This study compared the effects of two sprint-specific training programs against the natural development of speed, power and stiffness in a group of adolescent males. Forty-three male adolescents (aged 13-15 years) were randomly assigned to one of two training groups; backward running training (BRT = 26), or forward running training (FRT = 17). A physical education class (n=24) of similar age constituted a control group (CON). Both training groups performed running sessions matched for distance and intensity biweekly for eight-weeks. Parametric and magnitude-based inferences were used to analyze within group (pre-post measures) and between group (gain scores) for 10 m, 10-20 m and 20 m sprint times, vertical countermovement jump height (CMJ) and vertical leg stiffness. Both running groups significantly improved (p ≤ 0.05) in all performance tests from preto post-training, with effect sizes ranging from-1.25 to 0.63. When the groups were compared the BRT and FRT groups improved significantly (p ≤ 0.01) on all sprint performances and stiffness relative to the CON. The BRT group demonstrated favorable effects for 10 m and 20 m sprint performances (ES =-0.47 and-0.26, respectively) and CMJ height (ES = 0.51) compared to the FRT group. These results demonstrate that forward and backward sprint-specific training programs enhance speed and power measures more than natural development in adolescent male athletes. Furthermore, the greater training responses in sprint performance and CMJ ability indicate that BRT is a useful tool for improving concentric strength and power and may be classified as a sprintspecific training method.