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Journal: Gait & posture


The purpose of this study was to describe the effects of lower limb positioning and shoe conditions on stability levels of selected single leg ballet poses performed in demi-pointe position. Fourteen female non-professional ballet dancers (mean age of 18.4±2.8 years and mean body mass index of 21.5±2.8kg/m) who had practiced ballet for at least seven years, without any musculoskeletal impairment volunteered to participate in this study. A capacitive pressure platform allowed for the assessment of center of pressure variables related to the execution of three single leg ballet poses in demi pointé position: attitude devant, attitude derriére, and attitude a la second. Peak pressures, contact areas, COP oscillation areas, anterior-posterior and medio-lateral COP oscillations and velocities were compared between two shoe conditions (barefoot versus slippers) and among the different poses. Barefoot performances produced more stable poses with significantly higher plantar contact areas, smaller COP oscillation areas and smaller anterior-posterior COP oscillations. COP oscillation areas, anterior-posterior COP oscillations and medio-lateral COP velocities indicated that attitude a la second is the least challenging and attitude derriére the most challenging pose.

Concepts: Mass, Body mass index, Oscillation, Performance, Pressure, Ballet, Human leg, Positioning


Many biomechanical studies investigated pathology of flatfoot and effects of operations on flatfoot. The majority of cadaveric studies are limited to the quasistatic response to static joint loads. This study examined the unconstrained joint motion of the foot and ankle during stance phase utilizing a dynamic foot-ankle simulator in simulated stage 2 posterior tibial tendon dysfunction (PTTD). Muscle forces were applied on the extrinsic tendons of the foot using six servo-pneumatic cylinders to simulate their action. Vertical and fore-aft shear forces were applied and tibial advancement was performed with the servomotors. Three-dimensional movements of multiple bones of the foot were monitored with a magnetic tracking system. Twenty-two fresh-frozen lower extremities were studied in the intact condition, then following sectioning peritalar constraints to create a flatfoot and unloading the posterior tibial muscle force. Kinematics in the intact condition were consistent with gait analysis data for normals. There were altered kinematics in the flatfoot condition, particularly in coronal and transverse planes. Calcaneal eversion relative to the tibia averaged 11.1±2.8° compared to 5.8±2.3° in the normal condition. Calcaneal-tibial external rotation was significantly increased in flatfeet from mean of 2.3±1.7° to 8.1±4.0°. There were also significant changes in metatarsal-tibial eversion and external rotation in the flatfoot condition. The simulated PTTD with flatfoot was consistent with previous data obtained in patients with PTTD. The use of a flatfoot model will enable more detailed study on the flatfoot condition and/or effect of surgical treatment.

Concepts: Foot, Simulation, Normal distribution, Classical mechanics, Cultural studies, Ankle, Transverse plane, Arches of the foot


Pedobarography is commonly employed in patients with diabetic peripheral neuropathy (DPN). However there is no evidence regarding test-retest reliability of this technique in this population, and therefore it was the purpose of the current study to address this clear gap. Dynamic plantar loading and foot geometry data were collected during barefoot gait with the EMED platform (Novel GmbH, Germany) from 10 patients with DPN over two sessions, separated by 28 days. Intra-class Correlation Coefficients (ICCs) and Coefficients of Variation (CoVs) were calculated to determine test-retest reliability. For dynamic plantar loading, reliability differed by outcome measure and foot region, with ICCs of >0.8 and CoVs of <15% observed in most cases. For dynamic foot geometry, ICCs of >0.88 and CoVs of <3% were observed for hallux angle, arch index and coefficient of spreading, while sub-arch angle was less reliable (ICC 0.76, CoV 23%). Overall, the current study observed high levels of test-retest reliability which were generally commensurate with that previously reported in healthy populations.

Concepts: Foot, Reliability, Algebra, Test-retest, Comparison of assessments, Peripheral neuropathy, Diabetic neuropathy, Gait abnormality


Impaired gait may contribute to the increased rate of falls in cognitively impaired older people. We investigated whether gait under simple and dual task conditions could predict falls in this group. The study sample consisted of 64 community dwelling older people with mild to moderate cognitive impairment. Participants walked at their preferred speed under three conditions: (a) simple walking, (b) walking while carrying a glass of water and © walking while counting backwards from 30. Spatiotemporal gait parameters were measured using the GAITRite(®) mat. Falls were recorded prospectively for 12months with the assistance of carers. Twenty-two (35%) people fell two or more times in the 12month follow-up period. There was a significant main effect of gait condition and a significant main effect of faller status for mean value measures (velocity, stride length, double support time and stride width) and for variability measures (swing time variability and stride length variability). Examination of individual gait parameters indicated that the multiple fallers walked more slowly, had shorter stride length, spent longer time in double support, had a wider support width and showed more variability in stride length and swing time (p<0.05). There was no significant interaction between gait condition and faller status for any of the gait variables. In conclusion, dual task activities adversely affect gait in cognitively impaired older people. Multiple fallers performed worse in each gait condition but the addition of a functional or cognitive secondary task provided no added benefit in discriminating fallers from non-fallers with cognitive impairment.

