The article reviews theoretical positions that have played prominent roles in research and applications in sport psychology. It elaborates on the research evidence dealing with the immediate or acute effects of vigorous exercise on state anxiety. There is an extensive literature demonstrating that active, physically fit individuals experience a reduction in state anxiety following vigorous physical exercise. These effects occur in persons with high trait anxiety, as well as those who fall within the normal range, and these effects have been found to be independent of age and gender. It appears that the anxiolytic effects of exercise last for approximately 2- 3 hours, whereas passive interventions such as meditation and quiet rest have less persistent effects. The mechanisms responsible for exercise-induced tension reduction have not been identified, and research involving the question of "why" anxiety is reduced after exercise needs to be undertaken.