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David A. Hampton, Kevin W. Hollander and Jack R. Engsberg

A theory for equinus gait in cerebral palsy (CP) is that the strong plantarflexors prevent the weak dorsiflexors from achieving dorsiflexion, thereby causing the ankle to be in a plantarflexed position. Recent work has indicated that both the ankle dorsiflexors and plantarflexors are weak. The purpose of this research was to theoretically and experimentally demonstrate that equinus deformity gait could be a compensatory strategy for plantarflexor weakness. It was hypothesized that children with CP utilize an equinus position during gait as a consequence of their weakness. A two-dimensional, sagittal plane model estimating plantarflexor forces through the Achilles tendon was developed. Five able-bodied (AB) children were tested utilizing heel-toe and progressively increasing toe walking strategies. Four children with CP were tested as they walked using their equinus gait. Results demonstrated that AB children assuming the toe walking stance progressively reduced the plantarflexor force when compared to their heel-toe walking trials. However, their toe walking strategy could not reduce the plantarflexor force level to that of the children with CP during the gait cycle. It was concluded that the equinus deformity posture complemented the CP children's plantarflexor weakness. Therefore, by implementing a concomitant strategy to maintain a reduced force state, equinus deformity could be used as a compensatory mechanism for individuals with plantarflexor weakness.

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Lindsay K. Drewes, Patrick O. McKeon, Gabriele Paolini, Patrick Riley, D. Casey Kerrigan, Christopher D. Ingersoll and Jay Hertel

Context:

Kinematic patterns during gait have not been extensively studied in relation to chronic ankle instability (CAI).

Objective:

To determine whether individuals with CAI demonstrate altered ankle kinematics and shank-rear-foot coupling compared with controls during walking and jogging.

Design:

Case control.

Setting:

Motion-analysis laboratory.

Participants:

7 participants (3 men, 4 women) suffering from CAI (age 24.6 ± 4.2 y, height 172.6 ± 9.4 cm, mass 70.9 ± 8.1 kg) and 7 (3 men, 4 women) healthy, matched controls (age 24.7 ± 4.5 y, height 168.2 ± 5.9 cm, mass 66.5 ± 9.8 kg).

Interventions:

Subjects walked and jogged on a treadmill while 3-dimensional kinematics of the lower extremities were captured.

Main Outcome Measures:

The positions of rear-foot inversion–eversion and shank rotation were calculated throughout the gait cycle. Continuous relative-phase angles between these segments were calculated to assess coupling.

Results:

The CAI group demonstrated more rear-foot inversion and shank external rotation during walking and jogging. There were differences between groups in shank-rear-foot coupling during terminal swing at both speeds.

Conclusions:

Altered ankle kinematics and joint coupling during the terminal-swing phase of gait may predispose a population with CAI to ankle-inversion injuries. Less coordinated movement during gait may be an indication of altered neuromuscular recruitment of the musculature surrounding the ankle as the foot is being positioned for initial contact.

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Ronita L. Cromwell and Roberta A. Newton

Age-related adaptations during walking create a more stable walking pattern, which is less effective for forward progression and might be related to balance deficiencies. This study determined the relationship between walking stability and measures of balance in older adults. Seventeen older and 20 young adults performed the Berg Balance Test (BBT) and walked 10 m. Walking velocity (WV) and cadence were measured, and a gait-stability ratio (GSR) was calculated. Higher GSR indicated that a greater portion of the gait cycle was spent in double-limb support. Age-group comparisons established declines in BBT scores and WV and increases in GSR with age. Significant relationships were identified for BBT Item 12 (alternate stepping on a stool) with WV (r = .58, r 2 = .34) and GSR (r = −.74, r 2 = .54). The correlation of BBT Item 12 with GSR was stronger than with WV (p < .05). Results indicated a strong relationship between increased gait stability and decreased balance for a dynamic weight-shifting task. Therefore, GSR is a better indicator of balance deficits during walking than is WV alone.

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C. Collin Herb, Lisa Chinn and Jay Hertel

Context:

Lateral ankle sprain (LAS) is one of the most common injuries in active individuals. Chronic ankle instability (CAI) is a condition that commonly occurs after LAS and is associated with long-term disability and a high risk of multiple ankle sprains. Ankle taping is a commonly used intervention for the prevention of ankle sprains.

Objective:

To analyze the ankle-joint coupling using vector coding during walking and jogging gait with the application of ankle tape and without ankle tape in young adults with and without CAI.

