Unilateral Support Research Articles

Tai Chi Exercise can Improve the Obstacle Negotiating Ability of People with Parkinson's Disease: A Preliminary Study.

[Purpose] The purpose of this study was to examine the effects of Tai Chi (TC)-based exercise on dynamic postural control during obstacle negotiation by subjects with mild or moderate Parkinson’s disease (PD). [Subjects] Twelve subjects (mean age, 65.3±6.1 years) diagnosed with idiopathic PD were enrolled for this study. [Methods] All the subjects were tested a week before and 12 weeks after the initiation of the TC exercise. In the test, they were instructed to negotiate an obstacle from the position of quiet stance at a normal speed. They were trained with TC exercise that emphasized multidirectional shift in weight bearing from bilateral to unilateral support, challenging the postural stability, three times per week for 12 weeks. Center of pressure (COP) trajectory variables before and after TC exercise were measured using two force plates. [Results] A comparison of the results between pre- and post-intervention showed a statistically significant improvement in anteroposterior and mediolateral displacement of COP. [Conclusion] Twelve weeks of TC exercise may be an effective and safe form of stand-alone behavioral intervention for improving the dynamic postural stability of patients with PD.

Level of Mobility Limitations and Falls Status in Persons With Multiple Sclerosis

ObjectiveTo investigate whether fall rates are constant across levels of mobility limitations. DesignSecondary analysis of baseline assessments from a stratified randomized controlled trial. SettingCommunity. ParticipantsPersons with multiple sclerosis (N=365) were divided into 5 groups based on the mobility section of the Guy's Neurological Disability Scale (GNDS): no walking impairment (n=82); impaired walking, no aid (n=87); unilateral support (n=76); bilateral support to walk (n=78); or occasional wheelchair user (n=42). InterventionsNot applicable. Main Outcome MeasuresSelf-reported fall history (ie, retrospective) in the preceding 3 months. ResultsOne hundred twenty-four persons in the overall sample reported falling in the last 3 months (fall prevalence, 33.97%). Of the total sample, 17.8% reported 2 or more falls in the last 3 months. Chi-square analysis revealed a significant difference in the proportion of fallers across GNDS categories (χ2=42.64, P<.001). Post hoc analysis revealed that the group who walked with bilateral support had the greatest proportion of fallers (52.6%), while the group without walking impairment had the lowest proportion (15.9%). An examination of recurrent fallers as a function of group found that there were more recurrent fallers (70%) in the group that had a walking impairment but used no aid, relative to the other groups. ConclusionsThe current findings highlight that fall rates including recurrent fall prevalence are not uniform across mobility aid categories in persons with MS. Those using bilateral assistance for gait have the highest prevalence of fallers, and those with walking limitations and not yet using an aid had the greatest prevalence of multiple falls.

Singularities in bending behavior of plates with free corner supports

The objective of this paper is to examine the order of singularity at the points of discontinuity between simple support and free edge for a square plate case. The plate, without anchoring the corners, is partially simply supported along the central portion on four edges and subjected to a uniformly distributed load. It is well known that when a uniform load is applied to a square plate resting on the unilateral supports, parts of the plate in the vicinity of the corners will separate from the supports and the length of the supports becomes unspecified. At the points of transition from the unilateral support to free edge, the shear singularity is of the inverse-square-root type. In the case of a square plate supported by the simple supports with specified lengths, it is expected that the proper singularity should be in the order of an inverse square root in the moments at the points of transition from a simple support to a free edge. However, the results show that the singularity in the moments cannot be allowed, while the singularity in the shears is proper and still found to be the same order similar to that of the plate resting on the unilateral supports. In addition, there are nonzero corner forces applied at the corners of partially simply supported plate, while the corner forces vanish for the case of a plate unilaterally supported.

Changes in Condylar Position Using Different Types of Splints With and Without a Chinstrap: A Case-Control Study

The aim of this case-control study was to analyze and quantify if there is a different mechanical effect of stabilization and pivot splints with uni- or bilateral pivot of different heights and with and without an additional chinstrap, on the vertical, sagittal, and horizontal condyle position. A stabilization splint and splints with unilateral or bilateral posterior pivot support of 0.6 mm or 1.9 mm height were used with and without a chinstrap individually adjusted to 5N per side. Electronic-condylar-positionanalysis was performed using an ultrasound-based jaw-tracking system with an accuracy of 0.1 mm. Manual guided central position served as the reference point. Participants were 40 functional, asymptomatic volunteers with a mean age of 33.9 years. Main effect splint design (stabilization, uni-, bilateral pivot) was not significant. Pivoting height was reported as significant (p≤00.02) in all axes. Use of the chinstrap was significant (p≤0.03) in the X- and Y- axis, but not significant in the Z-axis. A post-hoc test revealed that use of a chinstrap led to significantly (p=0.003) less anterior and significantly (p=0.002) more inferior condyle displacement. Results indicate that the use of pivot splints only in combination with a chinstrap lead to a distractive effect of the condyles.

