A Prospective Study to Evaluate the Efficacy and Safety of Heat-Treated, Cultured, and Dried Lactiplantibacillus plantarum beLP1 in Improving Muscle Strength and Muscle Function

INTERVENTION: Dietary Supplement : Participants will be randomly assigned to either the investigational product group or the control group. [Investigational Product] Active Ingredient: Heat‐treated, cultured, and dried preparation of Lactiplantibacillus plantarum beLP1 Dosage Form: Hard capsule Content: 200 mg/capsule Storage Conditions: Store at room temperature (1–35°C), protected from direct sunlight and high temperature and humidity. Dosage and Administration: One capsule is to be taken orally once daily for 12 weeks (equivalent to 1 × 10¹¹ cells/day of the heat‐treated, cultured, and dried preparation of Lactiplantibacillus plantarum beLP1). [Control Product (Placebo)] The control product will be stored under the same conditions as the investigational product and administered in the same manner. Active Ingredient: Dextrin Dosage Form: Hard capsule Content: 200 mg/capsule CONDITION: Diseases of the musculoskeletal system and connective tissue PRIMARY OUTCOME: Quadriceps strength SECONDARY OUTCOME: ASM/Height 2 ASM/Weight?100 Blood biomarkers (TNF‐a, IL‐1ß, IL‐6, myostatin, follistatin) Bowel movement diary (bowel movement frequency, stool consistency, SBM, and CSBM) EQ‐5D‐3L(EuroQol Five‐dimensions Three‐level) Fecal microbiota GSRS(Gastrointestinal Symptom Rating Scale) Hamstring strength Handgrip strength MFR(Skeletal Muscle to Body Fat Ratio) Muscular endurance SMM(Skeletal Muscle Mass) SPPB(Short Physical Performance Battery) INCLUSION CRITERIA: 1) Adults aged 50 to 85 years, including both males and females. 2) Individuals whose handgrip strength measurements for both hands are at or below the age‐specific reference values (based on the 2022 National Health Statistics): ? Aged 50 to 59 years: =42 kg for males and =25.1 kg for females ? Aged 60 to 69 years: =38.5 kg for males and =24.1 kg for females ? Aged 70 to 85 years: =33.2 kg for males and =20.9 kg for females 3) Individuals with a Short Physical Performance Battery (SPPB) score of greater than 9. 4) Individuals who agree to participate in this clinical trial before its initiation and provide written informed consent by completing the Informed Consent Form (ICF).