Line Walking Research Articles

Turning in Parkinson's disease patients and controls: The effect of auditory cues

Turning is an impaired activity in persons with Parkinson's disease (PwPD). The current study examines the turning characteristics in PwPD (9 freezers and 10 nonfreezers) and 9 controls, and explores the effect of rhythmic auditory cues while turning. Turning parameters were collected from a 180 degrees left U-turn during a noncued and a cued condition, using a 3D measuring system. Auditory cues were supplied with a metronome at a rhythm equaling the subject's comfortable step frequency during straight line walking. Results showed that in contrast to controls, PwPD used a wider turning-arc and took smaller, narrower steps. In addition, they demonstrated a higher Coefficient of Variation (CV) of step duration (6.92%) compared to controls (4.88%, P < 0.05). The "wide-arc" turning strategy of PwPD was more prominent in freezers than in nonfreezers. Auditory cues reduced the CV of step duration in PwPD (both freezers and nonfreezers) during turning (from 6.92 to 6.00%, P < 0.05). In summary: Cueing reduced the gait-timing variability during turning, but PwPD maintained a wider arc to turn compared with controls.

Pedometer accuracy in physical activity assessment of preschool children

Yamax SW-200 pedometer validity during unstructured free play was assessed in 13 preschool children aged 4.1+/-0.6 years using the Children's Activity Rating Scale (CARS). Pedometer validity and hip placement reliability were also assessed during straight line walking. Data were analysed using regression analyses, 95% upper and lower prediction intervals and 95% limits of agreement. The prediction intervals for pedometry were wide when using the CARS as a criterion. Limits of agreement and prediction intervals for directly observed step counts were also wide for pedometers, calling into question their acceptability for use with preschoolers. Limitations of employing the CARS direct observation approach as a criterion measure of physical activity are also discussed.

The kinematics and kinetics of turning: limb asymmetries associated with walking a circular path

The biomechanics of changing direction while walking has been largely neglected despite its obvious relevancy to functional mobility. The world is filled with turns that must be negotiated. These turns carry an increased risk of injury due to a decrease in stability. A VICON 612 system measured joint kinematics and kinetics on 10 normal subjects for straight line walking (ST); turning, inside foot strike (IN); and turning, outside foot strike (OUT). All trials were completed at a self-selected walking speed and across a range of speeds from 0.6 to 1.3 m/s; the turn radius was 1 m. Significant differences between the conditions were detected using a mixed effects repeated measures ANCOVA with walking speed as a covariate. The most pronounced differences were demonstrated in the mediolateral ground reaction force impulse: in straight walking the impulses tended to shift the body toward the contralateral limb. In turning, the IN and OUT impulses shifted the body toward the ipsilateral and contralateral limbs, respectively. Knee flexion during stance was increased on the IN limb, while ankle plantarflexion increased on the OUT limb consistent with body lean during turning; differences in joint kinetics during turning were negligible. Self-selected turning was significantly slower than walking straight ahead (0.96+/-0.12 m/s versus 1.61+/-0.22 m/s) and turning at very slow speeds showed a non-uniform center of mass trajectory. Understanding the mechanisms of turning will provide insights driving design, therapy and intervention to increase functional navigation in amputees, the elderly and individuals with neuromuscular pathologies.

The Homeopathic Preparation Vertigoheel® Versus Ginkgo biloba in the Treatment of Vertigo in an Elderly Population: A Double-Blinded, Randomized, Controlled Clinical Trial

