MULTIFACTORIAL ANALYSIS OF SHOOTING ARCHERY

Abstract

In archery shooting there is a fixed sequence of movements the shooter performs bow holding, drawing, full draw, aiming, release and follow through stage This sequence allows the archer to get highly reproducible releases for achieving and maintaining good results. This implies the following: I ) the programming of the proper movement sequence during the different phases, 2) the control of body segments action; 3) the body and bow equilibrium maintenance. In such a complex motor task which involves multijoint coordination, a distinctive feature of the motor system is maximally exploited, namely the potential to execute the same motor task through different combination of motor equivalent actions. It was the purpose of this study the identification of the various strategies utilised by a group of different skilled archers and the evaluation of the role that skill has in movement execution This requires a simultaneous investigation of different kinds of variables, including kinematics, forces and EMG. Twelve archers of Italian Archery Federation were the subjects of this study. According to their FITA scores they were classified as intermediate (n = 7: FlTA scores ranging from 1180 to 1300) and high level archers (n = 5; FlTA scores > 1300). Twenty shoots for each archer were recorded and analysed. Electromiographic (EMG), kinematics and force platfor~n data were acqu~red and processed using the ELITE motion analysis system An electrical device attached to the bow was used to detect the moment of clicker closure, arrow release, and contact-loss of the arrow with the bowstring Surface EMG was collected from the finger flexor muscles and brachial biceps of the drawing arm, and from upper and lower back muscles, with a sampling rate of 1000 Hz Markers were placed on. the temporal bone and the mandibular joint to mark the head; shoulders, elbows, wrists and hands to mark the arms; iliac crests, knees, ankles, and third metatarsal heads to mark the lower limbs. In addition, three markers were placed on the backbone and other three were attached to the bow. Ground reaction forces and centre of pressure displacements were measured with a Kistler force platform at a sampling rate of 1000 Hz. Despite-the apparent intra and intersubject similarities in performing the shoots. slight differences were observed in both kinematics and EMG pattern. Results indicate that while there are common elements that are present in all subjects, strategies .vary in some ways that can be attributed to the skill and in others that may not attributed to the skill For example, the ways to come to full drawing position as well as EMG activity appear to be idiosyncratic, as each subject showed a unique configuration Among the disparities that may attributed to the skill. differences in the relative duration of the shooting phases, in arm and bow stability, and degree of activation of biceps brachial seem to be the most relevant.