THE NEED FOR MEASUREMENT OF TRUNK FLEXION

Abstract

The purpose of this study was to examine the problem related to the undulating variant in breaststroke. In most of the video-analysis systems that are available, the trunk is represented as one straight line, namely from shoulder to hip, instead of dividing the trunk into segments. The objective of this article is to determine the point at which a straight trunk is obtained in the analysis. However, an explanation can be found in the very low swimming velocity variation. Interpretation of the data is made in three critical phases. During the second part of the arm compression phase, the body is not cambered but 'broken. As a result, the upper trunk cannot decelerate to any degree, above the water surface and conversely, water cannot be accelerated behind the lower trunk. Consequently, in order to level off the velocity variation, during the first part of the recovery, water cannot push against the back; and during the propulsion phase of the legs, no forward transfer of momentum from the upper trunk can be expected.