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Nathan J. Crockett and Michelle A. Sandrey

Context:

Few studies have evaluated the long-term effects of prophylactic ankle-brace use during a sport season.

Objective:

To determine the effects of prophylactic ankle-brace use during a high school basketball season on dynamic postural control and functional tests.

Design:

Prospective repeated-measures design.

Setting:

High school athletic facility.

Participants:

21 healthy high school basketball athletes (13 girls, 8 boys).

Interventions:

The order of testing was randomized using the Star Excursion Balance Test (SEBT) for posteromedial (PM), medial (M), and anteromedial (AM) directions and 3 functional tests (FT) consisting of the single-leg crossover hop, single-leg vertical jump, and the single-leg 6-m hop for time at pre-, mid-, and postseason. After pretesting, the ankle brace was worn on both limbs during the entire 16-wk competitive basketball season.

Main Outcome Measures:

SEBT for PM, M, and AM and 3 single-leg FTs.

Results:

Dynamic postural control using the SEBT and the 3 FTs improved over time, notably from pretest to posttest. The left limb was different from the right limb during the single-leg vertical jump. Effect sizes were large for pretest to posttest for the 3 SEBT directions and 2 of the 3 FTs.

Conclusions:

The 16-wk basketball prophylactic ankle-brace intervention significantly improved dynamic postural control and single-limb FTs over time.

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James C. Radcliffe and Louis R. Osternig

Seventy subjects were tested for (a) percent body weight controlled (lowered and raised) by the lower extremities via parallel squat exercise, (b) maximum vertical jump-reach, and (c) maximal depth jump-reach from six heights ranging from 0.30 to 1.05 m. The results suggest that maximum parallel squat performance represents a small proportion (8%) of the variance contributing to controlling increasing depth jump heights and that specific improvement in jumping performance may be achieved by relatively small amplitude prestretch movements rather than large depth jump heights. The implications of the present findings for the use of depth jumping in conditioning and rehabilitative protocols are that (a) extreme care must be exercised in selecting jump heights, as there is considerable variability in individual tolerance to a given height, and (b) depth jumping should be contraindicated in cases where high impulse loads can disrupt healing tissue and, if it is used in postinjury situations, should be reserved for the end phase of rehabilitation.

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Isaac Selva Raj, Stephen R. Bird, Ben A. Westfold and Anthony J. Shield

Reliable measures of muscle strength and functional capacity in older adults are essential. The aim of this study was to determine whether coefficients of variation (CVs) of individuals obtained at the first session can infer repeatability of performance in a subsequent session. Forty-eight healthy older adults (mean age 68.6 ± 6.1 years; age range 60–80 years) completed two assessment sessions, and on each occasion undertook: dynamometry for isometric and isokinetic quadriceps strength, 6 meter fast walk (6MFWT), timed up and go (TUG), stair climb and descent, and vertical jump. Significant linear relationships were observed between CVs in session 1 and the percentage difference between sessions 1 and 2 for torque at 60, 120, 240 and 360°/s, 6MFWT, TUG, stair climb, and stair descent. The results of this study could be used to establish criteria for determining an acceptably reliable performance in strength and functional tests.

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John E. Kovaleski, Robert J. Heitman, Damon P.S. Andrew, Larry R. Gurchiek and Albert W. Pearsall IV

Context:

Isokinetic strength and functional performance are used to assess recovery after rehabilitation. It is not known whether low-speed closed-linear-kinetic isokinetic muscle strength correlates with functional performance.

Objective:

To investigate the relationship between linear closed (CKC) and open (OKC) concentric isokinetic strength of the dominant lower-limb extensors and functional performance.

Design:

Correlational analysis.

Setting:

University laboratory.

Participants:

Thirty uninjured men and women (age = 20.9 ± 2.4 years).

Main Outcome Measures:

Peak CKC and OKC isokinetic strength and best score from a shuttle run for time, single-leg vertical jump, and single-leg hop for distance.

Results:

Neither lower-limb CKC nor OKC isokinetic strength measured at low speeds correlated highly with performance on the functional tasks of jumping, hopping, and speed/agility.

Conclusions:

Although the basis of both closed and open isokinetic strength must be appreciated, they should not be the only determinants of functional performance.

