抄録
The aim of the present study was to investigate the differences in kinematics between two types of motor strategy for expert dart throwing. We divided eight experts into two groups based on the motor strategies they had demonstrated in a previous study (Nasu et al., 2014): group A were experts who had a longer time window in which a release could result in hitting the bull's eye, and group B were experts who had a shorter time window but greatly reduced their timing error. Each subject performed 60 dart throws, aiming at the center of the dart board (bull's eye). The movement of the dart, index finger, and joint motion of the upper extremity were captured using a motion capture system with 7 cameras (480 Hz, Oqus300, Qualysis Inc.). We compared the shape of the hand trajectory and joint kinematics between the groups. We found that experts in group A demonstrated a smaller shoulder angle (lower elbow height) and a larger angle of elbow flexion through forward swing than those in group B. These differences affected the time window that led to a successful throw, i.e. the time for which the mutually complementary relationship among the release parameters (especially the relationship between velocity and direction of motion) was maintained. These results may be useful as basic data to help clarify how throwing accuracy can be improved in several sports.
