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George Vagenas and Blaine Hoshizaki

This study investigated the phenomenon of lower extremity functional asymmetries in a group of competitive male distance runners (N = 29). Bilateral measurements were taken to assess selected variables of the talocalcaneal flexibility (goniometry) and of the isokinetic knee strength (Cybex II). Data analysis revealed significant asymmetries for both lower extremity functional parameters. The subjects were symmetric in the total range of motion of the subtalar joint and inversely asymmetric in the range of motion of calcaneal eversion and calcaneal inversion. The laterality patterns of functional asymmetries were found to be consistent and independent of the conventional upper and lower extremity lateral preferences. It was theorized that asymmetries in the lower extremities are characterized by joint-specific trends of bilateralism.

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Jay N. Hertel, Kevin M. Guskiewicz, David M. Kahler and David H. Perrin

The purpose of this study was to investigate the effects of induced anesthesia of the lateral ankle joint on proprioception as assessed in weight-bearing and non-weight-bearing conditions. Sixteen subjects were assessed under normal conditions and following an 8-cc injection of lidocaine into the anterior talofibular ligament of the ankle being tested. Center of balance and postural sway measurements were analyzed, revealing a significant lateral adjustment of center of balance during the stable tests compared to a medial adjustment during the dynamic tests under the anesthetized condition. ANOVA of postural sway scores revealed no main effect for condition (anesthesia vs. no anesthesia), but sway scores were higher during the two dynamic conditions as compared to the stable condition. ANOVA of joint position error scores revealed no main effect for condition. Findings suggest that inhibition of the joint receptor afferent fibers adversely affected joint proprioception as assessed while subjects were weight bearing but not while they were non-weight bearing.

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Angie Selseth, Marilyn Dayton, Mitchell L. Cordova, Christopher D. Ingersoll and Mark A. Merrick

Purpose:

To analyze vastus medialis obliquus (VMO) and vastus lateralis (VL) muscle activity during the concentric and eccentric phases of a lateral step-up exercise.

Design:

Repeated-measures. Dependent variable: the integrated electromyogram measured as a percentage of the maximal voluntary isometric contraction of the VMO and VL muscles. Independent variable: muscle contraction with 2 levels (concentric and eccentric).

Subjects:

Twenty-three volunteers with no previous history of knee surgery or anterior knee pain.

Methods:

Surface electrodes were positioned over the VMO and VL, and electromyographic data were collected during the exercise.

Results:

The 2 muscle phases of contraction were different when both dependent variables were considered simultaneously (F 2,7 = 33.2, P < .001). Concentric contractions produced greater muscle activity for VL (P < .05) and VMO (P < .05).

Conclusions:

Because concentric contractions produce greater activity than eccentric contractions do during the lateral step-up exercise, they provide a stronger stimulus for muscle activation, which might result in greater muscle strength gains.

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Karen N. White, Katherine B. Gunter, Christine M. Snow and Wilson C. Hayes

The Quick Step measures reaction time and lateral stepping velocity. Upon a visual cue, participants step to the side as quickly as possible. Instrumentation includes floor pads with pressure-sensitive switches and two timers. In all, 109 older adults who had experienced a recent fall, 46 older adult nonfallers, and 24 young adults volunteered for testing. Reliability for reaction time and stepping velocity was good to excellent (intraclass correlation = 0.69–0.85). Multivariate analysis of variance revealed a significant difference between groups, p < 0.01, but not between stepping directions, p = 0.62–0.72, for both reaction time and stepping velocity. Reaction times were different among the three groups, p < 0.01, with the young adults having the fastest times and the older adult fallers having the slowest times. Lateral stepping velocity was faster among the young adults than for the two older groups, p < 0.01, but did not differ between the older adults, p = 0.29. It is concluded that the Quick Step is a simple and reliable tool for determining reaction time and lateral stepping velocity, and that this test can be used to detect a significant difference in reaction time between older adult fallers and nonfallers.

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Hiroki Aoki and Shinichi Demura

Purpose:

This study aimed to compare the laterality, and its gender difference, of hand grip and elbow flexion power according to load in right hand–dominant individuals.

Results:

The subjects were 15 healthy young males (age 22.1 ± 0.7 y, height 171.3 ± 3.4 cm, mass 64.5 ± 4.1 kg) and 15 healthy young females (age 22.4 ± 1.0 y, height 161.1 ± 3.0 cm, mass 55.4 ± 4.6 kg). Isotonic peak power was measured with 6 different loads ranging from 20% to 70% of maximum voluntary contraction (MVC) for grip and elbow flexion movements.

