This study’s goals were to examine the consequences of an acute hamstring injury on performance and mechanical properties of sprint-running at the time of returning to sports and following the subsequent ~2 months of regular soccer training post-return. 28 semi-professional male soccer players, 14 with a recent history of unilateral hamstring injury and 14 without prior injury, participated in the study. All players performed two 50-m maximal sprints when cleared to return to play (Test 1), and 11 injured players performed the same sprint test about 2 months after returning to play (Test 2). Sprint performance (i. e., speed) was measured with a radar gun and used to derive linear horizontal force-velocity relationships from which the following variables procured: theoretical maximal velocity (V 0 ), horizontal force (F H0 ) and horizontal power (Pmax). When they returned to sports the injured players were moderately slower compared to the uninjured players. F H0 and Pmax were also substantially lower in the injured players. At Test 2, the injured players showed a very likely increase in F H0 and Pmax concomitant with improvements in early acceleration performance. Practitioners ought to contemplate assessing and training horizontal force production during sprint running after acute hamstring injuries in soccer players prior to their return to sports.