Alternative medical practices are common in the treatment of vertigo. This study compared the effects of Ginkgo biloba treatment with the homeopathic remedy Vertigoheel (Biologische Heilmittel Heel GmbH, Baden-Baden, Germany). Randomized, double-blinded, parallel group study. One hundred and seventy (170) patients, ages 60-80 years, with atherosclerosis-related vertigo. Patients were randomly allocated to receive treatment with either Vertigoheel (n = 87) or G. biloba (n = 83). The results were analyzed for the non-inferiority of Vertigoheel to G. biloba on the combined endpoint of changes from baseline to week 6 in dizziness score (assessed by questionnaire), frequency, duration, and intensity of vertigo episodes (recorded in patient diaries). Both treatments improved vertigo status. From a baseline mean value of 26.1 +/- 5.2 (on a 50-point scale) in the Vertigoheel group, the dizziness questionnaire score improved by -10.6 +/- 10.0, and by -10.7 +/- 9.0 from 25.8 - 4.7 in the G. biloba group. Statistical analysis of this endpoint showed that Vertigoheel was not inferior to G. biloba. The 95% confidence interval for the difference between treatment did not reach the inferiority threshold of 0.36 at any of the time points tested. The results were supported by the results of a line walking test, Unterberger's stepping test, and patient and physician global assessments of therapeutic effect. Both treatments were well tolerated. Vertigoheel is an appealing alternative to established G. biloba therapy for atherosclerosis-related vertigo.

Effects of age on balance control during walking

Shkuratova N, Morris ME, Huxham F. Effects of age on balance control during walking. Arch Phys Med Rehabil 2004;85:582–8. Objective To determine the effects of aging on balance control during walking. Design Two-group repeated-measures design. Setting Gait laboratory in Australia. Participants Convenience sample of 20 healthy older subjects (mean age, 72y) and 20 healthy young subjects (mean age, 24y). Interventions Changes in locomotor performance in response to perturbations to balance were quantified for healthy older adults compared with healthy young adults for (1) straight line walking at preferred speed, (2) straight line walking at fast speed, (3) figure-of-eight walking at preferred speed, and (4) figure-of-eight walking while performing a secondary motor task. Main outcome measures Gait speed, stride length, cadence, and double-limb support duration, using a footswitch system. Results Healthy older people screened for pathology had gait patterns comparable to young adults for straight line walking at preferred speed. However, multivariate analysis of variance (MANOVA) showed a significant interaction between age and speed when balance was perturbed by requiring subjects to change from walking at preferred to fast speeds (Pillai-Bartlett trace=.259, F 4,35=3.06, P<.029, partial η 2=.259). This occurred because older people did not increase their speed (F 1,38=7.65, P<.01, partial η 2=.168) or stride length (F 1,38=12.23, P<.01, partial η 2=.243) as much as did the young adults. MANOVAs did not show statistically significant interactions between age and turning conditions or age and dual task conditions, although older people walked more slowly and with shorter steps when turning or performing a secondary task. Conclusions Balance strategies during gait are task specific and vary according to age. In response to challenges to balance imposed by the requirement to change from preferred to fast walking, older people did not increase their speed and stride length to the same extent as did younger adults. This was possibly a strategy to maintain their stability.

The biomechanics and motor control of gait in Parkinson disease

Parkinson disease is a progressive neurological condition characterised by hypokinesia (reduced movement), akinesia (absent movement), tremor, rigidity and postural instability. These movement disorders are associated with a slow short-stepped, shuffling gait pattern. Analysis of the biomechanics of gait in response to medication, visual cues, attentional strategies and neurosurgery provides insight into the nature of the motor control deficit in Parkinson disease and the efficacy of current therapeutic interventions. In this article we supplement a critical evaluation of the Parkinson disease gait literature with two case examples. The first case describes the kinematic gait response of an individual with Parkinson disease to visual cues in the “off” phase of the levodopa medication cycle. The second case investigates the biomechanics and motor control of turning during walking in a patient with Parkinson disease compared with elderly and young control subjects. The results are interpreted in light of the need for gait analysis to investigate complex functional walking tasks rather than confining assessment to straight line walking, which has been the trend to date.

