This study analysed rotational angles and load trajectories in the standing position during hip joint rotation movement, and evaluated dynamic postural control ability based on data obtained using the newly devised Gyro-Medimator. This device comprising a pair of disc-type measuring instruments, with a rotational disc on top of a stabilometer, and is able to simultaneously obtain data on body rotational angles at the lower extremities and the load trajectory. The standard posture was set as the standing position with eyes open, knee and hip joints extended, legs slightly apart (37cm distance between the two disc centres), and upper limbs hanging downward. Trajectory data of each leg were obtained during maximum internal and external rotation movements of the hip joint, repeated 15 times over 30 seconds. Load trajectory diagrams were categorized into horizontal, rotational, and vertical types, which were further characterized in detailed analyses. The ability to control dynamic posture of the legs and pelvis could be detected from the shape of the trajectory, visually and objectively. These results suggest the possibilities of what could be achieved by using this new device, such as the ability to evaluate functional differentiation of the lower limbs and the impact of fatigue.

In sports, anxiety often leads to the poor motor performance of athletes and players. Verbal instructions by coaches help athletes succeed in performing motor routines in relaxed situations, while they may adversely affect their behaviours in anxious situations. For athletes with increased anxiety, avoidant instructions may cause performance breakdown, particularly towards counter-intentional directions. To date, counter-intentional errors caused by avoidant instructions have been studied within the framework of either Wegner’s ironic process theory (1994) or Eysenck’s attentional control theory (2007). However, very few studies have measured and assessed relevant cognitive functions to examine why or how avoidant instructions elicit counter-intentional errors. Here, we propose the hypothesis that attentional bias to threat-related stimuli interacts with avoidant instructions in anxious situations, consequently eliciting counter-intentional errors. A possible experimental paradigm for testing this hypothesis is also discussed.