muscle quality（筋肉の質）レビュー

加齢によるmuscle quality（筋肉の質）の変化に関するレビュー論文を紹介します。

David W. Russ, Kimberly Gregg-Cornell, Matthew J. Conaway and Brian C. Clark: Evolving concepts on the age-related changes in “muscle quality”. Journal of Cachexia, Sarcopenia and Muscle DOI: 10.1007/s13539-011-0054-2

下記のHPで全文PDFで見れます。
http://www.springerlink.com/content/u400w8658h7711j7/fulltext.pdf

muscle qualityとは、筋肉の質と私は訳していますが、筋肉量あたりの筋力の強さの意味です。muscle qualityが高い方は少ない筋肉量でも筋力が比較的強く、muscle qualityが低い方は筋肉量があっても筋力が比較的弱いです。

筋肉量と筋力に関連はありますが、筋力は筋肉量だけで決まるのではなく神経学的な影響も受けます。この論文では神経筋系の加齢による変化を脳から筋線維のレベルまで検討しています。神経学的な面がダイナペニア（加齢による筋力低下）に影響を与えている可能性があります。

ダイナペニアという言葉もありますが、サルコペニアの定義の主流は、加齢による筋肉量低下＋筋力低下もしくは身体機能低下となっています。そうするとこのサルコペニアの定義に中にダイナペニアは含まれます。○○ペニアという言葉がこれ以上増えないことを祈ります…。

Abstract
The deterioration of skeletal muscle with advancing age has long been anecdotally recognized and has been of scientific interest for more than 150 years. Over the past several decades, the scientific and medical communities have recognized that skeletal muscle dysfunction (e.g., muscle weakness, poor muscle coordination, etc.) is a debilitating and life-threatening condition in the elderly. For example, the age-associated loss of muscle strength is highly associated with both mortality and physical disability. It is well-accepted that voluntary muscle force production is not solely dependent upon muscle size, but rather results from a combination of neurologic and skeletal muscle factors, and that biologic properties of both of these systems are altered with aging. Accordingly, numerous scientists and clinicians have used the term “muscle quality” to describe the relationship between voluntary muscle strength and muscle size. In this review article, we discuss the age-associated changes in the neuromuscular system—starting at the level of the brain and proceeding down to the subcellular level of individual muscle fibers—that are potentially influential in the etiology of dynapenia (age-related loss of muscle strength and power).