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Tatiane Gorski, Thomas Rosser, Hans Hoppeler and Michael Vogt

Purpose:

To verify whether relative age effects (RAEs) occur among young male and female Swiss Alpine skiers of different age groups and performance levels. In addition, the efficacy of normalizing performance in physical tests to height and body mass to attenuate RAEs eventually present was tested.

Methods:

The Swiss Ski Power Test consists of anthropometric measures and physical tests for coordination and speed, endurance, and strength and has been used since 2004 to evaluate 11- to 19-y-old Swiss competitive Alpine skiers. The authors analyzed the distribution of 6996 tests performed by 1438 male and 1031 female Alpine skiers between 2004 and 2011 according to the athletes’ respective relative age quartiles. Differences in anthropometric measures and performance in physical tests according to quartile were assessed, and the possibility of attenuating eventual RAEs on performance by normalization of results to height and body mass was tested.

Results:

RAEs were found among all female and male age groups, with no differences between age groups. While performance level did not affect RAE for male skiers, it influenced RAE among female skiers. RAEs also influenced results in all physical tests except upper-limb strength. Normalization of results to body mass attenuated most RAEs identified.

Conclusion:

Small RAEs are present among young Swiss competitive Alpine skiers and should be taken into account in training and selection settings to prevent the waste of possible future talents. When ranking junior athletes according to their performance in physical tests, normalization of results to body mass decreases the bias caused by RAEs.

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Amy Barrette and Katherine Harman

-intensity athletes: a consensus statement . Scand J Med Sci Sports . 2010 ; 20 : 103 – 111 . PubMed ID: 20840568 doi:10.1111/j.1600-0838.2010.01195.x 20840568 10.1111/j.1600-0838.2010.01195.x 2. Curry T . A little pain never hurt anyone: athletic career socialization and the normalization of sports injury

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Alexandra F. DeJong, L. Colby Mangum, Jacob E. Resch and Susan A. Saliba

activity ratios (ARs), calculated from average thickness measures at heel strike (Equation  1 ) normalized to quiet stance (Equation  2 ). 40 In addition, percentage of gluteal muscle thickness change was calculated from quiet stance to average heel strike (Equation  3 ). 40 Average HS = HS 1 + HS 2 + HS

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Richard Robinson and Phillip Gribble

Context:

The Star Excursion Balance Test (SEBT) is composed of 8 reaching directions that are potentially measuring the same functional component, leading to the suggestion that the number of reach directions could be reduced without compromising the assessment of dynamic postural control.

Objective:

To determine whether the relationship of stance-leg angular displacement on normalized reach distance is a source of dynamic-postural-control measurement redundancy.

Design:

Single-session within-subjects design.

Setting:

Athletic training research laboratory.

Participants:

10 women and 10 men.

Interventions:

None.

Main Outcome Measures:

Normalized reach distance and angular displacement at the knee and hip.

Results:

Stepwise regression revealed that hip flexion and knee flexion, separately and in combination, accounted for 62% to 95% of the variance in reach distances.

Conclusion:

Similarity in lower extremity function could account for the previously observed measurement redundancy in the SEBT.

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Phillip A. Gribble, Richard H. Robinson, Jay Hertel and Craig R. Denegar

Context:

Deficits in static postural control related to fatigue have been investigated previously, but there is little evidence to link fatigue to performance measures of dynamic postural control.

Objective:

To investigate the effects of fatigue and gender on performance measures of the Star Excursion Balance Test (SEBT).

Design:

Mixed-model design.

Setting:

Research laboratory.

Participants:

16 healthy young adults.

Intervention:

Subjects performed the SEBT before and after 4 different fatiguing conditions.

Main Outcome Measures:

The normalized reach distances and sagittal-plane kinematics of the knee and hip were recorded.

Results:

Fatigue produced deficits in normalized reach distances and decreased knee flexion in all 3 reaching directions. Overall, women were able to reach farther than men while simultaneously demonstrating a greater amount of knee flexion.

Conclusions:

Gender differences were observed during performance of the SEBT, with women demonstrating greater reach distances and knee flexion, and fatigue amplified these differences.

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Brian P. Self, Anita M. Bagley, Teresa L. Triplett and Lonnie E. Paulos

The Pilates-based reformer is used by dancers for training and for injury rehabilitation. Knee kinematics and applied forces during demi-plié in fifth and in first positions were analyzed while dancers performed the motions (a) standing, (b) on the reformer equipped with two springs, and (c) on the reformer equipped with four springs. The highest forces, normalized to body weight, were obtained for the standing demi-plié, while the largest knee flexion angles occurred on the reformer with four springs. Greater range of motion was achieved in first position than in fifth, and females exhibited greater extension and higher normalized forces than males, It was also noted that force/knee angle relationships for the standing demi-plié and for the reformer tests were quite different. Reformer forces were totally dependent on the knee angle, whereas the forces during the standing demi-plié depended on the acceleration of the dancer's center of gravity.

