Exercise and comorbidity: the i3-S strategy for developing comorbidity-related adaptations to exercise therapy

Purpose: Exercise therapy is effective in a wide range of chronic diseases. Comorbid disease necessitates adaptations to exercise therapy. Guidance on how to develop such adaptations is currently not available. We present an innovative strategy for the development of comorbidity-related adaptations to exercise therapy in an index disease. Method: We previously developed comorbidity-related adaptations to exercise therapy in osteoarthritis. We now broaden this approach into a general strategy for the development of comorbidity-related adaptations to exercise therapy in an index disease. Results: The i3-S strategy consists of four steps. The first three steps involve creating an inventory of comorbid disease, an inventory of contraindications and restrictions on exercise therapy, and an inventory of potential adaptations to exercise therapy. In the fourth step, this information is synthesized into guidance on comorbidity-related adaptations to exercise therapy in the index disease. The adaptations concern physiological, behavioural and environmental factors. Conclusion: In view of the general effectiveness of exercise therapy and the high prevalence of comorbidity in older people, there is a great need for comorbidity-related adaptations to exercise therapy. We recommend to use and evaluate the i3-S strategy in future research. Implications for Rehabilitation Exercise therapy is effective in a wide range of chronic diseases. Comorbid disease necessitates adaptations to exercise therapy. Guidance on how to develop such adaptations is currently not available. We present an innovative strategy for the development of comorbidity-related adaptations to exercise therapy in an index disease. Researchers and clinicians can use this strategy to develop guidance on the adaptation of exercise therapy to comorbidity.