Comparison of High-Intensity Interval Training to Moderate-Intensity Continuous Training for Functioning and Quality of Life in Survivors of COVID-19 (COVIDEX): Protocol for a Randomized Controlled Trial.

OBJECTIVE: The purpose of this study was to compare high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) for feasibility, safety, adherence, and short- and long-term efficacy in improving functioning and health-related quality of life in survivors of coronavirus disease 2019 (COVID-19). METHODS: COVIDEX is a two-pronged, parallel-group, randomized controlled trial with an 8-week training intervention. The study participants will be 94 patients aged >18 years, admitted to a specialized post-COVID center. Participants will be randomized to HIIT (4 × 4 minutes of high-intensity work periods at 85% to 90% of peak heart rate) and MICT (47 minutes at 70% to 75% peak heart rate) groups for biweekly sessions for 8 weeks. The participants will undergo 2 phases of supervised training (phases 1 and 2) of 4 weeks each, in a public, specialized, post-COVID center. In phase 1, we will assess and compare the feasibility, acceptability, and short-term efficacy of HIIT and MICT intervention. In phase 2, the long-term efficacy of HIIT and MICT will be assessed and compared regarding function and health-related quality of life. To prevent any expectation bias, all study participants and assessors will be blinded to the study hypotheses. Group allocation will be masked during the analysis. All statistical analyses will be conducted following intention-to-treat principles. IMPACT: This study is the first randomized controlled trial that will compare the feasibility, safety, adherence, and efficacy of the HIIT and MICT intervention programs in this population. The findings will potentially provide important information and assist in clinical decision making on exercise to optimize the benefits of clinical health care in survivors of COVID-19.