This protocol is for a pragmatic mixed methods randomized parallel-group exploratory feasibility trial to examine all facets of a proposed future phase III trial on the use of wearable device to increase physical activity and possibly reduce pain amongst middle-aged people with musculoskeletal (MSK) chronic pain. The feasibility study is intended to answer the following research questions: Question 1 Evaluate the acceptability of all aspect of the study design of wearable devices as an intervention to increase physical activity in middle-aged adults with musculoskeletal chronic pain. Question 2: Is it feasible and acceptable to use wearable devices as an intervention to increase physical activity in middle-aged adults with musculoskeletal chronic pain? Question 3: How can using wearable device promote physical activity effectively in middle-aged adults with musculoskeletal chronic pain? Participants will be recruited from a National Health Service (NHS) pain clinic and randomised on a ratio1:3 into control group (standard care) and intervention group (standard care combined with wearable device). The feasibility study will last for 18 months, participants involvement will be for 24 weeks. Patients in both groups can participate in any physical activity, including planned, structured, and repetitive bodily movement exercise or occupational and recreational PA. Qualitative semi-structured interview will be conducted at baseline and week-12, while outcome measures will be conducted at baseline, 4-week, 8-week,12-week, and 24-week for all participants to examine their pain, physical activity, and their responses to the trial. Qualitative interview will be conducted for stakeholders which include clinicians and service managers after all patient data has been collected. This study has the potential to make an original contribution to provide key data on the feasibility, acceptability, and effectiveness of using wearable technology to support physical activity intervention for middle-aged adults with musculoskeletal chromic pain.