FueL Use During eXercise in Males and Females (FLUX)
Influence of Pre-exercise Nutrition on Exercise Fuel Use in Males and Females
This study will investigate whether pre-exercise nutrition influences sex differences in fuel utilization during endurance exercise. Twenty-four recreationally active adults (12 females and 12 males) will complete three experimental exercise trials in a randomized, counterbalanced crossover design. Before each trial, participants will consume either a carbohydrate beverage, a protein-based beverage, or a flavour-matched non-caloric beverage representing the fasted condition. Thirty minutes later, participants will complete 90 minutes of moderate-intensity cycling followed by a cycling time-to-task-failure test. Whole-body carbohydrate and fat oxidation, exogenous substrate oxidation, blood metabolites, and exercise performance will be assessed.
Descripción general del estudio
Estado
Estado
Condiciones
Condiciones
Intervención / Tratamiento
Intervención / Tratamiento
Descripción detallada
Sex differences in substrate utilization during fasted endurance exercise are well established, with females generally demonstrating greater reliance on fat oxidation and lower carbohydrate utilization than males. However, exercise is frequently performed following nutrient ingestion, and it remains unclear whether sex differences in substrate utilization persist when carbohydrate or protein is consumed before exercise.
This randomized, counterbalanced crossover study will compare three pre-exercise nutritional conditions: carbohydrate (CHO), protein (PRO), and fasted/placebo (FAST). Participants will complete each condition separated by a minimum three-day washout. Following an overnight fast, participants will consume the assigned beverage and rest for 30 minutes before completing 90 minutes of cycling at 65% of VO2peak. This will be followed by a two-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate.
The primary objective is to determine whether pre-exercise nutrition modifies sex differences in whole-body carbohydrate and fat oxidation and exogenous substrate oxidation during exercise. A secondary objective is to determine the effects of pre-exercise nutrition and sex on subsequent exercise performance.
Tipo de estudio
Tipo de estudio
Inscripción (Estimado)
Inscripción
Fase
Fase
- No aplica
Contactos y Ubicaciones
Estudio Contacto
Estudio Contacto
- Nombre: Jenna Gillen, PhD
- Número de teléfono: 4169783244
- Correo electrónico: jenna.gillen@utoronto.ca
Copia de seguridad de contactos de estudio
- Nombre: Victoria Bennett
- Número de teléfono: 4169783244
- Correo electrónico: victoria.bennett@mail.utoronto.ca
Ubicaciones de estudio
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Ontario
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Toronto, Ontario, Canadá, M5S 2C9
- Reclutamiento
- Goldring Centre for High Performance Sport
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Contacto:
- Jenna Gillen
- Número de teléfono: 4169783244
- Correo electrónico: jenna.gillen@utoronto.ca
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Contacto:
- Victoria Bennett
- Número de teléfono: 4169783244
- Correo electrónico: victoria.bennett@mail.utoronto.ca
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Criterios de participación
Criterio de elegibilidad
Criterio de elegibilidad
Edades elegibles para estudiar
Acepta Voluntarios Saludables
Géneros elegibles para el estudio
Descripción
Inclusion Criteria:
- Participating in ≥150 minutes of moderate-to-vigorous physical activity per week
- VO₂peak classified as "good" or above based on American College of Sports Medicine normative values: >35.0 mL/kg/min for females and >39.0 mL/kg/min for males
- Body mass index (BMI) between 18 and 27 kg/m²
- Participating in 3-5 structured exercise sessions per week
- Weight stable, defined as within ±2 kg for at least 6 months
- Non-smoker
- Females must be eumenorrheic
Exclusion Criteria:
- Polycystic ovarian syndrome (PCOS) or endometriosis Current use of oral contraceptives or oral contraceptive use within the previous 3 months Diagnosed cardiovascular or metabolic disease Hypergonadism or hypogonadism Use of medications for management of blood glucose or lipid metabolism Pregnant or <12 months postpartum Lactating or breastfeeding within 3 months of study commencement Menopausal Recreational tobacco smoking Inability to complete the study exercise protocols or comply with pre-trial dietary or physical activity controls Use of medications that may affect substrate metabolism, including corticosteroids or non-steroidal anti-inflammatory drugs (NSAIDs) Currently following a low-carbohydrate diet, such as a ketogenic or Atkins diet
Plan de estudios
¿Cómo está diseñado el estudio?
