INTRODUCTION: A large amount of knee extensor strength is often cited as a requirement for alpine ski racing success. Takashi et al. (1992) found that eccentric knee extension and flexion strength may be related to racing success in national caliber athletes. In contrast, Neumayr et al. (2003) found no correlation between muscle strength and racing performance in world class athletes. Few studies have examined these types of relationships in recreational athletes. The current study examined the relationship of isometric strength of the knee extensors and anthropometric measures to success in recreational alpine ski racing. METHOD: Twenty subjects (7 male, 13 female) were selected from an open-entry citizen-type alpine ski race. Age (Mean = 25.6 ± 13.4 y), height (168.8 ± 7.2 cm) and weight were obtained for all of the subjects (72.4 ± 12.3 kg). Ski racing ability was determined using the race times from a 25 gate citizen slalom race. Segment length for the dominant leg was obtained using a flexible steel tape following palpation. The shank of the leg was measured from the lateral malleolus to the head of the fibula. The upper leg was defined as the lateral epicondyle to the greater trochanter. Knee joint flexibility was determined with a manual goniometer. The subject stood upright with the anterior surfaces of both legs against a vertical surface, from which each knee was independently flexed as far as possible and knee angle was measured using the greater trochanter and lateral malleolus as alignment landmarks. Peak isometric knee extension torque was measured at 90 degrees of flexion. The subjects were seated on a bench with an adjustable cuff secured 10 cm below the tibial tuberosity on their dominant leg. This cuff was securely fastened by cable to an OR6-7-2000 (AMTI, Watertown, MA) force platform located behind the subject. The subject's non-restrained leg was also at 90 degrees with the foot resting on the floor. The subjects pushed against the cuff by extending their knee with maximum effort for a period of 5 sec. Data was collected from the force platform and analyzed using Biosoft 1.0. (AMTI, Watertown, MA). RESULTS AND DISCUSSION: Correlational analysis (SPSS v 11.5) indicated that only subject height was correlated to ski racing time (r = -.561, p < 0.01). Isometric knee extensor strength, knee flexibitity, and anthropometric variables were not significant (p > 0.05). Re-sampling cross-validation techniques (Jensen and Kline, 1994) used data from 16 randomly chosen subjects. The remaining data were used to cross-validate the regression equation. Height was the first variable entering the equation in 17 of 20 samples with mean multiple r = 0.65 ± 0.12. Left knee flexibility, sex, and knee strength entered the equation first one time each. In recreational alpine ski racing height seems to be an advantage, in contrast to the findings of Piper et al (1987). Taller athletes may be able to put more leverage on the ski, causing them to turn faster. However, isometric knee extension strength was not a factor. Moreover gender, which was also related to height, was not a factor in racing performance. CONCLUSION: The major finding of this study was the inability to correlate isometric knee extension strength to racing time in recreational alpine skiers. However, subject height was related to racing time and could be used to predict racing time.
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