title: Regional Myosin heavy chain distribution in selected paraspinal muscles.
abstract: METHODS
  Cross-sectional study with repeated measures design.
  
  
  OBJECTIVE
  To compare the myosin heavy-chain isoform distribution within and between paraspinal muscles and to test the theory that fiber-type gradients exist as a function of paraspinal muscle depth.
  
  
  BACKGROUND
  There is still uncertainty regarding the fiber-type distributions within different paraspinal muscles. It has been previously proposed that deep fibers of the multifidus muscle may contain a higher ratio of type I to type II fibers, because, unlike superficial fibers, they primarily stabilize the spine, and may therefore have relatively higher endurance. Using a minimally invasive surgical approach, using tubular retractors that are placed within anatomic intermuscular planes, it was feasible to obtain biopsies from the multifidus, longissimus, iliocostalis, and psoas muscles at specific predefined depths.
  
  
  METHODS
  Under an institutional review board-approved protocol, muscle biopsies were obtained from 15 patients who underwent minimally invasive spinal surgery, using the posterior paramedian (Wiltse) approach or the minimally invasive lateral approach. Myosin heavy chain (MyHC) isoform distribution was analyzed using SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) electrophoresis. Because multiple biopsies were obtained from each patient, MyHC distribution was compared using both within- and between-muscle repeated measures analyses.
  
  
  RESULTS
  The fiber-type distribution was similar among the posterior paraspinal muscles and was composed of relatively high percentage of type I (63%), compared to type IIA (19%) and type IIX (18%) fibers. In contrast, the psoas muscle was found to contain a lower percentage of type I fibers (42%) and a higher percentage of type IIA (33%) and IIX fibers (26%; P<0.05). No significant difference was found for fiber-type distribution among 3 different depths of themultifidus and psoas muscles.
  
  
  CONCLUSIONS
  Fiber-type distribution between the posterior paraspinal muscles is consistent and is composed of relatively high percentage of type I fibers, consistent with a postural function. The psoas muscle, on the other hand, is composed of a higher percentage of type II fibers such as in the appendicular muscles. Our data do not support the idea of a fiber-type gradient as a function of depth for any muscle studied.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Gilad J
authors.initials: GJ
authors.lastname: Regev
authors.forename: Choll W
authors.initials: CW
authors.lastname: Kim
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Thacker
authors.forename: Akihito
authors.initials: A
authors.lastname: Tomiya
authors.forename: Steven R
authors.initials: SR
authors.lastname: Garfin
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Ward
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lieber
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000032:analysis*; D016658:Psoas Muscles / Q000378:metabolism
chemical_list: D018995:Myosin Heavy Chains
references.citation: Neurosurg Focus. 2006 Mar 15;20(3):E6
references.pmid: 16599422
references.citation: Man Ther. 2006 Nov;11(4):254-63
references.pmid: 16716640
references.citation: Pflugers Arch. 1997 Dec;435(1):151-63
references.pmid: 9359915
references.citation: Fed Proc. 1986 Dec;45(13):2910-4
references.pmid: 3536589
references.citation: Spine (Phila Pa 1976). 1986 Sep;11(7):732-8
references.pmid: 3787345
references.citation: J Appl Physiol (1985). 1993 Nov;75(5):2337-40
references.pmid: 8307894
references.citation: Acta Med Okayama. 2000 Dec;54(6):235-41
references.pmid: 11132916
references.citation: J Spinal Disord. 1992 Dec;5(4):383-9; discussion 397
references.pmid: 1490034
references.citation: J Bone Joint Surg Am. 2009 Jan;91(1):176-85
references.pmid: 19122093
references.citation: Spine (Phila Pa 1976). 2003 Aug 1;28(15 Suppl):S26-35
references.pmid: 12897471
references.citation: Microsc Res Tech. 2000 Sep 15;50(6):500-9
references.pmid: 10998639
references.citation: J Mol Biol. 1999 Jul 2;290(1):61-75
references.pmid: 10388558
references.citation: Am J Physiol. 1994 Dec;267(6 Pt 1):C1723-8
references.pmid: 7545970
references.citation: Spine (Phila Pa 1976). 2005 Apr 15;30(8):870-6
references.pmid: 15834328
references.citation: J Orthop Res. 1997 Nov;15(6):881-7
references.pmid: 9497814
references.citation: Am J Anat. 1972 Jan;133(1):25-36
references.pmid: 5008883
references.citation: J Spinal Disord. 1992 Dec;5(4):390-6; discussion 397
references.pmid: 1490035
references.citation: Eur Spine J. 1994;3(6):331-5
references.pmid: 7532536
references.citation: Spine (Phila Pa 1976). 2002 Jan 15;27(2):E29-36
references.pmid: 11805677
references.citation: Acta Anat (Basel). 1983;116(2):152-7
references.pmid: 6880592
references.citation: Spine (Phila Pa 1976). 1993 Sep 1;18(11):1439-50
references.pmid: 8235814
references.citation: J Biomech. 2001 Mar;34(3):371-5
references.pmid: 11182129
references.citation: Clin Orthop Relat Res. 2006 Apr;445:175-80
references.pmid: 16456311
references.citation: J Electromyogr Kinesiol. 1999 Dec;9(6):363-77
references.pmid: 10597049
references.citation: Spine (Phila Pa 1976). 2004 Mar 15;29(6):628-34
references.pmid: 15014272
references.citation: SAS J. 2007 Aug 01;1(3):93-9
references.pmid: 25802585
references.citation: J Neurol Sci. 1973 Jan;18(1):111-29
references.pmid: 4120482
references.citation: Clin Biomech (Bristol, Avon). 1995 Sep;10(6):323-324
references.pmid: 11415574
references.citation: J Biomech. 1998 Aug;31(8):713-21
references.pmid: 9796671
references.citation: Acta Physiol Scand. 1987 Oct;131(2):195-202
references.pmid: 2960128
references.citation: Physiol Rev. 1996 Apr;76(2):371-423
references.pmid: 8618961
references.citation: Spine J. 2006 Jul-Aug;6(4):435-43
references.pmid: 16825052