Effect of Oral Creatine Supplementation on Single-Effort Sprint Performance in Elite Swimmers

Oral supplementation with creatine monohydrate (Cr.H2O) has been reported to increase muscle creatine phosphate levels. The aim of the present study was to determine the effect of such supplementation on performance of a single-effort sprint by elite swimmers. Thirty-two elite swimmers (M = 18, F = 14; age = 17-25 years) from the Australian Institute of Sport were tested on two occasions, 1 week apart. Tests performed were 25-m, 50-m, and 100-m maximal effort sprints (electronically timed with dive start, swimmers performing their best stroke), each with approximately 10 min active recovery. A 10-s maximal leg ergometry test was also undertaken. Swimmers were divided into two groups matched for sex, stroke/event, and sprint time over 50 m, and groups were randomly assigned to 5 days of Cr.H2O supplementation (4 · day-1 × 5 g Cr.H2O + 2 g sucrose, n = 16) or placebo (4 · day-1 × 5 g Polycose + 2 g sucrose, n = 16) prior to the second trial. Results revealed no significant differences between the group means for sprint times or between 10-s maximal leg ergometry power and work. This study does not support the hypothesis that creatine supplementation enhances single-effort sprint ability of elite swimmers.</p

Sprint training reduces urinary purine loss following intense exercise in humans

The influence of sprint training on endogenous urinary purine loss was examined in seven active male subjects (age: 23.1 ± 1.8 years, weight: 76.1 ± 3.1 kg, VO2peak: 56.3 ± 4.0 ml.kg-1.min-1). Each subject performed a 30s sprint performance test (PT), before and after 7 days of sprint training. Training consisted of fifteen 10s sprints on an air-braked cycle ergometer performed twice per day. A rest period of 50s separated each sprint during training. Sprint training resulted in a 20% higher muscle ATP immediately after PT, a lower IMP (57% and 89%, immediately following and after 10 min recovery from PT, respectively), and inosine accumulation (53% and 56%, immediately following and 10 min after the PT, respectively). Sprint training also attenuated the exercise-induced increases in plasma inosine, hypoxanthine (Hx) and uric acid during the first 120 min of recovery and reduced the total urinary excretion of purines (inosine + Hx + uric acid) in the 24 hours recovery following intense exercise. These results show that intermittent sprint training reduces the total urinary purine excretion after a 30s sprint bout