title: The geometric curvature of the lumbar spine during restricted and unrestricted squats.
abstract: BACKGROUND
  The main purpose of this study was to analyze the behavior of the geometric curvature of the lumbar spine during restricted and unrestricted squats, using a novel investigative method. The rationale for our hypothesis is that the lumbar curvature has different patterns at different spine levels depending on the squat technique used.
  
  
  METHODS
  Spine motion was collected via stereo-photogrammetric analysis in nineteen participants (11 males, 8 females). The reconstructed spine points at the upright neutral position and at the deepest position of the squat exercise were projected onto the sagittal plane of the trunk, a polynomial was fitted to the data, and were quantified the two-dimensional geometric curvature at lower, central and higher lumbar levels, besides the inclination of trunk and lumbosacral region, the overall geometric curvature and overall angle of the lumbar spine. The mean values for each variable were analysed with paired t-test (P<0.05).
  
  
  RESULTS
  The lumbar presents a flexion from upright neutral posture to deepest point of the movement, but for the lower lumbar the flexion is less intense if the knees travel anteriorly past the toes. The trunk and the lumbosacral region lean forward in both squat techniques and these effects are also reduced in unrestricted squats.
  
  
  CONCLUSIONS
  The data collected in the study are evidence that during barbell squats the lumbar curvature has different patterns at different spinal levels depending on the exercise technique. The lower lumbar spine appears to be less overloaded during unrestricted squats.
authors.affiliation: Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Mário
authors.initials: M
authors.lastname: Hebling Campos
authors.affiliation: Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Laizi I
authors.initials: LI
authors.lastname: Furtado Alaman
authors.affiliation: Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Aldo A
authors.initials: AA
authors.lastname: Seffrin-Neto
authors.affiliation: Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Vieira
authors.affiliation: Federal Institute of Education, Science and Technology of Goiás, Goiânia, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Costa de Paula
authors.affiliation: Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil - andre.claudio@gmail.com.
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Barbosa de Lira
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D011187:Posture; D016059:Range of Motion, Articular; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult