ABSTRACTREMY EMETO. THE INFLUENCE OF CONCURRENT EXERCISE ORDER ON POSITIVE AND NEGATIVE AFFECT. (Under the direction of DR. JOSEPH S. MARINO)Introduction: Understanding affective responses to exercise is necessary to increase adherence and reduce barriers to participation. This study will be the first to determine the relationship between positive and negative affect to blood lactate during and following exercise. We will test the hypotheses that exercise order influences affect and negative affect scores are associated with higher intra-session and post session blood lactate levels. Purpose: The purpose of this study is to determine whether the order in which aerobic and resistance training is performed influences affective responses. Methods: Each participant was screened for exclusion criteria and completed the physical activity readiness questionnaire (PARQ+). Participants then completed 3 lab visits. Results: Blood lactate levels increased in response to exercise and remained elevated 30 minutes post. When RT was performed first, participants experienced a greater sense of positive well-being prior to the start of the session. Psychological distress decreased 30 minutes post exercise compared to pre-exercise values. Fatigue remains elevated 30 minutes post exercise for both groups. We see a decrease in Tranquility for the RTAT group when comparing timepoints. We also see an increase in tranquility for the RTAT group when comparing timepoints. Conclusions: Exercise regardless of order does influence affective responses and will lead to an increase in blood lactate levels.