Swimming Form Analysis of Competitive Freestyle

Abstract

An underwater camera trucking system was developed to analyze swimming forms. Freestyle swimming forms were compared between a world top ranking swimmer with I-shaped pull stroke, a drug type pull stroke and a skillful swimmer with S-shaped pull stroke. The side views of the two swimming forms were analyzed in a two dimensional wireframe. In the catch and pull phase, the I-shaped pull swimmer moved the arm along the side of the body with the lead lag motion with the arm bent so that the elbow moved almost parallel to the water surface. The S-shaped pull swimmer moved the arm with the rotating motion around the shoulder with the arm straighten. In a stroke period of time, the former had a longer time ratio to generate thrust force and a shorter recovery time than the latter. It means that the I-shaped pull swimmer spent longer time to generate thrust force. In the comparison result of posture aspect ratio, the value of the former is higher because of the smaller vertical value due to the arm bent at the elbow. The rectangular wireframe of the I-shaped pull swimmer is thinner than that of the other.