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Effects of Acute Exercise in Fasting and Fed States in Individuals With Different Aerobic Fitness Levels

4 september 2026 bijgewerkt door: Suleyman Bulut, Hacettepe University

The Effect of Acute Exercise in the Fasted and Fed States on Peripheral Blood Mononuclear Cells and Metabolic Fuel Utilization in Individuals With Different Aerobic Fitness Levels

The aim of this study is to investigate the effects of aerobic fitness level, feeding status, and acute exercise on whole-body metabolic fuel utilization and mitochondrial function in peripheral blood mononuclear cells (PBMCs) in healthy young men.

The main questions it aims to answer are:

  1. Do individuals with high and low aerobic fitness levels differ in fat and carbohydrate oxidation at rest and during exercise following an overnight fast, and do their PBMC mitochondrial responses to acute exercise differ?
  2. Does feeding alter fat and carbohydrate oxidation at rest and during exercise compared with the fasted state in individuals with high aerobic fitness?
  3. Are PBMC mitochondrial respiration parameters and their exercise-induced changes associated with fat and carbohydrate oxidation during fasted exercise?

Studie Overzicht

Toestand

Nog niet aan het werven

Conditie

Interventie / Behandeling

Gedetailleerde beschrijving

This experimental study uses a mixed design incorporating both between- and within-subject comparisons to investigate the influence of aerobic fitness level, feeding status, and acute exercise on substrate oxidation and peripheral blood mononuclear cell (PBMC) mitochondrial function. Between-group comparisons will examine differences between individuals with high and low aerobic fitness under standardized fasted conditions, whereas within-subject comparisons of fasted and fed conditions will be performed in the high-fitness group. In addition, the repeatability of substrate oxidation measurements will be assessed in the high-fitness group.

A total of 30 healthy men aged 18-25 years with a body mass index (BMI) of 18.5-24.9 kg·m-² will be recruited. Participants will be classified into two groups according to maximal oxygen uptake (V̇O₂max). The high-fitness group will comprise 15 endurance-trained individuals with a V̇O₂max >55 mL·kg-¹·min-¹, whereas the low-fitness group will comprise 15 sedentary or physically inactive individuals with a V̇O₂max <45 mL·kg-¹·min-¹.

During the first laboratory visit, participants in both groups will undergo body composition assessment using dual-energy X-ray absorptiometry (DXA) and complete an incremental cycling test to determine V̇O₂max. Following sufficient recovery, participants will complete a 20-min familiarization cycling session at an intensity corresponding to 65% of V̇O₂max.

Participants in the high-fitness group will complete four laboratory visits in total. During the second and third visits, participants will arrive at the laboratory following an overnight fast. Resting metabolic rate (RMR) will be assessed, after which participants will complete 30 min of cycling exercise at 65% of V̇O₂max. These visits will be performed under identical standardized conditions to determine the repeatability of substrate oxidation measurements.

During the fourth visit, participants in the high-fitness group will arrive at the laboratory following an approximately 12-h overnight fast. RMR will first be assessed, followed by the collection of a venous blood sample immediately before exercise. Participants will then complete 30 min of cycling at 65% of V̇O₂max, and a second venous blood sample will be collected immediately after exercise. These samples will be used to assess exercise-induced changes in PBMC mitochondrial function under fasted conditions.

One hour after completing the fasted exercise trial, participants will consume an ad libitum meal consisting of pasta and meatballs. One hour after completion of the meal, RMR assessment and the 30-min cycling exercise trial at 65% of V̇O₂max will be repeated under fed conditions. No blood samples will be collected during the fed condition. Accordingly, comparisons between fasted and fed conditions will be restricted to outcomes related to whole-body substrate metabolism.

Participants in the low-fitness group will complete two laboratory visits. The first visit will include DXA assessment, determination of V̇O₂max, and the familiarization cycling session, as described above. During the second visit, participants will complete the fasted experimental condition. Following an approximately 12-h overnight fast, RMR will be assessed and a venous blood sample will be collected immediately before exercise. Participants will then complete 30 min of cycling at 65% of V̇O₂max, followed immediately by collection of a second venous blood sample. The low-fitness group will not complete the repeatability trials or the fed condition. Therefore, between-group comparisons of substrate oxidation and PBMC mitochondrial function will be performed using data obtained under the standardized fasted condition.

Respiratory gas exchange will be continuously measured during resting and exercise assessments to determine oxygen consumption (V̇O₂) and carbon dioxide production (V̇CO₂). These measurements will be used to calculate rates of fat and carbohydrate oxidation. Rating of perceived exertion (RPE) will be recorded every 5 min during exercise using the Borg 6-20 scale.

PBMCs will be isolated from venous blood samples collected immediately before and after the fasted exercise test. Mitochondrial oxygen consumption rate and proton efflux rate will be measured using a Seahorse XFe96 extracellular flux analyzer. These measurements will be used to evaluate exercise-induced changes in PBMC mitochondrial function and their relationship with whole-body fat and carbohydrate oxidation during exercise.

Participants will also complete a 24-hour dietary intake record before the main experimental visit.

