title: Validity of muscle thickness-based prediction equation for quadriceps femoris volume in middle-aged and older men and women.
abstract: BACKGROUND
  This study examined the validity of muscle thickness (MT)-based prediction equation for the muscle volume of the quadriceps femoris (QFMV) by evaluating the applicability of a prediction equation previously derived from young men and by developing a new prediction equation in middle-aged and older individuals.
  
  
  METHODS
  The MT at the midpoint of the thigh anterior and QFMV were determined using ultrasonography and magnetic resonance imaging in 30 men and 30 women aged 51 to 77 years. First, we examined the validity of the MT-based prediction equation previously developed for young men to estimate the QFMV of middle-aged and older individuals. Second, we allocated the subjects to validation or cross-validation group and developed a prediction equation for estimating the QFMV using a stepwise multiple regression analysis.
  
  
  RESULTS
  The published equation generated a small but a significant difference between the measured and estimated QFMV, with a systematic error depending on the size of QFMV. A multiple regression analysis for the validation group produced the following equation: QFMV (cm3) = (sex × 267.7) + (MT × 249.3) + (thigh length × 41.1) - 1663.7 (sex: man = 1, woman = 0). R2and SEE of the regression equation were 0.888 and 124.4 cm3(12.0 %), respectively. The developed equation was validated and cross-validated.
  
  
  CONCLUSIONS
  For middle-aged and older individuals, the prediction equation previously derived from young men is not applicable, and the newly developed prediction equation with sex, MT, and thigh length as independent variables is applicable for estimating QFMV.
authors: National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors: Miyuki
authors: M
authors: Nakatani
authors: National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan. y-takai@nifs-k.ac.jp.
authors: Yohei
authors: Y
authors: Takai
authors: Shibaura Institute of Technology, 307 Fukasaku, Saitama Minuma-ku, Saitama, 337-8570, Japan.
authors: Ryota
authors: R
authors: Akagi
authors: Doshisha University, 1-3 Tatara-miyakodani, Kyotanabe, Kyoto, 610-0394, Japan.
authors: Taku
authors: T
authors: Wakahara
authors: Meiji Gakuin University, 1518 Kamikurata, Totsuka-ku, Yokohama, Kanagawa, 244-8539, Japan.
authors: Norihide
authors: N
authors: Sugisaki
authors: Chukyo University, 101-2 Yagotohonmachi, Showa-ku, Nagoya, Aichi, 466-0825, Japan.
authors: Megumi
authors: M
authors: Ohta
authors: Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1192, Japan.
authors: Yasuo
authors: Y
authors: Kawakami
authors: National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors: Tetsuo
authors: T
authors: Fukunaga
authors: National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors: Hiroaki
authors: H
authors: Kanehisa
mesh_terms: D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology*; D000465:Algorithms; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009929:Organ Size / Q000502:physiology; D052097:Quadriceps Muscle / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods*
keywords: Bland–Altman plot; Cross validation; Magnetic resonance imaging; Ultrasonography