Dosage of Preventive or Therapeutic Exercise Interventions: Review of Published Randomized Controlled Trials and Survey of Authors.

OBJECTIVE: To describe the dose components and choice justifications in exercise interventions in a convenient sample of randomized controlled trials (RCTs).

DATA SOURCES: We searched the following databases: PubMed and Cochrane Central Register of Controlled Trials in 2014.

STUDY SELECTION: We included published RCTs evaluating preventive or therapeutic interventions in people with clinical conditions or at risk to develop health problems.

DATA EXTRACTION: Two reviewers independently extracted data and evaluated the adequacy of the justifications. We contacted and invited the trials authors to complete an online survey to ask for additional information on dose justifications and dose-effect relation.

DATA SYNTHESIS: We included 187 published RCTs. Of these, 68 (36%) reported a justification for the dose choice, and 135 (72%) reported 3 doses components. Most reported components were duration (96%) and frequency (93%). Sixty-six survey responders (response rate, 35%) provided additional information. When combining the publications and survey responses, 104 (56%) trials had a justification for the dose choice. We judged justifications adequate in 45 (43%) articles. From the survey responders, 39% indicated that intensity was the dose component that can have the greatest effect on their study results.

CONCLUSIONS: Most of the published RCTs adequately reported the dose components of their exercise interventions but only a small number provided sufficient justifications for dosage choices. Further studies are recommended to justify the exercise intervention dose choices.