Background
lethargy, fatigue, tiredness, muscular fatigue, Fatigue
Exercise-induced muscular fatigue is an unavoidable effect that can limit performance and accomplishment of training goals and thus has been a focus of research in sports and exercise. Fatigue can be categorized as either peripheral or central. Peripheral fatigue results from a number of aspects including accumulation of metabolites, protein breakdown, and carbohydrate consumption; whereas central fatigue is primarily the result of increasing levels of the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) that results in the feeling of total body fatigue (i.e. lethargy, tiredness, and loss of motivation) [Amino acids have been the focus of research for many years for their ability to enhance athletic performance by modifying fuel utilization during exercise, preventing fatigue, and improving recovery. BCAAs are unique among the essential amino acids for their role in numerous metabolic pathways that affect exercise [Arginine and citrulline are two amino acids that research has shown to reduce exercise-related accumulations of ammonia by promoting the urea cycle and nitric oxide (NO) biosynthesis. Research suggests that combining arginine and citrulline with BCAA supplementation may alleviate the excess ammonia produced during exercise and BCAA catabolism [Choline is an essential nutrient that has been a focus of recent research for improved performance as well. As a water-soluble quaternary amine of the vitamin B group, choline is important for a number of physiological pathways [The current study examined the effectiveness of chronic (7-day) supplementation of BCAAs, L-citrulline, and A-GPC on physical performance in trained cyclists. It was theorized that the supplement would result in improved performance by increasing peak and average power, reducing time to completion, and reducing measures of perceived exertion in a 20 km TT test and increasing time to fatigue and reducing measures of perceived exertion in a HIEC test as compared to a placebo.