title: Validation of measures from the smartphone sway balance application: a pilot study.
abstract: OBJECTIVE
  A number of different balance assessment techniques are currently available and widely used. These include both subjective and objective assessments. The ability to provide quantitative measures of balance and posture is the benefit of objective tools, however these instruments are not generally utilized outside of research laboratory settings due to cost, complexity of operation, size, duration of assessment, and general practicality. The purpose of this pilot study was to assess the value and validity of using software developed to access the iPod and iPhone accelerometers output and translate that to the measurement of human balance.
  
  
  METHODS
  Thirty healthy college-aged individuals (13 male, 17 female; age = 26.1 ± 8.5 years) volunteered. Participants performed a static Athlete's Single Leg Test protocol for 10 sec, on a Biodex Balance System SD while concurrently utilizing a mobile device with balance software. Anterior/posterior stability was recorded using both devices, described as the displacement in degrees from level, and was termed the "balance score."
  
  
  RESULTS
  There were no significant differences between the two reported balance scores (p = 0.818. Mean balance score on the balance platform was 1.41 ± 0.90, as compared to 1.38 ± 0.72 using the mobile device.
  
  
  CONCLUSIONS
  There is a need for a valid, convenient, and cost-effective tool to objectively measure balance. Results of this study are promising, as balance score derived from the Smartphone accelerometers were consistent with balance scores obtained from a previously validated balance system. However, further investigation is necessary as this version of the mobile software only assessed balance in the anterior/posterior direction. Additionally, further testing is necessary on a healthy populations and as well as those with impairment of the motor control system.
  
  
  METHODS
  Level 2b (Observational study of validity)(1.)
authors.affiliation: Department of Human Performance Studies, Wichita State University, Wichita, KS, USA.
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Patterson
authors.affiliation: Department of Industrial and Manufacturing Engineering, Wichita State University, Wichita, KS, USA.
authors.forename: Ryan Z
authors.initials: RZ
authors.lastname: Amick
authors.affiliation: Department of Human Performance Studies, Wichita State University, Wichita, KS, USA.
authors.forename: Tarunkumar
authors.initials: T
authors.lastname: Thummar
authors.affiliation: Department of Human Performance Studies, Wichita State University, Wichita, KS, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Rogers
keywords: Accelerometer; Single Leg Balance Test; Smartphone Application; Stability assessment