Objectives: Physical activity is an effective intervention for the prevention and management of chronic musculoskeletal pain (CMP). However, there is a lack of research to inform the intensity of physical activity that should be recommended. The aim of this study was to investigate the association between substituting 10 minutes of sedentary time with either 10 minutes of light physical activity (LPA) or moderate-to-vigorous physical activity (MVPA) and the CMP prevalence ratio. Design: Secondary Analysis (November 2015) of data from the Health Survey for England (2008). Setting: n/a Participants: 2313 adults (≥ 16 years). Interventions: n/a Main Outcome Measures: Sedentary time, LPA and MVPA were measured using accelerometry. We used isotemporal models to quantify the prevalence ratio for CMP of replacing 10 minutes of sedentary time with 10 minutes of LPA or MVPA. Results: The prevalence of CMP in this sample was 17%. The unadjusted prevalence ratio was 0.99 (95% CI: 0.97 to 1.01) for LPA and 0.76 (0.70 to 0.84) for MVPA. The fully adjusted prevalence ratio was 1.01 (95% CI: 0.99 to 1.02) for LPA and 0.89 (0.82 to 0.96) for MVPA. Conclusions: Substituting 10 minutes of sedentary time with an equivalent period of LPA was not associated with a reduction in the prevalence ratio for CMP, whereas the equivalent replacement with MVPA showed a small protective relationship. Regarding CMP prevalence, physical activity intensity appears to be important, with MVPA rather than LPA showing a protective relationship. Prospective studies are needed to investigate causality.