Journal of Cognitive Psychotherapy: An International Quarterly Volume 22, Number 4 • 2008 © 2008 Springer Publishing Company 303 DOI: 10.1891/0889-8391.22.4.303 Physical Exercise as Interoceptive Exposure Within a Brief Cognitive-Behavioral Treatment for Anxiety-Sensitive Women Brigitte C. Sabourin, BA Sherry H. Stewart, PhD Simon B. Sherry, PhD Dalhousie University, Halifax, Nova Scotia, Canada Margo C. Watt, PhD Dalhousie University, Halifax, and St. Francis Xavier University, Antigonish, Nova Scotia, Canada Jaye Wald, PhD University of British Columbia, Vancouver, Canada Valerie V. Grant, BA Dalhousie University, Halifax, Nova Scotia, Canada A brief cognitive-behavioral treatment intervention that included an interoceptive exposure (IE) component was previously demonstrated effective in decreasing fear of anxiety-related sensations in high anxiety-sensitive (AS) women (see Watt, Stewart, Birch, & Bernier, 2006). The present process-based study explored the specific role of the IE component, consist- ing of 10 minutes of physical exercise (i.e., running) completed on 10 separate occasions, in explaining intervention efficacy. Affective and cognitive reactions and objective physiological reactivity to the running, recorded after each IE trial, were initially higher in the 20 high-AS participants relative to the 28 low-AS participants and decreased over IE trials in high-AS but not in low-AS participants. In contrast, self-reported somatic reactions, which were initially greater in the high-AS participants, decreased equally in both AS groups over IE trials. Findings were consistent with the theorized cognitive and/or habituation pathways to decreased AS. Keywords: anxiety sensitivity; physical exercise; interoceptive exposure; cognitive behavioral approach A nxiety sensitivity (AS) is defined as the fear of anxiety-related bodily sensations arising from beliefs that these sensations have harmful physical, psychological, and/or social consequences (Reiss, 1991). AS is implicated in the development and maintenance of