title: Sit to stand in elderly fallers vs non-fallers: new insights from force platform and electromyography data.
abstract: BACKGROUND
  The sit-to-stand movement requires balance control and coordination between the trunk and lower limbs. For these reasons, it is commonly used in clinics for evaluating lower limb muscle function in the elderly. The aim of the present study was to point out re levant biomechanical and neurophysiological sit-to-stand parameters allowing comparison between elderly fallers and non-fallers.
  
  
  METHODS
  Ten elderly fallers and thirty non-fallers performed sit-to-stand movements. Sit-to-stand mechanical (maximal and mean force, impulse) and temporal parameters were measured in the vertical and anteroposterior axes using force platforms. Activity of rectus femoris, vastus lateralis, and gastrocnemius lateralis muscles was bilaterally recorded by surface electromyography.
  
  
  RESULTS
  Time to realize sit-to-stand movements was significantly longer in elderly fallers compared to non-fallers (p < 0.05). In the same way, maximal vertical force and mean posterior force applied on force platform were significantly lower (p < 0.05) in fallers than in non-fallers individual. At muscular activity level, results showed a main statistical difference in gastrocnemius lateralis muscle activity patterns between faller and non-faller groups.
  
  
  CONCLUSIONS
  Vertical and anteroposterior data from force platform, and gastrocnemius lateralis muscle activity determined during sit-to-stand movement are the most relevant parameters to differentiate fallers and non-fallers. Moreover, these factors highlight different strategies to rise from a chair between faller and non-faller group, suggesting that fallers would constantly adjust their control balance during the sit-to-stand movement.
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA4334), UFR Sciences et Techniques, LUNAM University, University of Maine, Avenue Olivier Messiaen, 72085, Le mans Cedex 9, France. fred.chorin@gmail.com.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Chorin
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Cornu
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA4334), UFR Sciences et Techniques, LUNAM University, University of Maine, Avenue Olivier Messiaen, 72085, Le mans Cedex 9, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Beaune
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA4334), UFR Sciences et Techniques, LUNAM University, University of Maine, Avenue Olivier Messiaen, 72085, Le mans Cedex 9, France.|Laboratory "Développement, Adaptation et Handicap, Régulations cardio-respiratoires et de la motricité" (EA 3450), Faculty of Medicine, University of Lorraine, Nancy, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Frère
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA4334), UFR Sciences et Techniques, LUNAM University, University of Maine, Avenue Olivier Messiaen, 72085, Le mans Cedex 9, France.
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Rahmani
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology
keywords: Fall; Force platform; Muscular activation; Sit-to-stand strategies