## 3 Results
### Main Findings of the Included Studies
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Article** & **Nationality** & **Study Design** & **Study Group** & **Intervention** & **Outcome** & **Main Findings** \\ \hline  & & & & n tot \(\pm\) 20 & 5 weeks (3 session/week) of & & & At the end of the treatment, there was a \\ [PERSON] et al. [67] & Prospective & & mean age \(\pm\) 39 years & aerobic training & 6 MVT, Modified & & statistically significant improvement in \\ European Journal of & \multirow{2}{*}{Pakistan} & \multirow{2}{*}{Pakistan} & \multirow{2}{*}{LOS in L10 \(\times\) 3-5 days} & (20-60 min/session) and & & & & \\  & & study & LOS in COVID-19 Unit \(\pm\) 5-6 days & breathing exercise training & & & \\  & & LOS in Rehabilitation Unit \(=\) nr & (10 min/session) & & & \\  & & & & n tot \(\pm\) 30 & & \\ [PERSON] et al. [48] & \multirow{2}{*}{Uniled} & \multirow{2}{*}{Observational} & \multirow{2}{*}{LOS in L10 \(\times\) nr} & \multirow{2}{*}{6 weeks (2 session/week) of & & & \\ Chronic Respiratory & & & mean age \(\pm\) 58 years & & & \\ Disease, 2021 & Kingdom & & & LOS in ICU \(=\) nr & & \\  & & & LOS in COVID-19 Unit \(\pm\) 10 days & & & \\  & & & LOS in Rehabilitation Unit \(=\) nr & & & \\ \hline \hline \end{tabular}
\begin{tabular}{c} Legend. \& \# MVT = minutes Walking Test; ESNT = Endurance Shutling Test; EACT = Functional Assessment of Chronic: Illness Therapy (fatigue score); ISWT = Incremental Shutling Test; nr = not reported. \\ \end{tabular}
\end{table} 
Table 4: Main findings of the included studies (observational studies). [PERSON] et al. [45] recruited four post-COVID-19 patients with several degrees of severity. During the rehabilitation program, based on cardiovascular and pulmonary rehabilitation principles, all patients reported dyspnea (CR10 ranged from 2 to 7). CR10 values were reduced for all cases at the end of the treatment, showing increased functional capacity and improved prognosis (CR10 ranged from 0 to 5). [PERSON] et al. [46] analyzed three males who underwent a telehealth rehabilitation program: patients were trained to exercise four days per week at first and then, progressively, six days a week. Primarily, a mode of aerobic exercise training ground-based walking training with a low starting intensity was administered. At the six-week time-point, fatigue score on the FSS deteriorated in two cases and, when interrogated, both patients described feeling the burden of returning to normal daily duties, work, and career roles whilst still recovering from COVID-19, which contributed to their feelings of amplified fatigue and low mood. [PERSON] et al. [47] performed a prospective interventional study at the outpatient department of the Bin-Innam Rehabilitation Centre in Pakistan. Twenty participants discharged from the hospital (negative PCR report) at least two weeks before were recruited and underwent a five-week (3 sessions/week) program of aerobic training and Buteyko Breathing Technique breathing exercise on-site under the supervision of a physiotherapist. The Borg dyspnea score improved from 4.5 (0.2) to 3.1 (0.1) with a \(p<0.001\) after five weeks of exercise training. Sub-group 1 was composed of patients who did not need ventilatory support during their acute phase of the disease, and they demonstrated a more remarkable improvement in dyspnea than sub-group 2, composed of patients who underwent non-invasive ventilation or mechanical ventilation support during their acute care setting (33% reduction in perception of dyspnea in group 1 compared to 31% in group 2). In the [PERSON] et al. [48] study, 30 individuals completed the COVID-19 rehabilitation program, consisting of two supervised sessions per week, for 6 weeks, of training composed by aerobic exercises, upper and lower limbs strength training, and educational discussions including breathlessness, cough, fatigue, fear and anxiety, memory and concentration, taste and smell, eating well, getting moving again, sleeping well, managing daily activities, and returning to work. The FACIT improved by 5 points (\(p<0.01\)), from 29 to 34 points.