VO2max and Substrate Crossover Point (VO2MAX-CROSS)
Higher VO2max Delays Substrate Switching and Shifts the Crossover Point to Greater Oxygen Uptake During Incremental Exerciseebys
Studieoversigt
Status
Betingelser
Intervention / Behandling
Detaljeret beskrivelse
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.
Undersøgelsestype
Tilmelding (Faktiske)
Fase
- Ikke anvendelig
Kontakter og lokationer
Studiesteder
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Tepebaşi
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Eskişehir, Tepebaşi, Tyrkiet (Türkiye), 26100
- Eskişehir Technical University
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Deltagelseskriterier
Berettigelseskriterier
Aldre berettiget til at studere
- Voksen
Tager imod sunde frivillige
Beskrivelse
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
Studieplan
Hvordan er undersøgelsen tilrettelagt?
Design detaljer
- Primært formål: Grundvidenskab
- Tildeling: N/A
- Interventionel model: Enkelt gruppeopgave
- Maskning: Ingen (Åben etiket)
Våben og indgreb
Deltagergruppe / Arm |
Intervention / Behandling |
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Eksperimentel: 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.
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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.
Andre navne:
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Hvad måler undersøgelsen?
Primære resultatmål
Resultatmål |
Foranstaltningsbeskrivelse |
Tidsramme |
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Time to reach the substrate crossover point
Tidsramme: Time Frame: Baseline (single test session, Day 1)
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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)
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Relative oxygen uptake at the crossover point
Tidsramme: 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
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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
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Sekundære resultatmål
Resultatmål |
Foranstaltningsbeskrivelse |
Tidsramme |
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Percentage of VO2max at the crossover point
Tidsramme: 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
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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
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Heart rate at the crossover point
Tidsramme: 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
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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
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Maximal oxygen consumption (VO2max)
Tidsramme: 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
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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
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Samarbejdspartnere og efterforskere
Sponsor
Efterforskere
- Ledende efterforsker: celil kaçoğlu, Ph.D., Eskişehir Teknik Üniversitesi
Publikationer og nyttige links
Datoer for undersøgelser
Studer store datoer
Studiestart (Faktiske)
Primær færdiggørelse (Faktiske)
Studieafslutning (Faktiske)
Datoer for studieregistrering
Først indsendt
Først indsendt, der opfyldte QC-kriterier
Først opslået (Faktiske)
Opdateringer af undersøgelsesjournaler
Sidste opdatering sendt (Faktiske)
Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier
Sidst verificeret
Mere information
Begreber relateret til denne undersøgelse
Nøgleord
Andre undersøgelses-id-numre
- EskisehirTU-SBF-CK-04
Plan for individuelle deltagerdata (IPD)
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IPD-planbeskrivelse
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