Resistance-Based Multicomponent Training Plus Nutrition Supplementation for Intrinsic Capacity and Disability Risk in Chinese Rural Older Adults

This study is a five-arm, parallel-group, assessor-blinded randomized controlled trial designed to evaluate the effects of resistance-dominant multicomponent training combined with nutritional supplementation on intrinsic capacity and disability risk among rural Chinese older adults. A total of 220 participants aged 60 years or older with mobility decline, nutritional risk, sarcopenia risk, or pre-frailty/frailty will be randomly assigned to one of five groups: control, nutrition supplementation alone, resistance training alone, resistance training plus nutrition supplementation, or resistance-dominant multicomponent training plus nutrition supplementation. The intervention will last 12 weeks. Exercise interventions will be conducted three times per week, and nutritional supplementation will include leucine-enriched whey protein and vitamin D. The primary outcomes are the Short Physical Performance Battery score, FRAIL score, and activities of daily living/instrumental activities of daily living scores. Secondary outcomes include gait speed, Timed Up and Go test, sit-to-stand performance, handgrip strength, nutritional status, protein intake, serum 25-hydroxyvitamin D, calf circumference, and appendicular skeletal muscle mass index.

Inclusion Criteria: 1. Aged 60 years or older. 2. Rural residents who have lived in the study area for at least 6 months and have no plan for long-term absence during the study period. 3. Able to walk independently or with a cane for a short distance. 4. Meeting at least one of the following risk characteristics: Short Physical Performance Battery score of 9 or lower, usual gait speed of 0.8 m/s or lower, Mini Nutritional Assessment Short Form score of 11 or lower, SARC-F score of 4 or higher, possible sarcopenia according to the Asian Working Group for Sarcopenia 2019 criteria, or FRAIL score of 1 to 3. 5. Able to understand the study requirements and provide written informed consent. Exclusion Criteria: 1. Unstable cardiovascular or cerebrovascular events within the past 6 months. 2. Severe uncontrolled hypertension, defined as resting systolic blood pressure of 180 mmHg or higher or diastolic blood pressure of 110 mmHg or higher. 3. Severe cognitive impairment that prevents understanding of or cooperation with the study procedures. 4. Severe osteoarticular disease or neurological disease affecting exercise safety. 5. Severe renal dysfunction, such as estimated glomerular filtration rate lower than 30 mL/min/1.73 m², or considered unsuitable for protein supplementation by the study physician. 6. Hypercalcemia, active kidney stones, or contraindications to vitamin D supplementation. 7. Allergy to whey protein or any component of the nutritional supplement. 8. Regular use of protein powder, beta-hydroxy-beta-methylbutyrate, creatine, or other nutritional supplements that may affect muscle metabolism within the past 3 months. 9. Participation in another interventional study.