To evaluate the clinical efficacy of Weizmannia coagulans BC99 in young Chinese patients with exercise-induced muscle damage compared with placebo, and to explore its effects on inflammatory responses and intestinal microbiota.

Inclusion Criteria:

1. Healthy adults aged 19-35 years, with no restriction on sex;
2. Physically active individuals with regular daily exercise training intensity and duration;
3. No history of allergy to protein products;
4. Body weight ≥50 kg for male subjects and ≥45 kg for female subjects; body mass index (BMI), calculated as weight (kg) divided by height squared (m²), within the range of 19.0-24.0 kg/m²;
5. No history of cardiovascular or cerebrovascular diseases, hypertension, diabetes, hepatic or renal dysfunction, or other underlying diseases or metabolic disorders;
6. Willingness to comply with the study protocol and study restrictions, and voluntary provision of written informed consent to participate in the study.

Exclusion Criteria:

1. History of allergic constitution or immunodeficiency;
2. Blood donation or significant blood loss (≥200 mL) within 3 months prior to administration of the investigational product;
3. Presence of severe diseases of major organs, including the cardiovascular system, lungs, liver, or kidneys, as well as diabetes mellitus, severe thyroid disorders, metabolic diseases, malignant tumors, or severe immune system diseases;
4. Use of medications affecting the intestinal microbiota (including antibiotics, microecological preparations, intestinal mucosal protectants, traditional Chinese medicines, etc.) for more than one consecutive week within 1 month prior to screening;
5. Any other condition that, in the investigator's judgment, makes the subject unsuitable for participation in the study.