Williams' Flexion Versus McKenzie
Extension Exercises For
Low Back Pain
In general, extension exercises may cause further damage in people with
spondylolysis, spondylolisthesis and facet joint dysfunction
(Harvey 1991), not to mention the possibility of
crushing the interspinous ligament (McGill
1998). While flexion
exercises should be avoided in persons with acute disc herniation
Brief History of Williams' Flexion Exercises
Dr. Paul Williams first published his exercise program in 1937 for patients
with chronic low back pain in response to his clinical observation that the
majority of patients who experienced low back pain had degenerative vertebrae
secondary to degenerative disk disease (Williams
1937). These exercises were developed for men under 50
and women under 40 years of age who had exaggerated lumbar lordosis, whose
x-ray films showed decreased disc space between lumbar spine segments (L1-S1),
and whose symptoms were chronic but low grade. The goals of performing
these exercises were to reduce pain and provide lower trunk stability
by actively developing the "abdominal, gluteus maximus, and hamstring muscles
as well as..." passively stretching the hip flexors and lower back
(sacrospinalis) muscles. Williams said: "The exercises outlined will
accomplish a proper balance between the flexor and the extensor groups of
postural muscles..." (Williams 1965, Williams 1937, Blackburn
1981, Ponte et al.).
Williams flexion exercises have been a cornerstone in the management
of lower back pain for many years for treating a wide variety of back problems,
regardless of diagnosis or chief complaint. In many cases they are
used when the disorders cause or characteristics were not fully understood
by the physician or physical therapist. Also, physical therapists often
teach these exercises with their own modifications. Williams suggested
that a posterior pelvic-tilt position was necessary to obtain best results
Examples of Williams' Flexion Exercises
Pelvic tilt. Lie on your back with knees bent, feet flat on
floor. Flatten the small of your back against the floor, without pushing
down with the legs. Hold for 5 to 10 seconds.
2. Single Knee to chest. Lie on your back with knees bent
and feet flat on the floor. Slowly pull your right knee toward your
shoulder and hold 5 to 10 seconds. Lower the knee and repeat with the
Double knee to chest. Begin as in the previous exercise.
After pulling right knee to chest, pull left knee to chest and hold
both knees for 5 to 10 seconds. Slowly lower one leg at a time.
Partial sit-up. Do the pelvic tilt (exercise 1) and, while holding
this position, slowly curl your head and shoulders off the floor. Hold
briefly. Return slowly to the starting position.
Hamstring stretch. Start in long sitting with toes directed
toward the ceiling and knees fully extended. Slowly lower the trunk
forward over the legs, keeping knees extended, arms outstretched over the
legs, and eyes focus ahead.
Hip Flexor stretch. Place one foot in front of the other with
the left (front) knee flexed and the right (back) knee held rigidly straight.
Flex forward through the trunk until the left knee contacts the axillary
fold (arm pit region).
Repeat with right leg forward and
left leg back.
Squat. Stand with both feet parallel, about shoulders
width apart. Attempting to maintain the trunk as perpendicular as possible
to the floor, eyes focused ahead, and feet flat on the floor, the subject
slowly lowers his body by flexing his knees.
Brief History of McKenzie Back Exercises
The McKenzie back extension exercises have been order by physicians and
prescribed by physical therapists for at least two decades
(McKenzie 1981). Robin McKenzie noted that
some of his patients reported lower back pain relief while in an extended
position. This went against the predominant thinking of Williams Flexion
biased exercises at this period of time.
Physical therapists can become "McKenzie certified", but the vast majority
of physical therapists who treat low back pain are not. McKenzie
has developed diagnostic categories that assign patient to specific treatments.
Patients evaluated by McKenzie certified therapists are most likely
to be placed into an extension biased exercise program. This is probably
why most people think of extension when talking about McKenzie exercises,
or because the original exercises were in opposition to Williams' flexion
The goal of McKenzie exercises is to centralized pain. If
a patient has pain in the lower back, right buttock, right posterior thigh,
and right calf, then the goal would be to "centralize" the pain to the lower
back, buttock, and posterior thigh. Then, "centralize" the pain to
the lower back and buttock, and finally just the lower back.
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Typical McKenzie Back Extension Exercises
Prone lying. Lie on your stomach with arms along your
sides and head turned to one side. Maintain this position for 5 to
Prone lying on elbows. Lie on your stomach with your weight
on your elbows and forearms and your hips touching the floor or mat.
Relax your lower back. Remain in this position 5 to 10 minutes.
If this causes pain, repeat exercise 1, then try again.
Prone press-ups. Lie on your stomach with palms near your
shoulders, as if to do a standard push-up. Slowly push your shoulders
up, keeping your hips on the surface and letting your back and stomach sag.
Slowly lower your shoulders. Repeat 10 times.
Progressive extension with pillows. Lie on your stomach
and place a pillow under your chest. After several minutes, add a second
pillow. If this does not hurt, add a third pillow after a few more
minutes. Stay in this position up to 10 minutes. Remove pillows
one at a time over several minutes.
Standing extension. While standing, place your hands in the
small of your back and lean backward. Hold for 20 seconds and repeat.
Use this exercise after normal activities during the day that place
your back in a flexed position: lifting, forward bending, sitting, etc.
