Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation.
Level 2 - randomized trial
Randomized, double-blind, placebo-controlled crossover trial in humans
PubMed 17957000 · doi:10.1152/physiolgenomics.00157.2007
What was done
Twelve young, healthy, nonobese men completed a randomized, double-blind, placebo-controlled crossover trial. Participants took either placebo or creatine monohydrate (20 g/day for 3 days, then 5 g/day for 7 days) for 10 days, followed by a 28-day washout before crossing over. Vastus lateralis muscle biopsies were analyzed for mRNA expression via cDNA microarrays and real-time PCR, and protein content via a protein kinase screen. Body weight, total body water, and fat-free mass were also evaluated.
What was found
Creatine supplementation significantly increased fat-free mass, total body water, and body weight (P < 0.05). It also significantly upregulated (1.3- to 5.0-fold) the mRNA content of genes and protein content of kinases involved in osmosensing, signal transduction, cytoskeleton remodeling, protein and glycogen synthesis regulation, satellite cell proliferation and differentiation, DNA replication and repair, RNA transcription control, and cell survival. Specific baseline and post-treatment numerical values for body composition were not provided in the abstract.
Why it matters
This study identifies large-scale transcriptional and kinase signaling changes in human skeletal muscle following creatine loading, supporting the concept that creatine-driven osmolarity changes trigger cellular growth and remodeling pathways.
Limits
The study is limited by a small sample size of 12 participants restricted entirely to young, healthy, nonobese men. The intervention period was short (10 days), and the abstract does not report exact numerical values or variance for the body composition metrics or individual gene targets.
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