2016 Update on bone health

Sarcopenia: Still important, clinical approaches to easily detect it

Beaudart C, McCloskey E, Bruyére O, et al. Sarcopenia in daily practice: assessment and management. BMC Geriatr. 2016;16(1):170.

In last year's update, I reviewed the article by He and colleagues¹¹ on the relationship between sarcopenia and body composition with osteoporosis. Sarcopenia, which is the age-related loss of muscle mass and strength, is important to address in patients. Body composition and muscle strength are directly correlated with bone density, and this is not surprising since bone and muscle share some common hormonal, genetic, nutritional, and lifestyle determinants.^12,13 Sarcopenia can be diagnosed via dual-energy x-ray absorptiometry (DXA) scan looking at lean muscle mass.

The term sarcopenia was first coined by Rosenberg and colleagues in 1989¹⁴ as a progressive loss of skeletal muscle mass with advancing age. Since then, the definition has expanded to incorporate the notion of impaired muscle strength or physical performance. Sarcopenia is associated with morbidity and mortality from linked physical disability, falls, fractures, poor quality of life, depression, and hospitalization.¹⁵

Current research is focusing on nutritional exercise/activity-based and other novel interventions for improving the quality and quantity of skeletal muscle in older people. Some studies demonstrated that resistance training combined with nutritional supplements can improve muscle function.¹⁶

Details of the study

Beaudart and colleagues propose some user-friendly and inexpensive methods that can be utilized to assess sarcopenia in real life settings. They acknowledge that in research settings or even specialist clinical settings, DXA or computed tomography (CT) scans are the best assessment of muscle mass.

Anthropometric measurements. In a primary care setting, anthropometric measurement, especially calf circumference and mid-upper arm muscle circumference, correlate with overall muscle mass and reflect both health and nutritional status and predict performance, health, and survival in older people.

However, with advancing age, changes in the distribution of fat and loss of skin elasticity are such that circumference incurs a loss of accuracy and precision in older people. Some studies suggest that an adjustment of anthropometric measurements for age, sex, or BMI results in a better correlation with DXA-measured lean mass.¹⁷ Anthropometric measurements are simple clinical prediction tools that can be easily applied for sarcopenia since they offer the most portable, commonly applicable, inexpensive, and noninvasive technique for assessing size, proportions, and composition of the human body. However, their validity is limited when applied to individuals because cutoff points to identify low muscle mass still need to be defined. Still, serial measurements in a patient over time may be valuable.

Related article:
2014 Update on osteoporosis

Handgrip strength, as measured with a dynamometer, appears to be the most widely used method for the measurement of muscle strength. In general, isometric handgrip strength shows a good correlation with leg strength and also with lower extremity power, and calf cross-sectional muscle area. The measurement is easy to perform, inexpensive and does not require a specialist-trained staff.

Standardized conditions for the test include seating the patient in a standard chair with her forearms resting flat on the chair arms. Clinicians should demonstrate the use of the dynamometer and show that gripping very tightly registers the best score. Six measurements should be taken, 3 with each arm. Ideally, patients should be encouraged to squeeze as hard and tightly as possible during 3 to 5 seconds for each of the 6 trials; usually the highest reading of the 6 measurements is reported as the final result. The Jamar dynamometer, or similar hydraulic dynamometer, is the gold standard for this measurement.

Gait speed measurement. The most widely used tool in clinical practice for the assessment of physical performance is the gait speed measurement. The test is highly acceptable for participants and health professionals in clinical settings. No special equipment is required; it needs only a flat floor devoid of obstacles. In the 4-meter gait speed test, men and women with a gait speed of less than 0.8 meters/sec are described as having a poor physical performance. The average extra time added to the consultation by measuring the 4-meter gait speed was only 95 seconds (SD, 20 seconds).