Experimental evidence of a strategy for a beat swing prior to a kip.
Throughout a beat swinging motion prior to a kip the gymnast changes the relative orientation of his legs and head-torso with respect to his arms. It was observed that if these changes occurred in a correct order he could rapidly increase his swing with his limited strength. If changes in orientation of the body parts did not take place in a correct phase, the person would immediately begin to lose any height gained. Previous measurements of the filmed motion of a gymnast performing this motion and his anthropometric dimension and were used to compute from the Dempster-Hanavan model the gymnast's center-of-mass (CM) and polar moment-of-inertia (I) at each instant throughout the maneuver. A simple mechanical model should be able to reproduce the time history of the CM. This model provides some insight into what might be required to increase one's swing. From filmed motion of "good" and "bad" beat swings leading to a kip and this simple model a simple strategy was devised. Graphs are presented which show that the simple strategy is related to the gymnast's radius-of-gyration. The simple strategy is only for the swinging motion. It was concluded that the strategy of the final, small segment of the kip was not the same as that during the swinging segment but a complex one of largely utilizing the accumulated angular momentum.
D000886:Anthropometry; D001696:Biomechanical Phenomena; D006173:Gymnastics; D006801:Humans; D008297:Male; D009068:Movement; D013997:Time Factors