Three studies were performed to evaluate the effects of jet lag on factors associated with sport performance. In Study 1, members of the USA Women's Soccer Team traveled to Taiwan; in Study 2, North American students and faculty traveled to Western Europe; and in Study 3, European students traveled to North America. After travel, there was disruption of mood state and a reduction in dynamic strength; peak 5-s power and 30-s work capacity were reduced for 2 days (5-s power: 9.8 vs. 9.0 vs. 9.0 W.kg-1; 30-s work capacity: 213 vs. 199 vs. 201 J.kg-1). In these studies, mood state, anaerobic power and capacity, and dynamic strength were affected by rapid transmeridianal travel, and even highly trained athletes suffered from jet lag. However, effects of travel on the variables tested were essentially eliminated after 3 or 4 days.