EFFECT OF ORAL CREATINE SUPPLEMENTATION ON SKELETAL-MUSCLE PHOSPHOCREATINE RESYNTHESIS

Biopsy samples were obtained from the vastus lateralis muscle of eight subjects after 0, 20, 60, and 120 s of recovery from intense electric ally evoked isometric contraction. Later (10 days), the same procedure s were performed using the other leg, but subjects ingested 20 g creat ine (Cr)/day for the preceding 5 days. Muscle ATP, phosphocreatine (PC r), free Cr, and lactate concentrations were measured, and total Cr wa s calculated as the sum of PCr and free Cr concentrations. In five of the eight subjects, Cr ingestion substantially increased muscle total Cr concentration (mean 29 +/- 3 mmol/kg dry matter, 25 +/- 3%; range 1 9-35 mmol/kg dry matter, 15-32%) and PCr resynthesis during recovery ( mean 19 +/- 4 mmol/kg dry matter, 35 +/- 6%; range 11-28 mmol/kg dry m atter, 23-53%). In the remaining three subjects, Cr ingestion had litt le effect on muscle total Cr concentration, producing increases of 8-9 mmol/kg dry matter (5-7%), and did not increase PCr resynthesis. The data suggest that a dietary-induced increase in muscle total Cr concen tration can increase PCr resynthesis during the 2nd min of recovery fr om intense contraction.