each year in north america there are approximately 175 , 000 non - contact acl injuries . one of the main causes of these injuries is the rotational and translational forces created when a player makes a sudden change in direction or stops . every athlete subjects their lower extremities to various forces that are unique to his or her mass , speed , and strength . these forces are affected by composition of the playing field surface , shoe sole design and construction , and other factors . using these and other factors , the level of force at which injury is inevitable is determined and an athletic shoe is created which will provide a mitigating deformation induced by a particular athlete &# 39 ; s pre - determined , pre - injury force threshold . a mitigating deformation of as little as 2 degrees can significantly reduce injurious forces . after the athlete has progressed through that particular force - generating movement , the shoe &# 39 ; s sole instantly returns to its original shape .