What Does Recent Research Suggest About William Flexion or McKenzie
A. Adams, et al. found that "extension can reduce stresses
in the posterior annulus of those discs that are most protected by the neural
arch. This protection may be related to disc height loss, to the morphology
of the neural arch, or both....
Discogenic pain is associated with stress concentrations in the posterior
annulus. That backward bending can reduce such stress peaks in some
discs could explain pain relief in some back pain patients undergoing extension
exercises... Pain relief would be anticipated only in those patients
whose painful discs can be stress shielded by the neural arch in extension,
and this may depend on factors such as disc height, and the precise shape
of the neural arch....
Backward bending may also correct any posteriorly displaced intradiscal
mass, which is presumably an embryonic stage of disc herniation. This
dynamic internal disc model may provide an explanation for the commonly noted
phenomenon of "centralization", in which distal pain is abolished and symptoms
move proximally, often in response to extension exercises (Adams
B. When rehabilitating patients with back dysfunction,
extension exercises that are presumably "passive" for the erector spinae
muscles are frequently used. The results of a study demonstrated that
"passive" extension exercises were not truly passive for lumbar back extensor
muscles. From a clinical perspective, if the performance of passive
back extension is important, extension in lying prone may not be the exercise
of choice and having patients lying prone may be the most beneficial
(Fiebert 1994 ).
C. In one of the more carefully conducted randomized trials
of nonsurgical back pain treatments undertaken in recent years, researchers
conclude that McKenzie back exercises provide slightly greater pain relief
than a placebo--the control group received a patient education booklet on
low back pain. Neither chiropractic manipulation nor McKenzie back
exercises provided a significant functional benefit.
One of the most important tests of a therapy's efficacy is how it affects
back problems over the long term. McKenzie proponents have argued that
their protocol reduces recurrences of back pain and decreases utilization
of services. This study showed evidence that McKenzie back exercises
do not reduce low back pain recurrence.
"This casts doubt on the ability of the self-care-oriented McKenzie
(back exercises) to reduce the utilization of services," suggest the researchers.
"There was no evidence that the higher initial costs of the physical
treatments were offset by later savings," they add (Cherkin
D. Nachemson arguably discredited Williams flexion back
exercises when his study showed that these exercises may significantly increased
the pressure within intervertebral discs of the lumbar spine
E. Two studies have shown that lower back stiffness may
only be a symptom of lower back pain and not the cause of it.
(Johannsen 1995, Mellin 1985) Johannsen,
et al. conclude that "...increased spinal mobility does not necessarily lead
to LBP (low back pain) improvement, and mobilizing exercises alone cannot
be recommended to LBP patients
F. Is there another explanation for symptom
relief resulting from McKenzie? What about tight iliopsoas muscles?
Isn't it more likely that the effectiveness of McKenzie extension
exercises is associated with the elongation of the iliopsoas muscles secondary
to the stretch positions. The truth is that there is no
data that shows that the exercise effect has anything to do with the
nucleus pulposis "moving"... (Jorgensson 1993, Ingber
Adams MA, May S, Freeman BJ, Morrison HP, Dolan P. Effects of backward
bending on lumbar intervertebral discs. Relevance to physical therapy treatments
for low back pain. Spine 2000 Feb 15;25(4):431-7.
Blackburn SE, Portney LG. Electromyographic activity of back musculature
during Williams' flexion exercises. Phys Ther 1981;61:878-885.
Cherkin DC et al., A comparison of physical therapy, chiropractic
manipulation, and provision of an educational booklet for the treatment of
patients with low back pain, New England Journal of Medicine, 1998;
Fiebert I, Keller CD. Are "passive" extension exercises really passive?
J Orthop Sports Phys Ther 1994 Feb;19(2):111-6.
Harvey J, Tanner S. Low back pain in young athletes: a practical approach.
Sports Med 1991;12:394-406.
Ingber R. Iliopsoas myofascial dysfunction: A treatable cause of "failed"
low back syndrome. Arch Phys Med Rehab (70): 382-386 (1989).
Johannsen F, et al. Exercises for chronic low back pain: A clinical
trial. J Ortop Sports Phys Ther. 1995;22:52-59.
Jorgensson A. The iliopsoas muscle and the lumbar spine. Australian
Physiotherapy 39(2): 125-132 (1993).
McGill SM. Low back exercises: evidence for improving exercise
regimens. Phys Ther. 1998;78:754-765.
Mellin G: Physical therapy for chronic low back pain: Correlations
between spinal mobility and treatment outcome. Scand J Rehabil Med
Nachemson AL. the influence of spinal movements on the lumbar intradiscal
pressure and on the tensile stresses in the annulus fibrosus. Acta
Orthop Scand 1963;33:183-207.
Ponte DJ, Jensen GJ, Kent BE. A preliminary report on the use of the
McKenzie protocol versus Williams protocol in the treatment of low back pain.
J Orthop Sports Phys Ther 1984;6:130-9.
Williams PC: Lesions of the lumbosacral spine: chronic traumatic
(postural) destruction of the intervertebral disc, J Bone Joint Surg 1937;29:
Williams PC: The Lumbosacral Spine. New York, NY, McGraw-Hill
Book Co, 1965, pp 80-98.