Effects of serum creatine supplementation on muscle creatine and phosphagen levels

Muscle Marketing USA (Valencia, CA) has claimed that liquid ATP Advantage™ Creatine Serum (CS) more effectively transports creatine to muscle than creatine monohydrate powder (CM). To date, no independent university lab has been able to verify label claims of the creatine content in CS and prior studies have shown no effect of CS supplementation on blood. creatine levels. This study examined whether CS supplementation has any affect on muscle adenosine triphosphate (ATP), free creatine (FCr), phosphocreatine (PC), or total creatine (TCr) levels. 40 male subjects (83±13 kg) with no history of creatine use had percutaneous muscle biopsies obtained from the vastus lateralis using standard procedures prior to and following 5-days of supplementing their diet in a randomized and double blind manner with either 5 mL of CS purportedly providing 2.5 grams of CM equivalent (LD-CS), 5 mL of a placebo (LD-P), 8 x 5 mL of CS purportedly providing 20 grams of CM equivalent (HD-CS), or 8 x 5 mL of P (HD-P). One group ingested 4 x 5 grams of CM for 5 days as a non-blinded benchmark control. Results revealed that none of the supplementation protocols had a significant effect on ATP concentrations. CM supplementation significantly increased muscle FCr content while remaining groups had no effects (LD-CS -12.3±11.3; LD-P -8.6±24.7; HD-CS 3.8±14.7; HD-P -2.7±14.1; CM 30.8±27.7 %, p=0.001). No significant differences were observed among groups in PC concentrations (p=0.53). These findings indicate that CS (at doses equivalent to 1 and 8 times label claims) is not an effective form of creatine to promote muscle creatine and/or phosphagen retention. Therefore, claims that that CS is a more effective form of creatine than creatine monohydrate appear to be false.