Studietype

Ingrijpend

Inschrijving (Geschat)

30

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.

Studiecontact

Studie Contact Back-up

Studie Locaties

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 volunteers aged 18-25 years
  • Body mass index between 18.5 and 24.9 kg/m²
  • Residing on the Hacettepe University Beytepe Campus

  • Eligibility for one of the following aerobic fitness groups

    • High aerobic fitness group: maximal oxygen uptake (VO2max) greater than 55 mL/kg/min and regular participation in endurance training.
    • Low aerobic fitness group: VO2max lower than 45 mL/kg/min and sedentary or not regularly physically active

Exclusion Criteria:

  • Current smoking
  • Regular or excessive alcohol consumption
  • Any musculoskeletal condition that may limit or prevent exercise
  • Allergy to any of the foods provided as part of the study meal
  • Currently following a weight-loss or other restrictive diet

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: Niet-gerandomiseerd
  • Interventioneel model: Parallelle opdracht
  • Masker: Geen (open label)

Wapens en interventies

Deelnemersgroep / Arm
Interventie / Behandeling
Experimenteel: High Aerobic Fitness: Fasted and Fed Conditions
Participants with a VO2max greater than 55 mL/kg/min who regularly perform endurance training will be assigned to this arm. Participants will complete two repeatability visits under overnight-fasted conditions, including resting metabolic rate measurement followed by 30 minutes of cycling at 65% of VO2max. During the main experimental visit, they will complete the same measurements in the fasted state, with venous blood samples collected immediately before and after exercise. They will subsequently consume an ad libitum meal, and one hour later, resting metabolic rate measurement and the cycling exercise test will be repeated in the fed state.
Gedragsmatig: Acute Moderate-Intensity Cycling Exercise
Participants will perform 30 minutes of continuous cycling exercise on a cycle ergometer at an intensity corresponding to 65% of their individual maximal oxygen uptake (VO2max). Both aerobic fitness groups will complete the exercise following an overnight fast. Participants in the high aerobic fitness group will also repeat the exercise one hour after consuming an ad libitum meal. Respiratory gas exchange will be measured throughout exercise to calculate fat and carbohydrate oxidation, and rating of perceived exertion will be recorded every five minutes using the Borg 6-20 scale.
Ander: Ad Libitum Mixed Meal
One hour after completing the fasted exercise test, participants in the high aerobic fitness group will be provided with an ad libitum mixed meal consisting of pasta and meatballs and will be allowed to eat until comfortably full. One hour after the meal, resting metabolic rate measurement and the 30-minute cycling exercise test at 65% of VO2max will be repeated under the fed condition. No blood samples will be collected during the fed condition.
Ander: Low Aerobic Fitness: Fasted Condition
Participants with a VO2max lower than 45 mL/kg/min who are sedentary or physically inactive will be assigned to this arm. Participants will complete the fasted experimental condition only. Following an overnight fast, resting metabolic rate will be measured and a venous blood sample will be collected immediately before 30 minutes of cycling at 65% of VO2max. A second venous blood sample will be collected immediately after exercise. Participants in this arm will not complete the repeatability visits or the fed experimental condition.
Gedragsmatig: Acute Moderate-Intensity Cycling Exercise
Participants will perform 30 minutes of continuous cycling exercise on a cycle ergometer at an intensity corresponding to 65% of their individual maximal oxygen uptake (VO2max). Both aerobic fitness groups will complete the exercise following an overnight fast. Participants in the high aerobic fitness group will also repeat the exercise one hour after consuming an ad libitum meal. Respiratory gas exchange will be measured throughout exercise to calculate fat and carbohydrate oxidation, and rating of perceived exertion will be recorded every five minutes using the Borg 6-20 scale.

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Change in PBMC Mitochondrial Oxygen Consumption Rate From Pre- to Post-Exercise
Tijdsspanne: Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Mitochondrial oxygen consumption rate (OCR) will be measured in peripheral blood mononuclear cells (PBMCs) using a Seahorse XFe96 extracellular flux analyzer. PBMCs will be isolated from venous blood samples collected immediately before and immediately after the fasted 30-minute submaximal cycling test. Pre- to post-exercise changes in OCR will be evaluated between the high and low aerobic fitness groups and examined in relation to whole-body fat and carbohydrate oxidation during exercise.
Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Change in PBMC Proton Efflux Rate From Pre- to Post-Exercise
Tijdsspanne: Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Proton efflux rate (PER) will be measured in peripheral blood mononuclear cells (PBMCs) using a Seahorse XFe96 extracellular flux analyzer. PBMCs will be isolated from venous blood samples collected immediately before and immediately after the fasted 30-minute submaximal cycling test. Pre- to post-exercise changes in PER will be evaluated between the high and low aerobic fitness groups and examined in relation to whole-body substrate oxidation during exercise.
Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Fat Oxidation Rate During Submaximal Exercise
Tijdsspanne: During each 30-minute submaximal cycling test performed at 65% of VO2max.
Whole-body fat oxidation rate, expressed in grams per minute (g/min), will be calculated using the Frayn stoichiometric equation from oxygen consumption (VO2) and carbon dioxide production (VCO2) measured by indirect calorimetry during 30 minutes of cycling at 65% of the participant's individual VO2max. Fat oxidation will be compared between the high and low aerobic fitness groups under fasted conditions and between the fasted and fed conditions within the high aerobic fitness group.
During each 30-minute submaximal cycling test performed at 65% of VO2max.
Carbohydrate Oxidation Rate During Submaximal Exercise
Tijdsspanne: During each 30-minute submaximal cycling test performed at 65% of VO2max.
Whole-body carbohydrate oxidation rate, expressed in grams per minute (g/min), will be calculated using the Frayn stoichiometric equation from oxygen consumption (VO2) and carbon dioxide production (VCO2) measured by indirect calorimetry during 30 minutes of cycling at 65% of the participant's individual VO2max. Carbohydrate oxidation will be compared between the high and low aerobic fitness groups under fasted conditions and between the fasted and fed conditions within the high aerobic fitness group.
During each 30-minute submaximal cycling test performed at 65% of VO2max.

