Efficacy of Home Inspiratory Muscle Training in Post-covid-19 Patients: a Randomized Clinical Trial

INTRODUCTION: Coronavirus 2019 disease (COVID-19), caused by the Severe Acute Respiratory Syndrome (SRAG) of coronavirus 2 (SARS-CoV-2) surpassed the global number of 119,603,761 cases, with more than 2,649,722 reported deaths . There is sufficient evidence for a possible post-covid-19 syndrome, designating sequelae with persistent symptoms. Respiratory muscle training improves respiratory muscle strength, exercise capacity, diaphragm muscle thickness, and dyspnea in various patient populations, especially in those with the greatest reduction in basal respiratory muscle strength. OBJECTIVE: To evaluate the effectiveness of a home inspiratory muscle training protocol in improving respiratory muscle strength, dyspnea and quality of life in post-Covid-19 patients. MATERIALS AND METHODS: This is a clinical, controlled, randomized and blind trial, which will be carried out at the Institute of Tropical Medicine of the Federal University of Rio Grande do Norte. The sample size will be performed using GPower software version 3.1.9.2 (Kiel, Germany) for Windows and will be established after conducting a pilot study with 5 participants in each group (total of 10 subjects) for a hypothetical two-way ANOVA test, using the main variable the Maximum Inspiratory Pressure (PImax.). The subjects included in the research will undergo three evaluation moments: Pre-training (Initial), Post-training (6 weeks) and Retention Test (24 weeks) for clinical evaluation form, anthropometric measures, respiratory muscle strength, volumes and capacities pulmonary symptoms, dyspnea, perceived exertion and fatigue, handgrip strength, six-minute walk test, anxiety and depression, post-covid functional status. After the initial assessment, all volunteers will receive a POWERbreathe® device (POWERbreathe®, HaB Ltd, Southam, UK) to carry out the training. EXPECTED RESULTS: provide a safe, effective and easy-to-perform treatment for post-covid-19 patients.

The subjects included in the research will go through three evaluation moments: Pre-training (Initial), Post-training (3 and 6 weeks) and Retention Test (12 and 24 weeks).

After recruitment, participants will be invited to attend the Institute of Tropical Medicine to carry out an initial assessment by an evaluator previously trained and blinded to the intervention allocation group and will include anamnesis and physical examination, with measurement of vital signs, anthropometric measurements, assessment of lung volumes, respiratory muscle strength, peripheral muscle strength, quality of life, anxiety and depression, functional status and the 6-minute walk test.

After the initial evaluation, all volunteers will receive a POWERbreathe® device (POWERbreathe®, HaB Ltd, Southam, UK), to carry out the training, and will be individually instructed on how to use it and on the performance of the protocol. They will conduct an experimental session to familiarize themselves with the device that will not be considered for review. Every three days, volunteers will receive a phone call from researcher 2, who will not participate in the assessment, to confirm whether the exercise with the POWERbreathe® was being performed properly at the frequency and load set and if there were any doubts regarding the protocol. At the end of each week, participants will receive a video call from researcher 2 to adjust the device according to the weekly load progression of G1.

All evaluation moments (pre-training, post-training and retention test) will be performed by a single evaluator (Evaluator 1) - who will not know which group the subject will be allocated to - and recorded in the evaluation form developed for the project. A second researcher (Evaluator 2) will be responsible for applying the training protocols to the subjects.

Eligibility Criteria:
Inclusion Criteria:

* subjects of both sexes, sedentary, within two months of a diagnosis of COVID-19 confirmed by RT-PCR, aged over 18 years and without any underlying respiratory disease, with adequate cognitive status defined through the Mini Mental State Examination and reduced muscle strength respiratory, defined through the assessment of the maximum inspiratory pressure.

Exclusion Criteria:

* subjects who present any condition that makes it impossible to carry out the assessments and protocols, complications that justify the interruption of data collection, such as syncope, severe chest pain, coughing up blood, those who request withdrawal from the study and who present adverse effects such as hospitalization by exacerbation of the clinical picture.