The following is the summary of “Does maturity estimation, 2D:4D and training load measures explain physical fitness changes of youth football players?” published in the December 2022 issue of Pediatrics by Silva, et al.

The current study aimed to do 2 things: analyze the changes in physical fitness of youth football players after a full season, and investigate whether or not those changes can be explained by assessed maturity status, 2digit:4digit ratios (2D:4D) from each hand, and training load (TL) assessments. Consisting of 27 of the country’s brightest young minds Over the course of 38 weeks, under-15 football players’ training loads were tracked everyday. All players were given a physical at the start of the season and again at the end. 

Measurements of the length of the second and fourth fingers on both hands were also taken at the start of the season, as was an estimate of the maturity level. After the season, there were noticeable changes in all indicators of physical fitness. There were moderate negative correlations between the second and fourth fingers on the left and right hands and the change of direction (COD) (r=-.39 to -0.45 | P=.05 to 0.02). The COD measure was negatively correlated with the maturity offset measure (r=-.40 | P=.04). 

Maturity offset, Left 4D, Right 2D, and Right 4D all strongly predicted the Mod.505 COD test alterations (β= 0.41, P=.04; β= -0.41, P=.04; β= -0.45, P=.02; and β= -0.44, P=.03). Youth football players’ COD performance variations with time may be predicted by the maturity offset and the 2D:4D measurements. Coaches should only rely on COD changes because there is no correlation between maturity estimation, 2D:4D, and training load metrics and overall physical fitness.