title: Influence of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing.
abstract: OBJECTIVE
  The present study was an attempt to investigate the effect of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing.
  
  
  METHODS
  Ten healthy subjects were recruited to stand for 2 h in three footwear conditions: barefoot, flat-bottomed shoe and unstable shoe. During standing, lower leg discomfort and EMG activity of medial gastrocnemius (MG) and tibialis anterior (TA) muscles were continuously monitored. Changes in lower leg volume over standing time also were measured.
  
  
  RESULTS
  Lower leg discomfort rating reduced significantly while subjects standing on unstable shoe compared to the flat-bottomed shoe and barefoot condition. For lower leg volume, less changes also were observed with unstable shoe. The activity level and variation of right MG muscle was greater with unstable shoe compared to the other footwear conditions; however regarding the left MG muscle, significant difference was found between unstable shoe and flat-bottomed shoe only for activity level. Furthermore no significant differences were observed for the activity level and variation of TA muscles (right/left) among all footwear conditions.
  
  
  CONCLUSIONS
  The findings suggested that prolonged standing with unstable footwear produces changes in lower leg muscles activity and leads to less volume changes. Perceived discomfort also was lower for this type of footwear and this might mean that unstable footwear can be used as ergonomic solution for employees whose work requires prolonged standing.
authors.affiliation: Department of Occupational Health, School of Health, Urmia University of Medical Sciences, Urmia, Iran.
authors.forename: Zanyar
authors.initials: Z
authors.lastname: Karimi
authors.affiliation: Department of Occupational Health, School of Health, Urmia University of Medical Sciences, Urmia, Iran. Electronic address: Allahyari@umsu.ac.ir.
authors.forename: Teimour
authors.initials: T
authors.lastname: Allahyari
authors.affiliation: Department of Biomechanics, Faculty of Mechanical Engineering, Sahand University of Technology, Tabriz, Iran.
authors.forename: Mahmood Reza
authors.initials: MR
authors.lastname: Azghani
authors.affiliation: Department of Epidemiology and Biostatistics, School of Health, Urmia University of Medical Sciences, Urmia, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Khalkhali
mesh_terms: D000328:Adult; D004576:Electromyography; D006801:Humans; D007866:Leg / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D059352:Musculoskeletal Pain / Q000209:etiology; D011187:Posture; D012775:Shoes; D013997:Time Factors; D055815:Young Adult
keywords: Discomfort; Leg volume; Muscle activity; Prolonged standing; Unstable footwear