Impact of high-intensity interval training on cardiac structure and function after COVID-19: an investigator-blinded randomized controlled trial

Iben Elmerdahl Rasmussen, Mathilde Løk, Cody Garett Durrer, Frederik Foged, Vera Graungaard Schelde, Josephine Bjørn Budde, Rasmus Syberg Rasmussen, Emma Fredskild Høvighoff, Villads Rasmussen, Mark Lyngbæk, Simon Jønck, Rikke Krogh-Madsen, Birgitte Lindegaard, Peter Godsk Jørgensen, Lars Køber, Niels Vejlstrup, Bente Klarlund Pedersen, Mathias Ried-Larsen, Morten Asp Vonsild Lund, Regitse Højgaard ChristensenRonan M G Berg*

*Corresponding author for this work
3 Citations (Scopus)


A large proportion of patients suffer from a persistent reduction in cardiorespiratory fitness after recovery from COVID-19, of which the effects on the heart may potentially be reversed through the effect of high-intensity interval training (HIIT). In the present study, we hypothesized that HIIT would increase left ventricular mass (LVM) and improve functional status and health-related quality of life (HRQoL) in individuals previously hospitalized for COVID-19. In this investigator-blinded, randomized controlled trial, 12 wk of supervised HIIT (4 × 4 min, three times a week) was compared with standard care (control) in individuals recently discharged from hospital due to COVID-19. LVM was assessed by cardiac magnetic resonance imaging (cMRI, primary outcome), whereas the pulmonary diffusing capacity (DLCOc, secondary outcome) was examined by the single-breath method. Functional status and HRQoL were assessed by Post-COVID-19 functional scale (PCFS) and King's brief interstitial lung disease (KBILD) questionnaire, respectively. A total of 28 participants were included (age 57 ± 10, 9 females; HIIT: 58 ± 11, 4 females; standard care: 57 ± 9, 5 females), LVM increased in the HIIT vs. standard care group with a between-group difference of 6.8 [mean, 95%CI: 0.8; 12.8] g; P = 0.029. There were no between-group differences in DLCOc or any other lung function metric, which gradually resolved in both groups. Descriptively, PCFS suggested fewer functional limitations in the HIIT group. KBILD improved similarly in the two groups. HIIT is an efficacious exercise intervention for increasing LVM in individuals previously hospitalized for COVID-19.NEW & NOTEWORTHY In this randomized clinical trial on individuals previously hospitalized for COVID-19, a 12 wk supervised high-intensity interval training (HIIT) scheme was found to increase left ventricular mass, whereas pulmonary diffusing capacity was unaffected. The findings indicate that HIIT is an efficacious exercise intervention for targeting the heart after COVID-19.

Original languageEnglish
JournalJournal of Applied Physiology
Issue number2
Pages (from-to)421-435
Number of pages15
Publication statusPublished - 1 Aug 2023


  • COVID-19
  • Cardiorespiratory Fitness
  • Female
  • Heart
  • High-Intensity Interval Training
  • Humans
  • Quality of Life


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