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Pazit Levinger, Wendy Gilleard and Cliff Coleman

Use of a shank shell has been shown to estimate tibial transverse rotations better than skin-mounted markers. However, the day-to-day reliability of the transverse tibial rotations using an individually molded shank shell has not been previously investigated. This study examined the between-tests and trials reliability of an individually molded shank shell for measuring peak tibial internal and external rotations, time of peak values, and tibia range of motion during 5 walking trials. The trial-to-trial reliability of tibial transverse rotations was measured in 14 healthy individuals while the test-retest reliability was measured in 10 persons on two occasions. Trial-to-trial reliability for peak transverse rotations, time of peak values, and tibia range of motion ranged from ICC (3,1) 0.59–0.95. The PCA between trials showed that 88–99% of values were within 3° of agreement. Test-retest reliability for peak rotations, tibia range of motion, and time of peak values ranged from ICC (3,1) 0.70–0.89 with SEM 1.6–2.21°, 0.021%, and 0.034%, respectively. The PCA between tests showed that 70–100% of values were within 3° of agreement. The use of an individually molded shell and the close attachment of the shank shell to the individual's shank resulted in reliable test-retest and trial-to-trial data.

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Chia-Wei Lin, Cheng-Feng Lin, Bih-Jen Hsue and Fong-Chin Su

The purpose of the current study was to evaluate the postural stability of singleleg standing on the retiré position in ballet dancers having three different levels of skill. Nine superior experienced female ballet dancers, 9 experienced, and 12 novice dancers performed single-leg standing in the retiré position. The parameters of center of pressure (COP) in the anterior-posterior and medial-lateral directions and the maximum distance between COP and the center of mass (COM) were measured. The inclination angles of body segments (head, torso, and supporting leg) in the frontal plane were also calculated. The findings showed that the novice dancers had a trend of greater torso inclination angles than the experienced dancers but that the superior experienced dancers had greater maximum COM-COP distance in the anterior-posterior direction. Furthermore, both experienced and novice dancers had better balance when standing on the nondominant leg, whereas the superior experienced dancers had similar postural stability between legs. Based on the findings, ballet training should put equal focus on both legs and frontal plane control (medial-lateral direction) should be integrated to ballet training program.

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Marie A. Johanson, Brian J. Cuda, Jonathan E. Koontz, Julia C. Stell and Thomas A. Abelew

Context:

Stretching exercises are commonly prescribed for patients and healthy individuals with limited extensibility of the gastrocnemius muscle.

Objective:

To determine effects of gastrocnemius stretching on ankle dorsiflexion, knee extension, and gastrocnemius muscle activity during gait.

Design:

Randomized-control trial.

Setting:

Biomechanical laboratory.

Participants:

Sixteen volunteers (9 men and 7 women, mean age = 27 y) with less than 5° of passive ankle-dorsiflexion range of motion randomly assigned to an experimental or control group.

Intervention:

The experimental group performed gastrocnemius stretching for 3 wk.

Main Outcome Measures:

Maximum ankle dorsiflexion, maximum knee extension, and EMG amplitude of the gastrocnemius muscles were measured between heel strike and heel-off before and after intervention.

Results:

No significant effect of group or time was found on maximum ankle dorsiflexion, maximum knee extension, or EMG activity of the medial or lateral gastrocnemius muscles between heel strike and heel-off. The experimental group had significantly greater passive ankle-dorsiflexion range of motion bilaterally at posttest than the control group.

Conclusions:

Stretching did not alter joint angles or gastrocnemius muscle activity in the early to midstance phase of gait.

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Daniel J. Petit, John D. Willson and Joaquin A. Barrios

Efforts to compare different surface marker configurations in 3-dimensional motion analysis are warranted as more complex and custom marker sets become more common. At the knee, different markers can been used to represent the proximal shank. Often, two anatomical markers are placed over the femoral condyles, with their midpoint defining both the distal thigh and proximal shank segment ends. However, two additional markers placed over the tibial plateaus have been used to define the proximal shank end. For this experiment, simultaneous data for both proximal shank configurations were independently collected at two separate laboratories by different investigators, with one laboratory capturing a walking population and the other a running population. Common discrete knee joint variables were then compared between marker sets in each population. Using the augmented marker set, peak knee flexion after weight acceptance was less (1.2−1.7°, P < .02) and peak knee adduction was greater (0.7−1.4°, P < .001) in both data sets. Similarly, the calculated peak knee flexion moment was less by 15–20% and internal rotation moment was greater by 11–18% (P < .001). These results suggest that the calculation of knee joint mechanics are influenced by the proximal shank’s segment endpoint definition, independent of dynamic task, investigator, laboratory environment, and population in this study.

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Ziva M. Rosker, Jernej Rosker and Nejc Sarabon

suggested that balance improved after the surgery, only body sway during the parallel stances was investigated. As herniation usually has a unilateral effect on the S1 nerve root—which is responsible for the innervation of ankle plantar flexors (S1) and dorsiflexors (L4), as well as hip abductors and

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Cameron T. Gibbons, Polemnia G. Amazeen and Aaron D. Likens

purpose of this study is to compare controlled and self-selected foot placement procedures and to understand the role that natural foot positioning plays in the control of posture during anteroposterior (AP; front-back) and mediolateral (ML; side-to-side) stances (see Figure  1 ). Figure 1 —Foot placement

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Gerda Strutzenberger, Adam Brazil, Timothy Exell, Hans von Lieres und Wilkau, John D. Davies, Steffen Willwacher, Johannes Funken, Ralf Müller, Kai Heinrich, Hermann Schwameder, Wolfgang Potthast and Gareth Irwin

-m race time. 3 After block clearance, the highest gain of horizontal velocity occurs during the first step, 4 followed by the second step, after which approximately half of the maximum horizontal velocity is achieved, 3 whereas vertical acceleration of the COM occurs similarly during both stance

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Tyler W.D. Muddle, David H. Fukuda, Ran Wang, Joshua J. Riffe, David D. Church, Kyle S. Beyer, Jay R. Hoffman and Jeffrey R. Stout

this study is to examine the effects of a 10-week introductory judo course on postural control during maximal bilateral isometric handgrip testing using different stance conditions and lower body power performance. Methods Participants A total of 20 healthy men and women between the ages of 18 and 35

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Wataru Kawakami, Makoto Takahashi, Yoshitaka Iwamoto and Koichi Shinakoda

previous studies suggested individuals with hallux valgus have hypermobility in the forefoot, 16 – 18 they did not show any difference in forefoot motion during the stance phase of the gait cycle between individuals with and without hallux valgus. A possible explanation is that they did not consider

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George Sofianidis, Anna-Maria Dimitriou and Vassilia Hatzitaki

experience in Tai Chi have stronger knee muscles, better static ( Hong, Li, & Robinson, 2000 ) and dynamic ( Tsang & Hui-Chan, 2003 ) balance control, lower movement variability during one-leg stance, and better balance confidence than controls ( Tsang & Hui-Chan, 2005 ). However, Tai Chi practitioners did