An analysis of splits leaps and gymnastic skill by physiological recordings.

The performance of a gymnastic exercise, the splits leap in rhythmic sports gymnastics, was compared with a subjective evaluation by an experienced referee who ranked the gymnasts skill. The execution of the splits leaps was quantified by measuring ground reaction forces, electromyographic activity in the leg muscles and by analyzing film. The referees evaluation of the splits leaps was found to depend on minimal bending in the knee joint of the take-off leg at touch-down and during the support phase. Maximal flexion in the knee joint was inversely correlated (r = -0.53, p less than 0.0002) with the ranking of the leap. The vertical component of the ground reaction force had a maximal amplitude of about 1900 N, equal to 3.5 times the force produced by the body weight of the gymnast. The record was smooth and without inflections in the highly ranked gymnasts, whereas the other gymnasts had one or two inflections in the rising phase of the vertical force record. Electromyographic activity in both the medial head of gastrocnemius and tibialis anterior began before touch-down. The pattern consisted of periods of activity with pauses in between. There was no correlation between rank and electromyographic pattern, but "talented" gymnasts had shorter periods of activity and longer pauses between the periods of activity.