Locomotor Performance in Highly-trained Young Soccer Players – Does Body Size Always Matter?

We all know that body dimensions affect athletic performance, especially in young players differing in maturation. However, how important is this effect is still unclear, and the available methods to account for differences in body dimensions have not been compared. In this study we compared the Aspire Qatari U15 players with the best french U15 players, and examined how their different body size affected their locomotor performance. The first interesting findings was to see how shorter (-7cm) and lighter (-10 kg) the Qatari are !! As you will also understand if you read all results in details, allometric scaling helps to account for these differences, but not always – body dimensions don’t explain everything ! Feedback appreciated, as always.

Screenshot - 9_11_2013 , 11_52_33 PM

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3 thoughts on “Locomotor Performance in Highly-trained Young Soccer Players – Does Body Size Always Matter?

  1. Dear Dr Buchheit great stuff as always, magnitude-based is definately of great value for sports science practisioners. I do have 1 point that I do not get: In table 1 MSS adjusted for BM gives a standarized difference between Qatari vs. French players of +0.18(-0.11;0.46) with chances (for smaller/similar/greater value) 2/54/44 and the qualitative outcome is interpreted as possibly faster although there are actually more chances for similar. But even if chances were different, say 2/48/50, the EF is +0.18 which points out to trivial difference (<than SWC of 0.2)

    • Thanks for the comment. This is always a bit of a game when it come to interpreting these numbers 🙂 You are right, while I interpreted 2/54/44 as ‘possibly faster’, you could have also said ‘possibly similar’.. but I thought that saying ‘similar’ knowing that there is a 44% change of being faster (and this is what I wanted to highlight) could be misleading. What is important is that you still have access to all the numbers in the table, so that you can decide yourself as you have just done 🙂
      For the 0.18 you are right – slightly below the SWC… if you round up to one decimal, we are ok…but what really matters is that the stdz change refers only to the magnitude, while the % chance to the likelihood for the magnitude to be true… so in practice you can have a possible (this is clear enough) but non substantial (not large enough) faster value.

      • Thanks for the quick reply. I realize now the interplay between magnitude of the effect and chances of that magnitude being true. This approach is so much superior than the “stiff” null-hypothesis testing. I have been struggling to analyze some of my own data using magnitude-based infferences and it is always very didactic to hear from you!!

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