Efeito da ingestão crônica de cafeína sobre parâmetros da relação força-velocidade-potência no sprint em jogadores de futebol

Abstract

Caffeine intake is recognized for increasing performance in laboratory experiments and in field studies. With this, some studies have addressed chronic caffeine intake, which is valuable from a practical point of view, given the high number of athletes who consume caffeine daily. To evaluate sprint performance measures, evaluation parameters are key to considering the sprint as a crucial physical determinant for performance in team sports. Based on this, it is proposed in the literature an alternative to evaluate the entire spectrum of forcevelocity (Fv) during the acceleration of the sprint, that is, the horizontal Fv profile, in order to obtain more understandable and significant information about the determinants of linear sprint performance. The aim of the study was to evaluate the effect of chronic caffeine intake through parameters of the strength-speed ratio in the sprint in soccer players. This is a research of quantitative approach, with an experimental and longitudinal design. A doubleblind, randomized, controlled, crossover design was employed, in which participants were randomly and counterbalanced under caffeine and placebo conditions. The sample consisted of 17 male soccer players, belonging to the under-17 category, all members of the same team that regularly participated in the competitions promoted by the Alagoas Football Federation. The anaerobic performance was evaluated by means of the sprint test, in which the participants performed three maximum sprints of 30 meters, with an interval of 2 minutes between each sprint. Descriptive statistics are presented as mean ± standard deviation. For the analysis of the sprints, the Dvideow application was used, and the best time between attempts was used to determine the components of the horizontal mechanical Fv profile. An analysis of variance of measurements (Two-Way ANOVA) was used to explore the effect of treatment between groups during the weeks. The study revealed significant differences between the time points for the caffeine and placebo groups in the variables maximum theoretical horizontal force (F0), maximum theoretical velocity (v0), slope (Slope), decrease in the proportion of horizontal to resultant force (Df) and maximum power (Pmax) (p < 0.05), but not for maximum horizontal to resultant force ratio (max (RF)) (p = 0.05) and total time (TT) (p = 0.287). Among the significant differences presented between the caffeine and placebo groups, the variables v0, max (RF) and TT (p < 0.05). The other variables did not present significant differences (p > 0.05). When comparing the two groups according to the interaction between treatment and time, both did not present significant differences in none of the variables presented by the study (p > 0.05). In conclusion, over the 12 weeks, there was an increase in the magnitude of F0 in both groups. However, only the group submitted to caffeine showed a significant change after the analysis of the intervention period. In addition, changes in the Pmax variable were observed, mainly due to the increase in F0 and the decrease in v0. In the Slope variable, a significant difference was identified between the groups, indicating a more pronounced tendency towards strength in the group that received the caffeine intervention.