The power production is force-velocity related. We hypothesized that speed-based training of lower limb using half-squat can lead to absolute and relative power improvements in concentric movement with the same external load. One group of 19 soccer players (age = 24.4 years, SD = 3.7 years) participated in a pretest-posttest power training protocol, consistent in 2 training sessions per week during 10 weeks, targeted to work the leg power by performing half-squat with a fixed external load (mean = 71.7, SD = 5.4) at 65% of 1 repetition maximum. Measurements of power (absolute [in watt] and relative [in watt per kilogram]), force (in newton), and velocity (in meter per second) (mean and peak) were made from a concentric movement of a half-squat exercise with a fixed external load. The training protocol increased relative power (mean = 47.5, SD = 47.5, p < 0.001) and absolute power (mean = 169.2, SD = 95.5, p < 0.001). Also, number of repetitions (mean = 2.9, SD = 2.4, p < 0.01), force (mean = 66.6, SD = 36.7, p < 0.001), and velocity (mean = 0.1, SD = 0.1, p < 0.001) were increased. However, only improved velocity was related to the changes in absolute (r = 0.939, p < 0.001) and relative (r = 0.757, p < 0.001) power. The speed-based training combined with moderate to high external load can lead to an improvement of absolute and relative power in concentric phases of half-squat in soccer players. This could be important for improving the performance of the players in the field.