Results:

The peak power was significantly larger in males than in females in both movements (ratio, males:females was 58.1:49.4%). The dominant right hand had larger peak power in all loads for hand grip power (ratio, dominant:nondominant was 83.6:71.1%) and in loads of 20% to 50% MVC for elbow flexion power (88.7:85.7%) in both genders, confirming laterality in both movements. The peak power ratio of the dominant right hand to the nondomi-nant left hand was significantly larger in hand grip than in elbow flexion for all loads in females.

Conclusion:

Even though laterality was confirmed in both grip and elbow flexion, gender difference is more marked in hand grip.

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Hiroshige Tateuchi, Noriaki Ichihashi, Masahiro Shinya and Shingo Oda

Patients with hip osteoarthritis (OA) have difficulty with mediolateral postural control. Since the symptom of hip OA includes joint pain, which mostly occurs upon initial movement, patients with hip OA might have disabling problems with movement initiation. This study aimed to identify the movement strategy during the anticipatory postural adjustments in the lateral step motion in patients with hip OA. We studied 18 female subjects with unilateral hip OA and 10 healthy subjects, and measured temporal, kinetic, and kinematic variables. Patients with hip OA required a longer duration of anticipation phase than the control subjects, the total duration of lateral stepping was not different between the groups. Displacement of the center of mass to the supporting (affected) side during the anticipation phase was not different between the two groups. These findings suggest that, in patients with hip OA, the center of mass slowly moved to the affected side. Furthermore, patients with hip OA showed greater shift of the trunk to the supporting side than did the control subjects. These movement characteristics might contribute to the achievement of both protection of the affected hip joint and quickness in the subsequent lateral step in patients with hip OA.

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Frank C. Mendel, Michael G. Dolan, Dale R. Fish, John Marzo and Gregory E. Wilding

Context:

High-voltage pulsed current (HVPC), a form of electrical stimulation, is known to curb edema formation in laboratory animals and is commonly applied for ankle sprains, but the clinical effects remain undocumented.

Objective:

To determine whether, as an adjunct to routine acute and subacute care, subsensory HVPC applied nearly continuously for the first 72 h after lateral ankle sprains affected time lost to injury.

Design:

Multicenter, randomized, double-blind, placebo-controlled trial.

Setting:

Data were collected at 9 colleges and universities and 1 professional training site.

Participants:

50 intercollegiate and professional athletes.

Interventions:

Near-continuous live or placebo HVPC for 72 h postinjury in addition to routine acute and subacute care.

Main Outcome Measure:

Time lost to injury measured from time of injury until declared fit to play.

Results:

Overall, time lost to injury was not different between treated and control groups (P = .55). However, grade of injury was a significant factor. Time lost to injury after grade I lateral ankle sprains was greater for athletes receiving live HVPC than for those receiving placebo HVPC (P = .049), but no differences were found between groups for grade II sprains (P = .079).

Conclusions:

Application of subsensory HVPC had no clinically meaningful effect on return to play after lateral ankle sprain.

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Danny Pincivero, Joe H. Gieck and Ethan N. Saliba

A treatment and rehabilitation protocol was implemented on a university football player sustaining a second-degree lateral ankle sprain. The initial treatment plan involved the application of the RICE principle (rest, ice, compression, and elevation). This particular rehabilitation protocol was aimed at restoring range of motion and function at the earliest possible time with the use of a cryokinetic technique developed by Knight and with progressive exercise. The subject in this case study returned to full participation 6 days postinjury. The results from this report indicate that a program of cryokinetics and functional progressive exercise performed within pain-free limits can greatly enhance the return of an athlete to competition.

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Jae P. Yom, Kathy J. Simpson, Scott W. Arnett and Cathleen N. Brown

One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity.

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Alison C. McDonald, Elora C. Brenneman, Alan C. Cudlip and Clark R. Dickerson

As the modern workplace is dominated by submaximal repetitive tasks, knowledge of the effect of task location is important to ensure workers are unexposed to potentially injurious demands imposed by repetitive work in awkward or sustained postures. The purpose of this investigation was to develop a three-dimensional spatial map of the muscle activity for the right upper extremity during laterally directed submaximal force exertions. Electromyographic (EMG) activity was recorded from fourteen muscles surrounding the shoulder complex as the participants exerted 40N of force in two directions (leftward, rightward) at 70 defined locations. Hand position in both push directions strongly influenced total and certain individual muscle demands as identified by repeated measures analysis of variance (P < .001). During rightward exertions individual muscle activation varied from 1 to 21% MVE and during leftward exertions it varied from 1 to 27% MVE with hand location. Continuous prediction equations for muscular demands based on three-dimensional spatial parameters were created with explained variance ranging from 25 to 73%. The study provides novel information for evaluating existing and proactive workplace designs, and may help identify preferred geometric placements of lateral exertions in occupational settings to lower muscular demands, potentially mitigating fatigue and associated musculoskeletal risks.