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Resting Fat Oxidation Rate
Tijdsspanne: During the resting metabolic assessment before the fasted and fed exercise conditions.
Resting fat oxidation rate, expressed in grams per minute (g/min), will be calculated from oxygen consumption (VO2) and carbon dioxide production (VCO2) measured by indirect calorimetry during the resting metabolic assessment. Resting fat oxidation will be compared between the high and low aerobic fitness groups under fasted conditions and between the fasted and fed conditions within the high aerobic fitness group.
During the resting metabolic assessment before the fasted and fed exercise conditions.
Resting Carbohydrate Oxidation Rate
Tijdsspanne: During the resting metabolic assessment before the fasted and fed exercise conditions.
Resting carbohydrate oxidation rate, expressed in grams per minute (g/min), will be calculated from oxygen consumption (VO2) and carbon dioxide production (VCO2) measured by indirect calorimetry during the resting metabolic assessment. Resting carbohydrate oxidation will be compared between the high and low aerobic fitness groups under fasted conditions and between the fasted and fed conditions within the high aerobic fitness group.
During the resting metabolic assessment before the fasted and fed exercise conditions.
PBMC Glycolytic Proton Efflux Rate (glycoPER)
Tijdsspanne: Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Glycolytic proton efflux rate (glycoPER) will be calculated from the total proton efflux rate after correction for the mitochondrial contribution to extracellular acidification. Measurements will be obtained from PBMCs isolated from venous blood samples collected immediately before and immediately after the fasted submaximal exercise test using a Seahorse XFe96 extracellular flux analyzer.
Immediately before and immediately after the fasted 30-minute cycling test at 65% of VO2max.
Resting Metabolic Rate
Tijdsspanne: Before fasted exercise in both groups and 1 hour after the meal before fed exercise in the high-fitness group.
Resting metabolic rate, expressed in kilocalories per day (kcal/day), will be measured using a Q-NRG indirect calorimetry system in canopy mode. Measurements will be performed after an overnight fast in both aerobic fitness groups. In the high aerobic fitness group, resting metabolic rate will also be reassessed one hour after the ad libitum meal and before the fed exercise test.
Before fasted exercise in both groups and 1 hour after the meal before fed exercise in the high-fitness group.

Andere uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Rating of Perceived Exertion During Submaximal Exercise
Tijdsspanne: Every 5 minutes during each 30-minute submaximal cycling test.
Perceived exertion will be rated using the Borg 6-20 scale during each 30-minute submaximal cycling test. Higher scores indicate a greater perceived level of exercise intensity and effort.
Every 5 minutes during each 30-minute submaximal cycling test.
Ad Libitum Energy Intake
Tijdsspanne: During the ad libitum meal provided 1 hour after completion of the fasted exercise test.
Total energy intake will be determined from the amount of the standardized pasta-and-meatball meal consumed ad libitum by participants in the high aerobic fitness group. The meal will be prepared using standardized recipes and ingredient quantities to allow quantification of the energy consumed.
During the ad libitum meal provided 1 hour after completion of the fasted exercise test.

Medewerkers en onderzoekers

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

Sponsor

Hacettepe University

Onderzoekers

  • Hoofdonderzoeker: Süleyman BULUT, PhD, Hacettepe University, Faculty of Sport Sciences
  • Hoofdonderzoeker: Muhammed M ATAKAN, PhD, Hacettepe University, Faculty of Sport Sciences

Publicaties en nuttige links

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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 (Geschat)

15 november 2026

Primaire voltooiing (Geschat)

15 november 2027

Studie voltooiing (Geschat)

15 december 2027

Studieregistratiedata

Eerst ingediend

4 september 2026

Eerst ingediend dat voldeed aan de QC-criteria

4 september 2026

Eerst geplaatst (Werkelijk)

10 september 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

10 september 2026

Laatste update ingediend die voldeed aan QC-criteria

4 september 2026

Laatst geverifieerd

1 september 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Andere studie-ID-nummers

  • SBA 26/387

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 shared due to participant confidentiality and the absence of institutional data sharing infrastructure.

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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