Low-back pain is one of the most common health conditions worldwide. It is defined as pain below the costal margin and above the inferior gluteal folds. Current guidelines recommend management of chronic health (e.g., low back pain) conditions in older people at primary health care settings using active strategies (e.g., exercise). In non-specific low back pain, high quality evidence supports active strategies for general population. However, the management of non-specific low back pain in older people has been overlooked and evidence is limited to a small number of low powered randomized controlled trials with high risk of bias.

The primary outcomes will be pain intensity over the previous week and disability. The secondary outcomes will be: Global impression of recovery; frequency of falls; fear of falling; and Physical Active level.

This is a prospectively registered, open, two-arm randomized controlled trial comparing the group-based exercise and waiting list. The randomization sequence to our two groups of interest (i.e., group-based exercise or control) will be computer-generated by one of the investigators who will not be involved in the recruitment of participants. The sequence will be blocked (block sizes of 4, 6, and 8, in random order). Allocation will be concealed in sequentially numbered, sealed, opaque envelopes. Participants will be stratified by gender (female or male). The GBE comprises three sessions per week of group-based exercise in a local community center, for 8 weeks. Each group session will consist of 10 to 18 participants and each exercise session will last 60 minutes and consist of four stages: (1) five minutes warm up (i.e., self-regulated walk); (2) twenty minutes of moderate intensity walking; (3) thirty minutes of resistance training for the major muscles of the leg, trunk and arm and balance exercises that progress in difficulty; and (4) five-minute cool down period (i.e., self-regulated walk). Participants randomly allocated to control group will remain on a waiting list. In addition, weekly contact will be made to ensure that they do not start treatment during the study protocol. However, previous treatments like medications will be allowed. The sample size calculation was performed using the G*Power 3.1 software. A sample size of 120 participants was calculated (60 in each group), with a statistical power of 80%, alpha of 5%, and 20% dropout rate. The statistical analysis will be performed following the intention-to-treat analysis principles. Then, considering normal distribution, an analysis of mixed linear models (random intercepts and fixed coefficients) will be conducted, which incorporated terms for treatment, time, and the treatment-time interactions.

The practice of individualized exercise has been studied for the management of chronic non-specific low back pain in older people. However, the group exercise, even showing high quality evidence for the improvement of several important outcomes in this population, has been ignored until now. Thus, the results of this study have the potential to indicate a viable and accessible strategy for managing chronic non-specific low back pain in older people.