Is the Special Judo Fitness Test Index discriminative during formative stages? Age and competitive level differences in U13 and U15 children

Aim. The aim of the present study was to perform SJFT in children to analyse differences between groups of age and competition level. Methods. Thirty-four male children judo athletes aged under 13 (U13) and under 15 (U15) years-old were recruited from a local gym (amateurs) and the Spanish National Judo Team (SNT) and classified in three groups: U13 amateur, U15 amateur and U15 SNT. Children performed the SJFT in similar height and weight pairs. Age comparisons revealed no difference in SJFT index given the lower number of throws during the SJFT for U13 children (95% CIhigh = <23 vs. >22 and >23 throws) but the faster heart rate (HR) recovery (95% CIhigh = <150 vs. >150 and >147 bpm) compared to the U15 amateur and SNT groups. Results. Competitive level comparisons between U15 amateur and SNT revealed no difference in SJFT performance (throws, HR and index). Thus, the SJFT index is not a proper variable to detect differences between groups at these ages. Conclusions. These findings open the challenge to design appropriate conditioning test for children to better measure performance and develop adequate training and teaching plans during formative years. These findings open the challenge to design appropriate conditioning test for children during formative years to better measure performance and develop adequate training and teaching plans.