Greater concentrations of creatine in muscle improves performance
The effect of creatine supplementation has been studied in people with different levels of fitness and athletic ability, ranging from elite athletes to relatively unfit beginners.

Creatine supplementation had a performance-enhancing effect for a wide range of sports.

For sports that require speed, such as sprinting, long jump, swimming, kayaking/rowing, and for intensive strength training by bodybuilders and cyclists, short-term creatine supplementation can greatly improve performance in the areas of maximum strength and endurance (5-15%), with interval training in the maximum range (5-20%), with power production in short sprints (approx. 30%,) and in training with repetitive sprints (5-15%).

Different mechanisms are involved in the ergogenic effects of creatine supplementation:

1.Higher phosphocreatine concentrations serve as immediate reserves for ATP during exertion.
2.Increased phosphocreatine resynthesis rate during and after exertion due to increased levels of creatine.
3.Smaller decrease in muscle pH during exertion.
4.Greater training capacity.
5.Increase in muscle mass (absolute power output).
Short-term creatine supplementation over five days (20 g per day) increased the phosphocreatine resynthesis rate after recovery from intense exercise (Diagram 1)

Phosphocreatine resynthesis is critical for restoring muscle power at the beginning of the next set of intensive exercises. An increased resynthesis rate makes it possible to more intensive training sets, which is an advantage for explosive sports disciplines in particular.

During very intensive, repetitive forms of exercise there is enough ATP or 1-2 seconds, and phosphocreatine is available for the immediate regeneration of ATP. However, phosphocreatine stores last approximately 10 seconds. Increasing Phosphocreatine levels in muscle results in the delayed breakdown of phosphocreatine, which has a beneficial effect on muscle performance. More than 20 clinical trials have shown that creatine supplementation significantly improves muscle strength and/or performance during short bouts of high-intensity exercise.

The greatest improvements in performance can be found during series of repetitive high-intensity types of exertion that are interrupted by a fairly brief period of rest (e.g., 20-60 seconds). The rest breaks are sufficient to achieve greater recovery of phosphocreatine concentrations.

In one experiment, athletes were given 20 g creatine monohydrate per day for 6 days or placebo. They had to perform ten 6-second heats of high-intensity cycling exercise, interrupted by 30-second recovery periods. The athletes were requested to achieve a speed of 140 rpm. The resistance on the training bicycle was set so that the athletes were unable to maintain the target speed for more than 4 to 6 intervals. No differences were observed between the two groups prior to creatine supplementation, but short-term creatine supplementation resulted in significantly improved performance (Diagram 2).

Creatine supplementation likewise produced less formation of lactate, even though the same amount of work was done (Diagram 3).

In an additional study, muscle lactate accumulation was 70% lower after creatine supplementation after 5 standardized 6-second heats of high-intensity exercise.

Creatine supplementation is common in these sports: bodybuilding, weightlifting, wrestling, rowing, cycling, mountain biking, tennis, skiing, American football, soccer, rugby, basketball, ice hockey, volleyball, handball, and track and field (sprinting, shot put, javelin and discus).