Nutritional Supplements for Exercise Performance
What You Need to Know Before You Apply
What is the purpose of this trial?
This study will examine how three commonly used pre-run nutritional supplements-caffeine, L-citrulline, and an exogenous ketone supplement-affect physiological and perceptual responses during a fixed-pace 5 km treadmill run in healthy, physically active runners.
Participants will complete one screening and baseline visit followed by four experimental visits in a randomized order. At each experimental visit, participants will receive caffeine, L-citrulline, an exogenous ketone supplement, or placebo before completing a fixed-pace 5 km treadmill run. Each participant will receive all four conditions and will therefore serve as their own control.
The study will evaluate measures including running economy, heart-rate responses, oxygen consumption, respiratory measures, blood lactate and ketone concentrations, perceived exertion, gastrointestinal symptoms, fatigue, energy, and focus. A randomly selected subgroup will also wear a continuous glucose monitor to explore glucose responses during the experimental visits. The study will also assess the feasibility and tolerability of completing repeated treadmill trials under the four supplement conditions.
Who Is on the Research Team?
Hossein Rafiei
Principal Investigator
St. Louis University
Are You a Good Fit for This Trial?
This trial is for healthy, physically active runners. Participants should not have any health conditions that would prevent them from safely running on a treadmill or taking nutritional supplements.Inclusion Criteria
Exclusion Criteria
What Are the Treatments Tested in This Trial?
Interventions
- Caffeine
- Exogenous Ketone (Beta-Hydroxybutyrate)
- L-Citrulline
Trial Overview
The study tests how three pre-run supplements—caffeine, L-citrulline, and exogenous ketones—affect physical and mental responses during a fixed-pace 5 km treadmill run compared to a placebo. Each participant tries all four options in random order.
How Is the Trial Designed?
4
Treatment groups
Experimental Treatment
Participants assigned to this randomized crossover sequence will receive placebo, followed by caffeine, exogenous ketone, and L-citrulline across four experimental visits. Each intervention will be administered 45 minutes before a fixed-pace 5 km treadmill run. Experimental visits will be separated by a minimum washout/recovery period of four days.
Participants assigned to this randomized crossover sequence will receive exogenous ketone, followed by placebo, L-citrulline, and caffeine across four experimental visits. Each intervention will be administered 45 minutes before a fixed-pace 5 km treadmill run. Experimental visits will be separated by a minimum washout/recovery period of four days.
Participants assigned to this randomized crossover sequence will receive L-citrulline, followed by exogenous ketone, caffeine, and placebo across four experimental visits. Each intervention will be administered 45 minutes before a fixed-pace 5 km treadmill run. Experimental visits will be separated by a minimum washout/recovery period of four days.
Participants assigned to this randomized crossover sequence will receive caffeine, followed by L-citrulline, placebo, and exogenous ketone across four experimental visits. Each intervention will be administered 45 minutes before a fixed-pace 5 km treadmill run. Experimental visits will be separated by a minimum washout/recovery period of four days.
Find a Clinic Near You
Who Is Running the Clinical Trial?
St. Louis University
Lead Sponsor
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