To investigate the relationship between adolescent sport activity and abnormalities of the lumbar spine on radiography and magnetic resonance imaging (MRI), 237 collegiate athletes (mean age 19.4), representing judo, wrestling, and track, were analyzed from the point of contact or noncontact sports. Radiologic and/or MRI abnormalities of the lumbar spine were found in 68.7% of contact sports athletes (judo and wrestling, n=147), 53.3% of noncontact sports athletes (track, n=90), 69.9% of athletes who have played contact sports over 9 years (C9 athletes, n=83), and 47.1% of atheletes who have done noncontact sports over 9 years (N9 athletes, n=17). Discopathy related abnormalities on radiologic examination were found in 25.3% and 11.8% of C9 and N9 athletes. Disc degeneration on MRI was found in 45.8% and 29.4% of C9 and N9 athletes. Spondylolysis was found in 31.3% of C9, 5.9% of N9, 31.3% of elementary-C (athletes who played contact sports during elementary school, n=96), 32.8% of elementary-L/I (limited contact/impact sports, n=58), and 8.6% of elementary-N athletes (noncontact sports, n=35), respectively. From these results, we concluded that contact sports activity during adolescence induces lumbar spine abnormalities at a higher rate compared to noncontact sports and that spondylolysis is related to contact or limited contact/impact sport activity during elementary school.