Supramaximal intermittent running performance in relation to age and locomotor profile in highly-trained young soccer players

The aim of the study was to examine supramaximal intermittent running performance in highly-trained young soccer players, with regard to age and locomotor profile. Twenty-seven Under 14, 19 U16 and 16 U18 highly-trained soccer players performed an incremental intermittent running test (30-15 Intermittent Fitness Test) to assess supramaximal intermittent running performance (V-IFT), an incremental running test to estimate maximal aerobic speed (VVam-Eval) and a 40-m sprint to estimate maximal sprinting speed (MSS). U16 and U18 presented very likely greater V-IFT (19.2 +/- 0.9, 19.7 +/- 1.0 vs. 17.4 +/- 0.9 km . h(-1)) and VVam-Eval (16.2 +/- 0.9, 16.7 +/- 1.0 vs. 14.6 +/- 0.9 km h(-1)) than U14, while there was no clear difference between U16 and U18. MSS (25.1 +/- 1.6, 29.3 +/- 1.6 and 31.0 +/- 1.1 km h(-1) for U14, U16 and U18) was very likely different between all groups. When data were pooled together, V-IFT was very largely correlated with VVam-Eval and MSS (overall r = 0.89, partial r = 0.74 and 0.29, respectively). Within-age group correlations showed that the older the players, the greater the magnitude of the correlations between V-IFT and VVam-Eval (r = 0.67, 0.73 and 0.87). In conclusion, the major predictors of V-IFT were, in order of importance, VVam-Eval and MSS; however, the older the players, the greater the correlations with VVam-Eval.