Samenvatting

Being able to perform a press handstand is required to progress to more difficult techniques on almost every apparatus. Therefore it is recommended to learn this skill at an early age. The press handstand requires a combination of high strength, flexibility and motor skills all of which are valued abilities. This study was performed to help gymnasts and coaches alike to provide insight in the press handstand motion, to be able to learn the movement by visualizing which skill, or skills, could be improved to be able to perform a press handstand. Previous research on the subject suggests the required torque decreasing as flexibility increases. Biomechanical equations support these claims. This raises the question “what is the influence of active hip abduction on the anteflexion torque required in the shoulder to perform the press handstand?”.
To provide an answer to the question at hand a kinematic model recreating the movement has been constructed based on human static anthropometry retrieved from literature and joint angles obtained from video footage of press handstands. This resulted in an equation to describe the required anteflecting shoulder torque in relation to the hip abduction during the press handstand:
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This equation was validated using EMG and video footage from four gymnasts performing five press handstands each. The recorded EMG signal was converted to torques using results from an MVC test to determine the maximal force generated by the shoulder anteflecting musculature measured on the trapezoid muscle and anthropometric properties of each subject. This resulted in establishing that the model in its current form is not valid (r = -0.35, p = 0.12).
Further investigation of the video footage has provided insights as to why this result came about; firstly it became apparent that of the four gymnasts used in the validation, two specific techniques of performing a press handstand have been used, whilst one gymnast was able to switch between techniques at will. During the construction of the model the variance of techniques has not been taken into account. Further research is needed in this field to be able to modify the model accordingly.
The number of gymnasts used in validating the model is a restriction of its own. Only 24.5% of the possible range of hip abduction angles has been used. With this number of people and limited use of the available abduction angles any outliers will have great effect on the validity of the model.
Finally and importantly there is no way to determine whether the torque calculated from the EMG results from the static position of the body segments or the angular acceleration of limbs. Whilst creating the model the angular acceleration has been ignored as in gymnastics it is preferred to perform a press handstand slowly.
The model, invalid in its current stage, suggests a decrease in required anteflecting shoulder torque when the gymnasts’ hip abduction increases. Additional research in the field of techniques used during the press handstand is required to provide answer to the question whether and how active hip abduction influences the anteflexion torque required in the shoulder to perform the press handstand