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Julie A. Siegmund, Kellie C. Huxel and C. Buz Swanik

Context:

Determining whether there are compensations in those with jumper’s knee (JK) might further our understanding of the condition.

Objective:

Comparing lower extremity kinematics and jump performance of basketball athletes with JK with those of healthy controls (C).

Design:

Repeated-measures control-match design.

Setting:

University laboratory.

Participants:

24 male basketball players (12 JK, 12 C) matched by height, weight, position, experience, and frequency of play.

Interventions:

Standing countermovement and running layup jumps.

Main Outcome Measures:

Maximum vertical-jump height, footfall landing, and lower extremity sagittal-plane kinematics.

Results:

There were no significant group differences (P > .05) in vertical-jump height (JK = 64.3 ± 8.6 cm, C = 63.0 ± 9.8 cm) or layup height (JK = 71.3 ± 11.6 cm, C = 73.3 ± 11.0 cm). JK subjects landed flat footed (50%) more than controls (8%). JK subjects showed significantly more hip flexion (JK = 105° ± 24.8°, C = 89.8° ± 14.1°; P = .039) with decreased hip acceleration during the countermovement (JK = −3039 ± 1392°/s2, C = −4229 ± 1765°/s2; P = .040). When landing from the countermovement jump, JK subjects had significantly less knee acceleration (JK = −4960 ± 1512°/s2, C = −6736 ± 2009°/s2; P = 023) and in the layup showed significantly less ankle dorsiflexion (JK = 106.5° ± 9.0°, C = 112.5° ± 7.7°; P = .048) and hip acceleration (JK = − 2841 ± 1094°/s2, C = −3912 ± 1575°/s2; P = .033).

Conclusion:

Compensatory strategies observed in JK subjects might help maintain performance, because their jump height was similar to that of healthy controls.

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Tyler J. Kirby, Jeffrey M. McBride, Tracie L. Haines and Andrea M. Dayne

The purpose of this investigation was to determine the relationship between relative net vertical impulse and jump height in a countermovement jump and static jump performed to varying squat depths. Ten college-aged males with 2 years of jumping experience participated in this investigation (age: 23.3 ± 1.5 years; height: 176.7 ± 4.5 cm; body mass: 84.4 ± 10.1 kg). Subjects performed a series of static jumps and countermovement jumps in a randomized fashion to a depth of 0.15, 0.30, 0.45, 0.60, and 0.75 m and a self-selected depth (static jump depth = 0.38 ± 0.08 m, countermovement jump depth = 0.49 ± 0.06 m). During the concentric phase of each jump, peak force, peak velocity, peak power, jump height, and net vertical impulse were recorded and analyzed. Net vertical impulse was divided by body mass to produce relative net vertical impulse. Increasing squat depth corresponded to a decrease in peak force and an increase in jump height and relative net vertical impulse for both static jump and countermovement jump. Across all depths, relative net vertical impulse was statistically significantly correlated to jump height in the static jump (r = .9337, p < .0001, power = 1.000) and countermovement jump (r = .925, p < .0001, power = 1.000). Across all depths, peak force was negatively correlated to jump height in the static jump (r = –0.3947, p = .0018, power = 0.8831) and countermovement jump (r = –0.4080, p = .0012, power = 0.9050). These results indicate that relative net vertical impulse can be used to assess vertical jump performance, regardless of initial squat depth, and that peak force may not be the best measure to assess vertical jump performance.

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Oliver Gonzalo-Skok, Julio Tous-Fajardo, Carlos Valero-Campo, César Berzosa, Ana Vanessa Bataller, José Luis Arjol-Serrano, Gerard Moras and Alberto Mendez-Villanueva

Purpose:

To analyze the effects of 2 different eccentric-overload training (EOT) programs, using a rotational conical pulley, on functional performance in team-sport players. A traditional movement paradigm (ie, squat) including several sets of 1 bilateral and vertical movement was compared with a novel paradigm including a different exercise in each set of unilateral and multi-directional movements.

Methods:

Forty-eight amateur or semiprofessional team-sport players were randomly assigned to an EOT program including either the same bilateral vertical (CBV, n = 24) movement (squat) or different unilateral multidirectional (VUMD, n = 24) movements. Training programs consisted of 6 sets of 1 exercise (CBV) or 1 set of 6 exercises (VUMD) × 6–10 repetitions with 3 min of passive recovery between sets and exercises, biweekly for 8 wk. Functional-performance assessment included several change-of-direction (COD) tests, a 25-m linear-sprint test, unilateral multidirectional jumping tests (ie, lateral, horizontal, and vertical), and a bilateral vertical-jump test.

Results:

Within-group analysis showed substantial improvements in all tests in both groups, with VUMD showing more robust adaptations in pooled COD tests and lateral/horizontal jumping, whereas the opposite occurred in CBV respecting linear sprinting and vertical jumping. Between-groups analyses showed substantially better results in lateral jumps (ES = 0.21), left-leg horizontal jump (ES = 0.35), and 10-m COD with right leg (ES = 0.42) in VUMD than in CBV. In contrast, left-leg countermovement jump (ES = 0.26) was possibly better in CBV than in VUMD.

