title: Difference in selective muscle activity of thoracic erector spinae during prone trunk extension exercise in subjects with slouched thoracic posture.
abstract: BACKGROUND
  The prone trunk extension (PTE) exercise is often used to strengthen the back extensors. Although altered trunk posture is associated with movement impairment, the influences of a slouched thoracic posture on muscle activity of the thoracic erector spinae and thoracic movement during the PTE exercise were overlooked in previous studies.
  
  
  OBJECTIVE
  To compare the muscle activity of the erector spinae muscles and the relative ratio of the thoracic and lumbar erector spinae muscles during a PTE exercise in subjects with and without slouched thoracic posture.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  University motion analysis laboratory.
  
  
  METHODS
  The study included 22 subjects with slouched thoracic posture (defined as ≥40°) and 22 age- and gender-matched healthy subjects.
  
  
  METHODS
  All participants performed the PTE exercise.
  
  
  METHODS
  Bilateral surface electromyographic signals of the longissimus thoracis, iliocostalis lumborum pars thoracis, and pars lumborum muscles were measured during PTE exercises. Thoracic kyphosis (the angle of T1 minus T12) and lumbar lordosis (absolute value of the angle of L5 minus T12) were recorded using inclinometers during the PTE exercise.
  
  
  RESULTS
  The results showed no difference in muscle activity of the erector spinae in subjects with slouched thoracic posture versus those without during the PTE exercise. However, selective recruitment of the erector spinae pars thoracis was decreased significantly, and the thoracic kyphotic angle and lumbar lordotic curve were increased, during the PTE exercise in subjects with a slouched posture.
  
  
  CONCLUSIONS
  Although the PTE exercise has historically been a key component of correction of hyperkyphosis, the increased spinal curvature inhibits muscle activation of the erector spinae pars thoracis in these individuals, thus limiting effective strength gains. Therefore, modified methods to maintain a neutral posture of the spine and facilitate muscle activation of the erector spinae pars thoracis are needed in these individuals.
authors.affiliation: Department of Physical therapy, Masan University, Changwon, South Korea(∗).
authors.forename: Kyung-hee
authors.initials: KH
authors.lastname: Park
authors.affiliation: Department of Physical Therapy, College of Biomedical Science and Engineering, INJE University 607 Obang-dong, Gimhae-si, Gyeongsangnam-do, South Korea, 621-749(†). Electronic address: ysrehab@inje.ac.kr.
authors.forename: Jae-seop
authors.initials: JS
authors.lastname: Oh
authors.affiliation: Department of Physical Therapy, INJE University, Gimhae, South Korea(‡).
authors.forename: Duk-hyun
authors.initials: DH
authors.lastname: An
authors.affiliation: Department of Physical Therapy, INJE University, Gimhae, South Korea(§).
authors.forename: Won-gyu
authors.initials: WG
authors.lastname: Yoo
authors.affiliation: Department of Physical Therapy, Jeonju Univerisy, Jeonju, South Korea(‖).
authors.forename: Jong-man
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Department of Physical Therapy, Daegu University, Daegu, South Korea(¶).
authors.forename: Tae-ho
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Physical Therapy, Graduate School, INJE University, Gimhae, South Korea(#).
authors.forename: Min-hyeok
authors.initials: MH
authors.lastname: Kang
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004576:Electromyography; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000503:physiopathology*; D008159:Lumbar Vertebrae; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D064170:Paraspinal Muscles / Q000503:physiopathology*; D016684:Prone Position / Q000502:physiology; D013904:Thoracic Vertebrae; D055815:Young Adult