Biochemical and subjective perceived exertion responses after dietary supplementation in Crossfit practitioners: a crossover study

Abstract

Introduction: The carbohydrates play a fundamental function in maintaining blood glucose levels and may influence the performance of physical activity. Objective: Considering this, the objective of the study was to compare the impact of fasting, pre-workout carbohydrate intake, and carbohydrate-based food supplement on the biochemical and subjective responses of effort in CrossFit practitioners. Materials and methods: The study was developed with a crossover design and involved 9 participants. The research involved anthropometric and food intake evaluation, analysis of blood glucose at three moments: one hour before the workout while participants were fasting, immediately before and after the workout, and application of a perceived exertion scale at the end of the activity. Participants underwent three intervention moments, in which they received a meal composed of pure grape juice and banana or Waxy Maize (WM) carbohydrate-based food supplement one hour before the workout or remained fasting. Statistical analyses were performed using the Friedman test, considering p<0,05 as significant. Results: It was observed that participants who ingested WM had an increase in blood glucose before the workout and a reduction in perceived effort during the exercise. In contrast, participants who were fasting had an increase in perceived effort during the physical activity. Conclusion: Therefore, it was concluded that the intake of the carbohydrate-based food supplement was able to reduce perceived effort, possibly due to the release of energy substrates for exercise performance.