Dynapenia and Aging: An Update

Abstract

In 2008, we published an article arguing that the age-related loss of muscle strength is only partially explained by the reduction in muscle mass and that other physiologic factors explain muscle weakness in older adults (Clark BC, Manini TM. Sarcopenia =/= dynapenia. J Gerontol A Biol Sci Med Sci. 2008;63:829-834). Accordingly, we proposed that these events (strength and mass loss) be defined independently, leaving the term "sarcopenia" to be used in its original context to describe the age-related loss of muscle mass. We subsequently coined the term "dynapenia" to describe the age-related loss of muscle strength and power. This article will give an update on both the biological and clinical literature on dynapenia-serving to best synthesize this translational topic. Additionally, we propose a working decision algorithm for defining dynapenia. This algorithm is specific to screening for and defining dynapenia using age, presence or absence of risk factors, a grip strength screening, and if warranted a test for knee extension strength. A definition for a single risk factor such as dynapenia will provide information in building a risk profile for the complex etiology of physical disability. As such, this approach mimics the development of risk profiles for cardiovascular disease that include such factors as hypercholesterolemia, hypertension, hyperglycemia, etc. Because of a lack of data, the working decision algorithm remains to be fully developed and evaluated. However, these efforts are expected to provide a specific understanding of the role that dynapenia plays in the loss of physical function and increased risk for disability among older adults.

Análise de métodos para detectar sarcopenia em idosas independentes da comunidade

“…This reduction in strength due to aging is known as "dynapenia" and can have an effect on physical performance. 22 According to the recommendations proposed by consensus in 2010 for sarcopenia assessments, the results of the present study indicate that the mean CC (used to assess muscle mass) did not identify the presence of sarcopenia in these independent community-dwelling elderly women. Nevertheless, the World Health Organization (WHO) considers CC to be a sensitive measurement of muscle mass in elderly individuals, which indicates age-related alterations and a reduction in physical activity.…”

Age-related changes in the rate of muscle activation and rapid force characteristics

“…The increased current life expectancy and rapid growth of the elderly population has presented researchers with additional incentive to continue to improve our understanding of the physiological changes that occur across the lifespan (Manini and Clark 2012). For instance, Deschenes (2011) recently suggested that "because of the marked increase in the number of people considered to be aged in industrialized countries, it is essential to expand our understanding of the influence of aging on the neuromuscular system…" p. 209.…”

Existe associação entre massa e força muscular esquelética em idosos hospitalizados?

“…[22][23][24][25] Muscle power generation is influenced by several morphological factors, which are related to tension per unit of mass, great activation capacity of the neuromuscular system, deterioration of contractile fibers, increase in the percentage of muscle infiltration by fat tissue, and decreased tendon stiffness, in addition to the reduction of muscle mass itself. 22,23,25 These factors may explain, in part, the low accuracy of mass in predicting strength shown in the study.…”

“…2,3,27 It is important to note that strength deficit is not the only determinant of worsening physical performance, as there are other systems involved. 22 The study has some limitations such as the fact that it is a cross-sectional study, therefore making it impossible to associate the evaluation of these variables over time. Another limitation was the use of a less accurate tool for quantification of muscle mass, since the instruments considered to be gold standard are expensive.…”