The Effect of Short-Term Interval Training during the Competitive Season on Physical Fitness and Signs of Fatigue: A Crossover Trial in High-Level Youth Football Players

Abstract

Four weeks of in-season endurance training can lead to relevant improvements in endurance capacity. The decreases in CMJ height and total-recovery score together with the increase in urea concentration might be interpreted as early signs of fatigue. Thus, the danger of overtaxing players should be considered.