The intestinal microbiome is a microbial system that is influenced by host genetics and environmental exposures such as nutrition, stress and medications. There is a growing body of evidence indicating the significant contribution of the gut microbiome to host health and disease. Furthermore, it has been shown that exercise may modify the microbiome composition. However, important mechanistic questions related to the possible associations between exercise and the human gut microbiome remain unanswered.

In this study, the investigators are using advanced state-of-the-art measurements of physical activity level and related metabolic parameters whether there is a connection between the microbiome and physical abilities in healthy participants and whether antibiotics consumption can influence host physical abilities and glycemic responses through changes induced in microbiome composition and function.

During all days of the study, participants will be connected to a continuous glucose monitor (CGM).

In the second segment of the study, participants will be randomized into two groups: antibiotics or placebo, which will be consumed for 7 days.

The third segment of the trial, participants will undergo an FMT/placebo administration for three consecutive days according to their randomization: participants who received antibiotics will receive FMT and participants who received placebo pills will receive placebo capsules in this segment as well.

During the study, participants will collect stool and buccal samples which will be used for microbiota profiling.

Furthermore, participants will undergo physical abilities test, anthropometric measurements, medical history questioners, blood and urine samples and Dual X-ray absorptiometry (DXA) test.

Inclusion Criteria:

• BMI<28
• Age - 20-35
• Are used to exercise in aerobic sports (running, swimming, Zumba, ball games, functional training, surfing, tennis, wrestling ext.).
• Exercise at least twice a week, for a minimum duration of the last 6 months.

Exclusion Criteria:

• Consumption of antibiotics (PO) or probiotics 3 months prior to the first day of the experiment.
• Diagnosis of type 1 or type 2 diabetes.
• Pregnancy, fertility treatments, breastfeeding women six months prior to enrollment and during the study.
• Chronic disease (e.g. AIDS, Cushing syndrome, CKD, acromegaly, hyperthyroidism etc.)
• Cancer and recent anticancer treatment
• Psychiatric disorders
• Coagulation disorders
• Gastrointestinal disorders
• Bariatric surgery
• Alcohol or substance abuse
• BMI>28
• Any physical condition precluding the completion of a routine effort test