Abstract
Objective. The purpose of this study was to examine the myoelectric activity of the erector
spinae muscles of the back in order to determine if the flexion relaxation phenomenon
occurs in seated forward flexion or slumped postures.
Background. The flexion relaxation phenomenon during standing forward flexion is well documented.
However, flexion relaxation in seated forward flexion has not been studied. It is
possible that flexion relaxation could be linked with low back pain that some individuals
experience during seated work.
Methods. Twenty-two healthy subjects (11 males, 11 females) participated in the study. Surface
electromyography was used to measure the level of muscle activity at the thoracic
and lumbar levels of the erector spinae muscles. An electromagnetic tracking device
measured the three-dimensional movement of the lumbar spine. Five trials each of standing
and seated forward flexion were performed.
Results. A slumped sitting posture yielded flexion relaxation of the thoracic erector spinae
muscles, whereas the lumbar erector spinae muscle group remained at relatively constant
activation levels regardless of seated posture. Thoracic erector spinae silence occurred
at a smaller angle of lumbar flexion during sitting than the flexion relaxation angle
observed during standing flexion relaxation.
Conclusions. Since the myoelectric activity of the lumbar erector spinae did not increase, it
is likely that the passive tissues of the vertebral column were loaded to support
the moment at L4/L5. Ligaments contain a large number of free nerve endings which
act as pain receptors and therefore could be a potential source of low back pain during
seated work.Relevance
Examination of flexion relaxation during seated postures may provide insight into
the association between low back pain and seated work.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Clinical BiomechanicsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- The biomechanics of lumbar disc herniation and the effect of overload and instability.J. Spinal Disord. 1988; 1: 16-32
- Occupational biomechanics. 2nd ed. John Wiley and Sons Inc, New York1990: 1-518
- Epidemiologic studies of low back pain.Spine. 1980; 5: 419-423
- Is sitting-while-at-work associated with low back pain? A systematic, critical literature review.Scand. J. Public Health. 2000; 28: 230-239
- Epidemiological and aetiological aspects of low back pain in vibration environments––an update.Clin. Biomech. 1996; 11: 61-73
- The function of the erector spinae muscles in certain movements and postures in man.J. Physiol. 1955; 129: 184-203
- EMG activities of the quadratus lumborum and erector spinae muscles during flexion-relaxation and other motor tasks.Clin. Biomech. 1996; 11: 392-400
- Flexion relaxation during lifting: implications for torque production by muscle activity and tissue strain at the lumbo-sacral joint.J. Biomech. 1995; 28: 199-210
- An electromyographic study of the instrinsic muscles of the back in man.J. Anat., London. 1962; 96: 509-520
- An electromyographic analysis of certain movements and exercises. I. Some deep muscles of the back.Anat. Rec. 1966; 155: 223-234
- Myoelectric activity in individual lumbar erector spinae muscles in sitting. A study with surface and wire electrodes.Scand. J. Rehabil. Med. Suppl. 1974; 3: 91-108
- Transfer of loads between lumbar tissues during the flexion–relaxation phenomenon.Spine. 1994; 19: 2190-2196
- Load pattern and pressure pain threshold in the upper trapezius muscle and psychosocial factors in medical secretaries with and without shoulder/neck disorders.Int. Arch. Occup. Environ. Health. 1997; 69: 423-432
- Pattern of muscle activity during stereotyped work and its relation to muscle pain.Int. Arch. Occup. Environ. Health. 1990; 62: 31-41
- Kinesiology: with special reference to electromyographic kinesiology.in: Cobb W.A. Duija H. Contemporary clinical neurophysiology. Elsevier Science Publishers, Amsterdam1978
- The static load component in muscle work.Eur. J. Appl. Physiol. 1988; 57: 305-310
- Lumbar erector spinae oxygenation during prolonged contractions: implications for prolonged work.Ergonomics. 2000; 43: 486-493
- Low back joint loading and kinematics during standing and unsupported sitting.Ergonomics. 2001; 44: 280-294
Salewytsch A. Determining biomechanical factors that predict low back pain in VDT operators. Masters thesis, University of Guelph, Guelph, ON, Canada, 2002
Salewytsch A, Callaghan JP. Can quantified lumbar spine postures and trunk muscle activation levels predict discomfort during prolonged sitting? In: Proceedings of the 31th Annual Conference of the Human Factors Association of Canada. University of Ottawa, Ottawa, 1999. p. 316–21
- The influence of backrest inclination and lumbar support on lumbar lordosis.Spine. 1979; 4: 52-58
- Three-dimensional X-ray analysis of normal movement in the lumbar spine.Spine. 1984; 9: 294-297
- Prolapsed intervertebral disc: A hyperflexion injury.Spine. 1982; 7: 184-191
- The resistance to flexion of the lumbar intervertebral joint.Spine. 1980; 5: 245-253
- Posture and the compressive strength of the lumbar spine.Clin. Biomech. 1994; 9: 5-14
- Electromyographic activity of the abdominal and low back musculature during the generation of isometric and dynamic axial trunk torque: implications for lumbar mechanics.J. Orthop. Res. 1991; 9: 91-103
- The relationship between lumbar spine load and muscle activity during extensor exercises.Phys. Ther. 1998; 78: 8-18
- Frequency response of spine extensors during rapid isometric contractions: effects of muscle length and tension.J. Electromyogr. Kinesiol. 1998; 8: 227-232
- Commonly adopted postures and their effect on the lumbar spine.Spine. 1988; 13: 197-201
- A reappraisal of the anatomy of the human lumbar erector spinae.J. Anat. 1980; 131: 525-540
- Partitioning of the L4/L5 dynamic moment into disc, ligamentous, and muscular components during lifting.Spine. 1986; 11: 666-677
- The innervation of the lumbar spine.Spine. 1983; 8: 286-293
- Creep response of the lumbar spine to prolonged full flexion.Clin. Biomech. 1992; 7: 43-46
- Passive tissues help the back muscles to generate extensor moments during lifting.J. Biomech. 1994; 27: 1077-1085
- Immunohistochemical study of nerves in lumbar spine ligaments.Spine. 1993; 18: 264-267
- Analyses of myo-electrical silence of erectors spinae.J. Biomech. 2001; 34: 491-496
- Erector spinae activation and movement dynamics about the lumbar spine in lordotic and kyphotic squat-lifting.Spine. 1992; 17: 327-334
- Muscular and kinematic behavior of the lumbar spine during flexion–extension.J. Spinal Disord. 1998; 11: 163-174
- Flexion–relaxation phenomenon in the back muscles. A comparative study between healthy subjects and patients with chronic low back pain.Am. J. Phys. Med. Rehabil. 1995; 74: 139-144
- Effect of trunk flexion speen on flexion relaxation of erector spinae.Aust. J. Physiother. 1995; 41: 241-243
- Posture related to myoelectric silence of erectores spinae during trunk flexion.Spine. 1984; 9: 740-745
- Timing of activation of the erector spinae and hamstrings during a trunk flexion and extension task.Spine. 2001; 26: 418-425
- Quantitative studies of the flexion-relaxation phenomenon in the back muscles.J. Orthop. Res. 1985; 3: 189-197
Article info
Publication history
Accepted:
March 25,
2002
Received:
August 16,
2001
Identification
Copyright
© 2002 Elsevier Science Ltd. Published by Elsevier Inc. All rights reserved.
