This is a cross-sectional study to determine the optimal inspiratory muscle training (IMT) intensity for stroke survivors. Participants will breathe through a pressure threshold inspiratory loading device with varying loads in random order. Each IMT intensity protocol consists of 10 breaths. During the test, accessory inspiratory muscle activity will be measured with surface electromyography (sEMG) and diaphragm thickness will be used to assessed with ultrasonography. Repeated-measures ANOVA will be used for statistical analysis to determine the most effective training intensity for future study.

Recruitment of participants after a stroke:

The inclusion criteria are:

• clinical diagnosis of ischemic and/or hemorrhagic stroke.
• age ≥ 18 years.
• duration of stroke ranges from 1 month to 12 months after diagnosis.
• had no facial palsy, which could prevent proper labial occlusion.
• had not undergone thoracic or abdominal surgery.
• could understand and follow the verbal instruction.
• stable cardiac conditions.
• no previous history of respiratory problems.

The exclusion criteria are:

• acute myocardial infarction or acute heart failure.
• acute pain on chest or abdominal.
• with the clinical signs of significant pulmonary disease.
• consciousness impaired.
• patient with nasal feeding tube, tracheal tube and/or any condition, which prevent the measurement or training.

Recruitment of healthy participants:

The inclusion criteria are:

• age ≥ 18 years.
• had not undergone thoracic or abdominal surgery.
• no previous history of respiratory problems.

The exclusion criteria are:

• acute myocardial infarction or acute heart failure.
• acute pain in the chest or abdominal.
• with the clinical signs of significant pulmonary disease.
• unstable hypertension, arrhythmias, or unstable cardiovascular conditions, such as fluctuations in blood pressure and heart rate, indicate poor cardiac prognosis or the need for vasopressor medications.
• pregnant.

People after stroke and healthy adults