In one study, 20 healthy men and women, aged 19 to 23, took 14 mg of creatine per pound of body weight per day (equals about 2.5 grams for a 175-pound person) or a placebo for six weeks. Before and after the study, researchers tested body composition, maximum knee-extension strength at 180 degrees, knee-muscle fatigue, and blood levels of creatine.
While the placebo group did not improve, the creatine group was 9 percent more resistant to muscle fatigue during high-intensity knee-extension exercises, saw creatine levels increase 182 percent, and did not gain weight.