title: Effects of age on muscle as measured by electrical impedance myography.
abstract: Electrical impedance myography (EIM) is a painless and non-invasive technique for the assessment of muscle which we apply here to the effects of normal aging. The paper presents a cross-sectional analysis of EIM data from the quadriceps and tibialis anterior of 100 healthy subjects (44 men, 56 women, ages 18-90 years). The principal EIM parameter, the spatially averaged phase theta(avg), shows a roughly quadratic reduction with increasing age, declining more steeply beyond 60 years. The correlation was stronger in men (quadriceps: r2 = 0.68 for men, 0.52 for women; tibialis anterior: r2 = 0.74 for men, 0.38 for women; p < 0.001 throughout). Additionally, four subjects (age greater than 75 years) were asked to return for repeat testing several years after their initial assessment. These longitudinal results qualitatively confirm the cross-sectional data, though with greater reductions in theta(avg) at high age. The findings of this study support the potential use of EIM as a simple and effort-independent test of muscle health in the elderly.
authors.affiliation: Department of Physics, Northeastern University, Boston, MA 02215, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Aaron
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Esper
authors.forename: Carl A
authors.initials: CA
authors.lastname: Shiffman
authors.forename: Kaca
authors.initials: K
authors.lastname: Bradonjic
authors.forename: Kyungmouk S
authors.initials: KS
authors.lastname: Lee
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009213:Myography / Q000379:methods; D052097:Quadriceps Muscle / Q000502:physiology*; D012189:Retrospective Studies