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Lachlan E. Garrick, Bryce C. Alexander, Anthony G. Schache, Marcus G. Pandy, Kay M. Crossley and Natalie J. Collins

kinematic variables of interest and the external KAM (normalized to body mass) were calculated from the 3 middle trials and averaged for further analyses. Where possible, variables of interest were selected to match the rating criteria utilized to classify single-leg squat performance. 7 Although the ankle

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Jeffrey B. Driban, Nicole Cattano, Easwaran Balasubramanian, Michael R. Sitler, Mamta Amin, Joseph Glutting and Mary F. Barbe

Context: To better understand why a knee develops osteoarthritis after joint trauma we need to assess the local biochemical changes. Unfortunately, it is challenging to obtain synovial fluid from a knee with no effusion. Objective: To describe the authors' protocol for aspirating synovial fluid from noneffused knees. Second, they demonstrate the validity of this method by evaluating the relationships between normalized and raw biomarker concentrations among knees with effusion (undergoing a traditional aspiration) and without effusion (requiring a saline-assisted aspiration). Design: Validation study based on secondary analyses from 2 cohort studies. Setting: Outpatient orthopedic clinic and basic-science laboratory. Participants: Participants had moderate to severe radiographic knee osteoarthritis (n = 15 with and 11 without effusion) and no osteoarthritis or effusion (n = 4). Interventions: The same orthopedic surgeon performed all synovial-fluid joint aspirations, including saline-assisted aspirations. Main Outcome Measures: The authors used multiplex enzyme-linked immunosorbent assays to determine 7 synovial-fluid biomarker concentrations. They then calculated correlations between raw and normalized (to total synovial-fluid protein content) biomarker concentrations. Results: The authors excluded 1 sample collected with a saline-assisted aspiration because it contained blood. Normalized biomarker concentrations had positive associations with raw biomarker concentrations (r = .77-99), with the exception of interleukin-13 and interleukin-1Β among knees that underwent a saline-assisted aspiration. Excluding interleukin-1Β, associations between normalized and raw biomarker concentrations were consistent between knees that had a saline-assisted or traditional aspiration. Conclusions:Saline-assisted aspiration is a valid technique for assessing the local biochemical changes in knees without effusion.

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Maude Bastien, Hélène Moffet, Laurent Bouyer, Marc Perron, Luc J. Hébert and Jean Leblond

The Star Excursion Balance Test (SEBT) has frequently been used to measure motor control and residual functional deficits at different stages of recovery from lateral ankle sprain (LAS) in various populations. However, the validity of the measure used to characterize performance—the maximal reach distance (MRD) measured by visual estimation—is still unknown.

Objectives:

To evaluate the concurrent validity of the MRD in the SEBT estimated visually vs the MRD measured with a 3D motion-capture system and evaluate and compare the discriminant validity of 2 MRD-normalization methods (by height or by lower-limb length) in participants with or without LAS (n = 10 per group).

Results:

There is a high concurrent validity and a good degree of accuracy between the visual estimation measurement and the MRD gold-standard measurement for both groups and under all conditions. The Cohen d ratios between groups and MANOVA products were higher when computed from MRD data normalized by height.

Conclusion:

The results support the concurrent validity of visual estimation of the MRD and the use of the SEBT to evaluate motor control. Moreover, normalization of MRD data by height appears to increase the discriminant validity of this test.

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Taku Wakahara, Hiroaki Kanehisa, Yasuo Kawakami, Tetsuo Fukunaga and Toshimasa Yanai

The purpose of this study was to examine the relationship between muscle architecture of the triceps brachii (TB) and joint performance during concentric elbow extensions. Twenty-two men performed maximal isometric and concentric elbow extensions against various loads. Joint torque and angular velocity during concentric contractions were measured, and joint power was calculated. Muscle length, cross-sectional areas, and volume of TB were measured from magnetic resonance images. Pennation angle (PA) of TB at rest was determined by ultrasonography. The PA was significantly correlated with the maximal isometric torque (r = .471), but not to the torque normalized by muscle volume (r = .312). A significant correlation was found between PA and the angular velocity at 0 kg load (r = .563), even when the angular velocity was normalized by the muscle length (r = .536). The PA was significantly correlated with the maximal joint power (r = .519), but not with the power normalized by muscle volume (r = .393). These results suggest that PA has a positive influence on the muscle shortening velocity during an unloaded movement, but does not have a significant influence on the maximum power generation in untrained men.