title: Free-living gait characteristics in ageing and Parkinson's disease: impact of environment and ambulatory bout length.
abstract: Gait is emerging as a powerful diagnostic and prognostic tool, and as a surrogate marker of disease progression for Parkinson's disease (PD). Accelerometer-based body worn monitors (BWMs) facilitate the measurement of gait in clinical environments. Moreover they have the potential to provide a more accurate reflection of gait in the home during habitual behaviours. Emerging research suggests that measurement of gait using BWMs is feasible but this has not been investigated in depth. The aims of this study were to explore (i) the impact of environment and (ii) ambulatory bout (AB) length on gait characteristics for discriminating between people with PD and age-matched controls.
  
  
  
  Fourteen clinically relevant gait characteristics organised in five domains (pace, variability, rhythm, asymmetry, postural control) were quantified using laboratory based and free-living data collected over 7 days using a BWM placed on the lower back in 47 PD participants and 50 controls.
  
  
  
  Free-living data showed that both groups walked with decreased pace and increased variability, rhythm and asymmetry compared to walking in the laboratory setting. Four of the 14 gait characteristics measured in free-living conditions were significantly different between controls and people with PD compared to two measured in the laboratory. Between group differences depended on bout length and were more apparent during longer ABs. ABs ≤ 10s did not discriminate between groups. Medium to long ABs highlighted between-group significant differences for pace, rhythm and asymmetry. Longer ABs should therefore be taken into account when evaluating gait characteristics in free-living conditions.
  
  
  
  This study provides encouraging results to support the use of a single BWM for free-living gait evaluation in people with PD with potential for research and clinical application.
authors.affiliation: Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK. silvia.del-din@ncl.ac.uk.
authors.forename: Silvia
authors.initials: S
authors.lastname: Del Din
authors.affiliation: Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Godfrey
authors.affiliation: Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK.
authors.forename: Brook
authors.initials: B
authors.lastname: Galna
authors.affiliation: Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK.
authors.forename: Sue
authors.initials: S
authors.lastname: Lord
authors.affiliation: Institute of Neuroscience/Newcastle University Institute for Ageing, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK.
authors.forename: Lynn
authors.initials: L
authors.lastname: Rochester
mesh_terms: D000368:Aged; D000375:Aging; D001696:Biomechanical Phenomena; D004777:Environment; D005260:Female; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D016138:Walking
keywords: Accelerometer; Ambulatory activity; Body worn monitor; Free-living data; Gait; Parkinson’s disease