Treating Low-Back Pain
Exercise Knowns and Unknowns
Brian J. Shiple, DO; Series Editor: Nicholas A. DiNubile, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 8 - AUGUST 97
In Brief: Clinical research on the efficacy of exercise in the treatment of low-back pain is not entirely consistent. However, the bulk of the literature and current practice favor active low-back pain treatment programs that focus on improving aerobic fitness and on increasing the strength, flexibility, and stability of the lumbar musculature. Maintaining activity in the acute phase and initiating a specific exercise program as symptoms allow are central strategies in speeding recovery, ameliorating persistent pain, and preventing recurrence. In addition to this approach, physical therapy, manipulation, and/or medication may be called for.
Back pain is among the most common complaints seen in primary care (second, in fact, only to the common cold) (1). An estimated 80% of the population suffers at least one episode in their lifetime, and in as many as 50% of cases, the problem will recur within the following 3 years (2).
The last decade has seen a major change—a "paradigm shift"—in the way back pain is understood and treated. As summarized in the clinical practice guidelines published by the federal Agency for Health Care Policy and Research (AHCPR) several years ago (3), the new approach avoids bed rest and narcotic painkillers—once the mainstays of acute therapy—to the extent possible. Surgery is regarded as rarely desirable, and necessary in perhaps 1% of cases.
Instead, modern treatment favors an approach that is conservative but active, and aims both to restore function quickly and prevent future episodes. While physical therapy, manipulation, and/or medication may be called for, the central element is exercise.
The Case Against Rest
The active flavor of modern low-back care reflects the role that deconditioning is believed to play in protracting acute episodes and in creating and maintaining chronic pain and disability. Rather than giving the back the opportunity to heal, inactivity leads to a loss of strength and endurance in the supporting lumbar musculature, promoting dysfunction and making microtraumatic injury more likely.
Bed rest, it appears, has no advantage in most cases and can, in fact, compromise recovery. In one study (4), patients given 2 days of bed rest recovered as well as those given 4, and lost fewer days from work. More recently, a controlled trial (5) involving 186 patients with acute, nonspecific back pain found that those assigned to 2 days of bed rest recovered more slowly than the control group, who were told to continue ordinary activities as much as possible. Results in the control group were statistically superior in the duration and intensity of pain, lumbar flexion, ability to work, and Oswestry back-disability index scores.
Without intervention, persistent low-back pain brings deconditioning of lumbar musculature. A study (6) found no deficit in muscle strength of individuals with low-back pain of less than 1 month, compared to controls, but significant declines in strength (of the trunk extensors in particular), when the condition had lasted longer. Another study (7) found diminished extensor endurance among postmen with a history of low-back pain.
Such changes may increase the risk of future problems. In one study, muscular strength relative to job demands was shown to be inversely related to the risk of back injury (8).
Decreased flexibility, another consequence of inactivity, can modify spinal mechanics in a way that increases strain on the lumbar area. Because the spinal disks are nourished by solute transport, which is promoted by movement (9), a lack of mobility may compromise their integrity at a physiologic level. Physical activity seems necessary to pump fluid through the spinal disks and keep them properly hydrated; by interfering with this process, it has been suggested, immobility can prolong pain.
Individuals with persistent low-back pain tend to restrict their general activities, and are thus prone to suffer a decline in aerobic fitness. This in itself may put them at risk of recurring problems. One widely cited study of 1,652 Los Angeles firefighters found the incidence of back injury to be 10 times higher among those who were least fit, compared to the most fit (10).
The Case for Exercise
In light of the above, exercise would seem, logically, to be a strategy of choice in the management of all phases of back pain: for treatment of the acute episode, amelioration of the chronic condition, and prevention of exacerbations and reinjury. Clinical experience (as ratified by the AHCPR guidelines) bears this out.
The scientific support for the exercise prescription, however, is less than overwhelming: Although many studies show a significant benefit from exercise, some do not. For example, Malmivaara et al (5), whose research indicated benefits of ordinary activity relative to bed rest in the acute phase (see above), also found that back-mobilizing exercises performed in the acute phase slowed recovery, though most tests contributing to this conclusion did not reach statistical significance. Further, the literature as yet provides no clear guidance regarding which form of exercise is most effective.
There are several reasons that research findings are predictably varied. Acute low-back pain episodes are often self-limiting, making it difficult to demonstrate superiority of treatment over placebo. In addition, many studies have involved small numbers, imprecise measurement, and ambiguous patient-selection criteria. Varying compliance levels may also explain some of the inconsistencies. In one study of extension exercise for chronic pain, for example, only the high-compliance subgroup maintained their gains after a year (11).
