In this section, the results obtained in this research will be presented, after reading all the articles eligible for analysis.
The analyzed population consisted of participants of both sexes in the post-COVID-19 rehabilitation process, with functional alterations (deficit in gait, strength, balance or reduced quality of life). The study included 302 adults, aged between 18 and 75 years, it was not possible to quantify how many men and how many women participated in the studies respectively, who were diagnosed with COVID-19.
One study assessed functional capacity through the 6-min walk test Li et al. (2022) . Another study PEHLIVAN et al., (2022)  investigated the functional performance of participants through a battery of short-term tests: 30-s sit-to-stand test, lower limb strength, baseline visual analogue scale fatigue score, and modified dyspnea score. No significant differences were found in the performance tests, however the visual analogue scale fatigue score was similar, the mMRC score was higher in the TG (p = 0.012).
Another study, Nambi et al. (2022) , evaluated muscle strength, muscle mass and quality of life. strength was measured with a portable dynamometer (Camry digital hand dynamometer, EH 101–17). Quality of life: It was subjectively measured using the Sarcopenia and Quality of Life (SarQol) questionnaire. After high and low intensity exercise. Strength improved in the handgrip strength group improved more (P < 0.001) in the low-intensity aerobic training group than in the high-intensity aerobic training group, but not in the amount of muscle. Quality of life showed greater improvement (P < 0.001) in the low-intensity group than in the high-intensity group.
Outro estudo, Foged et al. 2021 , realizou um protocolo intervalado de alta intensidade (HIIT), Foi utilizado três protocolos, com duração do exercício (38 min). Um aquecimento de 10 minutos foi seguido por um bloco de exercícios intervalados, com duração entre 21 e 25 minutos dependendo do protocolo específico, com o objetivo de avaliar a tolerância do exercício em pacientes pó-COVID-19. Outro estudo, Giardina et al. (2022), avaliaram o equilíbrio com uma plataforma estabilométrica, enquanto o equilíbrio dinâmico foi avaliado com o Mini BESTest e o teste Timed Up and Go.
Another study, Foged et al. 2021 , performed a high-intensity interval protocol (HIIT), three protocols were used, with exercise duration (38 min). A 10-min warm-up was followed by an interval exercise block, lasting between 21 and 25 min depending on the specific protocol, with the aim of assessing exercise tolerance in post-COVID-19 patients. Another study, Giardina et al. (2022) assessed balance with a stabilometric platform, while dynamic balance was assessed with the Mini BESTest and the Timed Up and Go test.
Regarding the protocols used, two articles by Giardinia et al. (2022) and Nambi et al. (2022) , provided a description of the intervention groups, types of therapy and form of application. The article by Giardinia et al. (2022) showed that there was a significant difference in the time taken to perform the TUG test between groups (P < 0.0001); in post-hoc, PwCOVID and PwAECOPD did not differ significantly (P = 0.274), while healthy subjects performed better than PwCOVID (P < 0.0001) and PwAECOPD (P = 0.008). As for the Mini-BESTest, and also in the TUG test, the effect size of the differences between post-COVID-19 and healthy individuals was greater than 0.8. The article by Nambi et al. (2022) , showed that after 6 months of intervention there was a significant improvement related to strength and quality of life in the low-intensity exercise group compared to the high-intensity group, with p value. 0.003. Three other studies, PEHLIVAN et al., (2022) , Foged et al. 2021  and Li et al. (2022)  did not provide the description of the intervention groups, nor types of therapy nor how they were applied. The sample was calculated in only one article Foged et al. 2021 .
Due to the heterogeneity of clinical trials in terms of types of protocols, participant characteristics, interventions and comparison groups, the types of protocols used in the functional rehabilitation of post-COVID-19 individuals remain uncertain. In addition, most studies analyzed some of their outcomes based on statistical significance, but it was not possible to calculate the magnitude of the treatment effect.
Table of Contents
The electronic search strategy identified a total of 364 records from the selected databases. After screening for duplicates, 14 articles were excluded, followed by the screening by titles and abstracts, another 298 articles were excluded, of these 47 potentially relevant records were submitted to full text review and of these, 5 articles of a scientific nature, of the type essays Randomized clinicians were included for the qualitative synthesis of this review. The detailed flowchart of the search strategy is shown in Fig. 1.
The Kappa score was used to evaluate the extracted data and verify the agreement between the evaluators regarding the inclusion and exclusion of the studies. it was observed that evaluator 1 decided to include 10 articles and evaluator 2 to include 7, and for 5 articles there was a concordant decision on inclusion. The non-inclusion results were concordant for 352 articles. For 7 articles there was disagreement for inclusion, and for 5 articles evaluator 1 decided for inclusion and evaluator 2 did not, and for 2 articles evaluator 2 decided for inclusion and evaluator 1 did not. The results of this analysis are shown in Table 2.
Main findings of selected studies
The eligible clinical studies selected for this systematic literature review were characterized according to the following variables analyzed: year of publication of the study, objective, sample size, intervention and main results found in each study, as shown in Table 3.
Results of the evaluation of the methodological quality of the studies using the PEDro scale
The articles were grouped according to the methodological quality assessment, according to the analysis of the PEDro scale items. According to the PEDro scale classification, one study reached 8 points, two studies reached 7 points, one reached 6 points and one reached 5 points. No studies reported conflicts of interest or funding related to commercial interests. The items that verify the quality of the studies are listed in Table 4, and are explained in the topic: Assessment of the methodological quality of the studies.