Concepts: Cognitive psychology, Units of measurement, International System of Units, Walking, Height, Length, Locomotion, SI base unit


Postural instability is a major unmet need in the treatment of Parkinson’s disease (PD) and its progression is not well understood. This study examined compensatory stepping taken in response to a backwards waist pull in participants with moderate PD (H&Y III) compared to age-range matched healthy controls (HC). The first step in the response was quantified in terms of strategy, temporal, kinematic, and center of pressure (COP) parameters previously observed to be significantly different in mild PD (H&Y II) compared to HC. Patients with moderate PD, compared to HC, utilized more steps to regain balance, had a longer weight-shift-time, and utilized a base-width neutral step to regain balance. However, there were no differences in ankle angle or COP location at landing as observed in mild PD, possibly due to the use of the base-width neutral step. These results suggest that moderate PD significantly impairs the compensatory response to a backwards pull. Further study should examine the progression of impairment in compensatory responses across PD severity levels, and the correlation with fall risk.

Concepts: Neurology, Parkinson's disease, Knowledge, Classical mechanics, James Parkinson, TVB Anniversary Awards, Balance disorder


Pregnant women experience numerous physical alterations during pregnancy which may place them at an increased risk of falls. The purpose of this study was to examine ground reaction forces (GRFs) during staircase locomotion in pregnant and non-pregnant women. METHODS: Data were collected on 29 pregnant women in their second and third trimesters, and on 40 control women. Subjects walked at their freely chosen speeds during stair ascent and descent. A force plate imbedded in the second stair, but structurally independent of the staircase, was used to collect GRF data (1080Hz). A marker placed on the L3/L4 spinal segment was used to determine ascent and descent velocity from a motion-capture system. In the statistical analyses, trimester (control, second trimester, third trimester) and subject were the independent variables. Stance time and ascent/descent velocity were analyzed with an ANOVA. Mediolateral excursion of the COP during the step was analyzed with an ANCOVA. The GRFs were categorized into anterioposterior, mediolateral, and vertical forces. A two factor MANCOVA (subject, trimester) was performed on each GRF category. Mass and velocity served as covariates in each analysis (a=0.05). RESULTS: The mediolateral excursion of the COP during ascent was greater in the third trimester (p=0.04). The anterioposterior braking impulse was greater in both ascent (p=0.01) and descent (p=0.01) during pregnancy. The vertical GRF loading rate during descent was greater in pregnant women than in controls (p=0.04). CONCLUSION: These alterations are likely related to increased instability during stairway walking and could contribute to increased fall risk during pregnancy.

Concepts: Pregnancy, Childbirth, Force, Walking, Reaction, Ground reaction force, Trimester, Stairway


High-heeled shoes are associated with instability and falling, leading to injuries such as fracture and ankle sprain. Knowledge of the motion of the body’s center of mass (COM) with respect to the center of pressure (COP) during high-heeled gait may offer insights into the balance control strategies and provide a basis for approaches that minimize the risk of falling and associated adverse effects. The study aimed to investigate the influence of the base and height of the heels on the COM motion in terms of COM-COP inclination angles (IA) and the rate of change of IA (RCIA). Fifteen females who regularly wear high heels walked barefoot and with narrow-heeled shoes with three heel heights (3.9cm, 6.3cm and 7.3cm) while kinematic and ground reaction force data were measured and used to calculate the COM and COP, as well as the temporal-distance parameters. The reduced base of the heels was found to be the primary factor for the reduced normalized walking speed and the reduced frontal IA throughout the gait cycle. This was achieved mainly through the control of the RCIA during double-leg stance (DLS). The heel heights affected mainly the peak RCIA during DLS, which were not big enough to affect the IA. These results suggest young adults adopt a conservative strategy for balance control during narrow-heeled gait. The results will serve as baseline data for future evaluation of patients and/or older adults during narrow-heeled gait with the aim of reducing the risk of falling.

Concepts: Force, Classical mechanics, Walking, Reaction, Ground reaction force, Newton's laws of motion, Heel, High-heeled footwear


The purpose of the study was to examine the accuracy of inclinometer functions of the ActiGraph GT3X+ (AG) (worn on the waist and wrist) and the activPAL (AP) in assessing time spent sitting, standing, and stepping.

Concepts: Insomnia, Gottfried Leibniz


The high energy cost of paraplegic walking using a reciprocating gait orthosis (RGO) is attributed to limited hip motion and excessive upper limb loading for support. To address the limitation, we designed the hip energy storage walking orthosis (HESWO) which uses a spring assembly on the pelvic shell to store energy from the movements of the healthy upper limbs and flexion-extension of the lumbar spine and hip and returns this energy to lift the pelvis and lower limb to assist with the swing and stance components of a stride. Our aim was to evaluate gait and energy cost indices for the HESWO compared to the RGO in patients with paraplegia.

Concepts: Kinetic energy, Pelvis, Human anatomy, Capacitor, Upper limb, Sacrum, Limb, Limbs


Although the vast majority of hamstring injuries in male soccer are sustained during high speed running, the association between sprinting kinematics and hamstring injury vulnerability has never been investigated prospectively in a cohort at risk.

Concepts: The Association, Injury