A Wearable System to Assess Risk for Anterior Cruciate Ligament Injury During Jump Landing: Measurements of Temporal Events, Jump Height, and Sagittal Plane Kinematics

The incidence of anterior cruciate ligament (ACL) injury remains high, and there is a need for simple, cost effective methods to identify athletes at a higher risk for ACL injury. Wearable measurement systems offer potential methods to assess the risk of ACL injury during jumping tasks. The objective of this study was to assess the capacity of a wearable inertial-based system to evaluate ACL injury risk during jumping tasks. The system accuracy for measuring temporal events (initial contact, toe-off), jump height, and sagittal plane angles (knee, trunk) was assessed by comparing results obtained with the wearable system to simultaneous measurements obtained with a marker-based optoelectronic reference system. Thirty-eight healthy participants (20 male and 18 female) performed drop jumps with bilateral and unilateral support landing. The mean differences between the temporal events obtained with both systems were below 5 ms, and the precisions were below 24 ms. The mean jump heights measured with both systems differed by less than 1 mm, and the associations (Pearson correlation coefficients) were above 0.9. For the discrete angle parameters, there was an average association of 0.91 and precision of 3.5° for the knee flexion angle and an association of 0.77 and precision of 5.5° for the trunk lean. The results based on the receiver-operating characteristic (ROC) also demonstrated that the proposed wearable system could identify movements at higher risk for ACL injury. The area under the ROC plots was between 0.89 and 0.99 for the knee flexion angle and between 0.83 and 0.95 for the trunk lean. The wearable system demonstrated good concurrent validity with marker-based measurements and good discriminative performance in terms of the known risk factors for ACL injury. This study suggests that a wearable system could be a simple cost-effective tool for conducting risk screening or for providing focused feedback.

Cervical epidural plasmacytoma presenting as ascending paraparesis

Background context Spinal epidural plasmacytomas are very rare and are usually localized in the cervicothoracic and lumbar spines. Purpose To present the first case of cervical dural plasmacytoma and discuss the treatment options for this entity. Study design Case report and review of the literature. Methods A 45-year-old man presented with gradually progressive legs to arms numbness preceded by upper respiratory tract infection and followed by rapid flaccid quadriparesis over 1 week. Because of the above symptoms, he was initially thought to have Guillain-Barré syndrome, but this diagnosis was ruled out by an emergency normal nerve conduction studies and needle electromyography. Cervical magnetic resonance imaging revealed an enhancing epidural mass at the C4–C7 level on T1-weighted images and increased signal on T2, causing spinal cord compression. Complete surgical evacuation was performed. Subsequent histology revealed plasmacytoma associated with anaplastic multiple myeloma, and the patient was referred to the hematology department for further treatment. Results Follow-up at 9 and 13 months after surgery revealed complete remission of the primary disease (multiple myeloma). The patient was neurologically improved and ambulatory with unilateral support. Conclusion The reported case describes the first epidural extramedullary plasmacytoma isolated in the cervical spine in the English literature. Emergent neuroimaging and surgery can dramatically affect prognosis of this rare spinal neoplasm.

The Effects of Tai Chi Based Exercise on Dynamic Postural Control of Parkinson's Disease Patients while Initiating Gait

[Purpose] The purpose of this study was to investigate the effects of Tai Chi (TC) based exercise on dynamic postural control when people with mild or moderate Parkinson's disease (PD) initiate gait. [Subjects] Ten people with PD, who ranged in age from 70 to 84 years, volunteered to participate in a 12-week intervention of TC exercise. [Methods] Participants with PD were tested pre- and post-intervention in a task in which they were instructed to initiate gait from the position of quiet stance. Participants with PD were trained with TC exercise that emphasizes a shift in weight bearing from bilateral to unilateral support, challenging postural stability, three times per week over a period of 12 weeks. Differences between pre- and post-test in COP displacement in the anteroposterior (A-P) and mediolateral (M-L) directions were assessed using two force plates. [Results] After practicing the TC exercise, participants with PD significantly increased A-P and M-L displacement of the COP. [Conclusion] TC exercise increased COP displacement in the A-P and M-L directions, thereby improving participants' ability to generate momentum to initiate gait and maintain lateral stability. The findings of this study support the use of TC exercise as an effective and safe rehabilitation strategy for some individuals with PD.

