This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Many studies have investigated the effects of physical activity on affect (i.e. mood and emotional states), and consistently found that acute bouts of exercise at a moderate intensity have positive influences on affect. However, little research has been done on the reverse relationship, that is, the effects of prior mood and emotional states on people's perceptions of exercise. This study will address this issue by specifically manipulating emotion during moderate physical exercise through the use of standardized pictures designed to produce emotional responses. The use of the International Affective Picture System (IAPS) will enable brief manipulation of emotion to directly test the relationship between a negative emotional state and perceived physical exertion. Subjects will consist of 30 women, ages 18-30. Subjects will run at a moderate pace on a treadmill, during which they will view negative or neutral pictures and be asked to periodically give numerical ratings regarding their emotional state and their perceived level of physical exertion. This will help us determine if negative emotion changes the way that people feel about exercise.