Background: Childhood is an important transitional period for the development of healthy physical activity (PA) behaviours, so it is important to understand its impact on a healthy lifestyle. Aim: This study aimed to determine the influences of sex, socioeconomic status (SES) and body composition (BC) on the relationships between PA, motor skills, motor- and health-related physical fitness in 5–8-year-olds. Setting: Participants were a subsample consisting of 299 children (150 boys, 149 girls, mean age 6.83 ± 0.96 years) from the Exercise, Arterial Modulation and Nutrition in Youth South Africa study (ExAMIN Youth SA). Methods: Anthropometric measures, health-related physical fitness (HRPF), motor-related physical fitness (MRPF), objectively measured PA and demographic information were determined. Results: Only 66% achieved the recommended 60 min of daily moderate vigorous physical activity (MVPA) with 19% classified as having unhealthy body composition (11% overweight, 8% obese). Fat-free mass and SES revealed small-to-moderate influences on the relationship between MVPA, standing broad jump (SBJ; r = 0.32), predicted VO2max (r = 0.28) and beep levels (r = 0.22). For MRPF, the quality of running (r = 0.12) and balancing were associated with MVPA. Adjusting for sex, BC and SES in the relationship between PA with HRPF and MRPF, reductions in most correlations were observed. Conclusion: Moderate vigorous physical activity levels were positively associated with HRPF, MRPF and some motor skills in 5–8-year-olds. Socioeconomic status (lower parental income, employment and education negatively influenced the association between MVPA and fitness [beeps, SBJ, O2max]). Contribution: This study provides knowledge with regard to the use of accelerometer for baseline data for PA, MRPF, HRPF as well as motor skills in South African children.

Puberty and the onset of menarche influences the motor performance of girls. However, the magnitude of these influences during varying maturity status, is not clear. This longitudinal study over two years aimed to investigate differences in motor fitness between early and late developing girls based on pre- and post-menarche status. A convenience sample (n = 58) of girls aged 13.51 ± 3.51, divided by means of the Status Quo method into pre (n = 13) and post-menarche (n = 45) groups, was used. Motor fitness was tested once annually by standardized protocols. Basic statistics, independent t-testing and a repeated measures ANOVA with a post hoc Bonferonni correction were used (p < 0.05 = statistical significance). Effect sizes were determined by Cohen’s d-values. Only explosive upper body strength differed significantly between groups during baseline, favoring post-menarche girls. Initially, post-menarche girls showed advantages in hand-eye coordination and speed (p > 0.05) with pre-menarche girls performing better in agility and explosive leg strength (p > 0.05). At 15.51 years, no significant, between-group differences were found. Pre-menarche girls surpassed post-menarche girls in hand-eye coordination and 0–40 m speed and post-menarche girls displayed higher explosive leg and upper body strength scores (p > 0.05). Our data show that the potential to excel in sport based on motor capabilities can only be accurately estimated 1–2 years after reaching menarche.

Pediatric obesity has become a growing global epidemic which has negative health consequences, including for South African children. This study aimed to determine the immediate and sustainable influences of a 9-week movement program on the body composition of 7 to 8-year-old school children in a rural area of South Africa. A two group, pre-test, post-test and re-test after six months experimental design was used to compare anthropometric measurements of the intervention group (IG) and control group (CG). Ninety-three schoolchildren (IG = 57; CG = 36) participated in the study. A 9-week movement program was followed twice a week for 30 min during school hours with an emphasis on improving BMI. Hierarchical Linear Modelling (HLM) was used to analyze the data with time, sex and group as predictors. Effect sizes was computed based on the Cohen’s d to assess the practical significance of findings. The intervention positively changed the waist circumference. The subscapular skinfold and BMI showed statistical and practically significant sustainable changes because of the intervention, although gender influenced these effects. School based movement interventions, focusing on improving fundamental movement skills (FMS), have the potential to contribute to a healthier BMI, skinfold thickness and circumferences among young children.

Background: Information on childhood body composition is critical to understanding children’s growth, development, and long-term health outcomes. BMI metrics, however, have several limitations for assessing and understanding changes in BMI. Therefore, understanding the influence of various body composition factors (covariates) that are linked to, and influence, BMI over time in growing children is important. This study aims to determine sex differences in longitudinal changes in covariates of BMI from 6 to 13 years. Methods: Participants (N = 332, 160 boys 172 girls) from North West Province in South Africa were assessed longitudinally at the following three time-points during their primary years of schooling: Grade 1 (6–7 years); Grade 4 (9–10 years); and Grade 7 (12–13 years). Covariates included: stature (cm); body weight (kg); sub-scapular-, calf-, and triceps skinfolds (mm); body fat percentage (%), relaxed forearm, waist and mid-upper arm circumferences; percentage fat weight; and percentage muscle weight. Correlational analysis and multiple stepwise regression analysis in SPSS analyzed the significance of the contributions of the different covariates to changes in BMI from 6 to 12 years. Results: Different covariates influence BMI in boys and girls at different ages and the covariates also change over time in boys and girls. Weight had the strongest influence on the BMI of boys and girls, although the prediction value decreased over time. Weight and stature were consistently the strongest BMI predictors across all ages in boys. In girls, a broader range of variables influences BMI from a younger age, where slightly higher BMI correlations with fat-related variables emerged, and the percentage of fat weight distribution was a strong influential factor. These findings indicate a more in-depth analysis of BMI to determine sound intervention strategies.

Adequate development of Fundamental Motor Skills (FMS) at a young age benefit holistic development and positive health outcomes. This study determined age and sex developmental differences in the state and the relationships between process and product assessments of four fundamental-motor skills (FMS) in five to eight-year-olds. An availability sample of 636 children; 291 boys, 345 girls, mean age of 6.8 ± 0.97 years in the North West Province of South Africa participated in the study. Spearman rank order correlations analyzed relationships between assessments, while sex and age differences were examined using independent t-testing and one-way ANOVA. Age showed significant developmental trajectories in all FMS. Older children were found to be more at risk for not learning FMS to mastery, while unique developmental patterns were also established compared to international trends. Strong to moderate significant practical associations (p < 0.05) emerged between process and product assessments in catching (r = 0.79), jumping (r = 0.40) running (r = −0.33) and kicking (r = 0.20), while also confirming that the strength of the associations varies depending upon the skill type. Associations strengthened with increasing age, were higher in girls in all FMS, while associations between behavioral criteria in all FMS also differed between FMS and sexes. These strong associations, need to be taken into consideration during the development of FMS towards obtaining full mastery.