Non-axisymmetric warping of a heavy circular plate on a flexible ring support

In this paper, we study the deformation and stability of a circular plate under its own weight and supported by a flexible concentric ring. Both bilateral and unilateral supports are considered. Von Karman’s plate model is adopted to formulate the equations of motion. A nonlinear Galerkin’s method based on two sets of assumed functions is used to discretize and solve the governing equations. Vibration method is used to predict the stability of the deformations. The linear analysis conducted previously predicts that the deformation is always axisymmetric. The current nonlinear analysis, however, shows that the axisymmetric deformation may become unstable when the dimensionless load, i.e., a ratio between the weight per unit area and the flexural rigidity of the plate, reaches a critical value. At this critical load, a stable non-axisymmetric deformation of the form cos nθ emerges following a pitch-fork bifurcation, where the integer n depends on the stiffness and the radius of the ring support. When the load increases further, more than one stable non-axisymmetric deformation may coexist. In a stable non-axisymmetric deformation with bilateral support, tension on the ring support may develop when the load reaches another critical value. In this situation, the circular plate will separate from the supporting ring in part of the angular region if the bilateral support is replaced by a unilateral one. The deformation with unilateral support is in general larger than the one with bilateral support.

The effects of unilateral medial arch support stimulation on plantar pressure and center of pressure adjustment in young gymnasts

The purpose of this study was to examine the contribution of tactile afferents from the medial arch of the foot on postural control. The center of pressure (CoP) position and right/left plantar pressure distributions of 13 gymnasts, with and without a medial arch support, were recorded by a force platform coupled with a baropedometry analysis. Stimulation of the subject's plantar sole was accomplished using a 3 mm thick medial arch insert. Right arch stimulation induced an ipsilateral increase of plantar pressure and a contralateral displacement of the CoP to the left. Left arch support also resulted in an ipsilateral increase in plantar pressure and displacement of the CoP to the right. Stimulation of the plantar arch may induce a perception that the body's center of mass has shifted toward the stimulated foot. To maintain stability, individuals may then shift their CoP in the opposite direction. This response may involve compensatory muscle activation strategies to adjust posture. Clinicians may apply these results in their use of foot orthoses to address postural anomalies in patients.

MRI for monitoring response to preventive treatment in multiple sclerosis

, two important mile-stones in the history of the disease, corre-sponding to limited walking ability and the need for unilateral support when walking, respectively. Nevertheless, a high degree of variability is present in terms of disease activity among patients during treatment and a relevant number of subjects treated with IFN-β or GA continue to experience clinical bouts and disease progression. Since alternative drugs more active against MS are currently available (i.e., mitox-antrone

Gait synchronized force modulation during the stance period of one limb achieved by an active partial body weight support system

Our purpose was to demonstrate the ability of an actively controlled partial body weight support (PBWS) system to provide gait synchronized support during the stance period of a single lower extremity while examining the affect of such a support condition on gait asymmetry. Using an instrumented treadmill and a motion capture system, we compared gait parameters of twelve healthy elderly subjects (age 65–80 years) during unsupported walking to those while walking with 20% body weight support provided during only the stance period of the right limb. Specifically, we examined peak three-dimensional ground reaction force (GRF) data and the symmetry of lower extremity sagittal plane joint angles and of time and distance parameters. A reduction in all three GRF components was observed for the supported limb during modulated support. Reductions observed in the vertical GRF were comparable to the desired 20% support level. Additionally, GRF components examined for the unsupported limb during modulated support were consistently similar to those measured during unsupported walking. Modulated support caused statistically significant increases in asymmetry for knee flexion during stance (increased 5.9%), hip flexion during late swing (increased 9.1%), and the duration of single limb support (increased 2.8%). However, the observed increases were similar or considerably less than the natural variability in the asymmetry of these parameters during unsupported walking. The ability of the active PBWS device to provide unilateral support may offer new and possibly improved applications of PBWS rehabilitation for patients with unilateral walking deficits such as hemiparesis or orthopaedic injury.

