Effects of Unsupervised Inspiratory Muscle Training on Ventilation Variability in Post-covid-19 Patients.

Patients will use a nasal clip and remain seated comfortably in a chair with back support, hip angle of 90˚, upper limbs resting on legs, and feet on floor. To measure MIP, patients will perform maximal expiration until residual volume, place the mouthpiece, and perform a maximal inspiratory effort against an occluded airway, and sustain for a minimum of one second.To measure MEP, the patient will inspire close to total lung capacity, place the mouthpiece, and perform a maximal expiratory effort against the occluded airway, maintaining for at least one second (NEDER et al.,1999). Patients will be constantly encouraged by the researcher during the test.For data analysis, at least three reproducible maneuvers will be performed with variability lower than 20%; the highest value will be registered. References values for the Brazilian population will be calculated according to age and gender (NEDER et al., 1999).

Pulmonary volume and capacity will be evaluated using a calibrated spirometer (Koko Digidoser model, Spide, Longmont, USA) in an acclimatized room. Patients will be advised to avoid large meals one hour before the test, food and drinks with caffeine for at least six hours before the test, and alcoholic drinks on the day of the test (ATS, 2019).The test will consist in performing an inspiratory maneuver until total lung capacity, followed by maximal and forced expiration to residual volume using the spirometer. Tests will be performed with patients seated and hips and ankles flexed at 90º. A minimum of three tests will be conducted with variation less than 5%; the highest forced expiratory volume in the first second and forced vital capacity obtained will be compared with predicted values for the Brazilian population (PEREIRA, et al., 2007).

The Medical Outcomes Study 36-Item Short Health Form Survey (SF-36) is a multidimensional questionnaire translated and validated for the Brazilian reality (CICONELLI et al., 1999; LAGUARDIA et al., 2011) that was developed to assess quality of life related to health. The instrument consists of 36 items, distributed in 8 domains that encompass two major components: the physical (physical aspects, bodily pain, general health status and physical function) and the mental (emotional aspects, social function, mental aspects and vitality). Scores range from 0 to 100 for each subscale, with higher scores indicating a better health-related quality of life (WARE; SHERBOURNE, 1992).

Handgrip strength will be measured using a hydraulic handheld dynamometer (Saehan1). Maximal isometric strength of the dominant hand will be assessed with patients seated comfortably in a chair, with knee and ankle joints at 90º, shoulder of dominant arm forward and in neutral rotation, elbow flexed at 90º near upper body, forearm in neutral position, and wrist between 0º to 30º of extension and 0º to 15º of ulnar deviation. Participants will be requested to perform maximal isometric strength for five seconds without moving other body parts (NOVAES et al., 2009). Three measurements will be performed with one-minute interval in between, and the average will be considered for analysis. Patients will be considered fragile if the average of three measurements is between 20% of lower distribution values, according to the World Health Organization (HOLAND et al., 2014).

Participants will perform the six-minute step test. They will be instructed to climb down the 20 cm step at a speed that allows them to perform the maximum number of steps in 6 minutes. They can start the test with any lower limb. The number of steps the participant takes will be counted at the end of the test (a cycle of going up and down will be considered as one step). Before and after the test, heart rate (HR) will be assessed (Polar Vantage NVTM, model 1901001, Oulu, Finland), blood pressure and SpO2, dyspnea and lower limb fatigue will be questioned using a modified Borg scale (0-10). Two tests will be carried out with an interval of 30 minutes between them and the values of the variables obtained in the best test, that is, the test in which the individual climbs the greatest number of steps will be used for analysis (ALBUQUERQUE et al., 2022).

Adverse effects and adherence will be assessed using a training diary will be given to all patients to assess adverse effects and adherence. After all training sessions, they will be encouraged to fill the diary, registering positive and negative observations and complications during and after training. Adherence will be assessed considering every time patients register the realization of the session. Fulfilled sessions will be added and then divided by the total number of sessions patients could perform.

Adherence to training will be considered by verifying the number of days that patient performed the sessions. The sum of all sessions performed will be divided by the total number of sessions that patients must perform. Adverse effects will consider all complications registered in the diary or mentioned during final evaluations.