Validating IAAO for Muscle Outcomes

What this study involves

The registry does not currently label this study as recruiting. Ask about its status before planning a screening visit.

Study type

Interventional

Phase

Not applicable

Age range

18 years - 35 years

Sex eligible

All sexes

Healthy volunteers

Accepted

Participants

8 Estimated

These are starting points, not an eligibility decision. The research team must review the full requirements.

About the research

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.

Who may be able to participate?

The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.

Inclusion Criteria:

• Participants will be aged 18-35 years old
• Participants will have a BMI within the normal range (i.e., 18.5-24.9) and waist-to-hip circumference ratio of \<0.95 for males and \<0.8 for circumference for females to ensure homogeneity of the sample population
• Participants are willing to abide by the compliance rules of this study (e.g., abstain from extraneous physical activity 48h prior to session 4
• Self-reported regular menstrual cycle (25-35d) within the last 3 months (female participants)
• Physical activity score of ≥24 units as measured by the Godin leisure time exercise questionnaire

Exclusion Criteria:

• Inability to adhere to any of the compliance rules judged by principal investigator
• Self-reported regular tobacco or illicit drug use (e.g., growth hormone or testosterone)
• Current use of hormonal contraceptives
• Individuals with a history of allergy to local anesthetics (e.g., lidocaine)

Treatment, groups and participation

The registry may describe treatments and study duration without a complete visit calendar. Ask the study team for the exact schedule, procedures, risks, costs and alternatives. Keep your usual care plan unless your treating clinician tells you otherwise.

Assignment

Not applicable

Masking

No masking

What researchers are measuring

Outcome measures describe what is being studied. They are not proof that a treatment works.

Primary measures

Research locations (1)

The overall study status and a local site’s status can differ. Confirm that location’s availability before traveling.

1 locations

Study team and timeline

Lead sponsor

University of Toronto

Study start

Dec 1, 2025 Actual

Primary completion

Apr 17, 2026 Actual

Study completion

Dec 20, 2026 Estimated

First posted

Jan 5, 2026 Actual

Last updated

Nov 9, 2026 Actual

Official study contacts

No central contact is listed. Check the locations and the official record.