Biomechanical approaches to understanding the potentially injurious demands of gymnastic-style impact landings

Gymnastic-style landings involving high-velocity impacts and controlled rotation during ground contact are performed regularly in sport e.g. during landing from a vertical jump or in dismounting from a gymnastics apparatus. Gymnasts are naturally exposed to a high frequency of impact landings and may be required to perform dismounts in excess of 200 times a week [1]. Unlike many other sports involving impact landings, gymnastic routines uniquely require a simultaneous address of performance and injury objectives. In dismounting, gymnasts are challenged by the need to modulate a prescribed rotation of the body orientation in flight to ensure the feet contact the ground. For example, when dismounting from the beam apparatus, gymnasts are frequently required to prepare for landing following a backward or forward somersault (rotation about the transverse axis) performed with high degrees of hip flexion (piked position). The subsequent ground contact or impact landing phase must be achieved using a safe, aesthetic and well-executed, double-foot landing. Although performed less frequently, single-foot impact landings such as performed in a floor routine, require similar performance and injury objectives to be addressed but typically require a succeeding skill to be performed.Constraints in the ability of a gymnast to satisfy the multiple requirements of competitive landing tasks have subsequently been linked to errors in performance and high injury incidence rates [2]. Performance deductions may, for example be incurred for the execution of an uneven landing involving the use of multiple, single-foot placements during the impact landing phase. A serious problem faced by modern-day gymnasts is however the subsequent injury risks associated with competitive landing tasks. In 1983, Hunter and Torgan [3] questioned the need to re-evaluate gymnastic scoring of dismounts following the high incidence of associated major acute knee injuries e.g. tears to the anterior cruciate lig