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Substrate MetabolismNCT07503990

Effects of Food Intake Sequence on Substrate Utilisation and Endurance Performance

A study testing Carbohydrate-last meal pattern and Carbohydrate-first meal pattern in people with Substrate Metabolism and Healthy Participants, run by Universidade do Porto at 1 site in Portugal.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

The goal of this clinical trial is to understand how consuming a pre-exercise meal in different food intake sequences affects substrate utilisation and endurance exercise performance in healthy trained athletes. Read more about this study

Who is it for?
Ages 18 to 64 years, men onlyHealthy volunteers can take part
What is being tested?
Carbohydrate-last meal pattern and Carbohydrate-first meal pattern
Could I receive a placebo?
No, everyone receives an active treatment
How many people
18 participants
Where
1 sitePortugal
Study dates
1 Apr 2026to 9 Jun 2026
Phase
Interventional
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 64 years
  • Men only
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • Adult (18-64 years old)
  • Men
  • Endurance-trained athletes (meeting training and performance caliber criteria ≥Tier 2; McKay et al., 2022)
  • Healthy (meeting the exclusion criteria for medical conditions)
  • Normal glucose tolerant according to the latest criteria established by the American Diabetes Association (2024): HbA1c <5.7%, fasting plasma glucose <5.6 mmol/L (100 mg/dL) or 2-h plasma glucose <7.8 mmol/L (140 mg/dL) during a 75-g OGTT
  • Able and willing to provide informed consent and safely comply with study procedures

Who cannot join

  • Any medical condition or behaviour deemed either to pose undue personal risk to the participant or introduce bias into the experiment (e.g. cardiovascular disease; alcohol or substance abuse; any condition affecting the glucose or lipid metabolism, reviewed on a case by case basis)
  • Any reported medication or supplementation that may interfere with the glucose metabolism (e.g., acarbose, insulin, metformin, semaglutide, thiazolidinediones, sulfonylureas, corticosteroids, thiazide diuretics) or lipid metabolism (e.g., statins, nicotinic acid, colestyramine anhydrous, ezetimibe, fibrates, L-carnitine). Other medication and supplementation will be reviewed on a case by case basis.
  • Known food allergy, intolerance or hypersensitivity to any of the test meal ingredients
  • Recent change in body mass (± 2 kg in the last 2 months)
  • Smoking

Trial locations and contacts

1 site in 1 country.

Portugal1 site
  • Cidade do Futebol

    Lisbon, Oeiras, 1495-433

Other trials in Portugal

About this study

Official title: Effects of Manipulating Food Intake Sequence in the Pre-exercise Meal on Substrate Utilisation and Endurance Performance in Athletes

The goal of this clinical trial is to understand how consuming a pre-exercise meal in different food intake sequences affects substrate utilisation and endurance exercise performance in healthy trained athletes. Specifically, the main questions it aims to answer are:

  • Does consuming the pre-exercise meal in different food intake sequences alter the whole-body utilisation of fat and CHO at rest and during prolonged exercise at moderate to heavy intensities?
  • Does consuming the pre-execise meal in different food intake sequences alter time-trial performance?
  • Does consuming the pre-exercise meal in different food intake sequences alter other metabolic and physiological responses before, during or after exercise (i.e., blood glucose, blood lactate, heart rate (HR), ratings of perceived exertion (RPE), appetite)?
Read more

To address these questions, researchers will compare eating the dietary sources of rapidly absorbed CHO at the end (CHO-last meal pattern) or at the start (CHO-first meal pattern) of a standardised pre-exercise meal, in a randomised, counterbalanced, crossover design. Two hours after starting the pre-exercise meal, participants will perform a 60-min submaximal test on a cycling ergometer at two different intensities (30 min at 90% of the ventilatory threshold (VT) 1 and 30 min at 50% VT1-VT2), followed by a 10-km cycling time trial (TT).

In the screening visit participants will:

  • Be screened for cardiometabolic conditions
  • Perform an 8-12-min graded exercise test to determine their maximal pulmonary oxygen uptake (VO2max) and non-invasive submaximal anchors of performance (VT 1 and VT 2)
  • Be familiarised to the experimental procedures

In experimental visits participants will:

  • Follow guidelines pertaining to dietary intake, exercise and sleep in the previous 24 hours
  • Have a standardised test meal in either the CHO-last or CHO-first food intake sequence
  • Have 3 drops of capillary blood (0,9 µL in total) collected to measure glucose and lactate pre-meal, 15, 30, 45, 60, 90 and 120 min post-meal, every 15 min during submaximal exercise and post-TT
  • Breathe into an indirect calorimetry mask for 5 min pre-meal, 15, 30, 45, 60, 90 and 120 min post-meal, every 15 min during submaximal exercise and post-TT
  • Wear a HR monitor continuously during submaximal exercise and the TT
  • Rate their appetite on visual analogue scales pre-meal, 15, 30, 45, 60, 90 and 120 min post-meal, and 30 min post-TT
  • Rate their perceived exertion on RPE scales every 15 min during submaximal exercise, post-TT and 30 min post-TT.

Data will be compared within-participant between food intake sequences using linear mixed-effects models with random intercepts, to account for repeated measurements, interindividual variability, and potential missing data.

Being tested
Carbohydrate-last meal pattern, Carbohydrate-first meal pattern
Keywords
food order, meal sequence, glucose metabolism, substrate utilisation, sport nutrition

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Carbohydrate-last meal patternOther

    Also called CHO-last, CL

    Skyr yoghurt, whey protein and almonds over ~5 min, immediately followed by white bread, strawberry jam, banana and pulp-free orange juice over ~10 min.

  • Carbohydrate-first meal patternOther

    Also called CHO-first, CF

    White bread, strawberry jam, banana and pulp-free orange juice over ~10 min, immediately followed by skyr yoghurt, whey protein and almonds over ~5 min.

