No acute effects of short-term creatine supplementation on muscle properties and sprint performance

In a double-blind, placebo, controlled study, we investigated the acute eff ects of short-term oral creatine supplementation (20 g . day(-1) for 6 days ) on muscle activation, fatigue and recovery of the m. quadriceps femoris d uring electrical stimulation, and on maximal performance during sprint cycl ing. The quadriceps muscles of 23 well-trained rowers were stimulated at di fferent frequencies (10, 20, 50, 100, 150 and 200 Hz). Furthermore, 40 repe titive, electrically stimulated (duration 220 ms, stimulation frequency 150 Hz) concentric contractions were imposed at a constant angular velocity of 180 degrees s(-1) over a range of 50 degrees (from 90 to 140 degrees knee angle), each extension/flexion cycle lasting 1200 ms. To determine recovery , torque was measured at 20, 50, 80, 120, 180 and 300 s after the last cont raction. In addition, two maximal 30-s sprints were performed on a cycle er gometer with 4 min rest in between. Following shortterm creatine supplement ation, body mass [mean (SEM)] increased (P < 0.05) from 85.7 (2.7) kg to 87 .3 (2.9) kg. Creatine supplementation had no effect on maximal voluntary is ometric torque and muscle activation, or on fatigue and recovery of dynamic exercise. There was also no significant effect on peak power, time to peak power and work to peak power, or total work during both sprints on the cyc le ergometer. II was concluded that short-term oral creatine supplementatio n resulted in increased body mass, but did not enhance muscle performance o r maximal output during sprint cycling.