All Spun Out - Limits of aerial techniques when performing somersaults

The somersault is a key skill in gymnastics and diving. Almost all the rotation required must be performed while the athlete is airborne; whilst airborne the athlete’s angular momentum is constant. The postures chosen, and any postural change that occurs while airborne, will determine the rotation achieved by the athlete. Equations are derived that describe the possible rotational states in terms of the somersault and twist rotation, thereby determining which rotational states are possible and useful for performing somersaults and twisting somersaults. Equations describing the results of idealised postural changes intended to initiate twist in a somersault are also derived. Inertial property data was both collated from the literature and estimated from measurements of current athletes. The data thus represented a range of ‘possible athletes’ which were applied to the derived equations of motion to predict which skills are achievable using different postures and actions. Recommendations were made as to the ‘best’ twist initiation actions and postures to use for different somersault skills. For twisting somersaults it was shown that previously published aerial techniques, and slight variations of these, are inadequate to allow the majority of athletes to achieve the highest numbers of twists per somersault observed in current international competition. It was concluded that contact twist or aerial techniques yet to be mathematically described must be used. Based on the predictions of skills achievable it was clear that some athletes have a natural advantage over others. Further, it was found that the postures or techniques which were the ‘best’ for one athlete were not necessarily the ‘best’ for all athletes. Differences in predicted skill achievement and which posture or technique was most suitable varied with the gender and squad (related to age and years of training) but these categories did not explain all of the variation