title: Errors in the ankle plantarflexor force production are related to the gait deficits of individuals with multiple sclerosis.
abstract: BACKGROUND
  Individuals with multiple sclerosis (MS) often have limited mobility that is thought to be due to the neuromuscular impairments of the ankle. Greater isometric motor control of the ankle has been associated with better standing postural balance but its relationship to mobility is less understood. The objectives of this investigation were to quantify the motor control of the ankle plantarflexors of individuals with MS during a dynamic isometric motor task, and explore the relationship between the ankle force control and gait alterations.
  
  
  METHODS
  Fifteen individuals with MS and 15 healthy adults participated in both a dynamic isometric ankle plantarflexion force matching task and a biomechanical gait analysis.
  
  
  RESULTS
  Our results displayed that the subjects with MS had a greater amount of error in their dynamic isometric force production, were weaker, walked with altered spatiotemporal kinematics, and had reduced maximal ankle moment at toe-off than the control group. The greater amount of error in the dynamic force production was related to the decreases in strength, step length, walking velocity, and maximal ankle moment during walking.
  
  
  CONCLUSIONS
  Altogether these results imply that errors in the ankle plantarflexion force production may be a limiting factor in the mobility of individuals with MS.
authors.affiliation: Department of Physical Therapy, Munroe-Meyer Institute, University of Nebraska Medical Center, 985450 Nebraska Medical Center, Omaha, NE 68198-5450, USA.
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Davies
authors.affiliation: Department of Physical Therapy, Munroe-Meyer Institute, University of Nebraska Medical Center, 985450 Nebraska Medical Center, Omaha, NE 68198-5450, USA.
authors.forename: Rashelle M
authors.initials: RM
authors.lastname: Hoffman
authors.affiliation: Department of Neurological Sciences, College of Medicine, University of Nebraska Medical Center, 988440 Nebraska Medical Center, Omaha, NE 68198-8440, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Healey
authors.affiliation: Department of Neurological Sciences, College of Medicine, University of Nebraska Medical Center, 988440 Nebraska Medical Center, Omaha, NE 68198-8440, USA.
authors.forename: Rana
authors.initials: R
authors.lastname: Zabad
authors.affiliation: Department of Physical Therapy, Munroe-Meyer Institute, University of Nebraska Medical Center, 985450 Nebraska Medical Center, Omaha, NE 68198-5450, USA. Electronic address: mkurz@unmc.edu.
authors.forename: Max J
authors.initials: MJ
authors.lastname: Kurz
mesh_terms: D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology; D016138:Walking / Q000502:physiology
keywords: Isometric; Torque; Variability; Walking