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Walter L. Jenkins, Dorsey Shelton Williams, Alex Durland, Brandon Adams and Kevin O’Brien

The use of foot orthoses has been evaluated during a variety of functional activities. Twelve college-aged active females wore two types of foot orthoses and performed a vertical jump to determine the biomechanical effect of the orthoses on lower extremity transverse plane movement during landing. Data collection included three-dimensional analysis of the tibia, knee, and hip. A repeated-measures ANOVA was performed to determine the differences between no orthoses, over-the-counter, and custom-made orthoses with transverse plane motion. At the hip joint, there was significantly less internal rotation (p < .05) in the over-the-counter condition as compared with the no orthoses condition. There was significantly less tibial internal rotation (p < .05) in the custom-made condition as compared with no orthoses. Over-the-counter devices decreased transverse plane motion at the hip, whereas custom-made devices decreased transverse plane motion of the tibia.

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Kevin M. Carroll, Jake R. Bernards, Caleb D. Bazyler, Christopher B. Taber, Charles A. Stuart, Brad H. DeWeese, Kimitake Sato and Michael H. Stone

load, vertical jump, and maximal strength in well-trained lifters. We hypothesized that the greater variations in training intensity and attention to fatigue management in RI SR would result in superior performance changes compared with RM training. Methods Subjects Fifteen well-trained males

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Christopher Thomas, Paul Comfort, Paul A. Jones and Thomas Dos’Santos

Purpose:

To investigate the relationships between maximal isometric strength, vertical jump (VJ), sprint speed, and change-of-direction speed (CoDS) in academy netball players and determine whether players who have high performance in isometric strength testing would demonstrate superior performance in VJ, sprint speed, and CoDS measures.

Method:

Twenty-six young female netball players (age 16.1 ± 1.2 y, height 173.9 ± 5.7 cm, body mass 66.0 ± 7.2 kg) from a regional netball academy performed isometric midthigh pull (IMTP), squat jumps (SJs), countermovement jumps (CMJs), 10-m sprints, and CoDS (505).

Results:

IMTP measures displayed moderate to strong correlations with sprint and CoDS performance (r = –.41 to –.66). The VJs, which included SJs and CMJs, demonstrated strong correlations with 10-m sprint times (r = –.60 to –.65; P < .01) and CoDS (r = –.60 to –.71; P = .01). Stronger players displayed significantly faster sprint (ES = 1.1–1.2) and CoDS times (ES = 1.2–1.7) and greater VJ height (ES = 0.9–1.0) than weaker players.

Conclusion:

The results of this study illustrate the importance of developing high levels of lower-body strength to enhance VJ, sprint, and CoDS performance in youth netball players, with stronger athletes demonstrating superior VJ, sprint, and CoDS performances.

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Vassilis Gerodimos, Andreas Zafeiridis, Stefanos Perkos, Konstantina Dipla, Vassiliki Manou and Spiros Kellis

This study examined from childhood to adulthood: (1) the effects of countermovement (use of stretch-shortening cycle-SSC) and arm-swing (AS) on vertical jumping (VJ) performance and (2) the ability to use the SSC and AS during VJ. Male basketball players (n = 106) were divided according to their age into: children (12.0 ± 0.23), young adolescents (14.5 ± 0.41), old adolescents (16.9 ± 0.27), and adults (21.9 ± 0.32). Each participant executed three maximal squat jumps (SJ), countermovement jumps without arms (CMJ) and with arms (CMJA). The contribution of SSC and AS was calculated by the augmentation (difference and percent change) in performance between CMJ and SJ, and CMJA and CMJ, respectively. CMJA performance was significantly (p < .05) higher than CMJ and SJ, and CMJ was higher than SJ within all age-groups. There were no significant differences (p > .05) among children, young and old adolescents, and adults in the percent contribution of SSC and AS to VJ performance. The variability in the contribution of SSC and AS to VJ performance was about twofold higher in children vs. adults. It appears that the ability to use the SSC and AS is not affected by the maturation process in males, trained in basketball.

