title: Influence of trunk muscle activity and stability in front and back holding.
abstract: OBJECTIVE
  A tandem carrying style is often used in the workplace, but carrying approaches are different for two people because of the holding load in the tandem posture. To understand these carrying styles, this study aimed to investigate the patterns of muscle activity and stability of the trunk influenced by front and back holding of a heavy load.
  
  
  METHODS
  Electromyography data of eight trunk and two hip muscles, as well as displacements of the trunk, were recorded for analysis while subjects stood statically holding a handle in the front and back of the body with and without load.
  
  
  RESULTS
  Without load, muscle activities during front holding mirrored those during back holding. With load, greater muscle activities were observed in the dorsal muscles of the trunk and lesser activities were noted in the ventral muscles in the two holding styles. More frequencies of trunk oscillations occurred in front holding with and without load.
  
  
  CONCLUSIONS
  The results revealed that back holding of load created more stability of the upper body, whereas front holding resulted in more instability of the trunk.
authors.affiliation: a Department of Sports Medicine , Shanghai University of Sport , China.
authors.forename: Qing-Guang
authors.initials: QG
authors.lastname: Liu
authors.affiliation: a Department of Sports Medicine , Shanghai University of Sport , China.
authors.forename: Qiang-Min
authors.initials: QM
authors.lastname: Huang
authors.affiliation: b Neurophysiological Research Center, NCC Medical Co. Ltd , China.
authors.forename: Feng-Hu
authors.initials: FH
authors.lastname: Wang
authors.affiliation: c Shanghai Ninth Peoples Hospital, Shanghai JiaoTong University School of Medicine , China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Fan
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D064131:Back Muscles / Q000502:physiology*; D002681:China; D004576:Electromyography; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D011187:Posture; D014891:Weight Lifting / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: electromyography; load posture; manual holding in front and back; trunk oscillation