Coronavirus-2019 (COVID-19) is a viral disease leading to respiratory dysfunction, but it may also affect the brain and result in the development of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This may be the result of the COVID-19 virus infecting regions of the brain responsible for respiratory control. The symptoms of COVID-19 long haulers and ME/CFS may be lessened via an 8-week inspiratory muscle training protocol which is a simple and easy training protocol which can be done at a patient's home. Thus, this project will investigate changes in the breathing and cardiovascular responses to stimuli in three groups of participants: 1) healthy control individuals; 2) patients diagnosed with ME/CFS (mild to moderate symptoms); and 3) individuals with previous COVID-19 infection with long-haul symptoms lasting for at least 1 year. Participants will 1) breathe hypoxic gas (10% O2) for 5 minutes; 2) breath hypercapnic gas (5% CO2) for 5 minutes; 3) breathe at a rate of 6 breaths per minute for a total of 8 breaths (paced deep breathing); and 4) complete 10 minutes upright tilt (70 degrees head up on a tilt-table). Patients will also complete 2 questionnaires concerning their symptoms and a 15 minute cognitive function test on a lab laptop. This will allow for the assessment of the brain's control over blood pressure and breathing. Participants will also complete a 6-minute walking exercise test at their own speed as a measure of their aerobic fitness. We hypothesize that COVID-19 survivors will have a worse cardiovascular and autonomic response and lower fitness, similar to ME/CFS patients, compared to healthy participants.Further, this will be improved after 8-weeks of inspiratory muscle training. These results may help clinicians recognize ME/CFS symptoms in patients recovering from COVID-19. https://clinicaltrials.gov/ct2/show/NCT05196529
