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RECRUITING

NCT07481578

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

Sponsor: Stefan De Smet

View on ClinicalTrials.gov

Summary

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.

Official title: ICARUS: Impact of Training Load on the Gut Microbiome and Its Relation to Exercise Performance, Muscle Phenotype, and Markers of Overreaching in Healthy Men: Phase A - Human Trial

Key Details

Gender

MALE

Age Range

18 Years - 45 Years

Study Type

INTERVENTIONAL

Enrollment

Start Date

2024-10-07

Completion Date

2027-05-31

Last Updated

2026-03-19

Healthy Volunteers

Yes

Conditions

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

Interventions

DIETARY_SUPPLEMENT

Supplement

The nature of the intervention does not allow blinding of study participants. However, to induce an 'expectancy-effect' in the control group, participants allocated to the control group will receive dietary placebo supplementation. Participants will be told (deceived) that this novel 'plant extract' is believed to have the potential to mimic training effects on gut health and exercise performance. The dietary placebo capsule will consist of 1 g sugar. Intake of the dietary placebo capsule will take place after a fasting state of six hours or more, at a fixed timepoint once a week, and under direct supervision of a research investigator (Sofie Engelborghs). The control group does not participate in any study-related training sessions, but will be asked to continue and monitor (Polar Pacer heart rate monitor) their normal physical activities and sports.

BEHAVIORAL

Moderate load exercise training

The moderate load training group will enroll in an exercise intervention of 8 weeks. This intervention consists of cycling sessions on an electromagnetically braked ergometer under direct supervision of the investigators at the Exercise and Muscle Physiology Group. Training intensities are prescribed based on the power output associated with the first and second lactate threshold and maximal power output obtained during a maximal incremental step test with capillary lactate measurements. Three types of training sessions will be prescribed: moderate-intensity continuous training (2x/week), high-intensity interval training (1x/week), and sprint interval training (1x/week). The training load will gradually increase over time, by increasing the session duration and/or intervals.

BEHAVIORAL

High load exercise training

Participants allocated to the high load training group will conduct a similar intervention as the moderate load training group, but with double the amount of training sessions (8x/week) throughout the last four weeks of the 8-week training program. The four weeks of high load training aims to induce a state of overreaching in some though not all participants allocated to the high load training group.

Inclusion criteria: * 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. Exclusion criteria: * 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.

Locations (1)

Exercise Physiology Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium

Leuven, Vlaams Brabant, Belgium