A systematic review that is ``rapid'' and ``living'': A specific answer to the COVID-19 pandemic.

Objective: This study aims to describe "rapid living" systematic reviews, an innovative methodological design used to systematically synthesize emerging evidence in the field of rehabilitation during the COVID-19 pandemic.

Study Design And Setting: A methodological paper, with a formative approach to rapid living systematic reviews.

Results: Based on our experience, we propose the following definition of rapid living SR: ``A dynamic method of knowledge synthesis that allows for the constant updating of new emerging evidence and refinement of its methodological quality.'' This method has the benefit of accelerating the conduct of traditional systematic reviews and allows for a synergistic adaptation of methodology based on the quality of the evidence with a flexibility to update results, methods and collaborations.

Conclusion: Our proposed methodology has been helpful to synthesize the rapidly evolving evidence in the field of rehabilitation during the pandemic. Similarly, it may be useful when a rapid answer is urgently needed to make informed decisions. The COVID-19 disease has shown that modern medical science has the ability to produce new knowledge at a rate never seen before. Therefore, our proposed rapid living systematic reviews provide the scientific community with a method to rapidly synthesize evidence when facing health emergencies.