WHAT WAS PROVEN BY LSU?
Methods- The effects of creatine supplementation on endurance and metabolism during high intensity intermittent exercise was examined using 18 males and females (age 19-26). The subjects were randomly divided into 2 groups (creatine and placebo) and the testing proceeded in two phases. During phase 1 both groups received a placebo. During phase 2 the placebo group again received a placebo, while the creatine group received creatine (C10). Testing consisted of a several high intensity intermittent cycling protocols on a stationary cycle ergometer. Both groups performed all test bouts (in random order) in phase 1 and again in phase 2.Testing consisted of : Continuous (Bout A) - Continuous pedaling at 150% VO2 peak until exhaustion. 30/60 (Bout B) - 30 seconds of pedaling at 150% VO2 peak followed by 60 seconds rest, repeated until exhaustion. 20/40 (Bout C) - 20 seconds pedaling at 150% VO2 peak followed by 40 seconds rest, repeated until exhaustion. 10/20 (Bout D) - 10 seconds pedaling at 150% VO2 peak followed by 20 seconds rest, repeated until exhaustion. Oxygen consumption was measured during all bouts using a Quinton Q-Plex I. Blood samples were also taken periodically during each bout for blood lactate analysis.
Results- The placebo group showed no significant change in time to exhaustion from phase 1 to phase 2 for any of the bouts tested. The creatine group, however, showed a significant increase in time to exhaustion on all bouts (see figure 1). Bout D was impacted significantly more than the other bouts with a more than twofold increase in time to exhaustion (note that bout D was truncated before subjects actually reached exhaustion because even at twice the performance time of phase 1 subjects reported feeling very little fatigue and the ability to continue indefinitely). Oxygen consumption showed no change from phase 1 to phase 2 for the placebo group, while the creatine group showed a significantly lower rate of oxygen consumption on bouts D and C (see figure 2 for Bout D VO2). Blood lactic acid values were also lower on bouts C and D for the creatine group only (see fig 3 & 4 for bout D lactate values).
Discussion- It has recently been demonstrated that supplementation with creatine can lead to an increase in skeletal muscle creatine levels of up to 50% (Harris et. al. 1992). Once creatine enters the muscle it is phosphorylated to creatine phosphate. Creatine phosphate is a major provider of energy during high intensity short term exercise. It is not surprising then that creatine supplementation can enhance the performance of this type of exercise. From a practical standpoint (based on the results of the present study) any sports that involve short bursts of activity followed by rest periods or periods of reduced activity might benefit tremendously from creatine supplementation (ex. football, basketball, soccer, track events, weightlifting etc...). For example, a football player that normally begins to slow down during the third quarter because of fatigue might (with creatine supplementation) be able to maintain his speed for the entire game. Since creatine also lowers lactic acid levels and the feeling of fatigue, this might allow for more intense or longer training sessions. The present study also showed that oxygen consumption was reduced by creatine supplementation. Since oxygen consumption is related to energy expenditure we might conclude that exercise efficiency (work/cost) was also improved. This might also allow for more intense training. Therefore creatine supplementation appears to be a valuable aid for the enhancement of training and performance of many athletic events.
Harris, R.C., Soderlund, K., and Hultman, E., (1992) Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation, Clinical Science, 83, 367-374.
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