Actively Recruiting
Impact of Training Load on the Gut Microbiome and Its Relation to Exercise Performance, Muscle Phenotype, and Markers of Overreaching in Healthy Men
Led by Stefan De Smet · Updated on 2026-03-19
45
Participants Needed
1
Research Sites
N/A
Total Duration
On this page
Sponsors
S
Stefan De Smet
Lead Sponsor
K
KU Leuven
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are studying how different amounts of supervised indoor cycling training affect gut health, including gut bacteria, substances produced by gut bacteria, and the gut barrier. The study focuses on healthy, recreationally active men aged 18 to 45 years. It aims to find out how moderate and high training loads influence levels of butyrate, a substance made by gut bacteria, and how these changes relate to fitness, muscle health, and signs of overreaching, a state of excessive training. Participants will be randomly assigned to one of three groups: a control group with no structured training receiving a weekly placebo capsule, a moderate-load training group completing eight weeks of supervised cycling sessions four times a week, or a high-load training group completing four weeks of moderate training followed by four weeks with double the training sessions. Training intensity is personalized based on exercise testing and follows a set schedule of different cycling session types. The study includes a 10-day taper period after the training. Participants will attend four assessment periods at baseline, mid-intervention (four weeks), post-intervention (eight weeks), and after the taper. During these times, they provide blood, stool, muscle, urine, saliva, and breath samples. They also complete fitness tests and questionnaires. Researchers will monitor exercise performance, gut microbiome changes, muscle adaptations, metabolic and vascular health, and recovery markers throughout the study. Training sessions and adherence are closely tracked until 10 days after intervention completion.
CONDITIONS
Brief Title
Impact of Training Load on the Gut miCrobiome And Its Relation to exeRcise Performance, mUscle Phenotype, and markerS of Overreaching in Healthy Men
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Males between 18 and 45 years old
- Recreationally active with weekly exercise between one and six hours
- Good health confirmed by sports medical screening and resting electrocardiogram
- Body Mass Index (BMI) between 18.5 and 27.5 kg/m²
- Ability to understand and speak Dutch
You will not qualify if you...
- Participation in strenuous competitive sports one month before or during the study
- Use of antibiotics, probiotics, NSAIDs, cholestyramine, or drugs affecting intestinal permeability within specified recent timeframes
- Vaccinations within one month before or during the study
- Blood or plasma donation within specified recent timeframes
- Diagnosis of inflammatory bowel disease, celiac disease, or irritable bowel syndrome
- Use of performance-enhancing medications or supplements affecting gut microbiome within two months before or during the study
- Substance abuse including alcohol consumption over three units per day on average
- Injury or medical conditions contraindicating exercise per medical assessment
- No access to smartphone or computer with internet
- Unwillingness to use study apps for activity, heart rate, sleep, and food intake tracking
- Participation in another interventional trial without approval
- Any other medical or personal reasons deemed unsuitable by the research team
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person) for sports medical screening and resting electrocardiogram
Duration - Approximately 1 week before intervention start
Participants attend a familiarization session to minimize learning effects and standardize procedures before starting the intervention. This includes performance and physiological testing procedures and instructions on study devices and diaries. Dietary plans are provided for consistency before assessments.
1 visit (in-person)
Duration - 8 weeks plus a 10-day taper period
Participants are assigned to one of three groups: control with supervised weekly placebo capsule and habitual exercise monitoring; moderate load training with 8 weeks of supervised cycling sessions; or high load training with 4 weeks of moderate followed by 4 weeks of high load cycling. Training sessions are supervised and prescribed based on individual physiological thresholds.
Weekly supervised placebo intake for control group; 4 sessions per week for moderate load group; up to 8 sessions per week for high load group during last 4 weeks
Duration - Four periods, each lasting 3 consecutive days, scheduled at baseline, 4 weeks, 8 weeks, and 10 days after intervention
Participants undergo four assessment periods consisting of home-based and study center-based procedures to collect biological samples and perform multiple tests related to gut microbiome, exercise performance, muscle phenotype, and other health markers. These assessments occur at baseline, mid-intervention, post-intervention, and post-taper.
1 to 4 visits (in-person) per assessment period
Trial Site Locations
Total: 1 location
1
Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
Leuven, Vlaams Brabant, Belgium, 3001
Actively Recruiting
Research Team
S
Stefan De Smet
S
Sofie Engelborghs
How is the study designed?
Study Type
INTERVENTIONAL
Masking
DOUBLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
BASIC_SCIENCE
Number of Arms
3
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