AVERAGE RESUlTANT IMPULSE PER PHASE IN SWIMMING: A TOOl FOR TECHNICAl ANALYSIS

  • F. Alves

Abstract

INTRODUCTION-Averaged impulses resulting from the difference between propulsion and body drag (ARI) can be calculated in each phase of a stroke cycle, providing us with information about the technical proficiency of the swimmer. Due to the instrumental difficulty in assessing total body centre of gravity displacement in swimming, the study of the hip joint point kinematics has been considered as an acceptable approach (Costill et al., 1987). The purpose of this study was to investigate the relationship between ARI, calculated from hip point kinematics, swimming economy and competitive performance. METHODS-Twelve well-trained male swimmers participated in this study (age: 17.75k1.82 years, height: 178.46k6.07 cm, body mass: 67.63k6.59 kg, and %FAT: 7.63k2.02). Each subject was filmed underwater (sagital plane) with a fixed video camera (60 Hz) and data was evaluated by a video analysing system. Identification of each of the three phases of the underwater hand path in fron! crawl, the downsweep (DS), the insweep (IS), and the upsweeptexit (USIE) and in backstroke, the initial downsweep (IDS), the upsweep (US), and the final downsweep (FDS), was made from the underwater hand path. Swimmers were splited into two groups according to the results of a swimming economy profile test. Competitive performance was assessed by best race times obtained within a period of two weeks. RESULTS-ARI variation per phase for the whole group is shown in the figure. In front crawl, best time in the 100m race was positively correlated with ARI in the DS (0.586, p