A review of papers published from 1991 to early 1995 (12) identified only 11 randomized, controlled trials of exercise for low-back pain that the author considered well-designed; these supported the efficacy of exercise for subacute and chronic pain, but not acute pain.
Of the four acute-pain studies that were analyzed, two reported no advantage to flexion or extension exercises, compared to placebo, and two reported that patients had better results with McKenzie's extension exercises than with flexion or mobilization (11).
In the one trial involving subacute pain (Lindstrom et al, Spine 1992;17:641-652), those who underwent a graded activity program returned to work more quickly, had fewer absences during the next 2 years, and had improved back mobility and fitness (11).
Six studies investigated exercise treatment for chronic pain. Two of three trials reported positive benefits with dynamic extension exercises. Two reported better results with intensive exercising than normal activity after 3 to 6 months of follow-up, but the advantage disappeared at 12 months' follow-up. Two studies that compared extension with flexion exercise had contradictory results (11).
Thus, while the literature gives, on balance, real if modest support to the overall value of exercise, it is more difficult to find data on which to base the choice of specific modalities.
There are a number of exercise protocols to choose from, but consensus as to the best has been elusive. For example, one study compared intensive training of muscle endurance with a protocol that emphasized coordination. Both groups improved in pain, disability, and spinal mobility. "More studies are needed before we can recommend any specific rehabilitation method," the authors concluded (13).
Similarly, the theoretical benefits of aerobic exercise are many: It may reduce obesity, an established risk factor for low-back pain (14); increase endorphins; and alter the perception of pain, perhaps by reducing anxiety and depression (15). But no randomized trials have actually shown an advantage to the modality (16).
A few studies do suggest a basis for matching the exercise to the patient. In one (17), gender and occupational demand made a difference. Intensive, dynamic exercises aimed at strengthening lumbar muscles were most effective for the female patients and for those with sedentary occupations, while physiotherapy that included isometric exercises for muscles of the legs and trunk was best for the men and for individuals who performed moderate to heavy work.
Exercise for Which Patients?
While awaiting further data, it seems reasonable to base practice on clinical experience, which suggests a major role for both general activity and specific back exercises to ease and shorten the acute episode and, afterward, to reduce the risk of recurrence and ameliorate chronic pain. This clinician, for one, considers exercise absolutely central in the vast majority—perhaps 95%—of cases (see patient handout, "Relieving Low-Back Pain With Exercise," on page 67).
I prescribe exercise in patients whose pain is of mechanical origin, notably those who have disk disease, myofascial injury, and "lumbar strain or sprain" (a diagnosis of exclusion that encompasses 80% of cases).
It is essential, of course, to identify those more serious situations where back problems are due to causes that require specific treatment. These include tumor, infection, fracture (especially if trauma preceded the pain), aortic aneurysm, and cauda equina syndrome, as well as inflammatory or rheumatic conditions and neurologic syndromes secondary to diabetes.
A full-scale diagnostic workup with radiographic studies is not routinely required, but the clinician should be alert for signs that something beyond the ordinary is involved. First onset of pain in a patient under 20 or over 50 should trigger suspicion. The possibility of tumor or infection is suggested by pain accompanied by unexplained weight loss, fever and chills, or lymphadenopathy; or worsening of pain when supine or at night. Bowel or bladder dysfunction and/or severe or progressive neurologic deficits (including saddle anesthesia or numbness in the legs) could mean cauda equina syndrome, a surgical emergency (1).
Such possibilities should be ruled out promptly: The sooner an exercise regimen is instituted, the briefer the opportunity for deconditioning.
The Exercise Prescription
For most patients, I prescribe a lumbar stabilization program: a set of exercises that aims to normalize the balance of strength between back flexors and extensors, without putting the spine in positions that may aggravate pain or exacerbate injury. These are typically begun quite early in the acute episode; if movement is painful, the first few days may be limited to isometric exercises.
Particularly if pain or dysfunction persists despite the lumbar stabilization regimen, flexion or extension exercises may be added. The choice depends on the patient and his or her condition. Flexion is often helpful for patients with osteoarthritis of the lower spine (especially for those with osteoarthritis of the facet joints), spondylolisthesis, or spinal stenosis, or in cases of lumbar strain/sprain when extension is painful (2). Flexion exercises should not be prescribed for patients who have significant disk pathology.
