ダイナペニアと加齢

ダイナペニアと加齢に関する最新のレビュー論文を紹介します。

Manini TM, Clark BC: Dynapenia and Aging: An Update. J Gerontol A Biol Sci Med Sci. 2011 Mar 28. [Epub ahead of print]

下記のHPで全文PDFファイルで読めるようです。

http://biomedgerontology.oxfordjournals.org/content/early/2011/03/27/gerona.glr010.full.pdf+html

この著者たちはサルコペニア＝加齢による筋肉量減少、ダイナペニア＝加齢による筋力減少と使い分けるべきで、サルコペニアとダイナペニアは別の概念と提案しています。

この論文では図のようなアルゴリズムでダイナペニアを診断することを提示しています。握力と膝伸展筋力を重視しています。その上で原因を神経原性と筋原性にわけて考えます。このアルゴリズムの詳細は下記のHPを参照してください。意見などの投票や投稿もできます。私も投票してみました。

http://dynapenia.blogspot.com/

確かに一定の関連はあるにせよ、筋肉量低下＝筋力低下ではありません。筋肉量と筋力はそれぞれ評価すべきだと思います。しかし現状では、サルコペニア＝加齢による筋肉量減少＋筋力減少という定義がもっとも有力なようです。また加齢以外の要因による筋力低下は、ダイナペニアとは別にミオペニアと呼ぶべきでしょう。ややこしい…。ミオペニアも含めて用語とその定義の混乱が早く落ち着くことを期待しています。

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.