Impact of Training Load on the Gut miCrobiome And Its Relation to exeRcise Performance, mUscle Phenotype, and markerS of Overreaching in Healthy Men

Recruiting now · Not applicable · Has a placebo group

Conditions studied: Exercise, Overreaching, Butyrate, Gut Microbiome, Exercise Performance, Skeletal Muscle, Glucose Tolerance, Hormones, Vascular Health, Muscle Adaptation, Physical Fitness, Heart Rate Variability (HRV), Anthropometric Measurements, Metabolic Health, Food Intake

In brief

The goal of this study is to learn how different amounts of supervised indoor cycling training change gut health (gut bacteria, the substances gut bacteria make, and the gut barrier integrity), and how these changes relate to changes in fitness, muscle health, and signs of doing too much training (a state called 'overreaching'). The study includes healthy, recreationally active men aged 18 to 45 years. The primary questions, for which the study is powered (sufficient participants included), are: 1. Does moderate load training change blood and faecal levels of butyrate (a short-chain fatty acid made by gut bacteria) after eight weeks compared with a control group? 2. Compared to moderate load training, do higher training loads lead to different responses in blood and faecal levels of butyrate? Researchers will compare: * A control group that does not complete structured training; * A moderate-load training group that completes eight weeks of supervised cycling (4x/week); * A high-load training group that completes four weeks of moderate-load training followed by four weeks of higher training load (twice the number of training sessions). Participants will: * Be randomly assigned to one of the three groups; * Complete 8 weeks of supervised indoor cycling sessions if assigned to a training group; * Complete four study assessment periods (baseline, after week four, after week eight, and after a short taper (rest period); * Provide blood, stool, skeletal muscle, urine, saliva, and breath samples during the assessment periods; * Complete fitness and performance tests and questionnaires during the assessment periods.

Key facts

Study ID: NCT07481578
Run by: Stefan De Smet
People needed: 45
Starts: 2024-10-07
Expected to finish: 2027-05-31
Last updated by the study team: 2026-03-19

Who can join

Age: 18 and older, up to 45. Sex: male. Healthy volunteers: accepted.

You may qualify if…

Males between 18 and 45 years old.
Recreationally active individuals, with a weekly exercise training volume between one and six hours per week.
Good health status confirmed by a sport medical screening, which includes a sport medical questionnaire and resting electrocardiogram.
Body Mass Index (BMI) between 18.5 and 27.5 kg/m².
Masters the Dutch language.

You may not qualify if…

Engagement in strenuous competitive sports one month prior to or during the study intervention.
Medication and vaccination: Pro- or antibiotic treatment during the past three months, non-steroidal anti-inflammatory drugs (NSAIDs) or cholestyramine during the past month, drugs interfering with intestinal permeability (e.g., prokinetics, laxatives, lubiprostone, loperamide, anti-spasmodics, linaclotide, proton pump inhibitors) during the past month. Vaccinations within one month prior to or during the study intervention.
Blood donations within three months or plasma donation within one month prior to or during the study intervention.
Inflammatory bowel disease (Crohn or colitis ulcerosa) or celiac disease.
Diagnosed irritable bowel syndrome.
Intake of any performance-enhancing medication or nutritional supplements known to modulate the gut microbiome in the two months prior to or during the study.
Substance abuse, including alcohol consumption of more than three units/day (weekly average).
Any injury or pathology considered a contraindication for performing physical exercise, as determined by the medical doctor overseeing the preparticipation medical screening.
No access to smartphone and/or computer with internet access.
No willingness to use the Polar Flow app and MijnEetmeter to collect physical activity, heart rate, sleep, and food intake data.
Concomitant participation in another interventional trial, without approval from the research team.
Any other reasons considered by the research team that the participant will not complete the study.

Where it is running

Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium — Leuven, Vlaams Brabant, Belgium (enrolling)

Full record on ClinicalTrials.gov

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