McKenzie extension exercises (18) are worth considering for patients with lumbar disk disease that does not require surgery, or when pain is due to or aggravated by flexion. Patient selection is based on a series of test exercises that determine which movements centralize the patient's pain; usually extension movements are most favorable, and become the basis of the exercise program.
Virtually all patients should be prescribed a program of aerobic exercise. Walking, swimming, or biking is usually best, in that these do not subject the back to repeated ballistic forces or place the spine in positions of strain. Walking is often the exercise of choice: In addition to its aerobic benefits, it promotes the balanced strengthening of lumbar flexors and extensors.
The goal should be a regular schedule of frequency and intensity sufficient to achieve aerobic conditioning (20 to 40 minutes, 3 to 5 times a week, increasing heart rate to 60% to 85% of maximum). But for sedentary individuals, any amount of exercise, even slow walking, is better than none early on. In most cases, the regimen can be gradually increased to a low aerobic level within 1 month, and to full levels of activity within 3 months.
A treatment modality that complements exercise is back hygiene: Patients should be educated about their condition and instructed in ways of sitting, standing, and lifting that reduce lumbar strain. Providing this information and encouraging compliance promotes personal responsibility for back care. Physical or occupational therapy or a "back school" program is often the best way to achieve this goal.
Physical therapy may be indicated in the treatment of an acute or subacute episode of low-back pain; manipulation may be helpful in subacute cases. Physical therapists can also play a useful role in educating patients and supervising them as they learn to perform exercises properly.
Medication is often necessary to relieve pain. Nonsteroidal anti-inflammatories are the standard prescription, both for pain and to reduce inflammation. In general, they should not be used longer than 6 to 12 weeks because of increasing risk of dangerous side effects. While it is most desirable to avoid narcotic analgesics, they may be indicated for a week or two in the presence of unrelenting pain secondary to lumbar herniation and radiculopathy.
For some patients with acute lumbar disk disease that has a significant radicular component, a short course (5 to 10 days) of oral steroids can be considered. The medication helps reduce inflammation around a herniated disk and reduce pain enough for exercise therapy to begin.
Patients whose pain has persisted for 3 months or longer may benefit from psychosocial intervention. High levels of stress, clinical depression, or secondary gain factors (like compensation or litigation) may be responsible for the "failure" of standard treatment. A referral to a psychologist or other mental health professional may be in order for evaluation and possible therapy.
Except in urgent situations (worsening neurologic signs suggesting severe disk compression, for example) surgery should not be considered until conservative therapy has been given an extensive trial. A referral for evaluation may be indicated for a patient who has failed to improve after several months of exercise and complementary therapy.
Even in those who have had surgery, exercise should play a central role in the postoperative plan to forestall return of symptoms. A standard lumbar stabilization program will strengthen muscles surrounding the surgical area and reduce the risk of aggravating weakened tissues. One randomized, controlled study found lumbar stabilization and extension exercise to be effective in reducing pain in patients who had undergone L-5 laminectomy at least a year previously (19).
Like other patients, those who have had surgery may need some encouragement to overcome long-standing fears that exercise will worsen their back problems, and education to convince them of its potential benefits.
The Clinical Art
Designing the exercise prescription that is best for each individual who has low-back pain remains something of a clinical art. In most cases, both aerobic and back-specific components will be included in the program. Any safe activity that mobilizes the patient (such as walking) will be useful for the aerobic component in the vast majority of cases. A lumbar stabilization program alone or in addition to flexion or extension exercises can help increase strength, flexibility, and stability of the back musculature. Efforts to characterize and correct the specific mechanical dysfunction responsible for the patient's pain and thereby targeting therapy will often be rewarded, giving patients the opportunity to recover lost function and comfort in their daily lives.
This article was prepared by contributing editor Carl Sherman.
Dr Shiple is director of primary care sports medicine and of the primary care sports medicine fellowship program for Crozer-Keystone Health System in Springfield, Pennsylvania. He is also an assistant clinical professor in the department of family medicine at Allegheny University of the Health Sciences in Philadelphia, Pennsylvania. Dr DiNubile is an orthopedic surgeon in private practice in Havertown, Pennsylvania. He is the director of Sports Medicine and Wellness at the Crozer-Keystone Healthplex in Springfield, Pennsylvania; a clinical assistant professor in the department of orthopedic surgery at the University of Pennsylvania in Philadelphia; and a member of the editorial board of The Physician and Sportsmedicine. Address correspondence to Brian Shiple, DO, Healthplex Medical Office Pavilion, 196 W. Sproul Rd, Ste 105, Springfield, PA 19064.