Little is yet known about what predicts a good effect for spinal injections in people with persistant (> 3 months) mechanical Low Back Pain (LBP). This study aims to follow people from the day of having a spinal injection (epidural or facet joint injection) for the next 6 weeks to identify how well the injection has worked in reducing participants’ pain and improving how much activity they can do, in their daily life. Even more importantly, we aim to find out if certain characteristics such as the presence of widespread pain, reduced ability and low mood can predict how well a person does within the 6 weeks following a spinal injection. Widespread pain can signify a change in how the nervous system is interpreting ongoing LBP and is important to identify as it may require additional treatment to improve. A prospective cohort study is planned, for which up to 50 people with persistnt LBP will be recruited in Beaumont Hospital. Taking part involves filling out questionnaires on the day of the spinal injection and then answering follow up questions by phone, at 2 and 6 weeks after the injection.