title: Novel algorithm for a smartphone-based 6-minute walk test application: algorithm, application development, and evaluation.
abstract: BACKGROUND
  The 6-minute walk test (6MWT: the maximum distance walked in 6 minutes) is used by rehabilitation professionals as a measure of exercise capacity. Today's smartphones contain hardware that can be used for wearable sensor applications and mobile data analysis. A smartphone application can run the 6MWT and provide typically unavailable biomechanical information about how the person moves during the test.
  
  
  METHODS
  A new algorithm for a calibration-free 6MWT smartphone application was developed that uses the test's inherent conditions and smartphone accelerometer-gyroscope data to report the total distance walked, step timing, gait symmetry, and walking changes over time. This information is not available with a standard 6MWT and could help with clinical decision-making. The 6MWT application was evaluated with 15 able-bodied participants. A BlackBerry Z10 smartphone was worn on a belt at the mid lower back. Audio from the phone instructed the person to start and stop walking. Digital video was independently recorded during the trial as a gold-standard comparator.
  
  
  RESULTS
  The average difference between smartphone and gold standard foot strike timing was 0.014 ± 0.015 s. The total distance calculated by the application was within 1 m of the measured distance for all but one participant, which was more accurate than other smartphone-based studies.
  
  
  CONCLUSIONS
  These results demonstrated that clinically relevant 6MWT results can be achieved with typical smartphone hardware and a novel algorithm.
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, Canada. ncapela@uottawa.ca.|Mechanical Engineering, University of Ottawa, Ottawa, Canada. ncapela@uottawa.ca.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Capela
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, Canada. elemaire@toh.on.ca.|Faculty of Medicine, University of Ottawa, Ottawa, Canada. elemaire@toh.on.ca.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Lemaire
authors.affiliation: Mechanical Engineering, University of Ottawa, Ottawa, Canada. nbaddour@uottawa.ca.
authors.forename: Natalie
authors.initials: N
authors.lastname: Baddour
mesh_terms: D061725:Accelerometry / Q000295:instrumentation / Q000379:methods; D000328:Adult; D000465:Algorithms; D005080:Exercise Test / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D012046:Rehabilitation / Q000295:instrumentation* / Q000379:methods; D000068997:Smartphone; D012984:Software; D016138:Walking