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Robert C. Weber and JoAnne Thorpe

The purpose of the study was to determine whether the technique of task variation with maintenance tasks interspersed is more effective than a constant task condition in a physical education setting in learning gross motor skills for severely disabled individuals. The subjects for the study included 28 males, 12 autistic and 16 severely mentally retarded students, ages 10 to 14 years. The design for this study was a pretest-posttest configuration with the I Can Assessment of Gross Motor Skills utilized to assess the basic skills of overhand throw, kick, vertical jump, slide, continuous bounce, and underhand roll. Results indicated that following a 6-week treatment period the task variation with maintenance tasks interspersed condition was significantly more effective at the .01 level in learning gross motor skills than a constant task condition. However, when autistic and severely mentally retarded individuals were compared, there were no significant differences.

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Jennifer M. Medina McKeon, Craig R. Denegar and Jay Hertel

The purpose of this study was to formulate a predictive equation to discriminate males from females using static and dynamic lower extremity (LE) alignments. Twenty-four healthy adults volunteered to participate. Three-dimensional motion analysis was used to assess the kinematics of the right hip and knee during two functional tasks. Six measures of static LE alignment were also performed. Statistical comparisons were made between males and females for all variables. Static and dynamic variables that were significantly different by sex were entered into separate discriminant analyses for each task. The resulting equations were each able to correctly predict 87% of the subjects by sex. Fifty-eight percent and 55% of the variance was explained by sex for the vertical jump and plant & jump, respectively. The frontal plane hip angle was the best predictor of sex for both tasks. While there were statistically significant differences between the sexes for static measures of LE alignment, kinematic measures were better at discriminating between sexes.

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Kensaku Suei, Leslie McGillis, Randy Calvert and Oded Bar-Or

We assess relationships among muscle endurance, strength, and explosiveness in forty-eight 9.6- to 17.0-year-old males divided into 3 maturational groups (Tanner Stages I, II-IV, and V). Peak torque during isometric knee extension and flexion was averaged to reflect strength. Mechanical power in the Sargent vertical jump was taken as explosiveness, and total work in the Wingate test reflected muscle endurance. Correlations (3 groups combined) among the variables, expressed in absolute terms, were r = .82 to .92, but only -.11 to .70 when expressed per body mass or lean thigh size. These correlations were distinctly lower in the Tanner V boys than in the 2 less-mature groups, which may suggest that specialization into discrete muscle performance characteristics does not occur before late puberty.

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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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Kevin R. Ford, Gregory D. Myer, Laura C. Schmitt, Timothy L. Uhl and Timothy E. Hewett

The purpose of this study was to identify alterations in preparatory muscle activation patterns across different drop heights in female athletes. Sixteen female high school volleyball players performed the drop vertical jump from three different drop heights. Surface electromyography of the quadriceps and hamstrings were collected during the movement trials. As the drop height increased, muscle activation of the quadriceps during preparatory phase also increased (p < .05). However, the hamstrings activation showed no similar increases relative to drop height. Female athletes appear to preferentially rely on increased quadriceps activation, without an increase in hamstrings activation, with increased plyometric intensity. The resultant decreased activation ratio of the hamstrings relative to quadriceps before landing may represent altered dynamic knee stability and may contribute to the increased risk of ACL injury in female athletes.

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Michael R. Bracko and Gilbert W. Fellingham

Fifty-four female and 77 male hockey players ranging in age from 10–15 years volunteered for this study. Demographic data included: age (AGE) and years of playing experience (YPE). Off-ice tests included: height (HGT), body mass (BM), lean body mass (LBM), predicted body fat % (FAT%), 40-yard dash (40YD), vertical jump (VJ), push-ups/min (PUPS), sit-ups/min (SUPS), and sit-and-reach flexibility (S&R). On-ice performance skating tests included: acceleration (ACC), agility (AGL), and speed (SPD). On-ice anaerobic power (AnPow) was calculated using the formula of Watson and Sargeant (IS). Generally speaking, the females and males in this study had similar results in office fitness. The males consistently out-performed the females in the on-ice tests. It would be difficult for females to compete with or against same-aged males based on the fact that males are superior skaters.