Creatine has been extensively researched and found to be a safe and useful supplement for building muscle size and strength. Like protein shakes, you won’t see results right away from supplementing with creatine. But a study published in The Journal of Sports Medicine and Physical Fitness suggests you could notice increased strength within 2 weeks.
Young male subjects supplemented with 0.07 grams of creatine per kilogram of body weight daily during 8 weeks of resistance training. They trained 3 times each week and had strength assessed for 6 exercises every 2 weeks.
Compared to subjects who received a placebo, subjects supplementing with creatine realized significantly greater strength gains on the bench press, leg press and shoulder press after 2 weeks of training. After 8 weeks, members of the creatine group were significantly stronger than placebo users on 4 of the 6 exercises. Researchers theorized greater muscle damage in the creatine group might be the result of greater training intensity.