## 3 Results
### Main Findings of the Included Studies  
A cohort of seven subjects was analyzed by [PERSON] et al. [44] after two consecutive negative SARS-CoV2 swabs. All post-COVID-19 patients experienced a patient-tailored rehabilitation intervention (30 min sessions, 1-2 sessions/day for 6 days/week), consisting of a progressively increased intensity of physical exercise. In this case series, COVID-19-related fatigue was showed by almost all patients (86%), but only Case 2, needing ICU during the acute phase, presented a severe perceived exertion (CR10 = 7). After the rehabilitation treatment, 71% did not show fatigue, while the other two cases described only a very light perception of effort. \begin{table}
\begin{tabular}{l l} \hline \hline _Articles excluded after title and abstract screening phase (\(n\) = 456) *_ \\ \hline Study design & 139 (31\%) \\ Not population of interest & 173 (38\%) \\ Not intervention of interest & 132 (29\%) \\ Not comparison of interest & 0 (0\%) \\ Not outcome of interest & 12 (3\%) \\ \hline _Articles excluded after full-text screening phase (\(n\) = 47)_ \\ \hline Study design & 14 (30\%) \\ Not population of interest & 11 (24\%) \\ Not intervention of interest & 8 (17\%) \\ Not comparison of interest & 0 (0\%) \\ Not outcome of interest & 14 (30\%) \\ \hline \hline \end{tabular} The exclusion of the articles followed the PICO model defined in the Methods Section. Data are expressed as counts (percentages). * = Papers were excluded also for more than one reason during the title and abstract screening phase and the full-text screening phase.  
\end{table} 
Table 2: Reasons for article exclusion by the present systematic review. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Article** & **Nationality** & **Study Design** & **Study Group** & **Intervention** & **Outcome** & **Main Findings** \\ \hline [PERSON] et al. [44] & & & n tot = 7 & & \\ Journal of Medical & Italy & Case series & mean age = 43.8 years & exercises 1/2 sessions per day & & \\ Virology 2020 & & & LOS in ICU + 4.7 days & of 30 min each for & Borg CR10 & but after rehabilitation treatment, \\  & & & LOS in COVID-19 Unit = 16.57 days & 6 days/week & 71\% did not show any fatigue. \\  & & & LOS in Rehabilitation Unit = nr & & \\ [PERSON] et al. [45] & & & n tot = 4 & Aerobic exercise & \\ Revista Brasileira & Brazil & & mean age = 56 years & 3 times/week, 30 min, & \\ de Terapia & & & LOS in ICU = 15 days & resistance exercise & Borg CR10 & CR10-associated dyspnea variables \\ Interisiva, 2020 & & & LOS in COVID-19 Unit = 19.75 days & 10 repetitions each & \\  & & & LOS in Rehabilitation Unit = 90 days & & \\  & & & n tot = 3 & Individual telerabilitation & \\  & & & male/female = 3/0 & program, including education & \\  & & & mean age = 70.6 years & and progressive exercise & 5 STS, 1 min STS, \\ Respiratory Case & Australia & & LOS in ICU = 13.43 days & sessions (15-30 min each) & FSS, mMRC & \\ Reports, 2020. & & & LOS in COVID-19 Unit = 12.8 & featuring breathing, aerobic, & \\  & & & LOS in Rehabilitation Unit = 42 days & and strength training & \\ [PERSON] et al. [49] & & & n tot = 1 & Individual telerabilitation & \\ American Journal of & & & male/female = 1/0 & program, using a treatable & \\ Medicine \& & & mean age = 46 years & trials approach, with weekly & \\ Rehabilitation, 2021 & & & LOS in ICU = 0 days & contact by a physiotherapist & \\  & & & LOS in COVID-19 Unit = 10 days & with multidisciplinary team & \\  & & & LOS in Rehabilitation Unit = 21 days & (MDT) input & \\ \hline \hline  & & Logan: 1 min STS = 1 min St to St