The joint evolution of mating system, floral traits and life history in Clarkia (Onagraceae): genetic constraints vs. independent evolution

Genetic correlations caused by pleiotropy or linkage disequilibrium may influence the joint evolution of multiple traits as populations or taxa diverge. The evolutionary transition from outcrossing to selfing has occurred numerous times and is often accompanied by phenotypic and genetic changes in multiple traits such as flower size, pollen-ovule ratio, stigma and anther maturity and the age of reproductive maturity. Determining whether the recurring patterns of multitrait change are because of selection on each trait independently and/or the result of genetic correlations among traits can shed light on the mechanism that accounts for such convergence. Here, we evaluate whether floral traits are genetically correlated with each other and/or with whole-plant traits within- and between-populations and taxa. We report results from a greenhouse study conducted on two pairs of sister taxa with contrasting mating systems: the autogamously selfing Clarkia exilis and its predominantly outcrossing progenitor C. unguiculata and the autogamous Clarkia xantiana ssp. parviflora and its outcrossing progenitor C. xantiana ssp. xantiana. We examined variation within and covariation among maternal families in three populations of each taxon with respect to the age at first flower, the rate of successive flower production and the number of days between bud break and anther dehiscence and stigma receptivity within individual flowers. Based on phenotypic divergence between sister taxa, bivariate regressions, correlations among maternal family means and analysis of covariance (ancova), we did not find unilateral support indicating that genetic constraints govern the joint distribution of floral and whole-plant traits.

Natural History of Multiple Sclerosis with Childhood Onset

The course and prognosis of childhood-onset multiple sclerosis have not been well described. We used data from 13 adult neurology departments affiliated with the European Database for Multiple Sclerosis (EDMUS) network to identify a cohort of 394 patients who had multiple sclerosis with an onset at 16 years of age or younger and a comparison group of 1775 patients who had multiple sclerosis with an onset after 16 years of age. We determined the initial clinical features, the dates of disease onset, and the occurrence of outcomes, including relapse, conversion to secondary progression, and irreversible disability as measured by scores of 4 (limited walking ability but ability to walk more than 500 m without aid or rest), 6 (ability to walk with unilateral support no more than 100 m without rest), and 7 (ability to walk no more than 10 m without rest while using a wall or furniture for support) on the Kurtzke Disability Status Scale (range, 0 to 10; higher scores indicate more severe disability). For patients with childhood-onset multiple sclerosis, the estimated median time from onset to secondary progression was 28 years, and the median age at conversion to secondary progression was 41 years. The median times from onset to disability scores of 4, 6, and 7 were 20.0, 28.9, and 37.0 years, respectively, and the corresponding median ages were 34.6, 42.2, and 50.5 years. In comparison with patients with adult-onset disease, those with childhood-onset disease were more likely to be female than male (female:male ratio, 2.8 vs. 1.8), were more likely to have an exacerbating-remitting initial course (98% vs. 84%), took approximately 10 years longer to reach secondary progression and irreversible disability, and reached these landmarks at an age approximately 10 years younger (P<0.001 for all comparisons). Patients with childhood-onset multiple sclerosis take longer to reach states of irreversible disability but do so at a younger age than patients with adult-onset multiple sclerosis.

Unilateral Support Resistance Training Incorporating the Hip and Knee

Unilateral Support Resistance Training Incorporating the Hip and Knee

Unilateral Support Resistance Training Incorporating the Hip and Knee

Unilateral Support Resistance Training Incorporating the Hip and Knee

Elastic analysis and application tables of rectangular plates with unilateral contact support conditions

In the present study, a numerical methodology for the elastic analysis of single plates is presented, which takes into account any unilateral support conditions (uplift potential) that can occur in one or more supporting boundaries. The plates are discretized with a fine mesh of finite elements and the unilateral support conditions are simulated through proper link elements, while the determination of the uplifted regions of the plates is part of the problem's solution. A parametric study is then carried out for rectangular edge-supported plates for various combinations of support conditions and aspect ratios. From the processing of the results of this analysis, proper application tables for the calculation of stress state of the plates were created, in a form similar to the well-known tables compiled by Czerny.

Influence of periodontal receptors on the jaw-jerk reflex amplitude in man.

