title: The effects of muscle strength on center of pressure-based measures of postural sway in obese and heavy athletic individuals.
abstract: BACKGROUND
  Obesity affects postural sway during normal quiet standing; however, the reasons for the increased postural sway are unknown. Improving muscular strength is regarded as a potential way to improve postural control, particularly for obese and overweight subjects. The purpose of this investigation is to evaluate the role of muscular strength on postural sway in obese and overweight individuals.
  
  
  METHODS
  Fifteen healthy weight (control group), seventeen obese (obese group) subjects and nine football players (heavy athletic group) participated in this investigation. Isometric knee extension force and postural sway were measured. Muscular strength was calculated in absolute measures as well as relative to body mass (muscular strength to body mass).
  
  
  RESULTS
  The heavy athletic group demonstrated significantly stronger (absolute) lower limb strength (1593.9 N (95% CI 1425.5, 1762.3)) than both the obese (796.2N (95% CI 673.8, 824.5)) and control (694.1N (95% CI 563.7, 824.5)) groups. As well, when muscular strength was expressed as a ratio to body mass the heavy athletic group had significantly higher values (1.27 (95% CI 1.11, 1.43)) than obese (0.78 (95% CI 0.66, 0.89) and control (1.00 (95% CI (0.88, 1.12)) individuals. Despite this, they swayed similarly to the obese (mean center of pressure speed of 0.83 cms(-1) (95% CI 0.72, 0.93) vs. 0.87 cms(-1) (95% CI 0.80, 0.95)), that is, significantly more than the controls (0.60 cms(-1) (95% CI 0.52, 0.68)).
  
  
  CONCLUSIONS
  Isometric knee extensor strength has a minimal effect on postural sway in heavier athletic individuals during normal quiet stance.
authors.affiliation: Faculty of Medicine, Kinesiology division, Laval University, Québec, Canada. grant-a.handrigan.1@ulaval.ca
authors.forename: Grant A
authors.initials: GA
authors.lastname: Handrigan
authors.forename: Felix
authors.initials: F
authors.lastname: Berrigan
authors.forename: Olivier
authors.initials: O
authors.lastname: Hue
authors.forename: Martin
authors.initials: M
authors.lastname: Simoneau
authors.forename: Philippe
authors.initials: P
authors.lastname: Corbeil
authors.forename: Angelo
authors.initials: A
authors.lastname: Tremblay
authors.forename: Normand
authors.initials: N
authors.lastname: Teasdale
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015444:Exercise; D005538:Football / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D007866:Leg / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure