title: Influence of vision on head stabilization strategies in older adults during walking.
abstract: BACKGROUND
  Maintaining balance during dynamic activities is essential for preventing falls in older adults. Head stabilization contributes to dynamic balance, especially during the functional task of walking. Head stability and the role of vision in this process have not been studied during walking in older adults.
  
  
  METHODS
  Seventeen older adults (76.2 +/- 6.9 years) and 20 young adults (26.0 +/- 3.4 years) walked with their eyes open (EO), with their eyes closed (EC), and with fixed gaze (FG). Participants performed three trials of each condition. Sagittal plane head and trunk angular velocities in space were obtained using an infrared camera system with passive reflective markers. Frequency analyses of head-on-trunk with respect to trunk gains and phases were examined for head-trunk movement strategies used for head stability. Average walking velocity, cadence, and peak head velocity were calculated for each condition.
  
  
  RESULTS
  Differences between age groups demonstrated that older adults decreased walking velocity in EO (p =.022). FG (p = .021), and EC (p = .022). and decreased cadence during EC (p = .007). Peak head velocity also decreased across conditions (p < .0001) for older adults. Movement patterns demonstrated increased head stability during EO. diminished head stability with EC, and improved head stability with FG as older adult patterns resembled those of young adults.
  
  
  CONCLUSIONS
  Increased stability of the lower extremity outcome measures for older adults was indicated by reductions in walking velocity and cadence. Concomitant increases in head stability were related to visual tasks. Increased stability may serve as a protective mechanism to prevent falls. Further, vision facilitates the head stabilization process for older adults to compensate for age-related decrements in other sensory systems subserving dynamic balance.
authors.affiliation: Department of Physical Therapy, Center for Rehabilitation Sciences, and Sealy Center on Aging, The University of Texas Medical Branch, Galveston 77555-1144, USA. rlcromwe@utmb.edu
authors.forename: Ronita L
authors.initials: RL
authors.lastname: Cromwell
authors.forename: Roberta A
authors.initials: RA
authors.lastname: Newton
authors.forename: Gail
authors.initials: G
authors.lastname: Forrest
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006257:Head; D006801:Humans; D008297:Male; D004856:Postural Balance; D014785:Vision, Ocular; D016138:Walking