1. Creatine supplementation strategies aimed at acutely increasing and maintaining skeletal muscle total creatine content in healthy, young volunteers.
- Author
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Pittas, George, Miller, Jan, Laithwaite, David, and Greenhaff, Paul
- Subjects
CREATINE ,SKELETAL muscle ,VOLUNTEERS' health ,MESSENGER RNA ,DEXTROSE - Abstract
Insight regarding dietary creatine (Cr) supplementation strategies to acutely increase and maintain muscle total creatine (TCr) content is missing. Healthy, young, men ingested 4 × 5 g Cr/day (d) for 5d, followed by 5 g/d for 28 d (Cr group, n=8). To achieve insulin mediated muscle Cr transport, another group (n=16) ingested 4 × 5 g Cr plus 95 g dextrose/d for 5d (CrCHO), and thereafter two sub-groups ingested 5 g of Cr (CrCHO1, n=8) or 5 g Cr plus 95 g dextrose/d for 28 d (CrCHO2, n=8). A fourth group ingested 4 × 5g of Cr plus 14 g protein, 7 g phenylalanine, 7 g leucine and 57 g dextrose/d for 5 d, and once/d thereafter for 28 d (CrPAC, n=8). Muscle biopsies were obtained at 0, and after 5 and 33 d. After 5 d, muscle TCr increased in Cr (p<0.001), CrCHO (p<0.001), and CrPAC (p<0.05) groups, and was numerically greatest in CrCHO; achieving a content reported to be an average maximum (150 mmol/kg). After 33 d, TCr also increased to ~150 mmol/kg in the Cr group (p<0.05), remained unchanged from 5 d in CrCHO2, and tended to decline in CrCHO1. Muscle TCr remained unchanged from 5 d in CrPAC after 33 d, being less than the Cr group (p<0.05). Muscle Cr transporter mRNA expression changed modestly, but the increase in muscle TCr after 5 d was inversely associated with fold-change in mRNA expression (r=0.502, p<0.05). A maximum increase in muscle TCr is achieved after 5 d Cr ingestion alongside 95 g dextrose, and continued consumption of Cr with dextrose will maintain this maximum. Ingestion of Cr alone will achieve a high muscle TCr content too, but takes longer. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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