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Richard C. Nelson

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Richard C. Nelson

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Edited by Richard C. Nelson

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Edited by Richard C. Nelson

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Edited by Richard C. Nelson

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Patrick Kennedy, Peter Brown, Somadeepti N. Chengalur and Richard C. Nelson

The performance of male and female swimmers (N = 397) competing in the preliminary heats of the four 100-meter swimming events during the Seoul Olympic Games was videotaped and later analyzed to determine stroke rate (SR) and stroke length (SL). These data were combined with age, height, and final time (FT) values for statistical analyses which included the relationships among these variables, comparison of male and female performance, and assessment of differences in the four events. The results revealed the following ranges of correlations between SR and SL (rs from −0.65 to −0.90), SL and FT (rs from −0.32 to −0.80), height and SL (0.19 to 0.58), and age and FT (-0.16 to −.051). The factor of SL was identified as the dominant feature of successful swimming performance. The men were older and taller, had longer stroke lengths and higher stroke rates (two of four events), and swam faster than the women. The differences in final times across the four events (freestyle fastest, breaststroke slowest) were due to specific combinations of SR and SL, with neither parameter being consistently dominant.

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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.

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Richard C. Nelson, Ted S. Gross and Glenn M. Street

The purpose of this report was to provide a model analysis of biomechanical films taken during the women's gymnastic vaulting events of the 1984 Los Angeles Olympic Games. Although a majority of the optional vaults were filmed, only the 16 vaults performed by the competitors in the individual championships were examined. The analysis included calculations of temporal, spatial, and velocity parameters as the gymnast's center of mass moved through four phases of the vault. The phases were identified as Reuther board contact, prehorse flight, horse contact, and posthorse flight. A representative profile of a female gymnast competing in the Games was compiled based on these parameters. This profile indicated that the gymnasts were much smaller than the average population, efficient in the use of the Reuther board and the horse to reach and maintain CM velocities necessary to complete the vault, and agile enough to perform complex airborne rotations during an average posthorse flight duration of .80s.

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Gerald A. Smith, Jill McNitt-Gray and Richard C. Nelson

Cross-country ski technique is undergoing rapid evolution. Alternate stride skating was the dominant technique during the 1985–86 racing season (double poling is synchronized with the “strong” side skate; no poling occurs with the “weak” side skate). High-speed films were made of elite male racers at the Holmenkollen World Cup races, Oslo, Norway (March 1986), skating up a 7° hill. Digitized data were filtered and processed to determine three-dimensional coordinates throughout a complete skating cycle. Ten skiers were analyzed, representing a range of performances. Over the 10-km race length, cycle rates for all skiers were similar; however, cycle lengths were significantly related to cycle velocity. The correlation between cycle velocity and length was r = 0.85. Ski angles were found to be asymmetrical. Weak-side ski angles were negatively related to cycle velocity; strong-side ski angles were similar for all skiers. Center of mass (CM) position throughout the cycle exhibited characteristic differences between faster and slower skiers. CM velocity vector direction was related to cycle velocity. Thus, faster skiers tended to maintain CM motion more nearly aligned with the forward direction.

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Doris I. Miller, Ewald Hennig, Marc A. Pizzimenti, Ian C. Jones and Richard C. Nelson

Reaction forces elicited from the 10-m platform by the 29 male and 26 female competitors in the Fifth World Diving Championships during the takeoffs for dives from the back group were analyzed and related to their patterns of motion. Major changes in linear and angular momentum occurred during the final period of upward acceleration. During this “final weighting” phase, maximum vertical reactions of 3.0 to 4.0 times body weight (BW) and maximum horizontal reactions in the “propulsive” direction of 0.5 BW were recorded. Further, the moment of vertical platform reaction with respect to the center of gravity, which was dominant and promoted backward rotation, was opposed by the moment of the horizontal component. At final contact with the platform, higher vertical velocities were more evident for back dives than multiple back somersaults, and for dives performed in tuck than in pike, and in pike than in straight positions.