To study the role of periodontal mechanoreceptors in the modulation of the human jaw-jerk reflex, 60 reflexes were elicited in each of six healthy individuals under three different conditions: (a) with unilateral tooth support on the ipsilateral side; (b) with support on the contralateral side; and (c) with support and local anesthesia of the periodontal tissues on the ipsilateral side. During all conditions, background muscle activity and mandibular displacement were kept as constant as possible. Using on-surface EMG and the amplitude of the first peak of the biphasic jaw-jerk potential as the outcome variable, a condition-dependent reflex amplitude was found for the visually controlled right anterior temporalis muscle. Specifically, the 'ipsilateral support plus anesthesia' condition yielded higher amplitudes than the 'ipsilateral support' condition. Highest amplitudes were found for the 'contralateral support' condition. It was concluded that periodontal mechanoreceptors on the ipsilateral side have an inhibitory effect on the jaw-jerk reflex amplitude in the anterior temporalis muscle.

Relapses and Progression of Disability in Multiple Sclerosis

The influence of the patterns of onset of multiple sclerosis and relapses of the disease on the time course of irreversible disability is controversial. In 1844 patients with multiple sclerosis who were followed for a mean (+/- SD) of 11 +/- 10 years, we determined the time of the clinical onset of the disease, the initial course (relapsing-remitting or progressive) and the subsequent course (relapsing-remitting, secondary progressive, or primary progressive), the times of relapses, the time to the onset of irreversible disability, and the time course of progressive, irreversible disability. We used three scores on the Kurtzke Disability Status Scale (range, 0 to 10, with higher scores indicating more severe disability) as measures of the severity and progression of disability: a score of 4 (limited walking ability but able to walk for more than 500 m without aid or rest), a score of 6 (ability to walk with unilateral support no more than 100 m without rest), and a score of 7 (ability to walk no more than 10 m without rest while leaning against a wall or holding onto furniture for support). We used Kaplan-Meier analyses to determine the influence of relapses on the time to the onset of irreversible disability. The median times from the onset of multiple sclerosis to the assignment of a score of 4, a score of 6, and a score of 7 on the disability scale were longer among the 1562 patients with a relapsing-remitting onset of disease (11.4, 23.1, and 33.1 years, respectively) than among the 282 patients who had progressive disease from the onset (0.0, 7.1, and 13.4 years, respectively; P<0.001 for all comparisons). In contrast, the times from the assignment of a score of 4 to a score of 6 were similar in the two groups (5.7 and 5.4 years, P=0.74). The time course of progressive, irreversible disease among patients with the primary progressive type of multiple sclerosis was not affected by the presence or absence of superimposed relapses. Among patients with multiple sclerosis, relapses do not significantly influence the progression of irreversible disability.

Influence of alteration of occlusal relationship on activity of jaw closing muscles and mandibular movement during submaximal clenching.

The aim of this study was to investigate the relationships between occlusal contacts, responses of muscles, and jaw movements during simulated clenching. Seven healthy human males who possessed complete natural dental arches with normal occlusion, ranging from 24 to 29 years of age, volunteered for this study. Acrylic occlusal stops were fabricated for the lower jaw to simulate various occlusal conditions. Vertical movements of the lower jaw were measured by four sets of linear variable differential transformers. Simultaneously, electromyographic (EMG) activity from the bilateral masseter and anterior temporal muscles was measured. Under experimentally altered occlusal conditions, the subjects performed clenching tasks at 50% of their maximal voluntary contraction level. Analysis of EMG responses revealed clenching on the unilateral occlusal support tended to cause a unilateral activity of the ipsilateral anterior temporalis. Analysis of the movement amplitude revealed a significant difference between the experimental occlusal conditions (P < 0.05). Clenching on unilateral occlusal stops caused a larger upward movement on the contralateral side. Bilateral first premolar clenching without molar support caused a larger upward movement of the mandible in the posterior region, whereas bilateral second molar clenching did not cause a significant upward movement.

Reciprocated community support and small town - small business success

This paper presents an empirical test of the significance of reciprocated community support, in contrast with traditional economic factors and unilateral support, in the success of small businesses in small towns. The central hypothesis is that entrepreneurs who make non-market contributions to their community and whose community supports them, are more likely to consider their businesses to be successful. Logistic regression is used to analyse survey data from over 800 small businesses in 30 small towns of the state of Iowa (USA). The authors found that the interaction effect of an entrepreneur's service to the community, reciprocated by community support of the business, is the single most significant determinant of business success among dozens of indicators and characteristics of the respondent, the business, and the small towns in the sample. In addition, it was found that business people who feel successful expect to expand. These findings are relevant to rural development. The expansion of existing businesses is an important component of regional job growth.