This study investigates the functional effects of probiotics on athletes by administering Weizmannella coagulans BC99 for 12 weeks. It aims to assess the probiotic's influence on skeletal muscle content, athletic performance, and protein digestion and metabolism. This is achieved by monitoring changes in digestive enzymes, amino acids, body composition, and hormone levels. The research seeks to offer a theoretical foundation for optimizing athletes' training and nutrition strategies and suggests the potential of probiotics in enhancing nutrient absorption and utilization, particularly in individuals with compromised digestive capabilities.

Inclusion Criteria:

1. Voluntarily, in writing, and signing the informed consent form, agreeing to participate in this study;
2. Agree to abide by the protocol and study restrictions;
3. The subject is not allergic to protein products;
4. Male or female subjects aged 18 to 35 years old (including 18 and 35 years old);
5. Male subjects should weigh no less than 50 kilograms. Female subjects must weigh no less than 45 kg. Body mass index (BMI) = weight (kg)/height (m)2, body mass index is in the range of 19.0 to 24.0 kg/m2;
6. No history of hidden risks of cardiovascular and cerebrovascular diseases, hypertension, diabetes, liver/kidney function, etc. and metabolic abnormalities.

Exclusion Criteria:

1. Patients with allergies and immune deficiency;
2. Donated blood or lost a large amount of blood (≥200 mL) within 3 months before taking the trial drug;
3. Other systemic diseases, including cardiovascular disease, lung disease, liver disease, kidney disease and other serious lesions of important organs, severe metabolic diseases (diabetes, thyroid disease), severe immune system diseases; no cardiovascular and cerebrovascular diseases, hypertension , diabetes, liver/kidney function and other hidden dangers and metabolic abnormalities.
4. Drugs that affect intestinal flora (including antibacterial drugs, microecological preparations, intestinal mucosal protective agents, Chinese patent medicines, etc.) have been used continuously for more than 1 week within 1 month before screening;
5. Subjects judged by other researchers to be unfit to participate.

Double（Participant,Investigator）