Conclusions:

Eight weeks of EOT induced substantial improvements in functional-performance tests, although the force-vector application may play a key role to develop different and specific functional adaptations.

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Dean G. Higham, David B. Pyne, Judith M. Anson and Anthony Eddy

Although the characteristics of 15-a-side rugby union players have been well defined, there is little information on rugby sevens players.

Purpose:

The authors profiled the anthropometric, physiological, and performance qualities of elite-level rugby sevens players and quantified relationships between these characteristics.

Methods:

Eighteen male international rugby sevens players undertook anthropometric (body mass, height, sum of 7 skinfolds, lean-mass index), acceleration and speed (40-m sprint), muscle-power (vertical jump), repeatedsprint- ability (6 × 30-m sprint), and endurance (Yo-Yo Intermittent Recovery test and treadmill VO2max) testing. Associations between measurements were assessed by correlation analysis.

Results:

Rugby sevens players had anthropometric characteristics (body mass 89.7 ± 7.6 kg, height 1.83 ± 0.06 m, sum of 7 skinfolds 52.2 ± 11.5 mm; mean ± SD) similar to those of backs in international 15-player rugby union. Acceleration and speed (40-m sprint 5.11 ± 0.15 s), muscle-power (vertical jump 66 ± 7 cm), and endurance (VO2max 53.8 ± 3.4 mL · kg−1 · min−1 ) qualities were similar to, or better than, those of professional 15-a-side players. Coefficients of variation ranged from 2.5% to 22%. Relative VO2max was largely correlated with Yo-Yo distance (r = .60, .21−.82; 90% confidence interval) and moderately correlated with 40-m sprint time (r = −.46, −.75 to −.02) and repeated-sprint ability (r = −.38, −.72 to .09).

Conclusions:

International rugby sevens players require highly developed speed, power, and endurance to tolerate the demands of competition. The small between-athletes variability of characteristics in rugby sevens players highlights the need for relatively uniform physical and performance standards in contrast with 15-a-side players.

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Joanne E. Richards, Timothy R. Ackland and Bruce C. Elliott

Thirty-seven females, aged initially between 10 and 13.5 years, completed a mixed longitudinal study over 3.3 years to investigate the effect of training volume and growth upon gymnastic performance. Gymnasts undergoing high volume training (mean = 30 hrs/week: Group 1) and moderate volume training (mean = 15 hrs/week: Group 2) were tested at 4-month intervals on growth measures including height, mass, skinfolds, and segment lengths, as well as the strength of lower limb, upper limb, and trunk musculature. Functional gymnastic development was observed through the assessment of generic, whole body rotation tasks, a vertical jump, and a v-sit action. The high training volume gymnasts were significantly smaller but markedly stronger than those gymnasts in Group 2 despite the size disadvantage. Consequently, Group 1 gymnasts were able to produce higher velocities for front and backward rotations and a faster v-sit action. These training group differences remained significant after initial size differences were taken into account via an analysis of covariance.

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Senshi Fukashiro, Dean C. Hay and Akinori Nagano

This paper reviews the research findings regarding the force and length changes of the muscle-tendon complex during dynamic human movements, especially those using ultrasonography and computer simulation. The use of ultrasonography demonstrated that the tendinous structures of the muscle-tendon complex are compliant enough to influence the biomechanical behavior (length change, shortening velocity, and so on) of fascicles substantially. It was discussed that the fascicles are a force generator rather than a work generator; the tendinous structures function not only as an energy re-distributor but also as a power amplifier, and the interaction between fascicles and tendinous structures is essential for generating higher joint power outputs during the late pushoff phase in human vertical jumping. This phenomenon could be explained based on the force-length/velocity relationships of each element (contractile and series elastic elements) in the muscle-tendon complex during movements. Through computer simulation using a Hill-type muscle-tendon complex model, the benefit of making a countermovement was examined in relation to the compliance of the muscle-tendon complex and the length ratio between the contractile and series elastic elements. Also, the integral roles of the series elastic element were simulated in a cyclic human heel-raise exercise. It was suggested that the storage and reutilization of elastic energy by the tendinous structures play an important role in enhancing work output and movement efficiency in many sorts of human movements.

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Jason D. Vescovi, Teena M. Murray and Jaci L. VanHeest

Purpose:

The primary purpose of this study was to determine whether positional profiling is possible for elite ice hockey players by examining anthropometric characteristics and physiological performance. In addition, performance ranges and percentiles were determined for each position (forwards, defensemen, and goalkeepers) on all dependent variables.

