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VO2max and Substrate Crossover Point (VO2MAX-CROSS)

28 augustus 2026 bijgewerkt door: 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.

Studie Overzicht

Toestand

Voltooid

Conditie

Interventie / Behandeling

Gedetailleerde beschrijving

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.

Studietype

Ingrijpend

Inschrijving (Werkelijk)

20

Fase

  • Niet toepasbaar

Contacten en locaties

In dit gedeelte vindt u de contactgegevens van degenen die het onderzoek uitvoeren en informatie over waar dit onderzoek wordt uitgevoerd.

Studie Locaties

  • Turkije (Türkiye)
    • Tepebaşi
      • Eskişehir, Tepebaşi, Turkije (Türkiye), 26100
        • Eskişehir Technical University

Deelname Criteria

Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.

Geschiktheidscriteria

Leeftijden die in aanmerking komen voor studie

  • Volwassen

Accepteert gezonde vrijwilligers

Ja

Beschrijving

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

Studie plan

Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.

Hoe is de studie opgezet?

Ontwerpdetails

  • Primair doel: Fundamentele wetenschap
  • Toewijzing: NVT
  • Interventioneel model: Opdracht voor een enkele groep
  • Masker: Geen (open label)

Wapens en interventies

Deelnemersgroep / Arm
Interventie / Behandeling
Experimenteel: 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.
Gedragsmatig: 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.
Andere namen:
  • Bruce Treadmill Protocol
  • Maximal Incremental Exercise Test
  • Graded Exercise Testing (GXT)
  • Maximal Treadmill Exercise Test

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Time to reach the substrate crossover point
Tijdsspanne: 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
Tijdsspanne: 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

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Percentage of VO2max at the crossover point
Tijdsspanne: 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
Tijdsspanne: 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)
Tijdsspanne: 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

Medewerkers en onderzoekers

Hier vindt u mensen en organisaties die betrokken zijn bij dit onderzoek.

Sponsor

Celil Kaçoğlu

Onderzoekers

  • Hoofdonderzoeker: celil kaçoğlu, Ph.D., Eskişehir Teknik Üniversitesi

Publicaties en nuttige links

De persoon die verantwoordelijk is voor het invoeren van informatie over het onderzoek stelt deze publicaties vrijwillig ter beschikking. Dit kan gaan over alles wat met het onderzoek te maken heeft.

Algemene publicaties

Studie record data

Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.

Bestudeer belangrijke data

Studie start (Werkelijk)

1 mei 2026

Primaire voltooiing (Werkelijk)

30 juni 2026

Studie voltooiing (Werkelijk)

15 juli 2026

Studieregistratiedata

Eerst ingediend

25 augustus 2026

Eerst ingediend dat voldeed aan de QC-criteria

28 augustus 2026

Eerst geplaatst (Werkelijk)

2 september 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

2 september 2026

Laatste update ingediend die voldeed aan QC-criteria

28 augustus 2026

Laatst geverifieerd

1 augustus 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Andere studie-ID-nummers

  • EskisehirTU-SBF-CK-04

Plan Individuele Deelnemersgegevens (IPD)

Bent u van plan om gegevens van individuele deelnemers (IPD) te delen?

NEE

Beschrijving IPD-plan

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.

Informatie over medicijnen en apparaten, studiedocumenten

Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel

Nee

Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct

Nee

Deze informatie is zonder wijzigingen rechtstreeks van de website clinicaltrials.gov gehaald. Als u verzoeken heeft om uw onderzoeksgegevens te wijzigen, te verwijderen of bij te werken, neem dan contact op met register@clinicaltrials.gov. Zodra er een wijziging wordt doorgevoerd op clinicaltrials.gov, wordt deze ook automatisch bijgewerkt op onze website .

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