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Yi Wang, Wing K. Lam, Charis K. Wong, Lok Y. Park, Mohammad F. Tan and Aaron K.L. Leung

This study examined the effect of foot orthoses used on ground reaction forces, ankle, and knee kinematics when running at preferred and nonpreferred speeds. Sixteen runners ran on instrumented treadmills at various speeds (90%, 100%, and 110% of preferred speed) when wearing arch-support and flat-control orthoses. Two-way repeated analysis of variance (ANOVA) was performed on the mean and coefficient of variation of all variables. Results indicated that arch-support orthoses experienced larger maximum loading rates than flat-control orthoses (P = .017, 95% CI, 2.22 to 19.53). Slower speed was related to smaller loading rates (preferred: P = .002, 95% CI, −17.02 to −4.20; faster: P = .003, 95% CI, −29.78 to −6.17), shorter stride length (preferred: P < .001, 95% CI, −0.204 to −0.090; faster: P < .001, 95% CI, −0.382 to −0.237), and longer contact time (preferred: P < .001, 95% CI, 0.006–0.021; faster: 95% CI, 0.012–0.042). In arch-support condition, preferred speed induced higher stride length coefficient of variation (P = .046, 95% CI, 0.035–1.117) than faster speed, while displaying no differences in flat-control condition. These findings suggest that the use of arch-support orthoses would influence impact loading, but not spatial-temporal and joint kinematics in recreational runners.

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Iván Peña-González, Alba Roldan, Carlos Toledo, Tomás Urbán and Raúl Reina

Purpose: This study aimed (1) to explore the validity and reliability of a new and specific change-of-direction (COD) test that requires dribbling skills to classify international footballers with cerebral palsy (CP) and compare it with another valid and reliable COD test without ball dribbling and (2) to probe whether both tests can discriminate between the new CP football classes (ie, FT1, FT2, and FT3) established worldwide in 2018. Methods: This study involved 180 international para-footballers with CP from 23 national teams at the 3 regional competitions held in 2018. They performed 2 COD tests, the modified agility test (no dribbling skills) and the dribbling speed test (DST). Results: Reliability was excellent for both the modified agility test (intraclass correlation coefficient [ICC]2,1 = .91, SEM = 5.75%) and the DST (ICC2,1 = .92, SEM = 4.66%). The modified agility test and DST results were highly to very highly correlated to one another for the whole group and considering the sport classes (r = .60–.80; P < .001). A 1-way analysis of variance showed significant differences between sport classes in both tests (P < .001). However, among classes, there were significant differences between FT1 and FT2 and FT3 (P < .01, effect size = large) and low to moderate effect sizes between FT2 and FT3 for either test. Conclusion: The DST appears to be valid and reliable to classify CP football players within the new classification system. Regression analysis revealed that 18.2% of the variance in the new sport classes could be explained by the 2 examined tests.

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Thomas A. Haugen, Felix Breitschädel, Håvard Wiig and Stephen Seiler

Purpose: To quantify possible differences in countermovement jump height across sport disciplines and sex in national-team athletes. Methods: In this cross-sectional study, 588 women (23 [5] y, 66 [8] kg) and 989 men (23 [5] y, 82 [12] kg) from 44 different sport disciplines (including 299 medalists from European Championships, World Championships, and/or Olympic Games) tested a countermovement jump on a force platform at the Norwegian Olympic Training Center between 1995 and 2018. Results: Athletic sprinting showed the highest values among the men (62.7 [4.8] cm) and women (48.4 [6.0] cm), clearly ahead of the long jump/triple jump (mean difference ± 90% CL: 6.5 ± 5.0 and 4.3  ± 4.1; very likely and likely; moderate) and speed skating sprint (11.4 ± 3.1 and 7.5 ± 5.5 cm; most likely and very likely; very large and moderate). These horizontally oriented sports displayed superior results compared with more vertically oriented and powerful sports such as beach volleyball, weightlifting, and ski jumping, both in men (from 2.9 ± 4.7 to 15.6 ± 2.9 cm; small to very large; possibly to most likely) and women (5.9 ± 4.8 to 13.4 ± 3.4 cm; large to very large; very likely to most likely), while endurance sports and precision sports were at the other end of the scale. Overall, the men jumped 33% higher than the women (10.3, ±0.6 cm; most likely; large). Conclusions: This study provides practitioners and scientists with useful information regarding the variation in countermovement jump height among national-team athletes within and across sport disciplines.