An ergonomics model of training is described in which the demands of the game and the fitness profiles of soccer players are placed in perspective. The demands of the game may be gauged by monitoring the work rate of players during matches and the concomitant physiological responses. These indices suggest an increased tempo in contemporary professional soccer compared with previous decades, a trend replicated in the fitness levels of players. The simulation of the exercise intensity corresponding to match-play has enabled sport scientists to study discrete aspects of play under laboratory conditions. Observations highlight the value of exercising with the ball where possible, notably using activity drills in small groups. Small-sided games have particular advantages for young players, both in providing a physiological training stimulus and a suitable medium for skills work. While complementary training may be necessary in specific cases, integrating fitness training into a holistic process is generally advisable.