Related Experiment Video
Updated: Aug 5, 2026
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
High-intensity interval training vs. moderate-intensity continuous training in COVID-19 survivors (COVIDEX): A
Vinicius Afonso Gomes1,2, William de Suzart3, Fabiane Costa Santos Fontoura2
1Postgraduate Program in Medicine and Health, Universidade Federal da Bahia, Salvador, Brazil.
Background:
High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) have been widely studied in individuals with chronic conditions. However, no studies have compared these two exercise modalities in COVID-19 survivors.
Objective:
To compare the feasibility, safety, adherence, and short-term efficacy of HIIT and MICT in improving functioning and health-related quality of life in COVID-19 survivors.
Design:
Two-arm, parallel-group, single-center randomized clinical trial with a 1:1 allocation ratio, conducted according to intention-to-treat principles and designed as a precursor to a future definitive randomized clinical trial.
Setting:
A specialized post-COVID-19 rehabilitation center.
Participants:
Thirty COVID-19 survivors treated at a post-COVID-19 rehabilitation center.
Interventions:
HIIT (4 × 4 minutes at 85%-90% of peak heart rate) or MICT (40 minutes at 70%-75% of peak heart rate), both performed twice a week with isocaloric protocols for 4 weeks.
Main Outcomes Measures:
Eligibility and consent rates, attendance, retention, ability to achieve the prescribed intensity and duration, completion of the recommended sessions, adverse events, cardiopulmonary exercise testing, as well as other physical performance tests, questionnaires, and specific scales.
Results:
Eligibility and consent rates were 80% and 62.5%, respectively. One participant in the HIIT group and two in the MICT group discontinued the interventions. Attendance was 8 (7-8) sessions in the HIIT group and 7 (6-8) sessions in the MICT group. Both groups were able to achieve the prescribed intensity and duration, and no serious adverse events occurred in either protocol. Regarding short-term efficacy outcomes, no differences were observed between the two protocols for any variable.
Conclusion:
Both protocols appeared feasible, with similar short-term efficacy for functioning and health-related quality of life, demonstrating good adherence and safety. However, a definitive trial will be necessary to confirm these findings.
Trial Registration:
Brazilian Clinical Trials Registry (REBEC: RBR-5tvjs5t).
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