SummaryThe treatment effect of an activating spinal orthosis on back pain and back extensor strength was compared to a training group and to a control group. Between the groups, there was no significant difference in back pain, back extensor strength, or kyphosis index after the 6 months of treatment.PurposeThe aim of this study was to study the effect of treatment with an activating spinal orthosis on back pain, back extensor strength, and kyphotic index. Our hypothesis was that an activating spinal orthosis may be an alternative treatment to decrease back pain and increase back extensor strength.MethodsA total of 113 women aged ≥ 60 years with back pain and osteoporosis, with or without vertebral fractures, were randomized to three groups: a spinal orthosis group, an equipment training group, and a control group. All three groups were examined at baseline and followed up after 3 and 6 months. Statistical analyses were performed with a mixed model for repeated measures according to intention to treat (ITT) and per protocol (PP).ResultsA total of 96 women completed the study. Between the groups, there was no significant difference in baseline characteristics. Comparison between groups showed no significant difference in back pain, back extensor strength, or kyphosis index at the follow-up after 6 months according to ITT and PP analyses. Analysis in each group showed that the back extensor strength had increased by 26.9% in the spinal orthosis group, by 22.1% in the exercise training group and by 9.9% in the control group.ConclusionsSix months’ treatment by an activating spinal orthosis showed no significant difference in back pain, back extensor strength, or kyphosis index between the three groups. In the spinal orthosis group, present back pain decreased slightly and back extensor strength increased by 26.9% which indicates that the spinal orthosis may become an alternative training method.Clinicaltrials.com ID: NCT03263585Electronic supplementary materialThe online version of this article (10.1007/s11657-018-0555-0) contains supplementary material, which is available to authorized users.