Reference values for vastus lateralis fiber size and type in healthy subjects over 40 years old: a systematic review and metaanalysis

• Published in: Journal of applied physiology (1985) Vol. 115; no. 3; pp. 346 - 354
• Main Authors: Gouzi, Fares, Maury, Jonathan, Molinari, Nicolas, Pomiès, Pascal, Mercier, Jacques, Préfaut, Christian, Hayot, Maurice
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.08.2013
• Subjects: Adult; Aged; Aging - physiology; Algorithms; Anaerobic Threshold - physiology; Body Mass Index; Chronic illnesses; Correlation analysis; Data Interpretation, Statistical; Databases, Factual; Female; Gender; Heterogeneity; Human health and pathology; Humans; Leg - anatomy & histology; Life Sciences; Male; Middle Aged; Multivariate analysis; Muscle Fibers, Skeletal - physiology; Muscle Fibers, Skeletal - ultrastructure; Muscle Fibers, Slow-Twitch; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - physiology; Musculoskeletal diseases; Older people; Reference Values; Regression Analysis; Tissues and Organs; atrophy; skeletal muscle fiber; healthy subject; chronic disease; elderly
• DOI: 10.1152/japplphysiol.01352.2012
• ISSN: 8750-7587; 1522-1601

Skeletal muscle atrophy is a major systemic impairment in chronic diseases. Yet its determinants have been hard to identify because a clear research definition has not been agreed upon. The reduction in muscle fiber cross-sectional area (CSA) is a widely acknowledged marker of muscle atrophy, but no reference values for the muscle fiber CSA at the age of the onset of chronic disease have ever been published. Thus, we aimed to systematically review the studies providing data on fiber CSA and fiber type proportion in the vastus lateralis of the quadriceps of healthy subjects (age >40 yr) and then to pool and analyze the data from the selected studies to determine reference values for fiber CSA. We followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and identified 19 studies, including 423 subjects that matched the inclusion criteria. On the basis of fiber type and gender, the mean fiber CSA and the lower limits of normal (LLNs) were (%type I*60) + 1,743 μm 2 and (%type I*60) − 718 μm 2 , respectively, for men; and (%type I*70) + 139 μm 2 and (%type I*70) − 1,485 μm 2 , respectively, for women. There was no significant heterogeneity among subgroups of fiber type and gender. The pooled type I fiber proportion was 50.3% (LLN = 32.9%). In multivariate analysis, fiber CSA was significantly correlated with V̇o 2 peak ( r = 190.92; P = 0.03), and type I fiber proportion was correlated with age ( r = −0.024; P = 0.005), body mass index ( r = 0.096; P = 0.005), and V̇o 2 peak ( r = −0.053; P = 0.005). Our metaanalysis of a homogeneous set of studies is the first to provide valuable LLNs for fiber CSA according to fiber type and gender. This analysis will be improved by prospective assessment in well-characterized healthy subjects.