Cardio is known to be helpful in lowering your blood pressure, the mechanism behind that is not completely understood. A 2019 study looked at the mechanism, believing that bacteria in the mouth creating nitrites, compounds which help relax the blood pressure.
They found that by inhibiting the bacteria following cardio by using mouthwash actually reduced the blood pressure lowering effects of performing the cardio, and the associated muscle oxygenation.
Keep your cardio efficient, avoid the mouthwash around a good workout.
