Alex M Noonan1, Thomas R Oxland2,3,4, Stephen H M Brown5. 1. Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada. 2. Department of Orthopaedics, The University of British Columbia, Vancouver, Canada. 3. International Collaboration on Repair Discoveries (ICORD), The University of British Columbia, Vancouver, Canada. 4. Department of Mechanical Engineering, The University of British Columbia, Vancouver, Canada. 5. Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada. shmbrown@uoguelph.ca.
Abstract
PURPOSE: Various aspects of paraspinal muscle anatomy, biology, and histology have been studied; however, information on paraspinal muscle contractile function is almost nonexistent, thus hindering functional interpretation of these muscles in healthy individuals and those with low back disorders. The aim of this study was to measure and compare the contractile function and force-sarcomere length properties of muscle fibers from the multifidus (MULT) and erector spinae (ES) as well as a commonly studied lower limb muscle (Extensor digitorum longus (EDL)) in the rat. METHODS: Single muscle fibers (n = 77 total from 6 animals) were isolated from each of the muscles and tested to determine their active contractile function; all fibers used in the analyses were type IIB. RESULTS: There were no significant differences between muscles for specific force (sFo) (p = 0.11), active modulus (p = 0.63), average optimal sarcomere length (p = 0.27) or unloaded shortening velocity (Vo) (p = 0.69). However, there was a significant difference in the rate of force redevelopment (ktr) between muscles (p = < 0.0001), with MULT being significantly faster than both the EDL (p = < 0.0001) and ES (p = 0.0001) and no difference between the EDL and ES (p = 0.41). CONCLUSIONS: This finding suggests that multifidus has faster cross-bridge turnover kinetics when compared to other muscles (ES and EDL) when matched for fiber type. Whether the faster cross-bridge kinetics translate to a functionally significant difference in whole muscle performance needs to be studied further.
PURPOSE: Various aspects of paraspinal muscle anatomy, biology, and histology have been studied; however, information on paraspinal muscle contractile function is almost nonexistent, thus hindering functional interpretation of these muscles in healthy individuals and those with low back disorders. The aim of this study was to measure and compare the contractile function and force-sarcomere length properties of muscle fibers from the multifidus (MULT) and erector spinae (ES) as well as a commonly studied lower limb muscle (Extensor digitorum longus (EDL)) in the rat. METHODS: Single muscle fibers (n = 77 total from 6 animals) were isolated from each of the muscles and tested to determine their active contractile function; all fibers used in the analyses were type IIB. RESULTS: There were no significant differences between muscles for specific force (sFo) (p = 0.11), active modulus (p = 0.63), average optimal sarcomere length (p = 0.27) or unloaded shortening velocity (Vo) (p = 0.69). However, there was a significant difference in the rate of force redevelopment (ktr) between muscles (p = < 0.0001), with MULT being significantly faster than both the EDL (p = < 0.0001) and ES (p = 0.0001) and no difference between the EDL and ES (p = 0.41). CONCLUSIONS: This finding suggests that multifidus has faster cross-bridge turnover kinetics when compared to other muscles (ES and EDL) when matched for fiber type. Whether the faster cross-bridge kinetics translate to a functionally significant difference in whole muscle performance needs to be studied further.
Authors: Kelsey Y Gsell; Derek P Zwambag; Dale E Fournier; Cheryle A Séguin; Stephen H M Brown Journal: Spine (Phila Pa 1976) Date: 2017-10-01 Impact factor: 3.468
Authors: Stephen H M Brown; Diane E Gregory; J Austin Carr; Samuel R Ward; Koichi Masuda; Richard L Lieber Journal: Spine (Phila Pa 1976) Date: 2011-10-01 Impact factor: 3.468
Authors: Venus Joumaa; Kevin R Boldt; Sang Kuy Han; Keyoung Jin Chun; Walter Herzog Journal: Spine (Phila Pa 1976) Date: 2021-07-07 Impact factor: 3.468