The safety of creatine supplementation has been investigated, however, the safety of a high-dose/short-term or low-dose/long-term supplementation dosing scheme, combined with a resistance training program, a commonly used dosing scheme, has not yet studied. The aim of this study was to evaluate physical performance and the safety of the cited creatine supplementation dosing scheme in a double-blind placebo-controlled study by assessing blood and urine health indicators in subjects undertaking resistance training.

Thirty-four healthy male subjects were randomly assigned to creatine supplement (CREA/7 days, 0.3 g/kg body mass+21 days, 0.03 g/kg) or placebo (PLA) group and both groups participated in a resistance training intervention (6 exercises, 3 sets of 8–12 repetitions per exercise at 85% of 1RM, 3 d/week). Blood and urine samples were collected pre-, 7 and 30 days post-supplementation. For blood (26 parameters) and urine markers (15), between-group differences were calculated by using 2 groups (CREA and PLA)×2 measures (“POST7 minus PRE” and “POST30 minus PRE”) terms.

The CREA group exhibited significant body weight and 1RM increase (POST30 minus PRE) of all evaluated exercises, when compared to PLA group. Regarding the blood and urine health markers, only hematocrit, LDL, Uric Acid, Phosphatase Alkaline and Creatinine exhibited between-group differences, but with small magnitude of differences and maintained into the range of clinical reference values.

Our data suggest that creatine supplementation the used dosing scheme, concomitantly with resistance training, improves physical performance with no evident risk or protection to health for young weightlifters.