title: Triceps-surae musculotendinous stiffness: relative differences between obese and non-obese postmenopausal women.
abstract: BACKGROUND
  There is a lack of research into the relationship between obesity and muscle-tendon unit stiffness in postmenopausal women. Muscle-tendon unit stiffness appears to affect human motion performance and excessive and insufficient stiffness can increase the risk of bone and soft tissue injuries, respectively. The aim of this study was to investigate the relationship between muscle-tendon unit stiffness and obesity in postmenopausal women.
  
  
  METHODS
  105 postmenopausal women (58 [SD 5.5] years) participated. Four groups (normal weight, pre-obese, obesity class I and obesity class II) were defined according World Health Organization classification of body mass index. The ankle muscle-tendon unit stiffness was assessed in vivo with a free oscillation technique using a load of 30% of maximal voluntary isometric contraction.
  
  
  RESULTS
  ANOVA shows significant difference in muscle-tendon unit stiffness among the groups defined (P<0.001). Post hoc analysis reveals significant differences between the following groups: normal weight-pre-obese; normal weight-obesity class I and normal weight-obesity class II. The normal weight group had stiffness of 15789 (SD 2969) N/m, pre-obese of 19971 (SD 3678) N/m, obesity class I of 21435 (SD 4295) N/m, and obesity class II of 23497 (SD 1776) N/m.
  
  
  CONCLUSIONS
  Obese subjects may have increased muscle-tendon unit stiffness because of fat infiltration in leg skeletal muscles, range of motion restrictions and stability/posture reasons and might be more predisposed to develop musculoskeletal injuries. Normal weight group had identical stiffness values to those reported in studies where subjects were not yet menopausal, suggesting that stiffness might not be influenced by menopause.
authors.affiliation: Department of Sport Science - CIDESD, University of Beira Interior, Covilhã, Portugal. afaria@ubi.pt
authors.forename: Aurélio
authors.initials: A
authors.lastname: Faria
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Gabriel
authors.forename: João
authors.initials: J
authors.lastname: Abrantes
authors.forename: Rui
authors.initials: R
authors.lastname: Brás
authors.forename: Helena
authors.initials: H
authors.lastname: Moreira
mesh_terms: D000843:Ankle Joint / Q000502:physiology; D001823:Body Composition; D015992:Body Mass Index; D004867:Equipment Design; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009129:Muscle Tonus; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009765:Obesity / Q000150:complications*; D009991:Oscillometry / Q000379:methods; D017698:Postmenopause; D016059:Range of Motion, Articular / Q000502:physiology