Detalles de diseño
- Propósito principal: Ciencia básica
- Asignación: Aleatorizado
- Modelo Intervencionista: Asignación cruzada
- Enmascaramiento: Doble
Número de brazos
Armas e Intervenciones
Grupo de participantes/brazoGrupo de participantes/brazo |
Intervención / TratamientoIntervención / Tratamiento |
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Experimental: Carbohydrate (CHO)
Participants will consume a carbohydrate beverage following an overnight fast. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate. |
A carbohydrate beverage providing 1 g glucose/kg body mass, enriched with 1 mg/kg body mass [U-13C6]-D-glucose for assessment of exogenous carbohydrate oxidation, with calorie-free flavouring. The beverage will be consumed within 5 minutes, 30 minutes before exercise. |
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Experimental: Protein (PRO)
Participants will consume a protein-based beverage following an overnight fast. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate. |
A protein-based beverage providing 0.45 g protein/kg body mass and supplemented with 0.24 g fat/kg body mass to match the energy content of the carbohydrate condition. The beverage is enriched with L-[1-13C]leucine and flavour-matched to the carbohydrate beverage. It will be consumed within 5 minutes, 30 minutes before exercise. |
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Comparador de placebos: Fasted (FAST)
Participants will remain fasted and consume a non-caloric, flavour-matched beverage. Thirty minutes after beverage consumption, participants will complete 90 minutes of cycling at 65% of VO2peak, followed by a 2-minute rest and a cycling time-to-task-failure test at 85% of maximal work rate. |
A non-caloric beverage consisting of water and sugar-free flavouring, flavour-matched to the carbohydrate beverage. The beverage will be consumed within 5 minutes following an overnight fast, 30 minutes before exercise. |
¿Qué mide el estudio?
Medidas de resultado primarias
Medidas de resultado primarias
Medida de resultado |
Medida Descripción |
Periodo de tiempo |
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Whole-body carbohydrate oxidation
Periodo de tiempo: During the 90-minute exercise bout
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Whole-body carbohydrate oxidation will be calculated from oxygen consumption (VO2) and carbon dioxide production (VCO2) measured by indirect calorimetry during 90 minutes of moderate-intensity cycling. Carbohydrate oxidation will be compared between the carbohydrate, protein, and fasted conditions and between females and males. |
During the 90-minute exercise bout
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Whole-body fat oxidation
Periodo de tiempo: During the 90-min exercise bout
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Whole-body fat oxidation will be calculated from VO2 and VCO2 measured by indirect calorimetry during 90 minutes of moderate-intensity cycling. Fat oxidation will be compared between the carbohydrate, protein, and fasted conditions and between females and males. |
During the 90-min exercise bout
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Exogenous glucose oxidation
Periodo de tiempo: During the 90-min exercise bout
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Exogenous glucose oxidation will be determined during the carbohydrate condition using breath 13CO2 enrichment following ingestion of [U-13C6]-D-glucose. Breath samples will be analyzed by isotope ratio mass spectrometry, and exogenous glucose oxidation will be calculated using 13CO2 enrichment and carbon dioxide production. |
During the 90-min exercise bout
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Exogenous leucine oxidation
Periodo de tiempo: During the 90-min exercise bout
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Exogenous leucine oxidation will be determined during the protein condition using breath ¹³CO₂ enrichment following ingestion of L-[1-¹³C]leucine. Breath samples will be analyzed by isotope ratio mass spectrometry, and exogenous leucine oxidation will be calculated using breath ¹³CO₂ enrichment and carbon dioxide production. |
During the 90-min exercise bout
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Medidas de resultado secundarias
Medidas de resultado secundarias
Medida de resultado |
Medida Descripción |
Periodo de tiempo |
|---|---|---|
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Time to task failure
Periodo de tiempo: Immediately following the 90-min exercise bout
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Exercise performance will be assessed as time to volitional exhaustion during a cycling time-to-task-failure test performed at 85% of maximal work rate following the 90-minute moderate-intensity cycling bout. |
Immediately following the 90-min exercise bout
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Colaboradores e Investigadores
Patrocinador
Patrocinador
Investigadores
Investigadores
- Investigador principal: Jenna Gillen, PhD, University of Toronto
Fechas de registro del estudio
Fechas importantes del estudio
Inicio del estudio (Estimado)
Inicio del estudio
Finalización primaria (Estimado)
Finalización primaria
Finalización del estudio (Estimado)
Finalización del estudio
Fechas de registro del estudio
Enviado por primera vez
Enviado por primera vez
Primero enviado que cumplió con los criterios de control de calidad
Primero enviado que cumplió con los criterios de control de calidad
Publicado por primera vez (Actual)
Publicado por primera vez
Actualizaciones de registros de estudio
Última actualización publicada (Actual)
Última actualización publicada
Última actualización enviada que cumplió con los criterios de control de calidad
Última actualización enviada que cumplió con los criterios de control de calidad
Última verificación
Última verificación
Más información
Términos relacionados con este estudio
Palabras clave
Términos MeSH relevantes adicionales
Otros números de identificación del estudio
Otros números de identificación del estudio
- HSREB50670
Plan de datos de participantes individuales (IPD)
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Información sobre medicamentos y dispositivos, documentos del estudio
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