Effects of Pre-Run Nutritional Supplements During a Fixed-Pace 5 km Treadmill Run
Fueling the Kilometers: Effects of Pre-Run Nutritional Supplements on Physiological Responses During a Fixed-Pace 5 km Treadmill Run
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.
Visão geral do estudo
Status
Descrição detalhada
This is a randomized, single-blind, placebo-controlled crossover study designed to compare acute physiological and perceptual responses to three pre-run nutritional supplements and placebo during a controlled fixed-pace 5 km treadmill run. Healthy, physically active runners will complete one screening/baseline visit and four experimental visits. Each participant will complete all four experimental conditions in randomized order and will serve as their own control. A minimum washout/recovery period of four days will separate experimental visits.
At each experimental visit, participants will receive one of four pre-run conditions: caffeine at 4 mg/kg body weight, L-citrulline at 7 g, an exogenous ketone supplement providing 11.5 g beta-hydroxybutyrate (BHB), or placebo. Study products will be provided in a standardized beverage vehicle, followed by a 45-minute waiting period before the treadmill run.
The primary physiological outcomes of interest are running economy and heart-rate drift during the fixed-pace 5 km treadmill run. Additional outcomes include oxygen consumption, carbon dioxide production, ventilation, respiratory exchange ratio, heart-rate recovery, capillary blood lactate and ketone concentrations, rating of perceived exertion, gastrointestinal symptoms, subjective fatigue, energy, focus, and participant-reported perceptions of the assigned supplement condition.
A prespecified randomly selected subgroup of up to 12 enrolled participants will use a Dexcom Stelo continuous glucose monitor during the experimental phase. CGM-derived glucose responses will be analyzed as exploratory outcomes within this subgroup only.
The study will also evaluate feasibility and tolerability, including visit completion, adverse events, supplement-related symptoms, gastrointestinal symptoms, and completeness of study measurements. The results are intended to characterize within-participant differences among the four conditions and provide preliminary data for future confirmatory studies.
Tipo de estudo
Inscrição (Estimado)
Estágio
- Não aplicável
Contactos e Locais
Contato de estudo
- Nome: Hossein Rafiei, PhD, RD, ACSM-CPT
- Número de telefone: 314-977-8675
- E-mail: hossein.rafiei@health.slu.edu
Locais de estudo
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Missouri
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St Louis, Missouri, Estados Unidos, 63104
- Recrutamento
- Saint Louis University, Allied Health Building
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Contato:
- Hossein Rafiei, PhD RD
- Número de telefone: 314-977-8675
- E-mail: hossein.rafiei@health.slu.edu
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Contato:
- E-mail: hossein.rafiei@health.slu.edu
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Investigador principal:
- Hossein Rafiei, PhD, RD, ACSM-CPT
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Critérios de participação
Critérios de elegibilidade
Idades elegíveis para estudo
Aceita Voluntários Saudáveis
Gêneros Elegíveis para o Estudo
Descrição
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
Plano de estudo
Como o estudo é projetado?
Detalhes do projeto
- Finalidade Principal: Ciência básica
- Alocação: Randomizado
- Modelo Intervencional: Atribuição cruzada
- Mascaramento: Solteiro
Armas e Intervenções
Grupo de Participantes / Braço |
Intervenção / Tratamento |
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Experimental: Sequence 1: Caffeine-L-Citrulline-Placebo-Ketone
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. |
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 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. 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. 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. |
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Experimental: Sequence 2: L-Citrulline-Ketone-Caffeine-Placebo
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. |
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 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. 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. 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. |
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Experimental: Sequence 3: Ketone-Placebo-L-Citrulline-Caffeine
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. |
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 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. 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. 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. |
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Experimental: Sequence 4: Placebo-Caffeine-Ketone-L-Citrulline
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. |
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 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. 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. 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. |
O que o estudo está medindo?
Medidas de resultados primários
Medida de resultado |
Descrição da medida |
Prazo |
|---|---|---|
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Running Economy (VO₂) During the Fixed-Pace 5 km Treadmill Run
Prazo: During the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.
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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. |
During the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.
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Heart-Rate Drift During the Fixed-Pace 5 km Treadmill Run
Prazo: Throughout the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.
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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. |
Throughout the fixed-pace 5 km treadmill run at each of the four experimental visits, approximately 45 minutes after supplement/placebo ingestion.
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Medidas de resultados secundários
Medida de resultado |
Descrição da medida |
Prazo |
|---|---|---|
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Mean Oxygen Consumption (VO₂) During the Fixed-Pace 5 km Treadmill Run
Prazo: During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
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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. |
During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
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Mean Carbon Dioxide Production (VCO₂) During the Fixed-Pace 5 km Treadmill Run
Prazo: During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
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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. |
During the fixed-pace 5 km treadmill run at each of the four experimental visits, beginning approximately 45 minutes after supplement/placebo ingestion.
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Ventilation
Prazo: During the fixed-pace 5 km treadmill run at each of the four experimental visits.
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Pulmonary ventilation will be measured using indirect calorimetry during the fixed-pace 5 km treadmill run and compared across supplement conditions. |
During the fixed-pace 5 km treadmill run at each of the four experimental visits.
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Respiratory Exchange Ratio
Prazo: During the fixed-pace 5 km treadmill run at each of the four experimental visits.
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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. |
During the fixed-pace 5 km treadmill run at each of the four experimental visits.
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1-Minute Heart-Rate Recovery After the Fixed-Pace 5 km Treadmill Run
Prazo: From exercise cessation to 60 seconds after completion of the fixed-pace 5 km treadmill run at each of the four experimental visits.
