The diagnosis of spondylolysis is a major cause of concern for patients and their families, especially when the patients are young athletes with promising futures in their sports. In this study, 3152 case histories of high-level athletes were evaluated to determine which sports had a higher prevalence of spondylolysis. The overall percentage of spondylolysis among athletes in this study (8.02%) was not very much higher than that among the general population, which varies between 3% and 7%. However, when each sport was considered separately we found much higher values for some sports, with the highest percentages occurring in throwing sports (26.67%), artistic gymnastics (16.96%), and rowing (16.88%). The analysis of the biomechanical movements involved in the sports with greater prevalence of spondylolysis has led us to include the element of torsion against resistance as another possible causative factor for spondylolysis that should be added to the already known causative mechanisms, lumbar hyperextension and rotation. We have divided the sports into three risk groups according to the prevalence of spondylolysis shown and the characteristics of the sample, and we recommend systematic radiological examination of the lumbar spine in athletes considered to be at greater risk of developing spondylolysis.