Costal breathing, in other words diaphragmatic breathing, is used by the Starfish Project and McGuire Programme.
Starfish Project website: www.starfishproject.co.uk
Among our members there is a mixed response to the approach of such courses. While they clearly help some, they will not be right for everyone. The McGuire programme and Starfish Project both teach similar techniques but are very different in their size, structure and cost.
Costal breathing resources
Stuttertalk.com has a series of podcasts on costal breathing.
There is a 'Keep it costal' app linked off our Apps and software page.