Paul, Darren J The effect of a concentrated period of soccer-specific fitness training with small-sided games on physical fitness in youth players. [electronic resource] - The Journal of sports medicine and physical fitness Jun 2019 - 962-968 p. digital Publication Type: Journal Article ISSN: 1827-1928 Standard No.: 10.23736/S0022-4707.18.08547-X doi Subjects--Topical Terms: AdolescentCase-Control StudiesHeart Rate--physiologyHigh-Intensity Interval Training--methodsHumansMalePhysical Fitness--physiologySoccer--physiology