| Artistic gymnastics is a dynamic sport that is enjoying increasing popularity. Unfortunately, there has also been an increase in the number of lower extremity injuries, particularly to the Achilles tendon and anterior cruciate ligament. Routines on all apparatii contain complex skills such as the double back somersault. Variability in all performance aspects must be accounted for in the landing phase. The purpose of the study was to assess dynamic lower extremity joint loading of elite gymnasts during the landing phase of a double back somersault.;The data analysis consisted of three phases: (a) an inverse dynamic analysis of the double back somersault and landing, (b) a kinetic analysis of the landing phase, and (c) a direct dynamic simulation of the most skilled subjects' performances. Data from the inverse dynamic analysis were applied to kinetic data to derive shear and compressive components of the knee and hip resultant joint forces. Kinematic data from the inverse dynamic analysis as well as the kinetic data served as control functions to a four segment simulation model of the gymnast to assess the result of changes in these parameters on movement outcomes.;Kinematic descriptors indicated that several different landing strategies were employed. Temporal constraints implied the need for the gymnast to pre-program these strategies. Resultant joint forces and moments were of great magnitude and short duration. It was concluded that the ankle joint moments place a large tensile load on the Achilles tendon. Dynamic knee joint loads appear to load the anterior cruciate ligament, however, the joint capsule and musculature surrounding the knee undoubtedly play a significant role in the attenuation of the impact force. Loads were greatly reduced at the level of the hip joint.;Two male and three female elite gymnasts performed double back somersaults. Ground reaction force data for each foot were acquired from two Kistler force platforms interfaced to two Apple IIe computers. All performances were filmed at 100 fps using a Photosonics high speed 16mm camera. Subjects' performances were self-paced and the number of trials was comparable to a typical practice session. |
