PROLONGED_SITTING_POSTURE

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Are prolonged sitting postures
bad for the back?
Introduction
When one thinks about activities
which are ‘bad’ for the back,
strenuous things such as lifting,
bending, or certain sports usually
come to mind. However, prolonged
Sitting and the spine
Prolonged sitting is one of the most
potentially harmful activities most
people engage in. Erect sitting
involves disc pressures significantly
higher than that of normal standing.
CL IN IC I AN ’ S INFORMAT ION FOR SELF - HELP PROCEDURE S
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Fig. 1 Relationship of injury to history of spinal load (adapted from McGill SM 2000. Clinical
biomechanics of the thoracolumbar spine. In (Zeevi Dvir (ed.) Clinical Biomechanics. Churchill
Livingstone, Philadelphia).
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Journal of Bodywork and Movement Therapies (2002)
6(3),151^153
r 2002 Published by Elsevier Science Ltd.
This papermay bephotocopied for educational use.
doi: 10.1054/jbmt.2002.0293, available online at http://
www.idealibrary.com on
Craig Liebenson
Private Practice, 10474 Santa Monica Blvd., 202,
Los Angeles, CA 90025, USA
Correspondence to: C. Liebenson
Tel.: +1 310 470 2909; Fax: +1 310 470 3286;
E-mail: cldc@flash.net
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JOURNAL OF BODYWORK AND MOVEMENT THERAPIES JULY 2002
static postures, such as in sitting,
are also extremely detrimental for
the back. Both, too little or too
much strain is harmful (see Fig. 1).
In fact, epidemiologic studies show
that individuals in sedentary
occupations that involve sitting are
associated with a heightened risk of
disc herniations (Videman et al.
1990).
Sitting slumped forward (anterior
sitting) increases disc pressure
further, while slumping backwards
(posterior sitting) increases pressure
the most (Andersson et al. 1974,
1979).
After only 3min of full flexion of
the spine ligamentous creep, or
laxity, occurs which persists even
after 30min of rest! (McGill &
Liebenson
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Brown 1992, Gunning et al. 2001).
Even if the static posture is not
strenuous, if just 4% muscle effort is
encountered, a negative metabolic
state is established (Andersson 1990,
Sato et al. 1984). Adams et al. (1987)
believe that prolonged full flexion
renders the spine susceptible to
flexion overload during lifting.
According to Bogduk and Twomney
(1991), ‘After prolonged strain
ligaments, capsules, and
intervertebral discs of the lumbar
spine may creep, and they may be
liable to injury if sudden forces are
unexpectedly applied during the
vulnerable recovery phase’.
Wilder et al. (1996) showed that
the motor control signature
associated with low back pain
involves a slow reaction time,
decreased peak torque output, and
increased after discharges, when
irregular load is handled. Prolonged
sitting was shown to further disturb
these variables and a brief walking
break was required to improve them
again.
McGill and Norman (1993)
suggests that, if you need to lift
something after you have been sitting
for a while, you should extend your
spine a few times to warm it up. The
‘micro-breaks’ shown in the
accompanying Patient Self-Help
section are ideal ways to achieve this.
Is the disc really more
vulnerable in the morning?
The problems of prolonged flexion
are not limited to sitting and are
particularly magnified in the
morning. The morning is recognized
as a dangerous time for the spine.
Reilly et al. (1984) showed that 54%
of the loss of disc height (water
content) occurs in the first 30min
after arising. Disc bending stresses
are increased by 300% and
ligaments by 80% in the morning
(Adams et al. 1987). Avoidance of
early morning flexion has been
shown to be a wise strategy when
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recovering from acute low back pain
(Snook et al. 1998).
Therefore, avoidance of high-risk
activities early in the morning or after
sitting or stooping in full flexion is
crucial to injury or re-injury
prevention.
Walking and low back pain
Callaghan et al. (1999) found that
walking without flexibility increases
spinal load. Specifically, slow
walking with restricted arm swing,
increased ‘static’ spine loads.
Whereas, fast walking produced
more cyclic loading patterns. It was
determined that fast walking could
be used as a ‘safe’ back exercise.
Other researchers have consistently
reported that back pain patients
have a much stiffer and ‘guarded’
gait pattern than asymptomatic
individuals. Hussein et al. (1998,
1999) have reported that stride
length is decreased during the gait of
low back pain (LBP) individuals,
compared to normals. Lamoth et al.
(2002) recently found that pelvis–
thorax coordination in the LBP
group differed significantly from
that in the control group.
Specifically, they reported that the
gait of LBP patients was
characterized by a more rigid, less
flexible pelvis–thorax coordination
and slower gait velocity than in
asymptomatic individuals. In
asymptomatic individuals at gait
velocities above 3.0 km/h coupled
transverse plane rotation of the
pelvis and thoracic regions becomes
uncoupled due to counterrotation.
However, in LBP subjects this
uncoupling did not occur.
Indahl et al. (1995) have reported
that even if it hurts somewhat that
flexible walking is a safe and effective
exercise for low back pain patients.
Conclusion
Static postures such as prolonged
sitting or slow, stiff walking, are
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ODYWORK AND MOVEMENT THERAPIE
harmful to the spine. Regular
‘micro-breaks’, avoidance of early
morning flexion, ‘warm-up’ of the
spine before lifting after prolonged
sitting, and flexible walking are all
shown to be of value.
The conclusions to be reached
from the literature are summarized
in the following:
. Take frequent ‘micro-breaks’.
. Avoid sitting for prolonged
periods of time – no more than
20min if in severe pain (AHCPR
1994).
. Avoid lifting in the morning or
after prolonged sitting.
. ‘Warm-up’ your back by
extending your spine prior to
lifting anything.
. Walk with flexibility even if it is
uncomfortable to do so (Indahl et
al. 1995).
REFERENCES
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spinal posture on the compressive
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Fogleman MT, McCann KB 1998 The
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Videman T, Nurminen M, Troup JDG 1990
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Clinician’s information for self-help procedures
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S JULY 2002
	Introduction
	Figure 1
	Sitting and the spine
	Is the disc really more vulnerable in the morning?
	Walking and low back pain
	Conclusion
	REFERENCES