NCT07317921

Validating IAAO for Muscle Outcomes

Validating the Indicator Amino Acid Oxidation Technique for Muscle Outcomes

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 8 (estimated)
• Sponsor: University of Toronto · Academic / Other
• Sex: All
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

Consuming dietary protein stimulates whole-body and muscle protein synthesis, the latter of which is typically measured using invasive primed constant infusions of stable isotopes with concurrent muscle biopsies. Alternative non-invasive methodologies have been developed (namely the indicator amino acid oxidation (IAAO) technique) to estimate the impact of protein ingestion on whole-body protein synthesis as a proxy for determining dietary protein requirements. Given that the IAAO technique is based on principles of protein metabolism which occur in the liver, it is unclear how representative the IAAO outcomes of whole-body protein synthesis is to skeletal muscle protein synthesis. Validation of the IAAO technique against gold-standard, biopsy-derived measures of muscle metabolism (i.e., muscle protein synthesis) would assist in mitigating the invasiveness of muscle physiology and nutrition research.

Conditions

• Protein Metabolism

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	Protein + Stable Isotope Tracer Beverage	Participants will consume 12 half-hourly (6 hours) isoenergetic, isonitrogenous beverages containing 0.9g/kg fat-free mass/day protein. Drinks will be enriched with stable isotopes \[2H5\]Phenylalanine and \[1-13C\]Phenylalanine, which will respectively allow for determination of muscle protein synthesis and whole-body protein synthesis over the subsequent 6 hours of feeding

Timeline

• Start date: 2025-12-01
• Primary completion: 2026-03-20
• Completion: 2026-05-20
• First posted: 2026-01-05
• Last updated: 2026-01-05

Locations

1 site across 1 country: Canada