It is difficult to ascertain for an individual high jumper the optimum values of the horizontal velocity and height of the center of mass at the end of the approach ran (VHO and H0, respectively) and of the activeness of the arms during the takeoff phase (AACT), because they depend on each athlete’s ability to resist buckling of the takeoff leg. However, the strongest jumpers will generally be those with the largest vertical elocity values at the end of the takeoff phase (VZ1). Therefore, VZ1 may serve as a rough indicator of a high jumper’s ability to resist buckling. This project derived equations that permit the use of the measured VZ1 value of a high jumper to predict what values should be expected for VHO, H0, and AACT. Comparison of the predicted and actual values of these parameters should help to diagnose the technique deficiencies of individual jumpers.
Jesús Dapena, Craig McDonald and Jane Cappaert
Raul Arellano, Peter Brown, Jane Cappaert and Richard C. Nelson
The performances of 335 male and female swimmers competing in 50-, 100-, and 200-m freestyle events at the 1992 Barcelona Olympic Games were videotaped and analyzed to determine stroke length (SL), stroke rate (SR), starting time (ST), turning times (TI = turn in, TO = turn out), finishing (end) time (ET), and average velocity (AV); relationships were then determined among these variables in addition to height, weight, age, and final time (FT). Differences were subsequently assessed within and among the events, and comparisons were made between male and female performances. ST, TI, TO, ET, and SL were identified as principal components of successful swimming performance at each distance. Results revealed statistically significant correlations between factors for all events. The men were older and taller; possessed longer stroke lengths; and started, turned, and swam faster than the women. As the race distance increased from 50 to 200 m, ST, TI, TO, SL, and ET increased for both men and women, while age, SR, and AV decreased.
Ross H. Sanders, Jane M. Cappaert and David L. Pease
The purpose of this study was to investigate the wave characteristics of breaststroke swimming. Particular emphasis was accorded the question of whether modern breast-stroke is "flylike" (referring to the butterfly stroke) and whether "waves" travel along the body during the breaststroke cycle. Selected body landmarks and the center of mass (CM) of 8 Olympic breaststroke swimmers were quantified. Fourier analysis was conducted to determine the amplitude, frequency composition, and phase characteristics of the vertical undulations of the vertex of the head, shoulders, hips, knees, and ankles. The differences in phase between these landmarks for the first (HI) and second (H2) Fourier frequencies were investigated to establish whether body waves traveled in a caudal direction. While the motion of the upper body was somewhat flylike, the velocity of the HI wave from the hips to ankles was variable among subjects and, for all subjects, was too slow to be propulsive. Contrary to what one would expect, the range of vertical motion of the CM was inversely related to the range of hip vertical motion. The two highest placing subjects, based on preliminary heat times (SI and S4), were distinguished by a large range of hip vertical motion and a small range of CM vertical motion.
Jane M. Cappaert, David L. Pease and John P. Troup
Twelve male 100-m freestyle swimmers were videotaped during the 1992 Olympic Games. Four cameras, two above water and two below, recorded the same stroke cycle of the swimmer at approximately the 40- to 45-m mark. The whole body and the recovering arms were digitized from the videotapes to recreate a complete stroke cycle. Body position variables and hand reaction forces (Schleihauf, 1979) were calculated. Swimmers were divided into elite and subelite groups based on their swimming velocity and were compared for differences in biomechanical variables. Elites used slightly lower hand forces while maintaining a higher propelling efficiency. Subelites had opposite rotations about the longitudinal axis of the body rather than symmetrical body roll. The elite swimmers were different from subelites in that their pulling patterns were more efficient and their body position was more streamlined. These variables assisted them in achieving faster swimming velocities without requiring higher propulsive forces.
Sergei V. Kolmogorov, Olga A. Rumyantseva, Brian J. Gordon and Jane M. Cappaert
The purpose of this study was to describe the hydrodynamic characteristics of the four strokes by gender and performance level. Active drag during maximal swimming was measured in each of the four swimming strokes (freestyle, butterfly, backstroke, and breaststroke) on males and females of varying ability levels using the perturbation method developed by Kolmogorov and Duplisheva (1992). Active drag (FDa), the hydrodynamic coefficient (Cx Da), and total external mechanical power output (Pto) were calculated at each swimmer's maximal swimming velocity. There were complex, nonlinear relationships between maximum swimming velocity and the three hydrodynamic indicators. The four swimming strokes were ranked in order of resistance based on the three hydrodynamic indicators. The order, from least to most resistance, was (1) freestyle, (2) backstroke, butterfly, (3) breaststroke. No statistical difference was seen between the backstroke and butterfly. Within each stroke, the most important factor for reducing active drag appeared to be individual biomechanical technique.