Tier 2 — strong

The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance during a marathon run

Buchman AL, O'Brien W, Ou CN, Rognerud C, Alvarez M, Dennis K, Ahn C
International journal of sports medicine 1999 20(5):315-321

Bibliography

PubMed
PMID 10452229
DOI
10.1055/s-2007-971137
Funding
Funding was not specified in the indexed abstract; the full funding disclosure has not been verified.
Competing interests
The accessible abstract does not establish the authors' competing interests; absence of a statement is not evidence of no conflicts.

Study snapshot

DesignRandomized controlled human intervention
ModelAdult humans
Sample23 marathon runners randomized in the indexed report
InterventionGlycine or arginine 10 g three times daily for 14 days; glycine used as the comparator
Duration14 days before a marathon; postrace follow-up to about 48 hours
EndpointsRace performance; Intestinal permeability; Muscle injury markers; Gastrointestinal symptoms

What the study showed, in plain terms

This study compared glycine with arginine before a marathon. Glycine was treated as a comparator, and there was no untreated arm to determine whether it independently improved performance.

Key findings

  • Muscle injury markers rose after the race in both groups.
  • The groups did not show a clear difference in intestinal permeability or most symptoms.
  • Race-time differences cannot establish an ergogenic effect of glycine without a neutral comparison.

What this study can and cannot tell us

Small active-comparator study with multiple outcomes.

The original abstract reports 23 randomized runners; larger numbers transcribed in later summaries should not replace the primary report.

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Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction