Health TrialsbyHealthPanel

Effects of Pre-Run Nutritional Supplements During a Fixed-Pace 5 km Treadmill Run

ConditionsExercise PhysiologyNutritional Supplementation
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-35
SponsorSt. Louis University

About 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.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

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

Disqualifiers

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

Trial design

Design model

Crossover

Treatments tested in this trial

  • Caffeine

    Dietary supplement

    Caffeine will be administered at exactly 4 mg/kg body weight. The individualized dose will be calculated using body weight measured at the baseline visit. The commercially manufactured capsule contents will be weighed by trained study staff using a calibrated analytical balance to obtain the protocol-specified dose. Caffeine will be dispensed in the standardized study beverage and consumed 45 minutes before the fixed-pace 5 km treadmill run.

  • L-Citrulline

    Dietary supplement

    L-citrulline will be administered at exactly 7.0 g. The commercially manufactured pure L-citrulline powder will be weighed using a calibrated analytical balance, dispensed in the standardized study beverage, and consumed 45 minutes before the fixed-pace 5 km treadmill run.

  • Exogenous Ketone (Beta-Hydroxybutyrate)

    Dietary supplement

    The exogenous ketone condition will consist of one 15 g serving of Nutricost Ketone BHB Salt 4-in-1 Powder, providing 11.5 g beta-hydroxybutyrate (BHB) as calcium, magnesium, sodium, and potassium BHB salts. The supplement will be dispensed in the standardized study beverage and consumed 45 minutes before the fixed-pace 5 km treadmill run.

  • placebo beverage

    Other intervention

    The placebo will be a study-prepared beverage containing water, food-grade lime flavoring, and stevia, with no active study supplement. It will use the same standardized final volume as the active conditions and will be consumed 45 minutes before the fixed-pace 5 km treadmill run.

Treatment groups

20 Participants
are divided into 4 treatment groups
Group A: Sequence 1: Caffeine-L-Citrulline-Placebo-KetoneExperimental treatment 4 interventions
Group B: Sequence 2: L-Citrulline-Ketone-Caffeine-PlaceboExperimental treatment 4 interventions
Group C: Sequence 3: Ketone-Placebo-L-Citrulline-CaffeineExperimental treatment 4 interventions
Group D: Sequence 4: Placebo-Caffeine-Ketone-L-CitrullineExperimental treatment 4 interventions

Trial outcomes

Primary outcomes

1

Running Economy (VO₂) During the Fixed-Pace 5 km Treadmill Run

Running economy will be assessed using oxygen consumption (VO₂) measured by indirect calorimetry during standardized portions of the fixed-pace 5 km treadmill run. Within-participant running-economy responses will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions.

Time frame
During the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.
2

Heart-Rate Drift During the Fixed-Pace 5 km Treadmill Run

Heart-rate drift will be assessed from continuous heart-rate monitoring as the change in heart rate over the course of the fixed-pace 5 km treadmill run. Within-participant heart-rate drift will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions.

Time frame
Throughout the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.

Secondary outcomes

1

Mean Oxygen Consumption (VO₂) During the Fixed-Pace 5 km Treadmill Run

Oxygen consumption (VO₂) will be measured continuously by indirect calorimetry and summarized as the mean body-mass-normalized VO₂ (mL/kg/min) during the fixed-pace 5 km treadmill run. Within-participant mean VO₂ will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions.

Time frame
During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
2

Mean Carbon Dioxide Production (VCO₂) During the Fixed-Pace 5 km Treadmill Run

Carbon dioxide production (VCO₂) will be measured continuously by indirect calorimetry and summarized as the mean VCO₂ (L/min) during the fixed-pace 5 km treadmill run. Within-participant mean VCO₂ will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions.

Time frame
During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
3

Ventilation

Pulmonary ventilation will be measured using indirect calorimetry during the fixed-pace 5 km treadmill run and compared across supplement conditions.

Time frame
During the fixed-pace 5 km treadmill run at each of the four experimental visits.
4

Respiratory Exchange Ratio

Respiratory exchange ratio (RER), calculated from oxygen consumption and carbon dioxide production, will be evaluated during the fixed-pace 5 km treadmill run and compared across supplement conditions.

Time frame
During the fixed-pace 5 km treadmill run at each of the four experimental visits.

Other outcomes

1

Interstitial Glucose Response During the Experimental-Visit Window in the CGM Subgroup

Interstitial glucose will be measured continuously using continuous glucose monitoring in the prespecified randomly selected CGM subgroup. Only CGM data collected from the pre-supplement baseline through completion of the immediate post-exercise assessments at each experimental visit will be retained for analysis. Inter-visit CGM data will not be analyzed. Within-participant glucose responses will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions.

Time frame
From pre-supplement baseline through completion of the immediate post-exercise assessments at each experimental visit.
2

Completion of All Four Experimental Visits

Feasibility will be assessed by the number and proportion of enrolled participants who complete all four randomized experimental visits and the full four-condition crossover protocol.

Time frame
Across each participant's approximately 4-6 weeks of study participation.
3

Participants Experiencing Adverse Events

Adverse events and adverse responses occurring in association with study supplementation or exercise testing will be recorded throughout study participation. The number and proportion of participants experiencing one or more adverse events will be summarized.

Time frame
From the first study visit through completion of the final study visit, approximately 4-6 weeks per participant.

Sponsors and contacts

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St. Louis University

Lead sponsor

Source ClinicalTrials.gov
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