Sao considerados como treinamento de forca exercicios que utilizam contracao muscular com resistencia obtida com o auxilio de pesos, maquinas, bem como exercicios utilizando o peso do proprio corpo. Alem disso, muitos estudos fazem referencia as diferentes velocidades de contracao muscular Objetivo: verificar os efeitos de diferentes velocidades de contracao (concentrica e excentrica) na forca muscular de jovens praticantes de treinamento de forca. Metodologia: O estudo foi conduzido durante 8 semanas de intervencao direta onde participaram 19 voluntarios de ambos os sexos, universitarios, que foram distribuidos em dois grupos, Grupo CONC: treinamento com contracao a concentrica rapida e a excentrica lenta (N=11, 22,76 ± 4,47 anos); Grupo EXC: treinamento com contracao concentrica lenta e a excentrica rapida (N=8, 20,23 ± 6,22 anos). Os individuos passaram por teste de Avaliacao da forca muscular para determinacao da Repeticao Maxima (RM) nos exercicios de Supino e Agachamento. Resultado: Em ambos os grupos foi observado o aumento da forca muscular, mas apenas o grupo EXC obteve resultados significativos na variavel RM Supino (32,03 ± 16,56 vs. 46,89 ± 26,04 Kg; ∆%= 46,4%; p=0,045) Conclusao: As diferentes acoes musculares com enfase em velocidades distintas contribuem efetivamente para o aumento de forca. Contudo, no presente estudo, as acoes concentricas lentas produziram indices mais significativos do que as acoes rapidas. ABSTRACT Effect of different contraction velocities on muscle strength in young Are considered as strength training exercises that use muscle contraction with resistance obtained with the support of weights, machines and exercises using the body's own weight. In addition, many studies refer to the different speed of muscle contraction Objective: to verify the effects of different contraction speeds (concentric and eccentric) in muscle strength of youth strength training practitioners. Methods: The study was conducted during 8 weeks of direct intervention with the participation of 19 volunteers of both sexes, students, who were divided into two groups, CONC Group: training with rapid concentric and slow eccentric contractions (N = 11, 22,76 ± 4,47 years); EXC Group: training with slow concentric and fast eccentric contractions (N = 8, 20,23 ± 6,22 years). Individuals underwent muscle strength evaluation test to determine the Maximum Repetition (RM) in the bench press and squat exercises. Results: In both groups was observed increased muscle strength, but only the EXC group achieved significant results in variable RM Bench press (32,03 ± 16,56 vs. 46,89 ± 26,04 kg; Δ% = 46,4%; p = 0,045) Conclusion: the different muscle actions with emphasis on different speeds contribute effectively to the increase in strength. However, in this study, the slow concentric actions produced more significant results than the fast actions.