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, 2 digit:4 digit (2D:4D) ratios from each hand, and training load (TL) assessments. About 27 highly privileged young adults The training loads of youth football players were tracked daily for 38 weeks. All players were given a physical at the start of the season and again at the end. At the start of the season, researchers also measured the length of the second and fourth fingers on both hands to get an idea of the individual’s maturity level.

After the season, there were noticeable changes in all measures of physical fitness. Changing the direction of motion (COD) was moderately correlated with the second and fourth fingers on both hands (r=-.39 to -0.45 | P=.05 to 0.02). Correlations between the maturity offset and changes in COD were negative and modest (r=-.40 | P=.04). Significant associations were found between the Mod.505 COD test and the maturity offset, Left 4D, Right 2D, and Right 4D (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 through time may be predicted using the maturity offset and the 2D:4D measurements. However, coaches should only focus on COD changes because there is no correlation between maturity estimation, 2D:4D measures, training load measures, and overall measures of physical fitness.