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.
研究概览
地位
条件
详细说明
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.
研究类型
注册 (估计的)
阶段
- 不适用
联系人和位置
学习联系方式
- 姓名：Jenna Gillen, PhD
- 电话号码：4169783244
- 邮箱：jenna.gillen@utoronto.ca
研究联系人备份
- 姓名：Victoria Bennett
- 电话号码：4169783244
- 邮箱：victoria.bennett@mail.utoronto.ca
学习地点
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Ontario
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Toronto、Ontario、加拿大、M5S 2C9
- 招聘中
- Goldring Centre for High Performance Sport
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接触：
- Jenna Gillen
- 电话号码：4169783244
- 邮箱：jenna.gillen@utoronto.ca
-
接触：
- Victoria Bennett
- 电话号码：4169783244
- 邮箱：victoria.bennett@mail.utoronto.ca
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-
参与标准
资格标准
适合学习的年龄
接受健康志愿者
有资格学习的性别
描述
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
学习计划
研究是如何设计的？
设计细节
- 主要用途：基础科学
- 分配：随机化
- 介入模型：交叉作业
- 屏蔽：双倍的
武器和干预
参与者组/臂 |
干预/治疗 |
|---|---|
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实验性的：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. |
|
实验性的：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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安慰剂比较：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. |
研究衡量的是什么？
主要结果指标
结果测量 |
措施说明 |
大体时间 |
|---|---|---|
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Whole-body carbohydrate oxidation
大体时间：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
大体时间：During the 90-min exercise bout
|
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
大体时间：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
大体时间：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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次要结果测量
结果测量 |
措施说明 |
大体时间 |
|---|---|---|
|
Time to task failure
大体时间：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
|
合作者和调查者
调查人员
- 首席研究员：Jenna Gillen, PhD、University of Toronto
研究记录日期
研究主要日期
学习开始 (估计的)
初级完成 (估计的)
研究完成 (估计的)
研究注册日期
首次提交
首先提交符合 QC 标准的
首次发布 (实际的)
研究记录更新
最后更新发布 (实际的)
上次提交的符合 QC 标准的更新
最后验证
更多信息
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