Chronic low back pain-associated paraspinal muscle dysfunction is not the result of a constitutionally determined "adverse" fiber-type composition

Spine (Phila Pa 1976). 2004 Mar 15;29(6):628-34. doi: 10.1097/


Study design: Investigative case control study.

Objectives: To determine whether excessive paraspinal muscle fatigue in chronic low back pain results from a paucity of muscle type I fiber content.

Summary of background data: Paraspinal muscle function is vital for spinal protection. Prospective studies suggest that excessive paraspinal muscle fatigability may increase risk of first-time low back pain. As contractile performance of the paraspinal muscles is governed by their constitutionally determined fiber composition, the question arises whether a constitutionally determined "adverse" composition could predispose to low back pain through impaired spinal protection.

Methods: Thirty-five male patients with chronic low back pain were compared with 32 male control patients of similar age and anthropometry. During Sorensen and 60% of maximum voluntary isometric contraction fatigue tests, median frequency declines in the paraspinal muscle surface electromyograph signal were monitored and correlated with muscle histomorphometry.

Results: Patients were weaker than controls during maximum voluntary isometric contractions (84.47 [28.44]vs. 98.74 [18.11] kg, respectively; P = 0.02) and more fatigable during their Sorensen tests (endurance time 105.29 [28.53]vs. 137.50 [40.38] sec, respectively; P < 0.01). There were no between-group differences in median frequency declines during the Sorensen (-0.37 [0.16]vs. -0.36 [0.12]%.sec) or 60% maximum voluntary isometric contraction (-0.42 [0.31]vs. -0.51 [0.29]%.sec) tests, for patients and controls, respectively. There were no between-group differences in the percent number of paraspinal muscle type I fibers (64 [11]vs. 64 [9]%) or the percent area occupied by type I fibers (67 [11]vs. 69 [9]%), for patients and controls, respectively. Type I and II muscle fiber narrow diameters were similar for both groups.

Conclusion: In the patients with chronic low back pain tested, their associated paraspinal muscle dysfunction was not the result of a constitutionally determined "adverse" fiber type composition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biopsy
  • Case-Control Studies
  • Electromyography
  • Female
  • Humans
  • Isometric Contraction
  • Low Back Pain / complications*
  • Male
  • Middle Aged
  • Muscle Fatigue / physiology*
  • Muscle Fibers, Fast-Twitch / ultrastructure*
  • Muscle Fibers, Slow-Twitch / ultrastructure*
  • Muscle, Skeletal / pathology*