Sarcopenia: What's in a Name?

Skeletal muscle aging: influence of oxidative stress and physical exercise

“…A shift in muscle fiber composition occurs in advancing age with a decrease in large fast-twitch glycolytic (Type II) fiber [9]. Changes in motor neurons have also been observed; with ageing, the number and activity of motor units are decreased impairing motor control [28, 29]. Alterations in the type of fibers may occur when type II myofibers are re-innervated by type I motor neurons [28].…”

“…Changes in motor neurons have also been observed; with ageing, the number and activity of motor units are decreased impairing motor control [28, 29]. Alterations in the type of fibers may occur when type II myofibers are re-innervated by type I motor neurons [28]. However, whether this motor unit change is a cause of sarcopenia or a compensatory adaptive response to sarcopenia is unresolved [12].…”

Muscle wasting in ageing and chronic illness

“…2 Of note, the thereby maintained cutpoints were found to have a predictive value on incident mobility impairment over 3 years of follow-up. 2,15 However, a current review article on sarcopenia argues '…that what we have…' would be '…an amalgamated and often conflicted description, rather than a definition, of the sarcopenic condition…'. 2 This is important because a more specific definition of agerelated muscle wasting is highly desirable on practical grounds because specific criteria are critical for identifying candidate patients for clinical trials that test therapies aimed at reversing or alleviating the complications of sarcopenia and its associated manifestations.…”

“…16 Recently, an international consensus on definition and classification of cancer cachexia confirmed this weight cut-off by stating that patients who have more than 5% loss of stable body weight over the previous 6 months, or a BMI of less than 20 kg/m 2 , and ongoing weight loss of more than 2% are classified as having cachexia. 15,18 The chronic one is the most Muscle wasting 59 frequent form and can be classified by its aetiology (i.e. 17 Muscle wasting diseases According to these overlaps and as the common phenomenon of both sarcopenia and cachexia is loss of muscle, a more integrative definition of age-related sarcopenia and chronic disease-related cachexia has been proposed recently, namely, the term 'muscle wasting diseases'.…”

Designing pharmaceutical trials for sarcopenia in frail older adults: EU/US task force recommendations

“…At least four operative definitions of sarcopenia have been published (3–6), and while they are all fundamentally similar, citing low muscle mass and problems with physical function, the lack of consensus on an accepted definition has stifled progress toward advancing understanding of the condition, developing new treatments, and conducting clinical trials (7). Sarcopenia is a major component of the geriatric syndrome of frailty (8); thus elderly individuals with sarcopenia are at increased risk of being frail.…”