As people age, they lose 20–30 % of muscle mass; at the age over 90, it is up to 50 %. Women lose on average 1 kg and men 2 kg of muscle mass per age decade. Incidence of sarcopenia is reported in about 5–13 % of persons between 60–70 years of age and in about 10–50 % of individuals older than 80 years. Similarly as osteoporosis and its consequences, also sarcopenia and its consequences have a significant impact on the health status of geriatric patients, representing a huge economic burden. For example, in the USA, the annual cost of consequences of osteoporotic fractures was calculated at 16.3 billion USD while that of sarcopenia at as much as 18.5 billion USD (Fig. 34.2). Sarcopenia increases twice the risk of falls and three times the risk of limitation of self-care capacity of patients [8, 11]. Analyses of groups of geriatric patients have shown that an absolute majority of them suffer both from sarcopenia and osteoporosis. Therefore this condition is sometimes called “sarcoporosis”. One of the priorities in the near future, which is currently intensively addressed, will be adoption of definition of sarcopenia, similarly as in osteoporosis.

Sarcopenia is certainly not a mere synonym for decrease of muscle mass. Its other symptoms include also functional disorders – decrease of muscle strength and of physical performance.

Muscle mass decrease seems to be responsible for up to 60 % of decrease of physical performance and impaired ability of patients with sarcopenia to perform activities of daily living, the rest being the question of muscle strength and quality. There are a number of methods for measuring muscle mass, strength and performance that are used primarily experimentally, although several procedures are routinely used in the clinical practice (Table 34.1). The simplest and best available combination of methods is measuring muscle mass by DXA, muscle strength by handgrip and physical performance by the test of the usual gait speed. Similarly as osteoporosis categorized into mild, more severe osteopenia and osteoporosis, sarcopenia may be divided into similar stages (Table 34.2).

Sarcopenia has also very similar etiopathogenetic causes as osteoporosis. It may be primary, age related, secondary, associated with limited mobility due to physical inactivity, or associated diseases or malnutrition.

In terms of interaction of sarcopenia and osteoporosis, the most alarming clinical situation occurs in patients with femoral neck fracture. It has been demonstrated that a ten-day bed rest in these patients may lead to a loss of up to 1.5 kg of lean body mass (LBM) which from the functional viewpoint equals a 15 % loss of muscle strength of lower extremities. No surprise, these patients have a poor prognosis unless they are promptly operated on, mobilized and supplied with adequate amounts of substrates for protein synthesis.

The effect of pharmacological treatment on sarcopenia remains questionable. The candidate medications are included in Table 34.3: however, practical use and available evidence-based data currently relate only to vitamin D and alfacalcidol [9, 10, 27, 29, 32, 33]. An essential therapeutic and preventive measure is regular physical activity. As mentioned above, limited mobility or immobility leads quite rapidly to significant progression of sarcopenia and subsequently, in the longer run, also to decrease in BMD (osteopenia follows sarcopenia). In this context, the old adage holds true: use it or lose it.

Both sarcopenia and osteoporosis are age-related processes, resulting from decreased muscle mass and quality, with similar etiological moments and almost the same pathogenesis. They also have similar consequences for human health – increased risk of falls and fractures. Sarcopenia is therefore currently intensively investigated by a whole number of research teams worldwide; in Europe it is primarily the European Working Group on Sarcopenia in Older People (EWGSOP).

Frailty syndrome (FS) is one of the core geriatric syndromes, which is considered a cornerstone (holy grail or raison d’etre) of the current geriatric medicine. Its principle is accumulation of age-related deficits compromising the ability to withstand stressors and to maintain immune system homeostasis. Physiological reserves are decreasing with the increasing risk of adverse consequences of ageing. To put it simply, it is a process of accelerated, unsuccessful ageing [12, 41]. Biological age is naturally influenced by a number of various deficits acquired by a particular person during the whole life and may largely vary between individuals. Accumulation of deficits and handicaps is growing exponentially at the end of life. FS is a vulnerable state of an individual associated with a high risk of an external trigger event provoking a cascade of consequences with adverse effects, complications (falls, injuries, recurrent infections, repeated hospital stay, worse convalescence, a higher risk of iatropathogenic factors), such as immobility, inability to perform activities of daily living or death in the worst case [21, 41, 42]. On the other hand, if properly detected, this state may be successfully treated and other problems may be effectively prevented. Thus, it is sort of “therapeutic window” in the ageing process associated with possible reversibility. Chronologically, it proceeds from the “frailty phenotype” through “prefrail” phase to the actual FS and its potential consequences (Fig. 34.3). The FS principle is based on the concept that human beings are not only a sum of individual parts and that it is necessary to evaluate comprehensively their state and risks. This phenomenon goes against the mainstream of the current atomized and overspecialized medicine, and as such it is not reflected in the current health insurance payment system.

In terms of diagnosis, there are on the one hand relatively complicated questionnaires evaluating a number of potential risks for an individual, with the resulting frailty index assessment (e.g. K. Rockwood’s approach), and on the other hand, there exists a substantially more simple and in terms of clinical practice more practical assessment and classification of the frailty phenotype based on syndromology (L. Fried’s approach – Fig. 34.4). Persons with a negative score are classified as “robust”. The presence of two of the above-mentioned symptoms defines the “prefrail” state of the frailty process, and the presence of three symptoms corresponds to the “frailty” state. FS prevalence in the population is estimated at 10–25 % in persons older than 65 years and at 30–45 % in those older than 85 years [26, 38, 39]. Adapted Fried’s criteria have been adopted by the American Geriatrics Society and have been recently introduced also in osteology. Similarly as in sarcopenia (sarcopenic obesity), the frailty syndrome may also pose a diagnostic problem in individuals with overweight, who are affected by the syndrome form called “fat-frail syndrome”. It is generally known that obese persons have usually better BMD values than asthenic individuals, but they are more susceptible to falls and, consequently, to fractures. The vicious “frailty cycle” starts by decreasing regular physical activity, contributing to additional physiological decrements in functional reserve capacity of multiple organ systems.