Education and Counseling to Prevent Low Back Pain
Efficacy of Risk Reduction continued...
Five controlled trials have evaluated the prevention of low back pain with exercise compared to no intervention.36-41 Two of these trials evaluated back-strengthening exercises. In one trial, nurses and aides with and without a history of prior back pain were randomized to receive instructions on exercises for strengthening back extensors (during five half-hour sessions), followed by 13 months of exercise sessions at work (averaging 6 hours per month), or no intervention.36 Intervention subjects demonstrated greater extensor strength, fewer self-reported days with low back pain, and reduced absenteeism related to low back pain; total absenteeism was not reported. In another hospital-based trial, employees with a history of low back pain during the year before enrollment were randomized to receive (a) 45-minute exercise sessions for strengthening back flexors, twice weekly for 3 months at work; (b) five 90-minute back education sessions; or (c) no intervention. The number of self-reported "painful months" was significantly less for subjects in the exercise group than in the other groups.37 Total days lost from work were not reported.
Three controlled trials evaluated exercise aimed at increasing cardiovascular fitness. In the first trial, 125 industrial workers with a history of back pain were randomized to receive aerobic exercise sessions once per week at work for 18 months, or no intervention.38 Withdrawal rates were high: 19 of the 67 controls and 21 of the 58 exercise subjects (including five who withdrew from the exercise group because of an increase in back or neck pain). Over the 18-month period there was a significantly greater decrease in mean number of back pain episodes, and in sick days attributable to back pain, in intervention subjects compared to controls. Total sick days were not reported, however. In a randomized controlled trial enrolling nurses with a history of back pain during the 2 years before enrollment, intervention subjects attended a 5-week program combining 4 hours of aerobic exercise and 4 hours of back education daily.39 Although study subjects had fewer self-reported back symptoms than controls at 6 months, it is not clear whether this was due to exercise, education, or both. At the 18-month followup, sick days for the intervention group had increased from baseline.40 In a nonrandomized trial of 45 nursing aides with mild nondebilitating low back pain,41 15 subjects attended training to increase aerobic capacity twice weekly for 8 weeks, 14 subjects were taught "short arm" lifting techniques to protect the back, and the remaining subjects served as controls. Following the intervention, subjects in the exercise cohort had significantly improved aerobic capacity, but there was no reduction in duration or frequency of recurrent back episodes compared with controls.
Thus, most of the trials showed a statistically significant benefit from exercise, but the effects were modest and of uncertain duration. The interventions used may not be relevant to the clinical setting since all allocated work time for exercise, thus greatly increasing the likelihood of compliance. In most of the trials, the authors do not specify whether the control groups continued to work while the intervention groups were allowed time during the workday for exercise.36-39,42 If so, the results may have been biased by the greater exposure time to work conditions associated with back injury in controls compared to the intervention subjects. A common methodologic problem is the lack of precision in specifying whether the goal was to prevent the first episode of low back symptoms, activity limitations, recurrent episodes, work absenteeism, or chronic disability.43 Finally, the inclusion criteria and clinical outcomes of the studies differ and therefore are difficult to compare. Thus, the evidence regarding the effectiveness of exercise in preventing low back pain is inconclusive.