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VO2max and Substrate Crossover Point (VO2MAX-CROSS)

2026年8月28日 更新者：Celil Kaçoğlu

Higher VO2max Delays Substrate Switching and Shifts the Crossover Point to Greater Oxygen Uptake During Incremental Exerciseebys

This study aims to investigate the relationship between maximal oxygen uptake (VO2max) and the substrate crossover point during incremental exercise. A total of 20 physical education students are recruited to complete a maximal incremental treadmill test using the standard Bruce protocol. Indirect calorimetry is utilized to assess oxygen uptake (VO2), carbon dioxide production (VCO2), and energy substrate utilization patterns. The substrate crossover point is operationally defined at a respiratory exchange ratio (RER) threshold of 0.85, indicating the metabolic transition toward predominant carbohydrate oxidation. The primary objective is to evaluate how variations in aerobic capacity influence the timing, oxygen uptake, and heart rate (HR) responses at this metabolic transition threshold.

研究概览

地位

完全的

条件

干预/治疗

详细说明

This study evaluates the relationship between maximal oxygen uptake (VO2max) and the substrate crossover point during incremental treadmill exercise in young, physically active individuals. Substrate utilization kinetics and metabolic flexibility represent critical components of cardiovascular conditioning and endurance performance; however, the impact of continuous variations in aerobic capacity on the onset of metabolic transition requires detailed investigation.

Participants undergo anthropometric testing followed by a maximal graded exercise test on a motor-driven treadmill following the standard Bruce protocol. Breath-by-breath expired gas analysis using indirect calorimetry continuously monitors oxygen uptake (VO2), carbon dioxide production (VCO2), and minute ventilation (VE) throughout the test. Respiratory exchange ratio (RER) values are calculated continuously. The substrate crossover point is operationally defined as the exercise intensity corresponding to an RER threshold of 0.85, representing the metabolic transition where carbohydrate oxidation becomes the predominant contributor to total energy expenditure over lipid oxidation.

Key outcome measures extracted at this threshold include:

Time to reach the crossover point (minutes)

Absolute oxygen uptake at crossover (liters per minute [L/min])

Relative oxygen uptake at crossover (milliliters per kilogram per minute [mL/kg/min])

Percentage of maximal oxygen uptake at crossover (%VO2max)

Heart rate at crossover (beats per minute [bpm])

Statistical associations between maximal aerobic capacity (VO2max) and the primary outcome measures at the crossover point are analyzed using linear correlation and regression models to determine how cardiorespiratory fitness alters substrate switching kinetics under progressive physical strain.

研究类型

介入性

注册 (实际的)

20

阶段

  • 不适用

联系人和位置

本节提供了进行研究的人员的详细联系信息，以及有关进行该研究的地点的信息。

学习地点

  • 土耳其（türkiye）
    • Tepebaşi
      • Eskişehir、Tepebaşi、土耳其（türkiye）、26100
        • Eskişehir Technical University

参与标准

研究人员寻找符合特定描述的人，称为资格标准。这些标准的一些例子是一个人的一般健康状况或先前的治疗。

资格标准

适合学习的年龄

  • 成人

接受健康志愿者

是的

描述

Inclusion Criteria:

  • Healthy male or female physical education students aged 18 to 30 years
  • Regularly physically active (participating in structured physical activity at least 3 days per week)
  • Medically cleared and capable of performing maximal graded treadmill exercise testing to voluntary exhaustion
  • Willing and able to provide written informed consent

Exclusion Criteria:

  • History of cardiovascular, pulmonary, metabolic, renal, or neuromuscular disorders
  • Acute musculoskeletal injury or orthopedic condition that impairs treadmill running or maximal exertion
  • Current use of prescription medications, stimulants, or dietary supplements known to alter metabolic rate, heart rate, or substrate oxidation
  • Use of tobacco, nicotine products, or alcohol within 24 hours prior to testing
  • Consumption of caffeine or vigorous physical exercise within 24 hours prior to the exercise trial

学习计划

本节提供研究计划的详细信息，包括研究的设计方式和研究的衡量标准。

研究是如何设计的？

设计细节

  • 主要用途：基础科学
  • 分配：不适用
  • 介入模型：单组作业
  • 屏蔽：无（打开标签）

武器和干预

参与者组/臂
干预/治疗
实验性的：Exercise Testing Group
: Healthy young adult participants who undergo a single maximal incremental treadmill exercise test using the Bruce Protocol to assess cardiorespiratory fitness (VO2max) and substrate crossover kinetics.
行为的：Incremental Graded Exercise Test (Bruce Protocol)
Participants perform a maximal treadmill exercise test following the standardized Bruce Protocol. The test begins with a warm-up, followed by progressive 3-minute stages with continuous increases in speed and incline until voluntary exhaustion. Indirect calorimetry is used continuously via breath-by-breath gas analysis to measure VO2VCO2, and RER for substrate crossover determination.
其他名称：
  • Bruce Treadmill Protocol
  • Maximal Incremental Exercise Test
  • Graded Exercise Testing (GXT)
  • Maximal Treadmill Exercise Test

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
Time to reach the substrate crossover point
大体时间：Time Frame: Baseline (single test session, Day 1)

Measure Description: Elapsed time (in minutes) from the start of the incremental treadmill test (Bruce protocol) to the point where the respiratory exchange ratio (RER) reaches 0.85, indicating the metabolic crossover where carbohydrate oxidation becomes the predominant fuel source.

