title: Isometric rate of force development, maximum voluntary contraction, and balance in women with and without joint hypermobility.
abstract: OBJECTIVE
  To determine differences between hypermobile subjects and controls in terms of maximum strength, rate of force development, and balance.
  
  
  METHODS
  We recruited 13 subjects with hypermobility and 18 controls. Rate of force development and maximal voluntary contraction (MVC) during single leg knee extension of the right knee were measured isometrically for each subject. Balance was tested twice on a force plate with 15-second single-leg stands on the right leg. Rate of force development (N/second) and MVC (N) were extracted from the force-time curve as maximal rate of force development (= limit Deltaforce/Deltatime) and the absolute maximal value, respectively.
  
  
  RESULTS
  The hypermobile subjects showed a significantly higher value for rate of force development (15.2% higher; P = 0.038, P = 0.453, epsilon = 0.693) and rate of force development related to body weight (16.4% higher; P = 0.018, P = 0.601, epsilon = 0.834) than the controls. The groups did not differ significantly in MVC (P = 0.767, P = 0.136, epsilon = 0.065), and MVC related to body weight varied randomly between the groups (P = 0.921, P = 0.050, epsilon = 0.000). In balance testing, the mediolateral sway of the hypermobile subjects showed significantly higher values (11.6% higher; P = 0.034, P = 0.050, epsilon = 0.000) than that of controls, but there was no significant difference (4.9% difference; P = 0.953, P = 0.050, epsilon = 0.000) in anteroposterior sway between the 2 groups.
  
  
  CONCLUSIONS
  Hypermobile women without acute symptoms or limitations in activities of daily life have a higher rate of force development in the knee extensors and a higher mediolateral sway than controls with normal joint mobility.
authors.affiliation: University Hospital Bern, Bern, Switzerland. christine.mebes@insel.ch
authors.forename: Christine
authors.initials: C
authors.lastname: Mebes
authors.forename: Astrid
authors.initials: A
authors.lastname: Amstutz
authors.forename: Gere
authors.initials: G
authors.lastname: Luder
authors.forename: Hans-Ruedi
authors.initials: HR
authors.lastname: Ziswiler
authors.forename: Matthias
authors.initials: M
authors.lastname: Stettler
authors.forename: Peter M
authors.initials: PM
authors.lastname: Villiger
authors.forename: Lorenz
authors.initials: L
authors.lastname: Radlinger
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D010865:Pilot Projects; D004856:Postural Balance / Q000502:physiology*; D011446:Prospective Studies