Design:

Observational laboratory study design. Patients walked and jogged on an instrumented treadmill while taped and not taped. Fifteen strides for each subject were collected and analyzed using a vector-coding technique to compare magnitude coupled motion, ratio of coupled motion, and the variability (VCV) within groups. Within-group means and 90% confidence intervals (CI) were compared between the taped and nontaped condition, and where the CIs did not overlap was considered significant.

Setting:

A 12-camera 3D motion-capture system with instrumented treadmill.

Patients:

12 patients with CAI and 11 healthy controls.

Main Outcome Measures:

Magnitude to coupled motion, ratio of coupled motion, and the VCV of shank–rear-foot joint coupling.

Results:

Magnitude of coupled motion and VCV were significantly lower in the taped condition than in the nontaped condition in both groups. Magnitude differences were identified near initial contact during walking and during swing phase of jogging. VCV differences were identified throughout the gait cycle at both walking and jogging. No differences were identified in theta between tape and nontaped conditions.

Conclusions:

A decrease in the magnitude of coupled motion and VCV may represent a protective mechanism of ankle taping in CAI and healthy patients during gait.

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Keith A. Stern and Jinger S. Gottschall

The purpose of our study was to determine if altering the insoles within footwear or walking barefoot, as an attempt to increase or decrease cutaneous stimuli, would improve dynamic balance during a hill-walking task. We hypothesize that compared with foam insoles or iced bare feet, textured insoles or bare feet will result in greater speeds, longer step lengths, narrower step width, shorter stance time, and less tibialis anterior (TA), soleus (SOL), and lateral gastrocnemius (LG) activity during key gait cycle phases. Ten, healthy college students, 5 men and 5 women, completed the protocol that consisted of level walking and downhill transition walking in five different footwear insole or barefoot conditions. During level walking, conditions with the hypothesized greater cutaneous stimuli resulted in greater step length, which relates to a more stable gait. In detail, the texture insole condition average step length was 3% longer than the regular insole condition, which was 5% longer than the ice condition (p < .01). The same signals of increased stability were evident during the more challenging downhill transition stride. Step length during the barefoot condition was 8% longer than the ice condition (p < .05) and step width during the regular footwear condition was 5% narrower than the foam condition (p = .05). To add, during the preswing phase of level walking, TA activity of the textured insole condition was 30% less than the foam insole. Although our data show that footwear conditions alter gait patterns and lower leg muscle activity during walking, there is not enough evidence to support the hypothesis that textured insoles will improve dynamic balance as compared with other footwear types.

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Josu Gomez-Ezeiza, Jordan Santos-Concejero, Jon Torres-Unda, Brian Hanley and Nicholas Tam

subphases, were associated with better oxygen cost of transport in elite race walkers. 5 Although recent gait analyses in race walking have mostly assessed peaks, range of motion, and other discrete parameters of the entire gait cycle, 5 – 7 a comprehensive understanding of the role and activity of the

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Adam M. Fullenkamp, Danilo V. Tolusso, C. Matthew Laurent, Brian M. Campbell and Andrea E. Cripps

rest). Motion analysis data collected during the treadmill conditions (MT or NMT) were captured from the last 30 seconds of a 90-second trial. Data Analysis Processed 3D marker trajectories were first analyzed to determine foot strike events and partition trial data into gait cycles. 19 Individual

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Original Research Dynamic Stability of Gait Cycles as a Function of Speed and System Constraints Ugo H. Buzzi * Beverly D. Ulrich * 7 2004 8 3 241 254 10.1123/mcj.8.3.241 Research Contextual Effects on Force Control and Timing in a Finger-Tapping Sequence with an Accentuated- or Attenuated

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Jaimie A. Roper, Ryan T. Roemmich, Mark D. Tillman, Matthew J. Terza and Chris J. Hass

temporally to 100% of the gait cycle. 10 The braking phase was defined using the anteroposterior ground reaction forces as the period from heel-strike through the first 50% of the single-limb stance period. Similarly, the propulsive phase was defined as the period from the 50% of the single-limb stance

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John McCleve, Luke Donovan, Christopher D. Ingersoll, Charles Armstrong and Neal R. Glaviano

inversion at preheel strike (HS), during HS, post HS, and throughout the majority of the gait cycle when compared to healthy counterparts. 13 , 14 This means that for every step an individual with CAI takes, they are closer to the mechanism of injury of a LAS and, therefore, may be at a greater risk of