents who meet PA recommendations vs. those who do not. Additionally, adolescents who believe that they were sufficiently physically active also reported better psychological functioning. This close relationship between adolescents' beliefs about their PA involvement and their sleep and psychological functioning was corroborated in the prospective analyses. CONCLUSION: Cognitive factors should be studied more intensively when elucidating the relationship among PA, sleep, and psychological functioning in young people, particularly when aiming to develop new exercise interventions targeting psychological outcomes.

Sleep Interventions Designed to Improve Athletic Performance and Recovery: A Systematic Review of Current Approaches.

BACKGROUND: Athletes experience various situations and conditions that can interfere with their sleep, which is crucial for optimal psychological and physiological recovery as well as subsequent performance. Conventional sleep screening and intervention approaches may not be efficacious for athletes given their lifestyle, the demands of training and travel associated with interstate/international competition. OBJECTIVES: The present systematic review aimed to summarize and evaluate sleep intervention studies targeting subsequent performance and recovery in competitive athletes. Based on the findings, a secondary aim was to outline a possible sleep intervention for athletes, including recommendations for content, mode of delivery and evaluation. METHODS: A systematic review was conducted based on the PRISMA guidelines in May 2016 with an update completed in September 2017. Ten studies met our inclusion criteria comprising a total of 218 participants in the age range of 18-24 years with athletes from various sports (e.g., swimming, soccer, basketball, tennis). A modified version of the quality assessment scale developed by Abernethy and Bleakley was used to evaluate the quality of the studies. RESULTS: The included studies implemented several sleep interventions, including sleep extension and napping, sleep hygiene, and post-exercise recovery strategies. Evidence suggests that sleep extension had the most beneficial effects on subsequent performance. Consistent with previous research, these results suggest that sleep plays an important role in some, but not all, aspects of athletes' performance and recovery. CONCLUSION: Future researchers should aim to conduct sleep interventions among different athlete populations, compare results, and further establish guidelines and intervention tools for athletes to address their specific sleep demands and disturbances.