title: Sit-to-walk and sit-to-stand-and-walk task dynamics are maintained during rising at an elevated seat-height independent of lead-limb in healthy individuals.
abstract: Sit-to-walk (STW) is a common transitional motor task not usually included in rehabilitation. Typically, sit-to-stand (STS), pause, then gait initiation (GI) before walking is used, which we term sit-to-stand-and-walk (STSW). Separation between centre-of-pressure (COP) and whole-body centre-of-mass (BCOM) during GI is associated with dynamic postural stability. Rising from seats higher than knee-height (KH) is more achievable for patients, but whether this and/or lead-limb significantly affects task dynamics is unclear. This study tested whether rising from seat-heights and lead-limb affects STW and STSW task dynamics in young healthy individuals.
  
  
  
  Ten (5F) young (29±7.7 years) participants performed STW and STSW from a standardised position. Five trials of each task were completed at 100 and 120%KH leading with dominant and non-dominant legs. Four force-plates and optical motion capture delineated key movement events and phases with effect of seat-height and lead-limb determined by 2-way ANOVA within tasks.
  
  
  
  At 120%KH, lower peak vertical ground-reaction-forces (vGRFs) and vertical BCOM velocities were observed during rising irrespective of lead-limb. No other parameters differed between seat-heights or lead-limbs. During GI in STSW there was more lateral, and less posterior, COP excursion than expected.
  
  
  
  Reduction in vGRFs and velocity during rising at 120%KH is consistent with reduced effort in young healthy individuals and is likely therefore to be an appropriate seat-height for patients. Lead-limb had no effect upon STSW or STW parameters suggesting that normative data independent of lead-limb can be utilised to monitor motor rehabilitation should differences be observed in patients. STSW should be considered an independent movement transition.
authors.affiliation: Centre of Human & Aerospace Physiological Sciences, King's College London, UK; Guy's & St Thomas' NHS Foundation Trust Physiotherapy Department, London, UK. Electronic address: gareth.jones@gstt.nhs.uk.
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Jones
authors.affiliation: School of Applied Sciences, London South Bank University, London, UK.
authors.forename: Darren C
authors.initials: DC
authors.lastname: James
authors.affiliation: Centre of Human & Aerospace Physiological Sciences, King's College London, UK; Guy's & St Thomas' NHS Foundation Trust Physiotherapy Department, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Thacker
authors.affiliation: Centre of Human & Aerospace Physiological Sciences, King's College London, UK.
authors.forename: Eleanor J
authors.initials: EJ
authors.lastname: Jones
authors.affiliation: Centre of Human & Aerospace Physiological Sciences, King's College London, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Green
mesh_terms: D000328:Adult; D005080:Exercise Test; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D011187:Posture / Q000502:physiology*; D016138:Walking
keywords: Healthy subjects; Lead Limb; Normative Data; Rehabilitation; Seat Height; Sit to walk