The purposes of the present investigation were therefore to determine if ingestion of 3 g/day of creatine monohydrate for 28 days would: 1) Increase muscle creatine phosphate and total creatine content at rest and at the end of prolonged endurance exercise; and 2) Increase PF-573228 clinical trial sprint performance at the end of a prolonged bout of endurance exercise. The present study is unique in that it is the first double-blind study to monitor
the effect of prolonged creatine supplementation at the level of the whole body, vascular compartment, and skeletal muscle Methods Subjects Twelve adult male (18-40 yr) endurance-trained (~160 km/wk) cyclists (Table 1) were studied before and after 28 days of ingestion of either 3 g/day creatine monohydrate (n = 6) or placebo (n = 6). The cyclists had been cycling at least 150 km/wk for the past year, and were familiarized with the cycle ergometer during testing of peak aerobic capacity and a 30-minute familiarization session the week prior to performance of the first endurance exercise test. Subjects had not been ingesting creatine or other dietary supplements other than a multivitamin
and carbohydrate beverages for at least MK-0457 order three months prior to the study as determined by questionnaire. The subjects were matched for body weight, percent body fat, VO2peak, and training distance cycled per week. The supplementation regime was administered in a double-blind fashion. The subjects participated in these investigations after completing a medical history and giving informed consent to participate according to the East Carolina University Human Subjects Committee. Table 1 Subject Characteristics Variables Creatine Pre (n = 6) Placebo Pre (n = 6) Creatine Post (n = 6) Placebo Post (n = 6) Age (yr) 25.5 ± 1.6 29.0 ± 0.9 —- —- Height (cm) 177.2 ± 1.9 180.1 ± 2.1 —- —- Weight (cm) 78.1 ± 3.2 78.0 ± 4.1 80.1 ± 3.3* 78.7 ± 4.2 Percent fat (%) Hydrostatic 12.4 ± 1.1 9.6 ±
1.4 12.1 ± 1.4 9.5 ± 1.6 VO2max (L/min) 4.1 ± 0.3 4.2 ± 0.1 4.1 ± 0.3 4.3 ± 0.2 Distance per week (km) 156.9 ± 36.4 163.6 ± 27.1 — — *Different from pre (P < 0.05) Protocol Cyclists click here were tested for peak aerobic capacity and body composition at least 48 hours prior to performance of a two-hour bout of cycling on an electronically-braked cycle ergometer (LODE, Diversified Inc., Brea, CA). The cyclists also completed a diet record for the three days prior to, and the day of, their two-hour cycling session. The experimental protocol is presented in Figure 1. The 2-hour bout consisted of 15 minutes of continuous exercise at 60% VO2peak followed by three, 10-second sprints performed at 110% VO2peak interspersed with 60 seconds cycling at 65% VO2peak. This protocol was repeated eight times, for a total continuous exercise time of two hours.