“…Breathing training is a part of several cognitive-behavioral treatment packages, of most meditative approaches (e.g., yoga, mindfulness meditation), and of other somatic therapies. Paradoxically, despite widespread clinical usage, only limited systematic data exist on the treatment efficacy of breathing training or PetCO 2 feedback (Bass, 1994). When breathing therapies have been shown to be effective for PD, critics have claimed that any success was probably the result of cognitive rather than physiological change (de Ruiter, Ryken, Garssen, & Kraaimaat, 1989;Salkovskis, Jones, & Clark, 1986).…”