Sarcopenia and frailty are highly prevalent, overlapping geriatric syndromes that significantly impact the health and independence of older adults. Sarcopenia is defined as the progressive, age-related loss of skeletal muscle mass, strength, and physical function. Frailty is a broader state of multi-system impairment that leads to a decreased physiological reserve and increased vulnerability to stressors. Both conditions are associated with severe adverse outcomes, including an increased risk of falls, physical disability, cognitive decline, prolonged hospitalizations, and premature mortality.

Key Pathophysiological Mechanisms The development of sarcopenia and frailty is driven by interconnected biological hallmarks of aging. The primary mechanisms include:

• Mitochondrial Dysfunction & Oxidative Stress: Impaired mitochondrial bioenergetics and elevated reactive oxygen species (ROS) lead to reduced ATP production, muscle fiber damage, and the degeneration of the neuromuscular junction.
• Inflammaging: Chronic, low-grade systemic inflammation disrupts muscle protein turnover, promotes insulin resistance, and accelerates muscle catabolism.
• Anabolic Resistance: Aging muscle becomes less responsive to anabolic stimuli (such as protein intake and exercise), shifting the physiological balance toward muscle degradation.

Diagnosis Clinical diagnosis relies heavily on assessing physical function. Major guidelines (like EWGSOP2 and AWGS) prioritize low muscle strength (measured via handgrip strength or chair stand tests) as the primary indicator of probable sarcopenia. Severity is assessed through physical performance metrics like gait speed or the Short Physical Performance Battery (SPPB). Muscle mass deficits are usually confirmed via dual-energy X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA). The SARC-F questionnaire is widely recommended as a rapid, self-reported screening tool.

Management and Interventions While pharmacological therapies remain largely investigational, lifestyle modifications are the cornerstone of treatment:

• Exercise: Progressive resistance training, often combined with aerobic exercise, is the most effective strategy to stimulate muscle hypertrophy, enhance strength, and restore mitochondrial function.
• Nutritional Supplementation: Combining exercise with targeted nutrition significantly boosts muscle preservation and clinical outcomes. Key supplements include high-quality protein, Leucine, β-hydroxy-β-methylbutyrate (HMB), creatine monohydrate, vitamin D, and Omega-3 fatty acids. Notably, interventions using HMB and adequate protein have been associated with preserved muscle mass, reduced hospital readmissions, and subsequent healthcare cost savings.