Pre-run Supplements on a 5K Run in Runners

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

In this randomized, single-blind, crossover trial, healthy runners complete four experimental visits, each with a different pre-run supplement or placebo, before a fixed-pace 5 km treadmill run. Measures include running economy, heart-rate drift, oxygen use, CO2 production, ventilation, RER, blood lactate and ketones, and perceptual factors like exertion and focus. A subset may wear continuous glucose monitors to observe glucose changes. Each participant acts as their own control with at least four days between visits.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Age 18-35 years
* Healthy adult
* Able to provide written informed consent
* Regularly engaged in running-based aerobic training at least 3 times per week for at least 30 minutes per session during the past 3 months
* Able to complete a 5 km run in under 30 minutes
* Able and willing to comply with treadmill testing, fingerstick testing, dietary standardization, supplement restrictions, and pre-visit instructions
* Participants randomly selected for the continuous glucose monitoring subgroup must also be willing to undergo Dexcom Stelo continuous glucose monitor placement and wear

Exclusion Criteria:

* Known cardiovascular, metabolic, pulmonary, or neurological disease that may increase the risk associated with exercise testing or materially influence study outcomes
* Uncontrolled hypertension or another cardiovascular condition that, in the investigator's judgment, makes vigorous treadmill exercise unsafe
* Diagnosed type 1 or type 2 diabetes mellitus or another known metabolic disease that may materially influence study outcomes
* Pregnant, breastfeeding, or planning pregnancy during the study period
* Current use of nitrate medications or phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil, tadalafil, or vardenafil
* Known sensitivity or allergy to caffeine, L-citrulline, exogenous ketone/BHB salt products, or any study beverage ingredient
* Current use of stimulant medications or other medications that may significantly influence cardiovascular, blood pressure, or metabolic responses to exercise, as determined by the investigator
* Musculoskeletal injury or condition that limits safe treadmill running
* Smoking or regular use of nicotine products
* Recent illness, surgery, or hospitalization that, in the opinion of the investigators, may interfere with safe participation or study outcomes
* Unable or unwilling to comply with study procedures or pre-visit standardization requirements
* Running fewer than 3 times per week or otherwise not meeting the running-training inclusion criterion

Where it's running

• Saint Louis University, Allied Health Building
  St Louis, Missouri, United States Recruiting

Study contacts

• Principal investigator: Hossein Rafiei — St. Louis University
• Study coordinator: Hossein Rafiei, PhD, RD, ACSM-CPT
• Email: hossein.rafiei@health.slu.edu
• Phone: 314-977-8675

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.