title: The combined effects of body weight support and gait speed on gait related muscle activity: a comparison between walking in the Lokomat exoskeleton and regular treadmill walking.
abstract: BACKGROUND
  For the development of specialized training protocols for robot assisted gait training, it is important to understand how the use of exoskeletons alters locomotor task demands, and how the nature and magnitude of these changes depend on training parameters. Therefore, the present study assessed the combined effects of gait speed and body weight support (BWS) on muscle activity, and compared these between treadmill walking and walking in the Lokomat exoskeleton.
  
  
  METHODS
  Ten healthy participants walked on a treadmill and in the Lokomat, with varying levels of BWS (0% and 50% of the participants' body weight) and gait speed (0.8, 1.8, and 2.8 km/h), while temporal step characteristics and muscle activity from Erector Spinae, Gluteus Medius, Vastus Lateralis, Biceps Femoris, Gastrocnemius Medialis, and Tibialis Anterior muscles were recorded.
  
  
  RESULTS
  The temporal structure of the stepping pattern was altered when participants walked in the Lokomat or when BWS was provided (i.e. the relative duration of the double support phase was reduced, and the single support phase prolonged), but these differences normalized as gait speed increased. Alternations in muscle activity were characterized by complex interactions between walking conditions and training parameters: Differences between treadmill walking and walking in the exoskeleton were most prominent at low gait speeds, and speed effects were attenuated when BWS was provided.
  
  
  CONCLUSIONS
  Walking in the Lokomat exoskeleton without movement guidance alters the temporal step regulation and the neuromuscular control of walking, although the nature and magnitude of these effects depend on complex interactions with gait speed and BWS. If normative neuromuscular control of gait is targeted during training, it is recommended that very low speeds and high levels of BWS should be avoided when possible.
authors.affiliation: Center for Human Movement Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Klaske
authors.initials: K
authors.lastname: Van Kammen
authors.affiliation: Rehabilitation Center 'Revalidatie Friesland', Beetsterzwaag, The Netherlands.
authors.forename: Annemarijke
authors.initials: A
authors.lastname: Boonstra
authors.affiliation: Rehabilitation Center 'Revalidatie Friesland', Beetsterzwaag, The Netherlands.
authors.forename: Heleen
authors.initials: H
authors.lastname: Reinders-Messelink
authors.affiliation: Center for Human Movement Sciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: den Otter
mesh_terms: D000293:Adolescent; D001835:Body Weight; D004576:Electromyography; D026241:Exercise Movement Techniques; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D005684:Gait; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016138:Walking; D055815:Young Adult