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)? 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
19
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.
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.
Cidade do Futebol
Lisbon, Oeiras, Portugal
RECRUITINGWhole-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.
Time frame: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)
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.
Time frame: Immediately upon completion of the time trial subsequent to the post-meal resting period (0-120 minutes) and standardised exercise protocol (120-180 minutes)
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.
Time frame: Immediately upon completion of the time trial subsequent to the post-meal resting period (0-120 minutes) and standardised exercise protocol (120-180 minutes)
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.
Time frame: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)
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.
Time frame: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)
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.
Time frame: Every 15 minutes post-meal (0-120 minutes), every 15 minutes throughout the subsequent standardised exercise protocol (120-180 minutes)
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.
Time frame: 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
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.
Time frame: 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
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.
Time frame: Continuously throughout the standardised exercise protocol (120-180 minutes) and subsequent time trial
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.
Time frame: 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
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.
Time frame: 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
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