Methods:

A retrospective, cross-sectional study design was used with performance data from ice hockey players (mean age = 18.0 ± 0.6 years) attending the 2001 (n = 74), 2002 (n = 84), and 2003 (n = 92) Combines. Four anthropometric characteristics and 12 performance tests were the dependent variables. A 3 × 3 (position × year) 2-way ANOVA was used to determine whether any significant interactions were present. No significant interactions were observed, so the data were collapsed over the 3-year period and positional characteristics were analyzed using a 1-way ANOVA.

Results:

Defenders were heavier and/or taller compared with the other 2 positions (P ≤ .01), whereas goalkeepers showed greater body-fat percentage compared with that of forwards (P = .001). It was found that goalkeepers had significantly lower strength measures for the upper body (P ≤ .043) and lower anaerobic capacity (P ≤ .039) values compared with at least one other position, but they had greater flexibility (P ≤ .013). No positional differences were observed for the broad jump, vertical jump, aerobic power, or curl-ups.

Conclusion:

The current findings provide evidence supporting the use of anthropometric measurements, upper body strength, and anaerobic capacity to effectively distinguish among positions for elite-level ice hockey players.

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Konstantinos Tambalis, Demosthenes Panagiotakos, Giannis Arnaoutis and Labros Sidossis

We aimed to model endurance, explosive power, and muscle strength in relation to body mass index (BMI) and physical-fitness tests in Greek children aged 7–10 years old. In the present large epidemiological study, anthropometric measurements and physical-fitness tests (i.e., multistage shuttle run, vertical jump, standing long jump, small ball throw and 30-m sprint) from 141,169 children were analyzed. Age- and sex-specific normative values for physical fitness tests were expressed as tabulated percentiles using the LMS statistical method. The correlation coefficients between BMI and performances were negative and significant for both sexes (p < .01) in all physical-fitness tests. The only exception was a positive correlation between ball throw and BMI (p < .01). Only 2.9% and 4.0% of boys and girls respectively, passed the upper quartiles in all tests. The performance in speed may serve as a predictive factor explaining, at least in part, the performance in aerobic endurance and explosive power in children aged 7–10 years. The presented population-based data for physical-fitness tests revealed that only a small percentage of these children are in the upper quartiles in all tests. Furthermore, the data suggests that speed performance can be used to predict physical fitness.

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Avery D. Faigenbaum, James E. McFarland, Neil A. Kelly, Nicholas A. Ratamess, Jie Kang and Jay R. Hoffman

The purpose of this study was to examine the influence of recovery time following a dynamic warm-up (DY) and a static stretch warm-up (SS) on power performance in adolescent athletes. Following baseline measures, 19 males (16.5 ± 1.1 yrs) performed the vertical jump (VJ) and seated medicine ball toss (MB) at the following time points after DY and SS: 2, 6, 10, 14, 18, 22 min. Analysis of variance revealed that VJ was significantly greater following DY than SS at 2, 6, 10, 14 and 18 min. Main effects indicated a significant increase in VJ from baseline at 2 and 6 min following DY (2.6–3.9%) and a significant decrease in VJ from baseline at 2, 6, 10, 14 and 18 min following SS (–3.2% to –7.0%). No significant interaction effects between DY and SS were observed for MB. These findings indicate that lower body power performance in male adolescent athletes can be enhanced following DY as compared with SS during the first 18 min of the post warm-up period.

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Nuttaset Manimmanakorn, Jenny J. Ross, Apiwan Manimmanakorn, Samuel J.E. Lucas and Michael J. Hamlin

Purpose:

To compare whole-body vibration (WBV) with traditional recovery protocols after a high-intensity training bout.

Methods:

In a randomized crossover study, 16 athletes performed 6 × 30-s Wingate sprints before completing either an active recovery (10 min of cycling and stretching) or WBV for 10 min in a series of exercises on a vibration platform. Muscle hemodynamics (assessed via near-infrared spectroscopy) were measured before and during exercise and into the 10-min recovery period. Blood lactate concentration, vertical jump, quadriceps strength, flexibility, rating of perceived exertion (RPE), muscle soreness, and performance during a single 30-s Wingate test were assessed at baseline and 30 and 60 min postexercise. A subset of participants (n = 6) completed a 3rd identical trial (1 wk later) using a passive 10-min recovery period (sitting).

Results:

There were no clear effects between the recovery protocols for blood lactate concentration, quadriceps strength, jump height, flexibility, RPE, muscle soreness, or single Wingate performance across all measured recovery time points. However, the WBV recovery protocol substantially increased the tissue-oxygenation index compared with the active (11.2% ± 2.4% [mean ± 95% CI], effect size [ES] = 3.1, and –7.3% ± 4.1%, ES = –2.1 for the 10 min postexercise and postrecovery, respectively) and passive recovery conditions (4.1% ± 2.2%, ES = 1.3, 10 min postexercise only).

Conclusion:

Although WBV during recovery increased muscle oxygenation, it had little effect in improving subsequent performance compared with a normal active recovery.