d5aa8617_University_of_Chicago_Medicine__Possible_cause
[Type of overuse injury] Spondylolisthesis [Symptoms] Back pain [Possible cause] 
This condition is caused by excessive flexion and extension of the low back. X-rays show that a part of one vertebra in the low back slips forward on the vertebrae below it. It is commonly seen in football linemen, gymnasts, and ice skaters.
Overuse Injuries - The University of Chicago Medicine
Possible cause