title: Leg muscle activity during walking with assistive devices at varying levels of weight bearing.
abstract: OBJECTIVE
  To evaluate the muscle activation patterns at varying levels of weight-bearing forces during assisted walking with an axillary crutch and a recently designed device that allows weight transfer through the pelvic girdle (ED Walker).
  
  
  METHODS
  Descriptive, repeated measures.
  
  
  METHODS
  University-based research laboratory.
  
  
  METHODS
  Twelve healthy volunteers (age, 39.6+/-13.6 y).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Electromyographic activity was recorded from the anterior tibialis, soleus, biceps femoris, and vastus lateralis muscles on a test leg during assisted axillary crutch and ED Walker ambulation. Force platform readings measured weight-bearing load (non, light, heavy). These values were normalized to normal walking gait.
  
  
  RESULTS
  In the vastus lateralis and soleus muscles, both devices allowed for approximately 50% and 65% reductions in electromyographic activity during the non-weight-bearing condition. During crutch ambulation, electromyographic activity of the soleus was significantly reduced compared with that required for normal walking at all levels of weight-bearing load. In the vastus lateralis for the weight-bearing conditions, the ED Walker required significantly higher electromyographic activity than crutch ambulation (light: 105.0%+/-12.3% vs 72.7%+/-10.1%; heavy: 144.8%+/-23.5% vs 100.0%+/-13.5%). Both devices required similar peak vertical ground reaction forces during the heavy weight-bearing conditions (crutch: 75%+/-1.6%; ED Walker: 73%+/-1.8%), whereas axillary crutch gait produced less force than the ED Walker in the light condition (32%+/-2.0% vs 48%+/-1.6%).
  
  
  CONCLUSIONS
  During walking with assistive devices, muscle activation patterns varied with weight-bearing load. The leg extensor muscles appeared to incur a greater reduction in muscle activity when compared with their flexor counterparts. Additionally, the ED Walker and axillary crutch differed with respect to their muscle activity levels and weight-bearing characteristics. Clinically, knowledge of these muscle activity and force characteristics may aid in the decision-making process of prescribing a device type and timeline to follow in restoring weight-bearing loads.
authors.affiliation: Musculoskeletal Research Laboratory, Department of Exercise Science, Syracuse University, NY 13244, USA. bcclar01@syr.edu
authors.forename: Brian C
authors.initials: BC
authors.lastname: Clark
authors.forename: Todd M
authors.initials: TM
authors.lastname: Manini
authors.forename: Nathaniel R
authors.initials: NR
authors.lastname: Ordway
authors.forename: Lori L
authors.initials: LL
authors.lastname: Ploutz-Snyder
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D003446:Crutches / Q000009:adverse effects / Q000592:standards*; D004576:Electromyography; D004867:Equipment Design; D006804:Ergonomics; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018579:Patient Selection; D010388:Pelvis / Q000502:physiology; D012656:Self-Help Devices; D014853:Walkers / Q000592:standards*; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing