EFFECTS OF CYP1A2 163 C>A POLYMORPHISM (rs762551) ON CAFFEINE KINETICS AND INGESTION ON ANAEROBIC CAPACITY, POWER AND PHYSICAL PERFORMANCE
Xanthine; genotype; nutritional supplementation; ergogenic effects; Cytochrome P450 1A2;
The present study constructed a literature review to analyze the current state of the art on caffeine supplementation (CAF) and the CYP1A2 163 C>A polymorphism on aerobic and anaerobic physical performance. The findings indicate that CAF improves the performance in aerobic tests, but the results of the interaction with the genotype are still very controversial and need more studies with better methodological qualities and with a larger sample size in order to have a more reliable population inference. On the anaerobic performance, the analysis shows that the CAF seems to have an influence in relation to the dosage, the exercise duration and its fatigue-inducing profile. In short-duration exercises with a low fatigue-inducing profile, CAF results are less effective and more controversial, while for exercises with slightly longer duration and with a higher fatigue-inducing profile, CAF has a more precise benefit. Regarding polymorphism in anaerobic performance, the results are still quite controversial, but the few articles that found a significant interaction between CAF supplementation and the studied CYP1A2 genotypes showed that AA homozygotes seem to have more influence on performance. The original article already published aimed to investigate whether variations in the 163 C> CYP1A2 genotypes modified the ergogenic effects of CAF on strength, power, muscular endurance, agility and endurance in adolescent athletes. One hundred adolescents (age = 15 ± 2 years) were recruited, ingested CAF (6 mg.kg−1) or placebo (PLA, 300 mg cellulose) 1 hour before performing a sequence of physical tests: handgrip strength, jumping verticals, agility test, crunches, crunches and the Intermittent Recovery Yo-Yo Test level 1. Compared to PLA, CAF improved the crunches, crunches test and increased the distance covered in the Yo-Yo IR1 test. There was no influence of CAF on handgrip strength, jump height with counter movement, jump height with stride and time in the agility test. When present, the ergogenic effect of CAF was not genotype dependent. Finally, the present study proposed a research project that aims to evaluate the kinetics of CAF within two hours after ingestion of the supplement and, in a second phase, to evaluate the effect of individualized acute intake of CAF associated with the genetic polymorphism of CYP1A2 about high-intensity physical performance. 45 physically active men aged 18 and over will be recruited. Anthropometric assessments will be carried out; food survey and energy intake guidelines for standardizing nutritional status; familiarization with high intensity protocols, maximal incremental test to determine maximal oxygen uptake (VO2max). The protocol will be divided into 2 days with the following tests: day 1 – Handgrip, maximum voluntary contraction and Wingate + EMG in contraction and Wingate + peak lactate after Wingate; day 2- Tests of jumps with countermovement, lumbar dynamometry and test against the clock of 1km on bicycle + peak lactate. Experimental Design: The project will be divided into two phases, the first for evaluating individual genetic polymorphism and evaluation of CAF kinetics, where, in a single visit to the laboratory, the subject will undergo a 4mL blood collection in a tube with EDTA to analysis of the genetic profile of CYP1A2. Then, the subject will ingest CAF and will have 4mL of blood collected every 15 minutes until the 135th minute, for serum extraction and storage for subsequent analysis of serum CAF. Subsequently, in the second phase of the study, individuals will be divided into 3 groups based on the genetic polymorphism: (1) homozygous AA, n=15, (2) heterozygous AC, n=15, (3) homozygous CC, n=15 and (4) grouped, n=45 (all subjects added, regardless of polymorphism, for data analysis). The subjects will receive CAF capsules and placebo, selected in random order according to each day of testing, after their plasmatic peak of CAF, previously analyzed, they will perform the tests according to each day of visit. The visits will be carried out separated by a minimum of 72 hours and a maximum of 96 hours apart. In all visits, the Borg's perceived exertion scale (6-20) will be used. Blood tests will be performed at the Laboratory of Applied Sports Sciences (LACAE) at the Federal University of Alagoas, at the Molecular and Cell Biology Laboratory at the Institute of Biological and Health Sciences and at the Experimental Nutrition Laboratory at the Faculty of Nutrition. Data analyzes will be performed using the statistical software Statistica® version 13.2, endowing a significance level of p < 0.05 and normality of distribution will be evaluated by applying the Shapiro-Wilk test and the homogeneity of variances by Levene's test. From these procedures, parametric or non-parametric methods will be used, as indicated, using the Factorial ANOVA test or its corresponding.