Análise cinemática das saídas Grab start e Track start para o nado crawl em nadadores infanto-juvenis

Abstract

This descriptive and comparative study aimed to analyze the kinematics variables of the Grab start and Track start during starting racings to crawl in children and youth swimmers. The sample consisted of 25 swimmers aged between 10 and 15 years. Data collection was performed in a pool of the DEF/UEM. Were used as measuring instruments: registration form three Panasonic digital camcorders, stopwatch, synchronizer for audio and visual starting signal and system for spatial reference calibrator. To gather data, each swimmer performed three rounds of 25 meters in front crawl for each kind of start, and had posted on anatomical points of the body markers retroreflectors. Video images were recorded on MiniDV and edited using the software Pinnacle Studio Plus version 9.4. To analyze the kinematic variables were scored points in a two-dimensional system using the Digital Video for Windows for Biomechanics (Dvideow). The calculations to determine the values of the points identified on the axes "X and Y" were performed in Matlab software for numerical calculations 7.4. The data were treated using nonparametric statistics, Mann-Whitney and Spearman correlation. The variable block time (,000), and flight distance showed statistically significant difference between the grab and track start. Angle of the start from the block was positively correlated with distance and flight time for the grab-start and for track start. It was concluded that the block time is shorter on track start type. The greatest flight distance is achieved from the grab start type. Shorter block times favor smaller start times to a distance of 10 meters and the total up to 25 meters swimming. Swimmers that take off the block with larger angles achieve greater distances and flight times for both types of starts. Greater distances of flight possible shorter times of starts until the first 10 meters of track swim to start.