Background & Study Aim: Parkour is a typical extreme form of physical activity (EFPA), commonly extreme sport. Parkour can be characterised as a high-intensity sport that demands motor actions like different jump techniques (vertical, horizontal, plyometric, long jumps), running, climbing, crawling and balancing. The aim of the present study was the effects of eight weeks of strength training on countermovement jump (CMJ) performance in parkour practitioners. Material & Methods: Twenty parkour practitioners without any systematic strength training program experience were distributed into 2 groups. The strength training group (SG) performed strength, and conventional parkour training and the control group (CG) only performed the conventional parkour training. Both types of training were performed 2 times per week. Results: The SG practitioners presented a significant increase in CMJ height (p = 0.000194), while the CG did not present a significant increase (p = 0.138). All SG practitioners showed a percentage increase in CMJ height, with a mean variation of 9.9 +/- 0.9%. Conclusions: Strength training increases the vertical jump height of parkour practitioners, which can positively influence performance in this modality. Therefore, the association of strength training with load protocol for muscular hypertrophy can increase the performance in parkour and should, therefore, be encouraged to the practitioners of this modality.