Efeitos agudos da suplementação de cafeína no metabolismo energético em indivíduos com alta ou baixa ativação do tecido adiposo marrom durante e após treinamento aeróbico e intervalado de alta intensidade

Abstract

Brown adipose tissue (BAT) is essential for energy expenditure. Its activation increases during physical exercise, contributing to improved metabolism. Physical activity can stimulate its function, promote body weight regulation and boosting metabolic health. This thesis aimed to study the thermogenic response of BAT and macronutrient utilization in physically active male individuals after caffeine ingestion and a moderate-intensity aerobic training session and highintensity interval training. This was a quasi-experimental, crossover study. Participants (n = 36) were professional soccer players. Participants were stratified into groups with high BAT activity (n = 16) or low BAT activity (n = 20) using infrared thermography (IT). Each group randomly completed a continuous aerobic training (EX) session and a high-intensity interval training (HIIT) session in two separate sessions, 7 days apart. One hour before measurements, each subject was randomly assigned to consume a caffeine capsule (375 mg) or placebo. Metabolic outcomes (energy expenditure: EE; substrate oxidation) were monitored by breath-by-breath ergospirometry during exercise and 30 min of recovery. The main results indicate that polynomial regression revealed significantly higher energy expenditure (EE) in the HBAT vs. LBAT groups (+25%, p < 0.01), with a peak EE in the HIIT-HBAT (3.7 ± 0.2 vs. 2.9 ± 0.3 kcal min⁻¹ in EX-LBAT; p = 0.004). EE decreased linearly in all groups (adjusted R² = 0.93). Carbohydrate oxidation (CHO) showed a biphasic decline (plateau until 40 min, then decline; R² = 0.91), with no differences between groups (p = 0.27). Lipid oxidation (LIP) peaked later in the HBAT groups (50 min: +15% vs. LBAT; p ≤ 0.0003), particularly after HIIT (R² = 0.89). Protein oxidation (PTN) remained low and similar in all groups (p > 0.06). In conclusion, BAT activity amplifies exercise-induced EE and increases LIP utilization at the end of exercise, with HIIT producing the most intense metabolic effects in individuals with HBAT. These findings highlight the role of BAT in modulating exercise metabolism. Furthermore, a synergistic effect between BAT and caffeine produced greater EE in all groups.