Effects of Resisted Sprint With Changes of Direction Training Through Several Relative Loads on Physical Performance in Soccer Players.

PURPOSE:: to compare the effects of resisted change of direction (COD) movements, using several relative loads, on soccer players' physical performance.

METHODS:: Fifty-four male soccer players were randomly assigned to one of the following 3 groups, which differed only in the magnitude of the external load used during the COD training: COD training without external load (COD-0; n = 16); COD training with a 12.5% body mass (BM) external load (COD-12.5; n = 19); and COD training with a 50% BM external load (COD-50; n = 19). Participants performed the specific COD training twice per week for 6 weeks. Before and after the training period a battery of tests was completed: countermovement jump (CMJ); 30 m running sprint (time in 10-m [T10 ], 20-m [T20 ] and 30-m [T30 ]); L-RUN test; and V-CUT test.

RESULTS:: Within-group comparisons showed substantial improvements in CMJ and T10 (likely) in COD-0, whereas CMJ, T10 and T20 were substantially enhanced (possibly to likely) in COD-50. COD-12.5 induced substantial improvements in all analyzed variables (likely to most likely). Between-groups comparisons showed better effects on all analyzed variables for COD-12.5 compared to COD-0 group (possibly to very likely), whereas COD-50 only showed possibly better effects than COD-0 on T10 . In addition, COD-12.5 induced a better effect on L-RUN and V-CUT tests than COD-50 (possibly to likely).

CONCLUSIONS:: These results indicate that COD training, especially moderate load (12.5% BM) resisted COD training, may have a positive effect on COD skills, running sprint performance and jumping ability in young soccer players.