PURPOSE This study aimed to verify the accuracy of three-dimensional (3D) motion data produced through artificial intelligence-based user motion recognition technology with images obtained using a smartphone monocular camera. This was done to explore the possibility of developing an application that can improve the reliability of the measurement of physical activity performing motions and feedback provision. METHODS To check the accuracy of the artificial intelligence-based 3D motion analysis system that utilized a semi-supervised learning method, a commercialized 3D infrared motion analysis system measured and compared motions on three movement planes, motions with limited joint movement, and fast motions in a wide moving range. RESULTS The motions on the coronal and sagittal planes produced through the 3D motion analysis application showed very high measurement accuracy; however, the accuracy of the measurement of motions on the horizontal plane, which could not be measured directly with a camera, was relatively lower than that of the coronal and sagittal planes. Accuracy in measuring 3D motion was moderate in moving motions and low in motions with limited joint movement. CONCLUSIONS For the developed 3D motion analysis system to be used in online physical education, the types of physical activities included in the program should be comprehensively composed through the analysis of the content system of the physical education curriculum and the resultant physical activities.
PURPOSE The purpose of this study is to examine the goalkeeper’s area of defense and how the range varies depending on the relative position of the goal, goalkeeper, and ball in a 9-meter jump shot during handball matches. METHODS Data was collected from seven qualifying divisions in mens handball from the 99th National Sports Festival in Korea. A total of 231, 9-meter jump shots were analyzed with the goalkeeper‘s area of defense measured from the point the ball left the shooter’s hand and calculated based on the relative position of the goal, goalkeeper, and ball. Video analysis was conducted using the Kwon3D 3.01 program and three-dimensional coordinates calculated using the DLT method. RESULTS First, dimension of handball goals measure 3m wide and 2m high, however, results show that goalkeeper’s actual area of defense was narrower than the width of the goal posts, while vertically, area exceeded the height of the cross bar. Second, if the goalkeeper defended the striker’s shot from the side rather than from the front, the goalkeeper’s defense range was higher for the opposite side of the goal post than the near side of the goal post. CONCLUSIONS Key factors influencing goalkeeper’s area of defense include height of shot and position of goalkeeper. Results also indicate that vertical movements are more important than horizontal movements for goalkeepers in handball thus such implementation in training may lead to performance enhancement.
