The purpose of the present study was to determine if this specific CYP1A2 polymorphism influences the ergogenic effect of caffeine supplementation in trained cyclists. Methods Subjects A total of 36 male recreationally competitive cyclists participated in the present study. One of these participants was excluded from the study
post-hoc, as their cycling performance differed by more than two standard deviations from the mean value of the group. Therefore, 35 cyclists (age = 25.0 ± 7.3 yrs, height = 178.2 ± 8.8 cm, weight = 74.3 ± 8.8 kg, VO2max = 59.35 ± 9.72 ml·kg-1·min-1) were used for data analysis. GDC-0449 chemical structure Written informed consent was obtained from all participants prior to participation and the study and consent form were approved by the James Madison University Institutional Review Board. Habitual caffeine intake
was self-reported by participants. Briefly, participants were asked for their average weekly intake of coffee, tea, soda, chocolate, and other caffeinated beverages. Typical milligram doses [14] were assigned to each and an approximate daily intake was obtained. Based on previous criteria [15], participants were then characterized as having low (0-150 mg·day-1), moderate CX-5461 datasheet (151-300 mg·day-1) and high (> 300 mg·day-1) caffeine intake. Maximal exercise test Cyclists began the test at a work rate of 150 W on an electrically braked cycle ergometer, with load increases of 20 W each minute until volitional exhaustion. Maximal oxygen uptake (VO2max) was defined as the highest 1-minute oxygen value obtained during the test. Oxygen uptake (VO2) was monitored continuously via a Sensormedics Vmax (Yorba Linda, CA) metabolic measurement system calibrated in advance
of all tests. Heart rate was monitored throughout the test using a Polar Heart Rate Monitor (Lake Success, NY). 40-kilometer time trial Time trials were performed on two separate occasions. Protein kinase N1 All testing was done in the morning following a 12-hour fast and at least 24 hours after any caffeine ingestion. Subjects were instructed to maintain their training and not increase or decrease their volume or intensity over the course of the study. One hour prior to testing, cyclists ingested capsules containing either 6 mg of anhydrous caffeine per kilogram body weight or white flour (placebo) randomly administered in double-blind fashion. Time trials were performed on an indoor cycle trainer (Velotron; Racermate, Seattle, WA) on a computer-simulated course. The course consisted of eight laps of a flat, five-kilometer loop. Cyclists were free to self-select the resistance by changing gears during the test and were allowed to track distance completed on the course via a video display. However, they were blinded to their time, speed, and power output during the trials. Water was available for the cyclists to ingest ad libitum.