I know most people are able to inhale air to expand their bellies (belly breathing), and some are able to make their bellies become larger by breathing in a certain pattern which imitates a pump to kind of slowly push out their abdominal walls with each breath.
May I know the mechanism behind this? (Pressure, volume in cavities, diaphragm movements)
What happens when a person retains this pushed out abdominal wall for a prolonged period? Will it cause hypoventilation (since the person is unable to breathe properly)?
Is this action similar to a Valsava manuever? Will this cause one's heart rate to speed up?