Various occupational inpatient rehabilitation programs are established in Norway. This study aimed to assess change in cardiorespiratory fitness, pain, anxiety, depression, and quality of life in persons on long-term sick leave due to musculoskeletal-, mental or unspecific disorders after participation in multicomponent inpatient occupational rehabilitation.

Twenty-five women and five men (mean age 45.2 years, SD 6.7, range 30–57) volunteered to participate in the study. The participants attended either 8 or 17 full days of occupational multicomponent rehabilitation including physical exercise, cognitive behavioral therapy in the form of acceptance and commitment therapy (ACT), and development of a tailored plan for return to work. Cardiorespiratory fitness was assessed by the Åstrand/Ryhming cycle test at the start and end of rehabilitation program, and at one-year follow-up. Changes in somatic and mental health were measured by questionnaires up to 4 months after start of the program.

Linear mixed models showed that the maximal oxygen uptake increased by 1.1 mL°kg-1°min^− 1 during the rehabilitation program and by 3.7 mL°kg-1°min^− 1 at one-year follow-up. There were minor improvements in somatic and mental health, and quality of life.

This study indicates that occupational inpatient multicomponent rehabilitation including physical exercise and ACT may promote a long-term increase in physical exercise that is sufficient to induce a significant increase in cardiorespiratory fitness.

The current study is not registered, but is part of a larger trial registered at clinicaltrials.gov (No.: NCT01926574, registered 21. Aug 2013).