External and internal load during the effort tests in different ages in young futsal players: association between leg power, shot speed and fatigue levels

Futsal is a sports game that features high intensity movements with change of speed or direction, present in several actions during the game. With this study is intended to analyse, compare and evaluate the predictive factor of leg power on shooting speed and fatigue levels in young futsal athletes in order to establish effort patterns in these ages, to prescribe training sessions adequately in terms of external/internal load. The study had 32 participants, male, aged between 12 and 17 years (Mean = 14.56}1.66). Participants were evaluated in relation to their lower limb power through the Chronojump system, the speed was measured through a radar placed on the goal line, and in relation to their fatigue levels through the Running Anaerobic Sprint Test (RAST). To identify the differences between groups, the tests of Kruskal Wallis and Mann Whitney were used, and also a simple linear regression tests for predictive values between variables. In relation to the shots speed, higher values were found in the older groups (P≤0.001), which is directly and significantly related to the higher values of lower limb power, also verified in the older athletes (P≤0.001). In relation to the fatigue levels, it increases as the age of the athletes is higher, verifying that the power of the lower limbs is a predictor variable of the fatigue index (P≤0.001). The analysis conducted indicate that there are significant differences in the association between shooting speed, lower limb power and fatigue indices according to the players levels studied.