We found physical activity involving stretching, regardless of whether it is achieved using yoga or more conventional exercises, has moderate benefits in individuals with moderately impairing low back pain. Finding similar effects for both approaches suggests that yoga’s benefits were largely attributable to the physical benefits of stretching and strengthening the muscles and not to its mental components. Although the specific exercises differed, most of the yoga and stretching class was spent performing exercises designed to stretch and strengthen back and leg muscles (roughly 45 to 50 minutes for yoga versus 60–65 minutes for stretching). Elements unique to the yoga class were 1) breathing exercises and a guided deep relaxation, 2) explicitly asking participants if they had difficulties in performing the postures at home or had any questions and 3) explicit guidance and reminders to practice with awareness of their body. Unique to the stretching class were 5 minutes of warm-up exercises and attempts to create group cohesion through discussion of non-back related topics.
We found yoga was relatively safe. Similar to other kinds of physical movement, harmful outcomes from yoga were mostly temporarily increased back pain,
We were able to identify 8 published clinical trials of yoga for chronic back pain3–6, 8, 9, 22, 23
but no systematic reviews. All included fewer than 50 participants per arm, with five including fewer than 30. The interventions used in these studies differed in many ways, including style of yoga (hatha yoga, Iyengar or viniyoga), hours of class time (from 12 to 72 hours, typically 15 hours), class frequency (from a weeklong retreat of comprehensive yoga to weekly classes of 60 to 90 minutes), and duration of delivery (from 1 to 24 weeks, median=12 weeks). While all studies included postures, breathing exercises and deep relaxation, two added meditation practice. Various control groups included waiting lists (n=3), usual care (n=3), educational information (n=1), and exercise (n=2). Only five studies collected post-intervention follow-up data. Six trials contained serious flaws (e.g., small sample sizes coupled with large baseline imbalances on key outcomes,3, 4, 22
very poor class attendance,23
and high loss to followup8, 9
). Despite their diversity, all trials concluded that yoga improved back-related function, symptoms, and/or reduced medication usage.
Recent meta-analyses of exercise for persons with chronic back pain have reported modest but clinically questionable effects of exercise compared with usual care.2, 24, 25
Further analyses found that stretching and strengthening exercises, supervised exercise, and individual tailoring of the exercises were associated with the best outcomes.24
Apart from tailoring, these features were part of our stretching classes.
Our self-care book was included in two trials evaluating slightly different group-based self-care educational interventions.26, 27
Both were found superior to usual care. However, we are unaware of studies that have evaluated it as a stand-alone intervention.
Principal strengths of our study are its relatively large size, well-characterized yoga intervention, inclusion of two comparison groups including one with exercise of comparable physical exertion, high follow-up rates, use of masked interviewers, and satisfactory adherence to the intervention. Moreover, our sensitivity analysis applying a non-ignorable imputation approach to handle missing data confirmed our conclusions.
This study had several limitations: disappointed self-care participants might have been more likely to report worse outcomes, participants were selected from a single site and were relatively well-educated and functional, there was no follow-up beyond 26 weeks, and the amount of stretching performed in the stretching class was substantially greater than typically found in publically available classes.
Yoga or stretching are reasonable treatment options for persons who are willing to engage in physical activities to relieve moderately-impairing back pain. Because yoga classes can vary enormously, clinicians are advised to recommend classes for beginners or that are therapeutically oriented with instructors who are comfortable modifying postures for persons with physical limitations. Clinicians recommending stretching classes should ensure that these contain sufficient back and leg-focused stretching. Patient preferences, availability of suitable classes and patient costs should also be considered. Future studies are needed to determine the usefulness of these interventions for more severely-impaired patients and those of lower socioeconomic status.