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Dimitrios Challoumas and Andreas Artemiou

overhead movement that requires both power and skill and consists of the following phases: windup, cocking, acceleration, deceleration, and follow-through. 3 , 4 Two of the most important factors determining the success of a spike are thought to be the magnitude of the vertical jump (vertical jump height

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Filip Sabol, Jozo Grgic and Pavle Mikulic

test of upper-body performance) but not the vertical jump height (a test of lower-body performance). By contrast, Martinez et al 4 reported that a caffeine-containing preworkout supplement did not enhance performance in the medicine ball throw test and the vertical jump test. The caffeine dose in the

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Sara L. Arena, Kelsey McLaughlin, Anh-Dung Nguyen, James M. Smoliga and Kevin R. Ford

Athletic individuals may differ in body segment inertial parameter (BSIP) estimates due to differences in body composition, and this may influence calculation of joint kinetics. The purposes of this study were to (1) compare BSIPs predicted by the method introduced by de Leva1 with DXA-derived BSIPs in collegiate female soccer players, and (2) examine the effects of these BSIP estimation methods on joint moment and power calculations during a drop vertical jump (DVJ). Twenty female NCAA Division I soccer players were recruited. BSIPs of the shank and thigh (mass, COM location, and radius of gyration) were determined using de Leva’s method and analysis of whole-body DXA scans. These estimates were used to determine peak knee joint moments and power during the DVJ. Compared with DXA, de Leva’s method located the COM more distally in the shank (P = .008) and more proximally in the thigh (P < .001), and the radius of gyration of the thigh to be further from the thigh COM (P < .001). All knee joint moment and power measures were similar between methods. These findings suggest that BSIP estimation may vary between methods, but the impact on joint moment calculations during a dynamic task is negligible.

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Khalid S. Almuzaini

The first purpose of the present study was to test sensitivity of the Wingate anaerobic test (WAnT) to alterations in resistance settings. The second purpose was to investigate whether using optimal braking force on WAnT enhances its relation with a 50-m dash, a vertical jump (VJ), or a standing long jump (LJ) tests. Twenty-three 12 year-old boys performed a 50-m dash, VJ, LJ, and WAnT using four braking force resistances (BFR; .065, .070, .075, and .080 kp/kg BM). Results revealed significant (p ≤ .05) differences among the four BFRs in peak power (PP) and in mean power (MP). Post hoc tests indicated significant differences among all of the four BFRs in PP and between the 0.065 and both the 0.075 and the 0.08 kp/kg BM in MP. Results of Pearson correlation coefficients indicated that using the optimal BFR for both PP and MP enhanced their relation with performance during the 50-m dash, VJ, and LJ tests. Also, partial correlation coefficients, controlling for body weight, height, percent fat, or body mass index supported these findings. It was concluded that for untrained, healthy 12-year-old boys, WAnT is sensitive to incremental alterations in resistance settings ranging from 0.065 to 0.080 kp/kg body mass. To be more specific, PP is sensitive to small increments in BFR, while MP is only sensitive to larger increments in BFR. Furthermore, optimizing resistance settings on WAnT enhances its relationship with anaerobic performance tasks, such as the 50-m dash, the VJ, and the LJ.

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Sergej M. Ostojic

The purpose of this study was to examine the effects of acute creatine-monohydrate supplementation on soccer-specific performance in young soccer players. Twenty young male soccer players (16.6 ± 1.9 years) participated in the study and were matched and allocated to 2 randomly assigned trials: ingesting creatine-monohydrate supplement (3 × 10-g doses) or placebo for 7 days. Before and after the supplementation protocol, each subject underwent a series of soccer-specific skill tests: dribble test, sprint-power test, endurance test, and vertical jump test. Specific dribble test times improved significantly in the creatine group (13.0 ± 1.5 vs. 10.2 ± 1.8 s; p < .05) after supplementation protocol. Sprint-power test times were significantly improved after creatine-monohydrate supplementation (2.7 ± 0.4 vs. 2.2 ± 0.5 s; p < .05) as well as vertical jump height (49.2 ± 5.9 vs. 55.1 ± 6.3 cm; p < .05) in creatine trial. Furthermore, dribble and power test times, along with vertical jump height, were superior in creatine versus placebo trial (p < .05) at post-supplementation performance. There were no changes in specific endurance test results within or between trials (p > .05). There were no between-trial differences in the placebo trial (p > .05). The main finding of the present study indicates that supplementation with creatine in young soccer players improved soccer-specific skill performance compared with ingestion of placebo.

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Jennifer J. Didier and Vanessa A. West

Edited by Patrick McKeon