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Heart-rate recovery will be calculated as the decrease in heart rate from the end of the fixed-pace 5 km treadmill run to 60 seconds after exercise cessation, expressed in beats per minute. Within-participant 1-minute heart-rate recovery will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions. |
From exercise cessation to 60 seconds after completion of the fixed-pace 5 km treadmill run at each of the four experimental visits.
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Capillary Blood Lactate Concentration
Prazo: Immediately before and immediately after the fixed-pace 5 km treadmill run at each experimental visit.
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Capillary blood lactate concentration will be measured using finger-prick blood sampling and a point-of-care analyzer before and after exercise. Pre- to post-exercise responses will be compared across supplement conditions. |
Immediately before and immediately after the fixed-pace 5 km treadmill run at each experimental visit.
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Capillary Blood Ketone Concentration
Prazo: Immediately before and immediately after the fixed-pace 5 km treadmill run at each experimental visit.
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Capillary blood ketone concentration will be measured using finger-prick blood sampling and a point-of-care analyzer before and after exercise. Pre- to post-exercise responses will be compared across supplement conditions. |
Immediately before and immediately after the fixed-pace 5 km treadmill run at each experimental visit.
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Rating of Perceived Exertion
Prazo: During and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Rating of perceived exertion will be assessed using the Borg 6-20 Rating of Perceived Exertion scale, where 6 represents no exertion and 20 represents maximal exertion; higher scores indicate greater perceived exertion. |
During and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Gastrointestinal Symptoms Severity
Prazo: During and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Gastrointestinal symptoms, including nausea, urge to vomit, bloating, belching, and abdominal cramping, will be assessed using visual analog scales anchored from no symptoms to the worst imaginable severity for each symptom. Higher values indicate greater symptom severity. Responses will be compared across the four supplement conditions. |
During and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Subjective Fatigue
Prazo: Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Participant-reported fatigue will be assessed using a single-item 0-10 numeric rating scale, where 0 indicates no fatigue and 10 indicates extreme fatigue. Scores and within-visit changes will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions. |
Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Subjective Energy Level
Prazo: Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Participant-reported energy will be assessed using a single-item 0-10 numeric rating scale, where 0 indicates no energy at all and 10 indicates extremely high energy. Scores and within-visit changes will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions. |
Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Subjective Mental Focus
Prazo: Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Participant-reported mental focus will be assessed using a single-item 0-10 numeric rating scale, where 0 indicates not at all focused and 10 indicates extremely focused. Scores and within-visit changes will be compared across the caffeine, L-citrulline, exogenous ketone, and placebo conditions. |
Immediately before supplement/placebo ingestion and immediately following the fixed-pace 5 km treadmill run at each experimental visit.
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Participant-Reported Guess of Assigned Supplement Condition
Prazo: Immediately following completion of each experimental visit.
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Following each experimental visit, participants will report which supplement condition they believe they received. Responses will be summarized and compared with the actual assigned condition to evaluate participant perception of treatment assignment. |
Immediately following completion of each experimental visit.
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Outras medidas de resultado
Medida de resultado |
Descrição da medida |
Prazo |
|---|---|---|
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Interstitial Glucose Response During the Experimental-Visit Window in the CGM Subgroup
Prazo: From pre-supplement baseline through completion of the immediate post-exercise assessments at each experimental visit.
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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. |
From pre-supplement baseline through completion of the immediate post-exercise assessments at each experimental visit.
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Completion of All Four Experimental Visits
Prazo: Across each participant's approximately 4-6 weeks of study participation.
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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. |
Across each participant's approximately 4-6 weeks of study participation.
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Participants Experiencing Adverse Events
Prazo: From the first study visit through completion of the final study visit, approximately 4-6 weeks per participant.
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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. |
From the first study visit through completion of the final study visit, approximately 4-6 weeks per participant.
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Colaboradores e Investigadores
Patrocinador
Investigadores
- Investigador principal: Hossein Rafiei, St. Louis University
Datas de registro do estudo
Datas Principais do Estudo
Início do estudo (Estimado)
Conclusão Primária (Estimado)
Conclusão do estudo (Estimado)
Datas de inscrição no estudo
Enviado pela primeira vez
Enviado pela primeira vez que atendeu aos critérios de CQ
Primeira postagem (Real)
Atualizações de registro de estudo
Última Atualização Postada (Real)
Última atualização enviada que atendeu aos critérios de controle de qualidade
Última verificação
Mais Informações
Termos relacionados a este estudo
Palavras-chave
Termos MeSH relevantes adicionais
- Aminoácidos, peptídeos e proteínas
- Produtos químicos orgânicos
- Compostos heterocíclicos
- Compostos heterocíclicos, 2 anel
- Compostos heterocíclicos, anel fundido
- Ácidos graxos
- Lipídios
- Ácidos, acíclico
- Ácidos carboxílicos
- Ácidos hidroxi
- Alcalóides
- Purinonas
- Purinas
- Aminoácidos
- Ácidos graxos, voláteis
- Butyrates
- Aminoácidos, diamino
- Cetonas
- Xantinas
- Hidroxibutiratos
- Ketone Bodies
- Cafeína
- Citrulina
- 3-Hydroxybutyric Acid
Outros números de identificação do estudo
- STUDY00000697
Plano para dados de participantes individuais (IPD)
Planeja compartilhar dados de participantes individuais (IPD)?
Descrição do plano IPD
Individual participant data will not be shared with outside researchers. Only de-identified, aggregate study results may be used for analysis, publication, or presentation, in accordance with the approved protocol and participant privacy protections.
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