title: Mobility in Old Age: Capacity Is Not Performance.
abstract: BACKGROUND
  Outcomes of laboratory-based tests for mobility are often used to infer about older adults' performance in real life; however, it is unclear whether such association exists. We hypothesized that mobility capacity, as measured in the laboratory, and mobility performance, as measured in real life, would be poorly linked.
  
  
  METHODS
  The sample consisted of 84 older adults (72.5 ± 5.9 years). Capacity was assessed via the iTUG and standard gait parameters (stride length, stride velocity, and cadence). Performance was assessed in real life over a period of 6.95 ± 1.99 days using smartphone technology to calculate following parameters: active and gait time, number of steps, life-space, mean action-range, and maximum action-range. Correlation analyses and stepwise multiple regression analyses were applied.
  
  
  RESULTS
  All laboratory measures demonstrated significant associations with the real-life measures (between r = .229 and r = .461). The multiple regression analyses indicated that the laboratory measures accounted for a significant but very low proportion of variance (between 5% and 21%) in real-life measures.
  
  
  CONCLUSIONS
  In older adults without mobility impairments, capacity-related measures of mobility bear little significance for predicting real-life performance. Hence, other factors play a role in how older people manage their daily-life mobility. This should be considered for diagnosis and treatment of mobility deficits in older people.
authors.affiliation: Institute of Movement and Sport Gerontology, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: Eleftheria
authors.identifier: 0000-0001-7762-1348
authors.initials: E
authors.lastname: Giannouli
authors.affiliation: Institute of Physiology and Anatomy, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: Otmar
authors.identifier: 0000-0003-0485-6765
authors.initials: O
authors.lastname: Bock
authors.affiliation: Department of Electrical, Electronic, and Information Engineering, University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy.
authors.forename: Sabato
authors.initials: S
authors.lastname: Mellone
authors.affiliation: Institute of Movement and Sport Gerontology, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: Wiebren
authors.initials: W
authors.lastname: Zijlstra
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D016138:Walking / Q000502:physiology*