This study is testing if a special breathing session can help people with Parkinson's disease (PD) breathe, speak, and cough better. Parkinsonism affects parts of the brain that control muscles, making it hard to breathe and talk. Two breathing methods will be tested: AIHH (acute intermittent hypercapnic hypoxia) and AIHN (acute intermittent hypercapnic normoxia). Hypercapnia means having more carbon dioxide in the blood. Hypoxia means low oxygen levels, and normoxia means normal oxygen levels.

Key Points:

• This is a one-time session study.
• No current participation in another research study is allowed.
• Participants must be 40-75 years old.

To join, you must have Parkinsonism, be able to walk 10 feet, and be cleared by a doctor. You should not join if you have other neurological conditions, severe illness, or are pregnant. Smoking or vaping in the past 5 years is not allowed. This study is for people who can follow directions and are willing to avoid donating blood during the study.