Specifically, he studied teams with football players aged between 10 and 14 years, and classified them into four age groups, according to date of birth. He took samples of players belonging to high quality playing line-ups, thanks to the Athletic Club Foundation teams of Sorbide (the centre which manages football sign-ups at this level) and also those from more modest categories, helped by the Galdakao and Ugao clubs. He also worked with a control population. Dr Zubero's thesis is entitled The importance of anthropometric and physiological characteristics of young, superior category football players in their process of selection.
Superior players vs other players
The Sorbide teams' players gave better results than those of the other teams and than those of the control population. Specifically, they have less fat content, higher muscular percentage, are more rapid and vigorous, are more dexterous with the ball and enjoy greater aerobic capacity. Nevertheless, the relation between weight and height to the quality of the player is not so clear. In fact, 10-11-year-old Sorbide players are leaner than the youngsters of the control population, but they are taller and heavier in the 12-13 years and 13-14 years age groups. As regards other differences, Dr Zubero studied the exact (decimal) age of each child, as well as the annual distribution of their dates of birth. He observed that Sorbide players had a greater decimal age and that, if the year of birth is considered overall, these are born earlier. Thus, the researcher concluded, these Bizkaian footballers between 10 and 14 years have the effect known as relative age. That is, while it is true that Sorbide footballers have better results, it could be that this is due precisely to the fact that they are older. In fact, it is stressed in the thesis that, in this period between 10 and 14 years, the differences that that may occur as regards age and maturity, although they be small, can give rise to great differences in anthropometric and physiological characteristics.
Regular first team players vs non-regular ones
At the same time, Dr Zubero calibrated the differences amongst the Sorbide players themselves, and analysed the results to see if these differences have anything to do with being a regular top team player or not. The results showed that those who play in the best teams have less fat content and are stronger and faster. He also observed the variations occurring over the football season with the aim of comparing their progress. The data showed these top players develop their physical skills much more notably. Particularly worthy of mention is the close relationship between improvement in speed and being a regular top team player.
As regards the decimal age and the level of maturity, regular top team players and non-regular ones in Sorbide teams have produced similar results. Thus, the researcher suggests that regular top team players are more advanced as regards body development, and this is the reason that their physical development throughout the season is much more striking. Taking into consideration all this data, Dr Zubero made a recommendation for trainers and managers in his thesis: in the selection trials, differences in the process of development of each of the children and adolescents should be taken into account.
Source: Elhuyar Fundazioa