Discussion
sudden cardiac death, myocarditis, fatigue
SUDDEN CARDIAC DEATH, MYOCARDITIS
The study shows that physical exercise is safe in patients with persisting symptoms post-COVID. Exercise improved endurance capacity, oxygen pulse, and strength compared to control. The self-reported quality of life and fatigue improved over time in both groups. In the follow-up period, the exercise group was more active and the MFI-20 improved more than in the control group. The physical training was not associated with additional effects on questionnaires or subdomains of fatigue compared to the patients randomized to the control group.Our systematic search of the ongoing trials investigating exercise in post-COVID patients identified 107 records. Six records were removed due to duplication in different databases. Ultimately, 15 studies were found reporting a randomized design with an exercise intervention and a control group that underwent no intervention. Most of the studies (One major limitation compared to the other studies is the shorter duration of our training intervention.The improvement in quality of life and fatigue post-COVID over time is supported by the literature [Additionally, we found a higher daily activity in the exercise group in the follow-up period which is supportive of the under-representation of persons with reduced motivation. On the other hand, this greater activity can also be discussed as the cause of the improvement in the MFI-20 in the follow-up period.The duration of the intervention may have been too short, however, we observed marked improvements in cardiovascular capacity in the intervention group. In one trial investigating exercise as a treatment option, the duration was 8 weeks compared to 4 weeks in our study. This study found effects in some fatigue-associated questionnaires, but the MFI-20 questionnaire was not used [The symptoms post-COVID are characterized by physical fatigue, reduced activation, and impaired motivation. Our study shows that an individually planned and structured training regimen is highly effective in improving cardiovascular capacity, e.g. the maximum oxygen uptake and the oxygen pulse, in this patient population. Training effects have been consistently associated with a reduction of cardiovascular as well as all-cause mortality [In addition to the assessment of potentially positive effects, the safety of exercise post-COVID needs to be established. Physical exercise can promote sudden cardiac death in patients with myocarditis [In conclusion, an individualized exercise program is a safe and well-tolerated treatment option in patients with persisting symptoms post-COVID. These patients significantly improve in physical performance after 4 weeks compared to patients without exercise intervention and these positive effects persist after the intervention ended. Exercise had no beneficial effect on fatigue symptoms or quality of life in our study. Additional results from longer or different exercise interventions on quality of life and fatigue are eagerly awaited.