From muscle wasting to sarcopenia and myopenia: update 2012
Human muscle undergoes constant changes. After about age 50, muscle mass decreases at an annual rate of 1–2 %. Muscle strength declines by 1
From muscle wasting to sarcopenia and myopenia: update 2012
Human muscle undergoes constant changes. After about age 50, muscle mass decreases at an annual rate of 1–2 %. Muscle strength declines by 1.5 % between ages 50 and 60 and by 3 % thereafter. The reasons for these changes include denervation of motor units and a net conversion of fast type II muscle fibers into slow type I fibers with resulting loss in muscle power necessary for activities of daily living. In addition, lipids are deposited in the muscle, but these changes do not usually lead to a loss in body weight. Once muscle mass in elderly subjects falls below 2 standard deviations of the mean of a young control cohort and the gait speed falls below 0.8 m/s, a clinical diagnosis of sarcopenia can be reached. Assessment of muscle strength using tests such as the short physical performance battery test, the timed get-up-and-go test, or the stair climb power test may also be helpful in establishing the diagnosis. Serum markers may be useful when sarcopenia presence is suspected and may prompt further investigations. Indeed, sarcopenia is one of the four main reasons for loss of muscle mass. On average, it is estimated that 5–13 % of elderly people aged 60–70 years are affected by sarcopenia. The numbers increase to 11–50 % for those aged 80 or above. Sarcopenia may lead to frailty, but not all patients with sarcopenia are frail—sarcopenia is about twice as common as frailty. Several studies have shown that the risk of falls is significantly elevated in subjects with reduced muscle strength. Treatment of sarcopenia remains challenging, but promising results have been obtained using progressive resistance training, testosterone, estrogens, growth hormone, vitamin D, and angiotensin-converting enzyme inhibitors. Interesting nutritional interventions include high-caloric nutritional supplements and essential amino acids that support muscle fiber synthesis.
KeywordsSarcopenia Muscle mass Prevalence Morbidity
1 A history of muscle loss
2 How to measure muscle mass and muscle strength?
Prevalence of sarcopenia
n (% female)
Sarcopenia definition (assessment method)
5,036 (56.4 %)
Categories of skeletal mass index, defined as muscle mass normalized for height (BIA)
Moderate sarcopenia, m: 70.7 %, f: 41.9 %; severe sarcopenia, m: 17.1 %, f: 10.7 %
1,458 (100 %)
All >70 years; mean 80.3 ± 3.8 years
Appendicular skeletal muscle mass <2 SD below the mean of a young female reference group (DEXA)
Calf muscle cross-sectional area more than 2 SD below population mean (CT scan)
m: 20 % at 65 years, 70 % at 85 years; f: 5 % at 65 years, 15 % at 85 years
NHANES III (USA)
>18 years; 30 % >60 years
Skeletal mass index was defined as muscle mass/body mass x 100; sarcopenia class I defined as skeletal muscle mass 1–2 SD, sarcopenia class II defined as skeletal muscle mass >2 SD from the mean of young subjects (BIA)
In subjects aged >60 years: sarcopenia class I, m: 45 %, f: 59 %; sarcopenia class II: m: 7 %, f: 10 %
808 (47.3 %)
m: 73.6 ± 5.8 years; f: 73.7 ± 6.1 years
Appendicular skeletal muscle mass <2 SD below the mean of a young reference population (substudy of DEXA)
<70 years, m: 13.5–16.9 %, f: 23.1–24.1 %; 70–74 years, m: 18.3–19.8 %, f: 33.3–35.1 %; 75–80 years, m: 26.7–36.4 %, f: 35.3–35.9 %;>80 years, m: 52.6–57.6 %, f: 43.2–60.0 %
The broadness in the range of sarcopenia prevalence is partly due to the heterogenecity of study populations, but also due to the different techniques used to assess muscle mass. Dual-energy X-ray absorptiometry (DEXA) is currently considered the gold standard. The name is derived from the fact that two X-ray beams are used with different energy levels of minimal intensity. Other methods used to measure muscle mass include bioelectrical impedance, computed tomography, magnetic resonance imaging, urinary excretion of creatinine, anthropometric assessments, and neutron activation assessments. Depending on the actual technique used in different studies and on the cutoff values chosen, the prevalence of muscle mass may vary considerably (Table 1). Many institutions use handgrip strength as a standard measure for assessing muscle strength. Physical performance can be analyzed using simple and easy-to-do tests such as the short physical performance battery test, usual gait speed, the timed get-up-and-go test, or the stair climb power test. More recently, Scharf and Heineke have argued that “a combination of serum markers, diagnostic imaging, and functional tests of muscle function would constitute an ideal biomarker panel”. A recent consensus statement  acknowledges that the list of potential serum markers of sarcopenia is quite long. It embraces markers of inflammation (e.g., C-reactive protein, interleukin