What is the intervention? This section should specify the details about the intervention of interest for the review, for example, the nature of intervention, frequency, intensity, timing, and details about those administering the intervention. The same kind of information should be specified for all comparators considered in the review. Where possible, the intervention should be described in detail, particularly if it is multifaceted. A more detailed analytical framework can be used to refer to these complexities. If the review is examining a class or group of interventions, a comprehensive list of identified examples should be provided for the reader. Reviewers should plan any subgroup analysis based on different modes, timing, etc. of the intervention during the protocol stage and account for them in the inclusion criteria. For example, ‘inspiratory muscle training includes any mode (threshold loading, resistive, hyperpneic,) practiced at least daily for no less than 4 weeks’ allows the reviewers to consider different types of training but specifies the minimum training period.