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Cui Zhang, Qipeng Song, Wei Sun, and Yu Liu

little attention has been paid to the dynamic stability of older adults during stair descent under a concurrent dual-task condition. Among various postural stability assessment methods, dynamic stability is the most comprehensive method that is used to quantify the dynamic control of the center of mass

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David Rhodes, Jill Alexander, and Matt Greig

ability is best represented. Arguably, when relating these findings to injury risk, the effected output is often the focus, relating strongly to dynamic stability responses. Dynamic stability can be quantified through various subjective or objective means, such as single-leg landing, single-leg hop and

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Hamed Shahidian, Rezaul Begg, and David C. Ackland

, which has a significant influence on gait stability due to its proportion of whole-body mass, 12 exhibits LyE values that increase during cognitive load associated with talking while walking in older-aged subjects, suggesting greater gait instability. 13 , 14 Local dynamic stability measures have

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Kazem Malmir, Gholam Reza Olyaei, Saeed Talebian, Ali Ashraf Jamshidi, and Majid Ashraf Ganguie

Muscle fatigue may affect any part of the procedure and interfere with postural stability. Postural stability has been assessed under static and dynamic conditions. Dynamic stability, which is defined as the ability to maintain stability during movement, is considered as a prerequisite for an athlete

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Kristin D. Morgan

reconstructed limb compared with their nonreconstructed limb. 4 , 6 , 7 At this level, individuals possess the strength to perform more demanding tasks and can progress to exercise-based rehabilitation programs that are aimed at restoring dynamic stability. 8 , 9 Unfortunately, despite this and similar

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Kathy Liu and Gary D. Heise

Dynamic stability is often measured by time to stabilization (TTS), which is calculated from the dwindling fluctuations of ground reaction force (GRF) components over time. Common protocols of dynamic stability research have involved forward or vertical jumps, neglecting different jump-landing directions. Therefore, the purpose of the present investigation was to examine the influence of different jump-landing directions on TTS. Twenty healthy participants (9 male, 11 female; age = 28 ± 4 y; body mass = 73.3 ± 21.5 kg; body height = 173.4 ± 10.5 cm) completed the Multi-Directional Dynamic Stability Protocol hopping tasks from four different directions—forward, lateral, medial, and backward—landing single-legged onto the force plate. TTS was calculated for each component of the GRF (ap = anterior-posterior; ml = medial-lateral; v = vertical) and was based on a sequential averaging technique. All TTS measures showed a statistically significant main effect for jump-landing direction. TTSml showed significantly longer times for landings from the medial and lateral directions (medial: 4.10 ± 0.21 s, lateral: 4.24 ± 0.15 s, forward: 1.48 ± 0.59 s, backward: 1.42 ± 0.37 s), whereas TTSap showed significantly longer times for landings from the forward and backward directions (forward: 4.53 ± 0.17 s, backward: 4.34 0.35 s, medial: 1.18 ± 0.49 s, lateral: 1.11 ± 0.43 s). TTSv showed a significantly shorter time for the forward direction compared with all other landing directions (forward: 2.62 ± 0.31 s, backward: 2.82 ± 0.29 s, medial: 2.91 ± 0.31 s, lateral: 2.86 ± 0.32 s). Based on these results, multiple jump-landing directions should be considered when assessing dynamic stability.

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Samuele Contemori, Andrea Biscarini, Fabio M. Botti, Daniele Busti, Roberto Panichi, and Vito E. Pettorossi

, no research studies have specifically assessed the static and dynamic stability of the shoulder with IIMA to reveal possible impairments in the shoulder sensory and motor control functions. Therefore, the specific aim of this study is to examine the shoulder sensorimotor control in professional

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Paul A. Borsa, Eric L. Sauers, and Scott M. Lephart

Functional training for the purpose of restoring dynamic joint stability has received considerable interest in recent years. Contemporary functional training programs are being designed to complement, rather than replace, traditional rehabilitation protocols. The purpose of this clinical commentary is to present a management strategy for restoring dynamic stability in the posterior cruciate ligament (PCL)-injured knee. The strategy presented integrates five key concepts: (a) planned variation of exercise, (b) outcomes-based assessment, (c) kinetic chain exercise, (d) proprioception and neuromuscular control, and (e) specificity of activity. Pertinent research findings and a clinical rationale are provided for using functional training in the restoration of dynamic stability in the PCL-injured knee.

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Susan Miniello, Geoffrey Dover, Michael Powers, Mark Tillman, and Erik Wikstrom

Context:

Previous studies have suggested that cryotherapy affects neuromuscu-lar function and therefore might impair dynamic stability. If cryotherapy affects dynamic stability, clinicians might alter their decisions regarding returning athletes to play immediately after treatment.

Objective:

To assess the effects of lower leg cold immersion on muscle activity and dynamic stability of the lower extremity.

Design:

Within-subject time-series design with 1 pretest and 2 posttests.

Setting:

A climate-controlled biomechanics laboratory.

Participants:

17 healthy women.

Interventions:

20-minute cold-water immersion.

Main Outcome Measures:

Preparatory and reactive electromyographic activity of the tibialis anterior and peroneus longus and time to stabilization after a jump landing.

Results:

Preparatory activity of the tibialis anterior increased after treatment, whereas preparatory and reactive peroneus longus activity decreased. Both returned to baseline after a 5-minute recovery. Time to stabilization did not change.

Conclusions:

Lower leg cold-immersion therapy does not impair dynamic stability in healthy women during a jump-landing task. Return to participation after a cryotherapy treatment is not contraindicated for healthy athletes.

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Ugo H. Buzzi and Beverly D. Ulrich

The purpose of this study was to examine the dynamic stability of two groups of children with different dynamic resources in changing contexts. The stability of the lower extremity segments of preadolescent children (8–10 years old) with and without Down syndrome (DS) was evaluated as children walked on a motorized treadmill at varying speeds. Tools from nonlinear dynamics, maximum Lyapunov exponent, and approximate entropy were used to assess the behavioral stability of segmental angular displacements of the thigh, shank, and foot. Our results suggest that children with DS show decreased dynamic stability during walking in all segments and that this might be a consequence of inherently different subsystem constraints between these groups. Differences between groups also varied, though not uniformly, with speed, suggesting that inherent differences could further constrain the behavioral response to changing task demands.