Molecular hydrogen (H2) is potentially a novel therapeutic gas for acute post-coronavirus disease 2019 (COVID-19) patients because it has antioxidative, anti-inflammatory, anti-apoptosis, and antifatigue properties. The aim of this study was to determine the effect of 14 days of H2 inhalation on the respiratory and physical fitness status of acute post-COVID-19 patients. This randomized, single-blind, placebo-controlled study included 26 males (44 ± 17 years) and 24 females (38 ± 12 years), who performed a 6-min walking test (6 MWT) and pulmonary function test, specifically forced vital capacity (FVC) and expiratory volume in the first second (FEV1). Symptomatic participants were recruited between 21 and 33 days after a positive polymerase chain reaction test. The experiment consisted of H2/placebo inhalation, 2 × 60 min/day for 14 days. Results showed that H2 therapy, compared with placebo, significantly increased 6 MWT distance by 64 ± 39 m, FVC by 0.19 ± 0.24 L, and, in FEV1, by 0.11 ± 0.28 L (all p ≤ 0.025). In conclusion, H2 inhalation had beneficial health effects in terms of improved physical and respiratory function in acute post-COVID-19 patients. Therefore, H2 inhalation may represent a safe, effective approach for accelerating early function restoration in post-COVID-19 patients.

Clinic of Rehabilitation and Physical Medicine University Hospital Ostrava 708 52 Ostrava Czech Republic

Discipline of Biokinetics Exercise and Leisure Sciences School of Health Sciences University of KwaZulu Natal Durban 4041 South Africa

Faculty of Health Sciences Palacký University Olomouc 775 15 Olomouc Czech Republic

Faculty of Physical Culture Palacký University Olomouc 771 11 Olomouc Czech Republic

Research Institute for Sport and Exercise University of Canberra Bruce ACT 2617 Australia

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