Equations predicting maturity status: Validation in a cross-sectional sample to assess physical growth and body adiposity in Chilean children and adolescents

Objective: To validate regression equations that predict the state of maturity (MS) to evaluate the physical growth and body fatness of Chilean children and adolescents. Material and methods: A transversal study was carried out in 8,094 school children between 6.0 and 18.9 years old. Weight, standing height, sitting height, and waist circumference (WC) were evaluated. Peak growth rate (PVC) was estimated by the mathematical model 1 of Preece-Baines (MPB). Mirwald's equations (based on age, weight, standing height, sitting height, and leg length) and Moore's equations (based on age, weight, and standing height) were used to estimate MS. The body mass index (BMI) was calculated. Results: The BMP showed that the PVC in men was 10.33 ± 0.29 years and in women was 12.81 ± 0.27 years. Using Mirwald's equation, men reached MS at 14.09 ± 0.8 APVC and women at 11.6 ± 0.9 APVC, while using Moore's equation, men reached 13.7 ± 0.6 APVC and women at 12.1 ± 0.6 APVC. There were significant differences between MPB with Mirwald, MPB with Morre, and between Mirwald and Moore (p < 0.001). Explanation values by MS category were Mirwald's equation [men (early R² = 0.81, mean R² = 0.69 and late R² = 0.09) and women (early R² = 0.83, mean R² = 0.83 and late R² = 0.77)], Moore's equation [men (early R² = 0.93, mean R² = 0.70 and late R² = 0.79) and women (early R² = 0.89, mean R² = 0.89 and late R² = 0.83)]. Percentiles were created for weight, height, CC and BMI. Conclusion: It was verified that Moore's and Mirwald's equations differ with the mathematical model MPB in both sexes. However, Moore's equation could be useful for the evaluation of MS in Chilean children and adolescents.