Supplementary Table 1. Sample size per age group, and sample sizes and descriptive statistics for chronological age (CA), RUS score, TW2 SA and TW3 SA of non-skeletally mature players and for CA of skeletally mature players by age group in each series of youth soccer players

CA group / N / RUS Score <1000 / RUS Score =1000
CA, years / RUS Score / TW2 SA / TW3 SA / CA, years
n / M / SD / M / SD / M / SD / M / SD / n / M / SD
Portugal A [35,36]
11 / 9 / 9 / 11.7 / 0.2 / 425 / 112 / 12.9 / 1.5 / 11.8 / 1.4
12 / 20 / 20 / 12.6 / 0.3 / 470 / 104 / 13.6 / 1.4 / 12.4 / 1.3
13 / 6 / 6 / 13.7 / 0.3 / 760 / 135 / 16.1 / 0.8 / 15.1 / 0.9
14 / 22 / 21 / 14.6 / 0.3 / 793 / 137 / 16.3 / 0.9 / 15.3 / 0.9 / 1 / 14.7
15 / 37 / 22 / 15.6 / 0.3 / 875 / 95 / 16.8 / 0.6 / 15.8 / 0.6 / 15 / 15.7 / 0.3
16 / 30 / 11 / 16.3 / 0.2 / 947 / 45 / 17.3 / 0.4 / 16.2 / 0.2 / 19 / 16.6 / 0.3
17 / 15 / 5 / 17.7 / 0.2 / 976 / 5 / 17.6 / 0.1 / 16.4 / 0.0 / 10 / 17.6 / 0.2
Portugal B [30,37]
11 / 62 / 62 / 11.5 / 0.3 / 397 / 77 / 12.4 / 1.4 / 11.4 / 1.1
12 / 25 / 25 / 12.5 / 0.2 / 431 / 96 / 13.0 / 1.6 / 11.9 / 1.4
13 / 80 / 80 / 13.6 / 0.3 / 574 / 131 / 14.7 / 1.1 / 13.5 / 1.2
14 / 46 / 46 / 14.5 / 0.3 / 669 / 158 / 15.4 / 1.1 / 14.3 / 1.2
15 / 59 / 42 / 15.5 / 0.3 / 753 / 129 / 16.0 / 0.8 / 15.0 / 0.9 / 17 / 15.6 / 0.3
16 / 35 / 21 / 16.4 / 0.3 / 779 / 119 / 16.2 / 0.7 / 15.2 / 0.8 / 14 / 16.6 / 0.3
17 / 8 / 4 / 17.2 / 0.1 / 941 / 35 / 17.2 / 0.4 / 16.2 / 0.2 / 4 / 17.1 / 0.1
Belgium A [29,38]
11 / 55 / 55 / 11.6 / 0.3 / 366 / 59 / 11.8 / 1.4 / 10.9 / 1.0
12 / 141 / 141 / 12.5 / 0.3 / 406 / 70 / 12.7 / 1.3 / 11.6 / 1.1
13 / 140 / 140 / 13.5 / 0.3 / 476 / 92 / 13.7 / 1.2 / 12.5 / 1.1
14 / 114 / 112 / 14.5 / 0.3 / 592 / 145 / 14.9 / 1.2 / 13.7 / 1.3 / 2 / 14.3 / -
15 / 82 / 69 / 15.5 / 0.3 / 688 / 131 / 15.6 / 0.8 / 14.6 / 0.9 / 13 / 15.6 / 0.2
16 / 36 / 14 / 16.5 / 0.3 / 747 / 130 / 16.0 / 0.8 / 15.0 / 0.8 / 22 / 16.6 / 0.2
17 / 4 / 2 / 17.3 / - / 754 / - / 16.1 / - / 15.1 / - / 2 / 17.3 / -
Belgium B [39]
11 / 9 / 9 / 11.6 / 0.1 / 414 / 46 / 13.0 / 0.9 / 11.8 / 0.7
12 / 10 / 10 / 12.5 / 0.3 / 431 / 37 / 13.4 / 0.6 / 12.1 / 0.5
13 / 13 / 13 / 13.6 / 0.3 / 459 / 45 / 13.7 / 0.6 / 12.4 / 0.6
14 / 11 / 11 / 14.6 / 0.2 / 632 / 138 / 15.2 / 1.0 / 14.1 / 1.2
15 / 10 / 10 / 15.5 / 0.3 / 768 / 113 / 16.1 / 0.7 / 15.1 / 0.8
16 / 4 / 4 / 16.6 / 0.2 / 825 / 83 / 16.5 / 0.5 / 15.5 / 0.5
Spain[24]
12 / 6 / 6 / 12.8 / 0.2 / 532 / 55 / 14.5 / 0.5 / 13.3 / 0.6
