title: Relationships between muscle strength and indices of muscle cross-sectional area determined during maximal voluntary contraction in middle-aged and elderly individuals.
abstract: The present study examined how muscle cross-sectional area (CSA) indices determined at rest and during maximal voluntary contraction (MVC) are related to muscle strength in middle-aged and elderly individuals (22 men and 36 women, 51-77 years). The muscle thickness (MT) of elbow flexors and circumference (C) at the level 60% distal to the upper arm was measured by ultrasonography and a measuring tape, respectively, both at rest and during isometric MVC of elbow flexion. The muscle strength (F) of elbow flexors was calculated by dividing the torque developed during MVC by the forearm length of each subject. The product of MT and C (MTxC) and the square of MT (MT) were defined as the muscle CSA indices. The F was significantly correlated with MTxC during MVC (r = 0.905, p < or = 0.001) and at rest (r = 0.778, p < or = 0.001), with the former relationship significantly stronger than the latter (p < or = 0.001). Similarly, F was significantly correlated with MT both during MVC (r = 0.896, p < or = 0.001) and at rest (r = 0.780, p < or = 0.001), and there was also a significant difference between the correlation coefficients (p < or = 0.01). These findings show that, in middle-aged and elderly individuals, muscle strength is more closely related to muscle CSA indices during MVC than at rest. It is concluded that the present muscle CSA indices taken during MVC enable easy and practical evaluation of the muscle strength per size of elbow flexors in middle-aged and elderly individuals.
authors.affiliation: Graduate School of Sport Sciences, Waseda University, Saitama, Japan. carp_crespo_0522@ruri.waseda.jp
authors.forename: Ryota
authors.initials: R
authors.lastname: Akagi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Takai
authors.forename: Emika
authors.initials: E
authors.lastname: Kato
authors.forename: Makoto
authors.initials: M
authors.lastname: Fukuda
authors.forename: Taku
authors.initials: T
authors.lastname: Wakahara
authors.forename: Megumi
authors.initials: M
authors.lastname: Ohta
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukunaga
mesh_terms: D000368:Aged; D001132:Arm / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D019415:Torque