Creatine Supplementation

63 deutekom et al50 assessed the effects of cr

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Unformatted text preview: ed the effects of Cr supplementation on muscle properties and sprint performance. Twenty-three well trained rowers were randomly assigned to either a Cr group (n = 11; 20 g/day for 6 days) or a placebo group (n = 12). Testing consisted of 40 consecutive electrical stimulations of the quadriceps at an activation frequency of 150Hz, which was equal to 30% of maximal voluntary isometric peak torque. Repeated measures ANOVA indicated that there was a significant increase in body mass for the Cr group compared with the placebo group. However, there was no group difference for maximal voluntary torque generation, muscle activation as elicited by electrical stimulation, and recovery from the electrically stimulated exercise. Additionally, there were no differences between groups peak power, time to peak power, or work to peak power[50] during the sprint tests. Wiroth et al.[47] examined the potential ergogenic effects of Cr supplementation on maximal pedalling performance by recruiting three groups of subjects (G1 = sedentary, n = 14, mean age 70.1 years; G2 = trained cyclists, n = 14, mean age 66.4 years; and G3 = young sedentary, n = 14, mean age 26.0 years). Within each group, Cr was administered (5g three times daily for 5 days) using a double-blinded, randomised design. Subjects performed five maximal 10-second sprints with 60 seconds of passive recovery between each sprint, with power output, work done and heart rate being recorded during each sprint. Maximal power was significantly increased only for G1 and G3, suggesting that Cr was beneficial in previously untrained older and younger populations but not in previously trained individuals.[47] This is in contrast to the findings of Rawson et al.[11] who reported no significant increases in force or power output in older subjects during an isokinetic test following 5 days of Cr loading. It is possible that the increased training status of the trained cyclist Sports Med 2005; 35 (2) The Effects of Creatine in Sport and Exercise group may have reduced the responsiveness to Cr loading. Assessment of intramuscular Cr s...
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