Mechanical contribution to lumbar stress injuries in female gymnasts.

Because female gymnasts as a group display higher than average incidences of stress-related pathologies of the lumbar spine, it was of interest to evaluate mechanical factors which are potential contributors. Lumbar hyperextension and impact forces were quantified for performances of five commonly executed gymnastics skills by four competitive collegiate women gymnasts. The skills performed were the front walkover, the back walkover, and the front handspring, the back handspring, and the handspring vault. Wielke's (1983) radius method was used to quantify lumbar curvatures from film data during normal relaxed standing postures and during subject performances of the five selected skills. A force platform was used to monitor vertical and lateral ground reaction forces at the terminations of the respective skill performances. Of the skills examined, the handspring vault produced the highest vertical and lateral impact forces, and the back handspring and back walkover required the greatest amounts of lumbar hyperextension. During the front and back walkovers and during the back handspring, maximum lumbar hyperextension occurred very close to the time that impact force was sustained by either the hands or the feet.