ABSTRACT
The importance of physical training for young athletes in order to ensure an optimal physical level as grown up athletes is still under debate. Studies on the effect of physical training with children are complicated by the fact that growth and maturation also influence the physical capacity (see Krahenbuhl et al., 1985). Physiological data such as maximal ventilation, oxygen uptake and heart rate, have been collected from children participating in sport activities (Daniels et al., 1978; Vaccaro and Clake, 1978; Mayers and Gutin, 1979), and this have also been the case in soccer (Caru et al., 1970; Berg et al., 1985; Bell, 1988). In the latter studies measurements have been obtained under laboratory conditions with continuous exercise protocols. However, it appears that intermittent field test results have higher validity for physical performance in soccer (Bangsbo and Lindquist, 1992). To throw further light on the need for physical training at a young age the intermittent exercise performance of youth soccer players in different age groups was evaluated.
