What is Sarcopenia
Sarcopenia is a progressive skeletal muscle disorder characterized by loss of muscle mass, strength, and physical function, leading to increased risk of falls, disability, and death 1.
Core Definition
Sarcopenia represents a syndrome involving the generalized and progressive deterioration of skeletal muscle across three key dimensions 1:
- Muscle mass: Quantitative loss of skeletal muscle tissue
- Muscle strength: Reduced force-generating capacity
- Physical performance/function: Impaired ability to perform daily activities
The condition primarily affects older adults as part of the aging process (primary sarcopenia), but can also develop secondary to disease, physical inactivity, or inadequate nutrition (secondary sarcopenia) 1.
Clinical Significance
The importance of recognizing sarcopenia lies in its association with serious adverse outcomes 2, 3:
- Impaired mobility and increased fall risk
- Higher morbidity and mortality rates
- Reduced quality of life
- Increased hospitalization and healthcare costs
- Greater risk of osteoporotic fractures when combined with low bone density
Diagnostic Approach
The ESPEN-endorsed European Working Group on Sarcopenia in Older Persons provides the algorithmic framework for diagnosis 1:
Muscle Mass Assessment
Use validated measurement techniques:
- DXA (Dual X-ray Absorptiometry): Appendicular skeletal muscle mass index <7.26 kg/m² (men) or <5.5 kg/m² (women)
- BIA (Bioelectric Impedance Analysis)
- CT scanning
Muscle Strength Assessment
Handgrip strength with cut-offs:
- <30 kg for men
- <20 kg for women
Physical Performance Assessment
Gait speed testing:
- <0.8 m/s (or <1.0 m/s by some criteria)
- Chair stand test for lower extremity function
Important Clinical Context
A critical pitfall is sarcopenic obesity, where muscle loss occurs while fat mass is preserved or increased 4. These patients may have normal body weight but marked weakness, making the condition easy to miss without specific assessment.
The definition has evolved significantly over recent decades—originally focused solely on muscle mass, current consensus emphasizes functional measures (strength and performance) as the primary diagnostic features 2, reflecting what matters most for patient outcomes.