A growing body of evidence indicates that aerobic exercise is an effective and cost-efficient treatment alternative for a variety of anxiety and mood disorders, including panic disorder (for a review, see Salmon, 2001). However, researchers have not examined whether exercise affects anxiety sensitivity, a known precursor of panic attacks and panic disorder (Ehlers, 1995). Anxiety sensitivity is conceptualized as an enduring fear of anxiety and anxiety-related sensations, brought about from the belief that these sensations can have harmful physical, psychological, or social consequences ( [Reiss and McNally, 1985] and [Taylor, 1999] ).
Individuals who are high in anxiety sensitivity have a tendency to misinterpret and catastrophize anxiety-related physiological sensations, which may contribute to or exacerbate the experience of panic ( [Clark, 1986] and [Reiss and McNally, 1985] ). Accordingly, interventions that reduce anxiety sensitivity have the potential to reduce the likelihood that individuals will experience panic attacks or develop panic disorder.
Significant reductions in anxiety sensitivity following ten to twelve sessions of cognitivebehavioral therapy (CBT) have been reported ( [McNally and Lorenz, 1987] and [Telch, Lucas, Schmidt, Hanna, Jaimez and Lucas, 1993] ). CBT treatment packages generally include exposure to feared somatic sensations, arousal reduction, and cognitive-restructuring techniques. Aerobic exercise is believed to reduce anxiety and panic symptoms through similar processes.
Specifically, aerobic exercise produces many of the same bodily sensations that often elicit anxiety reactions, such as increases in heart rate, respiration, and perspiration. Repeated exposures to anxiety-related interoceptive stimuli through exercise may therefore extinguish fear responses, accompanied by changes in how these stimuli are interpreted (de Coverley Veale, 1987). Furthermore, aerobic exercise reduces generalized arousal, including resting heart rate and muscle tension (Abadie, 1988). Based on the functional similarities between aerobic exercise and CBT, it is not surprising that some studies have found no differences in the efficacy of CBT and aerobic exercise in the reduction of anxiety ( [Fremont and Craighead, 1987] and [McEntee and Haglin, 1999] ).