A neurological and neurophysiological study of chloralkali workers previously exposed to mercury vapour

Neurological and neurophysiological examinations were conducted in 77 former chloralkali workers previously exposed to mercury vapour and 53 referents. The exposure had ceased on average 12.3 years prior to the study. There was a higher prevalence of reduced distal sensation (13.0% vs 1.9%), postural tremor (18.2% vs 7.5%) and impaired coordination (10.4% vs 1.9%) among the exposed subjects as compared to the referents. Abnormal Romberg's test (6.5% vs 0%) and line walking (7.8% vs 0%) were also more prevalent. The first negative peak in visual evoked response (N75) was bilaterally prolonged, and the median motor (55.9 m/s vs 58.0 m/s) and sensory nerve conduction velocity (55.6 m/s vs 59.0 m/s) were slightly reduced among the highly exposed subjects. The results indicate that slight neurological abnormalities, which in most cases could not be classified as disease, may persist many years after exposure cessation.

Computer-aided design of a leg for an energy efficient walking machine

Vehicles with legs instead of wheels have been studied for a number of years. One of the reasons for interest in such vehicles is that animals use only 10% as much energy as wheeled or tracked vehicles when traveling over rough terrain. The leg geometry is the most crucial aspect of the design since it strongly influences the efficiency of the vehicle. The legs should be simple in structure, and when the motion of the body is on a horizontal straight line, only one actuator per leg should be active in order to have good energy efficiency. The design of an energy efficient walking machine leg is described in this paper. In the design procedure, the motion of the leg is considered first, and a very simple leg developed from a 4-bar linkage and designed using a computer-aided interactive program is described. Second, the forces on this leg during a typical motion cycle are discussed. The leg is driven by a primary actuator for straight line walking and two secondary actuators which vary working height and change direction. A prototype of the leg is being built in The Department of Mechanical Engineering at The Ohio State University.

The control of walking in orthoptera

ABSTRACT A brief description is given of the anatomy, innervation and mechanical properties of the extensor tibiae muscles of the locust. Each is innervated by a ‘fast’ (FETi) and ‘slow’ (SETi) excitatory axon, one branch of a common inhibitor (Cl) and a fourth small axon (DUMETi). The prothoracic and mesothoracic extensors contract more rapidly than the metathoracic muscle but exhibit a stronger ‘catch’, which can be relaxed by Cl or FETi activity. Records were made of electrical activity in the extensor motor nerves in all the legs of locusts and lubber grasshoppers. During standing only the SETi axons were active. During straight line walking in the locust all three motor axons were active, except in the metathoracic leg. A detailed descrip­tion of the activity pattern of each axon is given. The activity in the grass­hopper was similar, but rather more variable. Measurements were made of the mechanical responses of the extensor muscles to these patterns of activity. As walking speeds increased the response to SETi activity approached a constant tension or muscle length which could be strongly modulated by the phasic contractions due to FETi activity. It is suggested that the timing of SETi activity is only important at low walking speeds, and that at high speeds it simply provides a return force for the flexor muscle. The Cl produces a slow effect and fires at the wrong time in the step to phasically relax the prothoracic or mesothoracic extensors, so it is suggested that its main role is in the relaxation of coxal muscles. The sources of motor neurone activity are discussed.

SALICYLATE SENSITIVITY IN CHILDREN REPORTED TO RESPOND TO SALICYLATE EXCLUSION

Twelve children, aged six to 13 years, whose parents reported an improvement in behavioural problems with use of the Feingold (K-P) diet for an average period of 12 months, were challenge-tested with 40 mg of acetylsalicylic acid in a double-blind, cross-over trial with ascorbic acid as a placebo. The children were tested within three hours of ingestion of either the experimental or placebo tablet with a battery of psychological and neurological tests, and were rated by a parent on an enlarged Conners' Parent-Teacher Questionnaire for four days after the ingestion of the tablet. It was found that significance was reached in tests of general cognitive capacity, line walking and the "finger-to-nose" tests, as well as increased disturbance in sleep patterns in these children.