13 / 7 / 7 / 13.5 / 0.4 / 585 / 154 / 14.9 / 1.0 / 13.7 / 1.2
14 / 13 / 13 / 14.7 / 0.3 / 820 / 111 / 16.4 / 0.7 / 15.5 / 0.7
15 / 10 / 2 / 15.7 / - / 883 / 146 / 17.0 / - / 15.9 / - / 8 / 15.6 / 0.3
16 / 4 / 1 / 16.0 / - / 833 / - / 16.5 / - / 15.3 / - / 3 / 16.0 / 0.4
Italy[10]
11 / 33 / 33 / 11.5 / 0.3 / 360 / 36 / 11.8 / 0.9 / 10.9 / 0.6
12 / 18 / 18 / 12.5 / 0.2 / 381 / 71 / 12.1 / 1.4 / 11.1 / 1.1
Mexico[43]
11 / 9 / 9 / 11.4 / 0.4 / 409 / 158 / 12.1 / 2.2 / 11.3 / 2.0
12 / 10 / 10 / 12.5 / 0.3 / 458 / 119 / 13.3 / 1.6 / 12.2 / 1.5
13 / 13 / 12 / 13.6 / 0.3 / 646 / 118 / 15.3 / 1.0 / 14.2 / 1.1 / 1 / 13.3 / -
14 / 3 / 2 / 14.3 / - / 788 / - / 16.3 / - / 15.3 / - / 1 / 14.7 / -
15 / 6 / 2 / 15.4 / - / 788 / - / 16.3 / - / 15.3 / - / 4 / 15.8 / 0.1
16 / 1 / 1 / 16.3 / -
17 / 4 / 4 / 17.4 / 0.2
Brazil[44]
11 / 13 / 13 / 11.6 / 0.2 / 388 / 51 / 12.4 / 1.2 / 11.3 / 0.9
12 / 20 / 20 / 12.6 / 0.2 / 495 / 99 / 14.0 / 1.0 / 12.8 / 1.1
13 / 39 / 38 / 13.6 / 0.2 / 620 / 119 / 15.1 / 0.9 / 14.0 / 1.1 / 1 / 13.6 / -
14 / 15 / 12 / 14.4 / 0.2 / 771 / 144 / 16.1 / 0.9 / 15.1 / 1.0 / 3 / 14.6 / 0.1
15 / 8 / 5 / 15.2 / 0.1 / 787 / 119 / 16.2 / 0.7 / 15.3 / 0.8 / 3 / 15.2 / 0.1
Thailand [42]
12 / 9 / 9 / 12.6 / 0.2 / 587 / 71 / 14.9 / 0.6 / 13.8 / 0.7
13 / 17 / 17 / 13.3 / 0.2 / 629 / 151 / 15.1 / 1.3 / 14.0 / 1.4
14 / 18 / 17 / 14.4 / 0.3 / 778 / 119 / 16.2 / 0.8 / 15.2 / 0.8 / 1 / 14.3 / -
15 / 12 / 8 / 15.2 / 0.3 / 799 / 107 / 16.3 / 0.6 / 15.4 / 0.7 / 4 / 15.5 / 0.3
16 / 6 / 2 / 16.0 / - / 696 / - / 15.7 / - / 14.7 / - / 4 / 16.2 / 0.1
Japan A [40,41]
11 / 45 / 45 / 11.6 / 0.3 / 374 / 72 / 11.9 / 1.6 / 11.0 / 1.2
12 / 45 / 45 / 12.6 / 0.3 / 551 / 112 / 14.4 / 1.3 / 13.3 / 1.3
13 / 35 / 34 / 13.5 / 0.3 / 613 / 145 / 15.0 / 1.2 / 13.8 / 1.3 / 1 / 13.9 / -
14 / 31 / 28 / 14.4 / 0.3 / 752 / 122 / 16.0 / 0.8 / 15.0 / 0.8 / 3 / 14.8 / 0.1
15 / 9 / 6 / 15.2 / 0.3 / 776 / 142 / 16.2 / 0.9 / 15.2 / 1.0 / 3 / 15.6 / 0.2
16 / 2 / 2 / 16.1 / -
Japan B [25]
11 / 55 / 55 / 11.6 / 0.3 / 380 / 76 / 12.0 / 1.6 / 11.0 / 1.3
12 / 72 / 72 / 12.6 / 0.3 / 490 / 145 / 13.5 / 1.8 / 12.4 / 1.7
13 / 70 / 67 / 13.5 / 0.3 / 674 / 167 / 15.4 / 1.2 / 14.3 / 1.3 / 3 / 13.8 / 0.1
14 / 60 / 53 / 14.6 / 0.3 / 813 / 167 / 16.4 / 1.2 / 15.3 / 1.2 / 7 / 14.6 / 0.3
15 / 29 / 11 / 15.3 / 0.3 / 887 / 106 / 16.9 / 0.8 / 15.9 / 0.6 / 18 / 15.6 / 0.2
16 / 1 / 1 / 16.0 / - / 923 / - / 17.0 / - / 16.1 / -