Study groups in NCT07503990
Study groupRoleWhat they receive
CL-CFExperimentalThe interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order at two study visits, separated by a wash-out period of at least 7 days. If participants are allocated to this study arm, they will receive the CL on the first visit and the CF on the second visit. The nutritional composition of the test-meal will comply to the current sports nutrition guidelines for the pre-exercise meal (i.e., 1-4 g of CHO/kg of body mass, moderate amounts of protein, low-fat and fibre content, 5-10 mL/kg of body mass of fluids) (Thomas et al., 2016). Participants will be encouraged to consume the meal in full within 15 minutes, at a comfortable pace, to mimic real eating circumstances.
Receives: Other: Carbohydrate-last meal pattern; Other: Carbohydrate-first meal pattern
CF-CLActive comparatorThe interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order at two study visits, separated by a wash-out period of at least 7 days. If participants are allocated to this study arm, they will receive the CF on the first visit and the CL on the second visit. The test-meal will be identical and isocaloric in both interventions of the study.
Receives: Other: Carbohydrate-last meal pattern; Other: Carbohydrate-first meal pattern

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Whole-body fat oxidation

    Difference between CHO-last and CHO-first meal patterns in the whole-body fat oxidation rate (g/min) over time adjusted for baseline, measured by indirect calorimetry.

    Measured: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)

  2. Time-trial performance

    Difference between CHO-last and CHO-first meal patterns in the time to complete (min:sec) a 10-km cycling TT, assessed using a validated cycle ergometer.

    Measured: Immediately upon completion of the time trial subsequent to the post-meal resting period (0-120 minutes) and standardised exercise protocol (120-180 minutes)

Secondary outcomes (9)
  1. Time-trial power output

    Difference between CHO-last and CHO-first meal patterns in the average power output (W) during a 10-km cycling TT, assessed using a validated cycle ergometer.

    Measured: Immediately upon completion of the time trial subsequent to the post-meal resting period (0-120 minutes) and standardised exercise protocol (120-180 minutes)

  2. Whole-body CHO oxidation

    Difference between CHO-last and CHO-first meal patterns in the whole-body CHO oxidation rate (g/min) over time adjusted for baseline, measured by indirect calorimetry.

    Measured: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)

  3. Respiratory exchange ratio (RER)

    Difference between CHO-last and CHO-first meal patterns in the RER over time adjusted for baseline, measured by indirect calorimetry.

    Measured: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)

  4. Energy expenditure

    Difference between CHO-last and CHO-first meal patterns in the energy expenditure rate (kcal/min) over time adjusted for baseline, measured by indirect calorimetry.

    Measured: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)

  5. Blood glucose concentrations

    Difference between CHO-last and CHO-first meal patterns in the capillary blood glucose concentrations (mmol/L) over time adjusted for baseline, measured by a validated glucometer.

    Measured: Every 15 minutes post-meal in the first hour (0-60 min), every 30 minutes in the second hour (60-120 min), every 15 minutes throughout the standardised exercise protocol (120-180 min) and immediately upon completion of the subsequent time trial

  6. Blood lactate concentrations

    Difference between CHO-last and CHO-first meal patterns in the capillary blood lactate concentrations (mmol/L) over time adjusted for baseline, measured by a validated lactate meter.

    Measured: Every 15 minutes post-meal in the first hour (0-60 min), every 30 minutes in the second hour (60-120 min), every 15 minutes throughout the standardised exercise protocol (120-180 min) and immediately upon completion of the subsequent time trial

  7. Heart Rate

    Difference between CHO-last and CHO-first meal patterns in the heart rate (bpm) over time adjusted for baseline, assessed as 15-minute averages during exercise using a validated heart rate monitor.

    Measured: Continuously throughout the standardised exercise protocol (120-180 minutes) and subsequent time trial

  8. Ratings of perceived exertion (RPE)

    Difference between CHO-last and CHO-first meal patterns in the absolute RPE over time, assessed during and after exercise using the validated modified Borg's 0-10 scale.

    Measured: Every 15 minutes during the standardised exercise protocol (120-180 minutes), immediately upon completion of the subsequent time trial, 30 minutes after completion of the time trial

  9. Subjective appetite ratings

    Difference between CHO-last and CHO-first meal patterns in the appetite ratings (mm) over time adjusted for baseline, assessed at rest and after exercise using validated 100-mm visual analogue scales.

    Measured: Every 15 minutes post-meal in the first hour (0-60 minutes), every 30 minutes in the second hour (60-120 minutes), and 30 minutes after completion of the time trial

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted31 Mar 2026
  2. Study start1 Apr 2026
  3. Primary completion9 Jun 2026
  4. Study completion9 Jun 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Basic science
Allocation
Randomised
Intervention model
Crossover
Model description
This study is designed as a randomised, counterbalanced, crossover, superiority trial with two groups. Block randomization will be performed by an external researcher with a 1:1 allocation ratio, and allocation concealment will be ensured through the use of sequentially numbered, opaque, sealed envelopes.
Masking
Single blind
Who is masked
Outcomes assessor
Enrolment
18 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07503990
Sponsor's protocol ID
FOODSEQ-SUEP
Other IDs
2022.12954.BD
Status last verified
Apr 2026
First submitted
14 Nov 2025
Last updated
10 Jun 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Anonymised IPD will be made available upon reasonable request directed to the corresponding author.

Questions about this trial

What is this clinical trial studying?

A study testing Carbohydrate-last meal pattern and Carbohydrate-first meal pattern in people with Substrate Metabolism and Healthy Participants, run by Universidade do Porto at 1 site in Portugal.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 10 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Portugal. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Whole-body fat oxidation (time frame: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jun 2026.

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