Maturational effect on physical capacities and anabolic hormones in under-16 elite footballers: a cross-sectional study

Purpose The purposes of this study were to describe the fitness and hormonal levels according to playing time (PT) (i.e., PT during season less (PT1) or more (PT2) than 50% of the total time) and maturation level (ML) (i.e., normal (ML1) and early maturity levels (ML2)), and to analyze the differences between groups for the measures of aerobic capacity, anaerobic power, power performance, and hormonal concentrations. Methods Twenty-four youth footballers of a U16 team participated in this study. Anthropometric measures, maturity status, growth hormone, insulin-like growth factor (IGF-1), maximal oxygen uptake, fatigue index, and countermovement jump were collected. Results Significant differences were found between both PT and ML groups for maturational status, aerobic capacity, power performance, and IGF1 concentrations. The interaction of PT and ML revealed significant differences for maturity offset and power performance. When using the skeletal age as a covariant, the previously significant differences found were reduced only to the fatigue index measure. Conclusions The response variables analyzed in the present study seem to be influenced by PT and ML. This must be considered when planning training, and coaches must be sensible to these effects as they may assume a preponderant role in PT.

Automated summary

The study found that different playing time and maturation levels can affect the maturational status, aerobic capacity, power performance, and IGF1 concentrations of youth footballers. Analyzing the interaction of playing time and maturation level revealed significant differences in maturity offset and power performance. After using skeletal age as a covariant, the previously significant differences were reduced to only the fatigue index measure.