Acute effect of betaine supplementation on muscular endurance during resistance exercise in trained men: a pilot and randomized study

Abstract

Objective: To analyse the acute effect of betaine supplementation on muscular endurance in weight training practitioners. Design: An experimental, crossover, randomized and double-blind study. Methods: The sample composed of 10 male subjects practicing resistance training (age: 23.71 ± 4.23 years old). Participants performed 2 sessions (i.e., Betaine x Placebo) with 3 sets of repetitions until failure with 70% of 1RM. The participants were provided 3 minutes of recovery between sets and 48 hours between sessions. The 24H food recall was evaluated before each exercise session. Results: There were no significant differences in carbohydrates (p = 0.732), protein (p = 0.684), fat (p = 0.271), or in total energy consumption (p = 0.865). A time effect occurred for the training session (F (2,18) = 54.626, p < 0.0001, η2 = 0.859), with a linear reduction in the number of repetitions performed throughout the series for both conditions (1set > 2set > 3set). However, there was no interaction (F (2,18) = 0.625, p= 0.546, η2 = 0.065) or condition effect (F(1,9) = 0.045, p = 0.837, η2 = 0.005). Conclusion: Acute betaine supplementation had no effect on muscular endurance performance in the bench press.