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The Study

Creatine supplementation increases glycogen storage but not GLUT-4 expression in human skeletal muscle.

In simple terms

This study saw that people who took creatine had more sugar stored in their muscles for a little while, but their muscle didn’t make more of the protein that helps bring sugar in. But we don’t know if the creatine actually caused this — maybe those people were just different in other ways.

38%

Analysis score

38/ 90

Maximum 90 for a randomized controlled trial.

Where the score came from

Reporting0
Methodology34
Publication100
Statistical23
Study type (basis of the score)
Randomized Controlled Trial
Level 1b - Individual RCT
What’s the bottom line?

Taking creatine for a week makes muscles store more sugar (glycogen), which pulls in water and makes muscles look bigger. But after a week, taking less creatine stops this effect.

Where does this study sit?

Systematic Reviews & Meta-analyses

Max 100

Randomized Trials

Max 90

Cohort Studies

Max 72

Case-Control

Max 58

Cross-Sectional

Max 44

Case Reports & Series

Max 30

Expert Opinion

Max 5
StrongerWeaker
Randomized Trials
Level 1b
38

38 / 100

Quality score

Participants are randomly assigned to treatment or control groups, minimizing bias. Considered the gold standard for testing whether an intervention causes an effect.

Cannot establish causation

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Key takeaways

Summary

Based on the study abstract and findings.

  1. 1Yes — more glycogen + water means muscles appear fuller and may feel slightly heavier, but it's temporary without continued high dosing.
  2. 2Muscle glycogen went up by 18±5% after 5 days of high-dose creatine, but dropped back down after 37 days of low-dose.

Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data

Publication

Journal

Clinical science

Year

2004

Authors

L. V. van Loon, R. Murphy, A. Oosterlaar, D. Cameron-Smith, M. Hargreaves, A. Wagenmakers, R. Snow

113 citations
Analysis v3
Fit Body Science verdict — we translate health studies into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.