Stroke Analysis During A Maximal Swimming Speed Test in Children And Adults

Abstract

Propulsion is one of the central issues in front crawl swimming regarding the process of stroke analysis. The dynamic relationship between stroke frequency, stroke length and the study of swimming speed, have been extensively used to characterize the competitive swimming technique and its efficiency. While stroke rate is generally related to fat mass; final velocity and resistive forces have been associated to body length and body surface area. There is still little information about differences in swimming performance between children and adults related to stroke characteristics. PURPOSE: To examine the contribution of stroke frequency, stroke length, stroke index and total distance, on swimming performance, during a maximal speed test in children and adults from different swimming groups. METHODS: We studied 32 male swimmers, 23 children 9 to 13 years old and 9 adults 18 to 23 years of age. Subjects were measured by weight and height. Swimmers performed a maximal 15m front crawl swim test in two series (S). S1: 15m-lap only with the arms (legs supported) and S2: 15m-lap front crawl (with both arms and legs). Time was recorded for S1 (arm-pulling maximal time) and S2 (front crawl maximal time). We obtained front crawl speed (V), stroke frequency, stroke length, stroke index (velocity multiplied by stroke length) and total distance (stroke frequency multiplied by stroke length). Groups were made according to S2 time. Group A (n=1 3) included children who completed S2 in less than 12s, group B (n=10) was made with the rest of children and group C (n=9) with adults. Descriptive statistics, one-way ANOVA and backward regression analysis at a p < 0.05 significance level were used. RESULTS: Age, weight and height were similar in A and B children groups and lower than in adults (p < 0.01). Adults were faster than A and B groups in S1 (9.81 ± 0.45 vs 11.73 ±1.10 and 14.34 ± 1.40s, p < 0.01) and S2 (9.02 ± 0.47 vs 10.72 ± 1.01 and 13.23 ± 0.76s, p < 0.01). V (m/s) was higher in adults (1.67 ± 0.08 vs 1.41 ±0.14 and 1.14 ± 0.06, p < 0.01). Stroke index (SIDX) and total distance (TD) were higher in C than in AandB swimmers (1.55 ± 0.18, 0.94 ±.20, 0.70 ± 0.07 for SIDX and 50.05 ± 2.60, 42.26 ±4.17, 34.25 ± 1.81 for TD, respectively, p < 0.001). Only TD and S1 showed a significant relationship with the front crawl maximal time score during the test, in all subjects (coefficients −0.172 and 0.321, respectively, R=0.994, R2= 0.989, p < 0.001). This correlation was also significant when the analysis was made by A, B and C groups (R = 0.995, 0.998 and 0.997, p < 0.001). CONCLUSIONS: Total distance seems to be the best predictor of swimming performance in this subjects, while stroke index and the rest of variables were not significant.