The results of the study have shown that there is a linear and non-linear relationship between MS and BSA in both sexes. However, the best fit in data concentration was observed in the quadratic non-linear relationship, where the explanatory power was higher from 1 to 3% and the RMSE evidenced lower values (RSME = 1080 and 1.175 in males and RMSE = 1.779 and 1.479 in females), with respect to the linear model (RSME = 1.130 and 1.190 in males and RMSE = 1.740 and 1.570 in females).
These findings indicate that the BSA can be considered an excellent predictor of MS in children and adolescents in a regional population of Chile. Therefore, future studies that intend to propose new methods for the evaluation of MS by anthropometry could include BSA in their prediction models.
In fact, since the publication of the study by Mirwald et al [18], in which the BSA prediction equation is proposed in both sexes, more than 20 years have elapsed, in which it has been widely used in school [5, 22, 23] and sports populations [24, 25, 26]. Even, the same study group using the same database, made an adjustment to the initial equations, in which seated height was eliminated, and published new equations with a lower prediction error (known as Moore equations).
In general, the original Mirwald equation has been criticized for its predictive ability, in which several limitations are highlighted in both sexes [4, 20, 27]. Even, recently some studies highlight that the equation modified by Moore et al [19] presents some important limitations that should be considered by researchers [4, 20, 28].
Therefore, perhaps it could be timely to include BSA in these two techniques predicting MS in children and adolescents of both sexes. In addition, the nonlinear relationship in both techniques should be considered, which could improve the explanatory power in the prediction models.
In essence, body size and body build over the years has been changing in pediatric patients of ethnic/racial background [29, 31], thus equations predicting MS possibly require updating their regression models.
For it is widely known that the techniques used to predict MS need periodic evaluations, so BSA could be an appropriate predictor to control for such variations in body shape and build during the growth and development stage.
In summary, although BSA is related to both techniques of MS in children and adolescents of both sexes, classically BSA has been considered by Brozek et al [32] as a long-established measure in measurements such as overlay, triangulation, planimetry, prediction from major body dimensions. Therefore, attention should be paid as a possible predictor of MS, as it is not surprising that several expressions correlating body surface area with direct measurements of body mass and length have been reported in the literature [33]. Although, additional or alternative variables and methods need to be considered as a complement to estimate somatic maturation [28].
In fact, maturation is a complex process involving changes in body structure and function, and these changes may vary among individuals and populations. Thus, their assessment by anthropometric techniques can help predict the maturity shift and accommodate individual differences among adolescents [18].
Meanwhile, studying methodologies to assess biological maturation during the stage of growth and development remains a gap, so future studies should continue to address strategies to generate new noninvasive methodologies.
Overall, this study has some limitations in its cross-sectional design, so future studies should use longitudinal designs to confirm our findings. For example, the most commonly used indicator of maturity in longitudinal studies during adolescence is peak PHV growth velocity which require serial measurements over several years around the years surrounding the onset of peak growth velocity [34]. In addition, we also highlight that it was not possible to model these data for children and adolescents of both sexes through mathematical models such as Preece-Baines [35] and Sitar [36]. It is suggested that future studies analyze such models and verify the associations with PHV. However, notwithstanding the above, we emphasize that this study is one of the first investigations that demonstrated the usefulness of BSA in children and adolescents. Furthermore, this information may be useful for researchers who have longitudinal databases, in which the use and applicability of the BSA in children and adolescents from various geographic regions of the world can be tested.