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Rodney Negrete and Jay Brophy

Objectives:

To determine (1) correlations between isokinetic lower extremity strength and functional performance and (2) correlations among different modes of isokinetic testing.

Design and Setting:

A correlational design with 6 measures. A series of strength, power, and agility tests was performed at a hospital-based outpatient physical therapy clinic.

Participants:

A volunteer sample of 29 male and 31 female, college-age subjects participated.

Measurements:

All subjects were tested in the following isokinetic tests: reciprocal leg press, single-leg squat, and knee extension. Performance tests included single-leg hop and vertical jump and a speed/agility test.

Results:

Analysis showed isokinetic knee extension, leg press, and single-leg squat strength significantly correlated to all functional tests. There were significant correlations among the 3 different isokinetic strength measures, as well.

Conclusions:

These results suggest a significant relationship between lower extremity open and closed chain isokinetic strength and functional performance testing.

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Anni Rava, Anu Pihlak, Jaan Ereline, Helena Gapeyeva, Tatjana Kums, Priit Purge, Jaak Jürimäe and Mati Pääsuke

The purpose of this study was to evaluate the differences in body composition, neuromuscular performance, and mobility in healthy, regularly exercising and inactive older women, and examine the relationship between skeletal muscle indices and mobility. Overall, 32 healthy older women participated. They were divided into groups according to their physical activity history as regularly exercising (n = 22) and inactive (n = 10) women. Body composition, hand grip strength, leg extensor muscle strength, rapid force development, power output, and mobility indices were assessed. Regularly exercising women had lower fat mass and higher values for leg extensor muscle strength and muscle quality, and also for mobility. Leg extensor muscle strength and power output during vertical jumping and appendicular lean mass per unit of body mass were associated with mobility in healthy older women. It was concluded that long-term regular exercising may have beneficial effects on body composition and physical function in older women.

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Ivan Vrbik, Goran Sporiš, Lovro Štefan, Dejan Madić, Nebojša Trajković, Irena Valantine and Zoran Milanović

Purpose:

The number of familiarization sessions in fitness assessments seems to be critical and inconsistent. Therefore, the primary aim of this research was to determine the number of familiarization attempts that stabilize the results in particular physical fitness tests. The secondary aim was to establish the test reliability through familiarization sessions.

Methods:

Thirty-nine primary school children participated in this research (age: 10.8 years, body mass: 40.6 ± 8.9 kg, and body height: 145.3 ± 7.2 cm). During six sessions, with one session every third day, participants performed the following tests to assess explosive strength (vertical jump and standing long jump), coordination (polygon backward and polygon with turn) and flexibility (toe touch).

Results:

The results of repeated analysis of variance (ANOVA) showed that there were significant increases (p < .05) in the polygon backward and polygon with turn performances from the first to third familiarization session. The standard error of measurement decreased as sessions progressed, indicating little within subject variation between the coordination test results following a familiarization period. Statistically significant differences were identified in the vertical jump test from the fourth test session compared with the first session. On the other hand, statistically significant differences for the standing long jump test were only found in the final session compared with the initial session. In the toe touch test, there were no significant increases from the first to the final familiarization session. All tests showed high a reliability coefficients, ranging from 0.979 to 0.991.

Conclusion:

Polygon backward and polygon with turn performance may be a practical, reliable method to assess coordination in primary school-aged children. However, completion of at least 3 practice sessions is suggested for participants to obtain a stable score. In addition, both jump tests are feasible for assessing skill-related fitness in young children, although the scientific reliability of the two tests should be questioned and the tests should be tailored to fit the age group of the children.

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Rebecca A. Skillen, Massimo Testa, Elizabeth A. Applegate, Eric A. Heiden, Andrea J. Fascetti and Gretchen A. Casazza

This study examined the effect of amino acids in a carbohydrate beverage on cycling performance. Twelve male athletes (28.5 pp2.1 yr) cycled at 75% VO2peak for 90 min followed by a ride to exhaustion at 85% VO2peak, before (T1) and on 2 consecutive days (T2 and T3) after 2 weeks of supplementation with 3.6% carbohydrate plus 1% amino acids (AA) or 4.6% carbohydrate-only (CHO) isocaloric beverages. Muscle damage was assessed by plasma creatine kinase (CK), and muscle fatigue by changes in vertical jump pre- to postexercise. Muscle soreness, overall fatigue, and changes in mood state were assessed using questionnaires. Plasma CK was lower for AA in T3 (214.0 ss13.5 vs. 485.9 11191.4 U/L immediately post, 213.9 ÷ 13.1 vs. 492.0 ÷ 199.4 U/L 5 hr post, and 194.9 ÷ 17.9 vs. 405.9 ÷ 166.6 U/L 24 hr postexercise in AA and CHO, respectively). Time to exhaustion decreased from T2 to T3 only in CHO (10.9 ÷ 2.5 to 12.6 ÷ 3.2 vs. 13.8 ÷ 2.8 to 7.8 ÷ 1.5 min in AA and CHO, respectively). Vertical-jump change from pre- to postexercise was greater in T3 for the CHO treatment. Total fatigue score and mood disturbance decreased significantly only with AA in T3. The addition of AA to a carbohydrate beverage after consecutive-day exercise bouts reduced muscle damage as indicated by CK levels, decreased fatigue, and maintained exercise performance compared with consuming carbohydrate alone.

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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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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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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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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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Niell G. Elvin, Alex A. Elvin, Steven P. Arnoczky and Michael R. Torry

Impact forces and shock deceleration during jumping and running have been associated with various knee injury etiologies. This study investigates the influence of jump height and knee contact angle on peak ground reaction force and segment axial accelerations. Ground reaction force, segment axial acceleration, and knee angles were measured for 6 male subjects during vertical jumping. A simple spring-mass model is used to predict the landing stiffness at impact as a function of (1) jump height, (2) peak impact force, (3) peak tibial axial acceleration, (4) peak thigh axial acceleration, and (5) peak trunk axial acceleration. Using a nonlinear least square fit, a strong (r = 0.86) and significant (p ≤ 0.05) correlation was found between knee contact angle and stiffness calculated using the peak impact force and jump height. The same model also showed that the correlation was strong (r = 0.81) and significant (p ≤ 0.05) between knee contact angle and stiffness calculated from the peak trunk axial accelerations. The correlation was weaker for the peak thigh (r = 0.71) and tibial (r = 0.45) axial accelerations. Using the peak force but neglecting jump height in the model, produces significantly worse correlation (r = 0.58). It was concluded that knee contact angle significantly influences both peak ground reaction forces and segment accelerations. However, owing to the nonlinear relationship, peak forces and segment accelerations change more rapidly at smaller knee flexion angles (i.e., close to full extension) than at greater knee flexion angles.