despite ongoing research examining exercise and its anxiolytic effects (petruzello, landers, hatfield, kubitz, & salazar, 1991), our understanding of this relationship is limited. the present study evaluated the effects of exercise on anxiety sensitivity (as), and sought to evaluate the effects of various exercise intensities as well as several potential moderating variables including perceived effort, credibility, and expectancy. it was hypothesized that exercise at both mild and moderate intensities would result in a reduction of as compared to a no-exercise control condition. in addition, it was hypothesized that perceived effort, credibility, and expectancy would moderate the relationship between exercise, and as. fifty-five participants (37 females and 18 males) were randomly assigned to one of three groups: 1) a no exercise control condition (n=18), 2) a mild exercise condition (n=19), and 3) a moderate exercise condition (n =18). all participants attended the lab a total of six times over a two week period, and completed measures for perceived effort, credibility, expectancy, and as. results indicate that participants in the two exercise conditions experienced a similar decrease in as while those in the no exercise condition experienced no significant change in as. this finding suggests that a very mild dose of exercise intervention is sufficient to improve scores of as in an at risk population. furthermore, the variables of expectancy, credibility, and perceived effort did not moderate the effects of exercise on as.