title: Effects of load position and force direction on back muscle loading in one-wheeled wheelbarrow tasks.
abstract: BACKGROUND
  Various parameters related to pushing/pulling tasks have been examined yet the effects of changing the load position in one-wheeled wheelbarrow task has not been examined.
  
  
  OBJECTIVE
  To explore the effects of load position and force direction on muscle activity during wheelbarrow tasks.
  
  
  METHODS
  Nine participants were recruited to take part in the experiment.
  
  
  METHODS
  Each participant performed 18 trials consisting of 2 force directions (push and pull) and 9 load positions. The dependent variables were EMG of erector spinae and gripping force. ANOVA was used to identify significant differences between force direction and load position in EMG and gripping force data.
  
  
  RESULTS
  Results showed that peak EMG was lowest for the left and right erector spinae when the load was positioned farther from the participant. Peak EMG of the bilateral erector spinae increased when the weight was near the participant and on the ipsilateral hand.
  
  
  CONCLUSIONS
  Based on the EMG results, we suggest that loads be arranged in the anterior part of the bin in order to reduce muscle activity on the spine during the wheelbarrow task. This finding also provides some directions in the improvement and ergonomic redesign of the one-wheeled wheelbarrow.
authors.forename: Su-Huang
authors.initials: SH
authors.lastname: Chen
authors.forename: Yung-Hui
authors.initials: YH
authors.lastname: Lee
authors.forename: Chiuhsiang Joe
authors.initials: CJ
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D004576:Electromyography; D018737:Hand Strength; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D064170:Paraspinal Muscles / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D055815:Young Adult
keywords: Electromyography(EMG); MMH; Push and pull; low back