The role of age, sex, anthropometry, and body composition as determinants of physical fitness in nonobese children aged 6–12

Abstract

Purpose The determinants of physical fitness in children have been given limited attention. In particular, the relative role of chronological age, sex, anthropometry, and body composition in physical fitness of children has been barely investigated. This cross-sectional study investigated determinants of physical fitness using a set of predictive variables including, in addition to chronological age and sex, a large panel of anthropometric measurements as well as body composition. The study was carried out in a convenience sample of children aged 6–12 participating in a summer camp. Methods One-hundred-ninety-three children (128 males) fulfilled all requirements and entered analysis. Health-related physical fitness components (speed, muscular power and balance) were explored by means of field tests, namely the 30-m dash test for running speed, the standing long jump and the seated chest pass test for lower limbs and upper body muscular power, respectively, and the flamingo balance test for static balance. Determinants of physical fitness were investigated by regression analysis using chronological age, sex, anthropometry, and body composition in a hierarchical approach. To minimize the expected effect of collinearity in predictor variables, an original statistical approach using Random Forests analysis was adopted. Results Age predicted 45.2%, 43.6%, 35.6% and 25.6%; and sex 9.5%, 10.7%, 6.3% and 2.0% of variance in the 30-m dash, seated chest pass, standing long jump, and flamingo balance test, respectively. Anthropometry and body composition explained a limited or no percentage of variance. The adjusted R2 (root mean square error) was 0.61 (0.31 s), 0.45 (0.32 m), 0.58 (0.15 m) and 0.41 (0.75 logs) for the 30-m dash, seated chest pass, standing long jump, and flamingo balance test, respectively making these models useful when physical fitness tests are not feasible. Conclusions We highlighted the respective role of chronological age, sex, anthropometry, and body composition in physical fitness of children in the wide age range 6–12 years. Data confirm and expand on previous literature by showing with a strictly conservative statistical approach that chronological age is a main determinant of physical fitness of both boys and girls, sex playing a limited role. The role of anthropometry was even less important, and no role was found for body composition. These findings should be considered when planning/implementing motor development or physical education programs.

Growth-related changes in anthropometry and physical fitness in girls aged 10-13 years

“…The results of the beforementioned study are contradictory with the statement made by Butterfield et al (2004), who found no association between longitudinal growth rates of height and body mass and improved running speed in children aged 11-13 years. The role of age in improving running speed in this period is possibly associated with an increasing stride length and frequency and neuromuscular coordination (Milanese et al, 2020). According to Whithall (2003) claims, the rate of progression of speed development is dramatically reduced in females at the age of 12, as we also confirm in our research.…”

“…Since that results in this research showed a moderate relation with explosive power and a weak relation with running speed and muscular strength and endurance, that is in relation findings of Malina et al (2004) and Milanese et al (2020)…”

“…Little et al (1997) Bouchard and Bar-Or (2004). Some latest research results demonstrated that in the period of growing up chronological age is a main determinant of physical fitness of both boys and girls, sex playing a limited role, while the role of anthropometry was less important (Milanese, Sandri, Cavedon, & Zancanaro, 2020).…”

Influence of Body Composition on Physical Fitness in Adolescents

“…These studies reported an R 2 score of 54% [29] and 48% [30], respectively. Similarly, Milanese et al [26] showed a predictive equation for the 30-m dash test, but in children and considering only sex and age. Its R 2 value (R 2 = 0.55) was lower than that obtained in our study.…”

“…There is no doubt that age, sex [25][26][27]29,30], and BMI [25,28] are determining factors for fitness status. Nevertheless, this study [26] suggests that other variables, such as muscle fibre recruitment or muscular coordination, could be considered when developing prediction equations, because they may influence the performance on fitness tests. Moreover, Milanese et al [26] reported that FFM and FM% were not significant determinants of physical fitness.…”