Time Frame: Baseline (single exercise test session, Day 1) Unit of Measure: Minutes
Time Frame: Baseline (single test session, Day 1)
Relative oxygen uptake at the crossover point
大体时间：Measure Description: Measured continuously during the incremental exercise test using indirect calorimetry, recorded specifically at the point where the respiratory exchange ratio (RER) reaches 0.85. Time Frame: Baseline

Measure Title: Relative oxygen uptake at the substrate crossover point Measure Description: Oxygen uptake (VO2) normalized to body weight (mL/kg/min) recorded at the moment the substrate crossover point (respiratory exchange ratio [RER] = 0.85) is reached during the maximal incremental treadmill test (Bruce protocol).

Time Frame: Baseline
Measure Description: Measured continuously during the incremental exercise test using indirect calorimetry, recorded specifically at the point where the respiratory exchange ratio (RER) reaches 0.85. Time Frame: Baseline

次要结果测量

结果测量
措施说明
大体时间
Percentage of VO2max at the crossover point
大体时间：Measure Description: Relative oxygen uptake (VO2) at the substrate crossover point (respiratory exchange ratio [RER] = 0.85) expressed as a % of the participant's maximal oxygen uptake (VO2max), calculated upon completion of the Bruce protocol

Measure Title: Percentage of maximal oxygen uptake at the substrate crossover point

Measure Description: Relative oxygen uptake (VO2) at the substrate crossover point (respiratory exchange ratio [RER] = 0.85) expressed as a percentage (%) of the participant's maximal oxygen uptake (VO2max) during the Bruce protocol treadmill test.

Time Frame: Baseline
Measure Description: Relative oxygen uptake (VO2) at the substrate crossover point (respiratory exchange ratio [RER] = 0.85) expressed as a % of the participant's maximal oxygen uptake (VO2max), calculated upon completion of the Bruce protocol
Heart rate at the crossover point
大体时间：Measure Description: Heart rate (HR) in beats per minute (bpm) measured continuously during the incremental treadmill test (Bruce protocol), recorded at the substrate crossover threshold (respiratory exchange ratio [RER] = 0.85). Time Frame: Baseline

Measure Title: Heart rate at the substrate crossover point Measure Description: Heart rate (HR) recorded in beats per minute (bpm) using a telemetric heart rate monitor at the point where the substrate crossover threshold (respiratory exchange ratio [RER] = 0.85) is achieved during the maximal incremental treadmill test (Bruce protocol).

Time Frame: Baseline
Measure Description: Heart rate (HR) in beats per minute (bpm) measured continuously during the incremental treadmill test (Bruce protocol), recorded at the substrate crossover threshold (respiratory exchange ratio [RER] = 0.85). Time Frame: Baseline
Maximal oxygen consumption (VO2max)
大体时间：Measure Description: Relative maximal oxygen uptake (VO2max in mL/kg/min) assessed at maximal exertion at the end of the Bruce protocol treadmill test to voluntary exhaustion via indirect calorimetry. Time Frame: Baseline

Measure Description:

The highest rate of relative oxygen uptake (VO2 in mL/kg/min) attained during the maximal graded exercise test (Bruce protocol) to voluntary exhaustion via indirect calorimetry.

Time Frame: Baseline
Measure Description: Relative maximal oxygen uptake (VO2max in mL/kg/min) assessed at maximal exertion at the end of the Bruce protocol treadmill test to voluntary exhaustion via indirect calorimetry. Time Frame: Baseline

合作者和调查者

在这里您可以找到参与这项研究的人员和组织。

赞助

Celil Kaçoğlu

调查人员

  • 首席研究员：celil kaçoğlu, Ph.D.、Eskişehir Teknik Üniversitesi

出版物和有用的链接

负责输入研究信息的人员自愿提供这些出版物。这些可能与研究有关。

一般刊物

研究记录日期

这些日期跟踪向 ClinicalTrials.gov 提交研究记录和摘要结果的进度。研究记录和报告的结果由国家医学图书馆 (NLM) 审查，以确保它们在发布到公共网站之前符合特定的质量控制标准。

研究主要日期

学习开始 (实际的)

2026年5月1日

初级完成 (实际的)

2026年6月30日

研究完成 (实际的)

2026年7月15日

研究注册日期

首次提交

2026年8月25日

首先提交符合 QC 标准的

2026年8月28日

首次发布 (实际的)

2026年9月2日

研究记录更新

最后更新发布 (实际的)

2026年9月2日

上次提交的符合 QC 标准的更新

2026年8月28日

最后验证

2026年8月1日

更多信息

与本研究相关的术语

关键字

其他研究编号

  • EskisehirTU-SBF-CK-04

计划个人参与者数据 (IPD)

计划共享个人参与者数据 (IPD)？

不

IPD 计划说明

Individual participant data will not be publicly shared due to privacy and ethical constraints aimed at protecting participant confidentiality. However, de-identified aggregated data or specific data sets may be made available from the corresponding author upon reasonable academic request.

药物和器械信息、研究文件

研究美国 FDA 监管的药品

不

研究美国 FDA 监管的设备产品

不

此信息直接从 clinicaltrials.gov 网站检索，没有任何更改。如果您有任何更改、删除或更新研究详细信息的请求，请联系 register@clinicaltrials.gov. clinicaltrials.gov 上实施更改，我们的网站上也会自动更新.

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