Somatosensory impairment and its association with balance limitation in people with multiple sclerosis

BackgroundSomatosensory impairments are common in multiple sclerosis. However, little data are available to characterize the nature and frequency of these problems in people with multiple sclerosis.ObjectiveTo investigate the frequency of somatosensory impairments and identify any association with balance limitations in people with multiple sclerosis.MethodsThe design was a prospective cross-sectional study, involving 82 people with multiple sclerosis and 30 healthy controls. Tactile and proprioceptive sensory acuity were measured using the Rivermead Assessment of Somatosensory Performance. Vibration duration was assessed using a tuning fork. Duration for the Timed Up and Go Test and reaching distance of the Functional Reach Test were measured to assess balance limitations. The normative range of sensory modalities was defined using cut-off points in the healthy participants. The multivariate linear regression was used to identify the significant predictors of balance in people with multiple sclerosis.ResultsProprioceptive impairments (66.7%) were more common than tactile (60.8%) and vibration impairments (44.9%). Somatosensory impairments were more frequent in the lower limb (78.2%) than the upper limb (64.1%). All sensory modalities were significantly associated with the Timed Up and Go and Functional Reach tests (p < 0.05). The Timed Up and Go test was independently predicted by the severity of the neurological lesion, Body Mass Index, ataxia, and tactile sensation (R2 = 0.58), whereas the Functional Reach test was predicted by the severity of the neurological lesion, lower limb strength, and vibration sense (R2 = 0.49).ConclusionsSomatosensory impairments are very common in people with multiple sclerosis. These impairments are independent predictors of balance limitation.     

The correlation between symptomatic fatigue to definite measures of gait in people with multiple sclerosis

There is a general consensus relating to the multidimensional aspects of fatigue in people with multiple sclerosis (PwMS), however, the exact impact of this symptom on gait is not fully understood. Our primary aim was to examine the relationship between definite parameters of gait with self-reported symptomatic fatigue in PwMS according to their level of neurological impairment. Spatio-temporal parameters of gait were studied using an electronic walkway. The Multiple Sclerosis Walking Scale (MSWS-12) questionnaire, a patient-rated measure of walking ability was collected. The Modified Fatigue Impact Scale (MFIS) questionnaire was used to determine the level of symptomatic fatigue. One hundred and one PwMS (61 women) were included in the study analysis. Subjects were divided into mild and moderate neurological impaired groups. Fatigue was correlated with 5 (out of 14) spatiotemporal parameters. However, correlation scores were all <0.35, thus considered as weak correlations. In the mild group, the double support period was the only variable positively correlated to fatigue (Spearman's rho = 0.28, P = 0.05). In the moderate group, step and stride length were solely negatively correlated to fatigue (Spearman's rho = 0.32, P = 0.03). In contrast to the definite gait parameters, the MSWS-12 self-questionnaire was moderately positively correlated to the level of fatigue. Scores for the total, mild and moderate groups were 0.54, 0.57 and 0.51; P < 0.01, respectively. The present results indicate that modifications in spatio-temporal parameters of gait are not closely related to symptomatic fatigue in PwMS. On the contrary, the self-reported MSWS-12 questionnaire is predisposed to level of fatigue in PwMS.     

The Romberg ratio in people with multiple sclerosis

Postural control relies on the integration of inputs from the visual, somatosensory and vestibular systems which are frequently impaired in people with Multiple Sclerosis (PwMS). In this situation, examining the Romberg ratio can be useful. This parameter can be interpreted as a gross indicator of a vestibular and proprioceptive contribution to postural control. Therefore, the primary objective of the current study was to examine whether the Romberg ratio differs between MS fallers, non-fallers and neurological disability levels. In addition, we clarified the association between the Romberg ratio values with validated gait and the balance tests in PwMS. Romberg ratio values were calculated according to the sway rate, total sway area and center of pressure (CoP) path length. The patient group included 542 PwMS (337 women) with a mean age of 42.3 (S.D = 13.8). In terms of fall status, significant differences were observed between the faller (n = 287) and non-faller (n = 255) groups solely in terms of the Romberg ratio-ellipse sway area: 2.76 (S.D = 2.46) vs. 2.24 (S.D = 2.01), P-value = 0.01. A significant increase in the Romberg ratio was found between the severe group (n = 50), the very mild (n = 245), mild (n = 186) and moderate (n = 61) groups for each of the three Romberg ratio quotients. Significant weak correlation scores were found between the Romberg ratio-ellipse sway area and all walking and balance outcome measures; the Pearson’s rho ranged from 0.172 to 0.270. The present data suggest that an elevated Romberg ratio quotient, especially according to the sway area, is an indicator of poor walking and balance capabilities in PwMS.     

Dynamically adjustable foot-ground contact model to estimate ground reaction force during walking and running

Human dynamic models have been used to estimate joint kinetics during various activities. Kinetics estimation is in demand in sports and clinical applications where data on external forces, such as the ground reaction force (GRF), are not available. The purpose of this study was to estimate the GRF during gait by utilizing distance- and velocity-dependent force models between the foot and ground in an inverse-dynamics-based optimization. Ten males were tested as they walked at four different speeds on a force plate-embedded treadmill system. The full-GRF model whose foot-ground reaction elements were dynamically adjusted according to vertical displacement and anterior-posterior speed between the foot and ground was implemented in a full-body skeletal model. The model estimated the vertical and shear forces of the GRF from body kinematics. The shear-GRF model with dynamically adjustable shear reaction elements according to the input vertical force was also implemented in the foot of a full-body skeletal model. Shear forces of the GRF were estimated from body kinematics, vertical GRF, and center of pressure. The estimated full GRF had the lowest root mean square (RMS) errors at the slow walking speed (1.0 m/s) with 4.2, 1.3, and 5.7% BW for anterior–posterior, medial–lateral, and vertical forces, respectively. The estimated shear forces were not significantly different between the full-GRF and shear-GRF models, but the RMS errors of the estimated knee joint kinetics were significantly lower for the shear-GRF model. Providing COP and vertical GRF with sensors, such as an insole-type pressure mat, can help estimate shear forces of the GRF and increase accuracy for estimation of joint kinetics.     

Acute effects of axial loading on postural control during walking and turning in people with multiple sclerosis: A pilot study

BackgroundImpaired sensory integration is heavily involved in gait control and accentuates fall risk in individuals with multiple sclerosis (MS). While axial loading has been found beneficial, little is known about the effect of non-specific axial loads on gait parameters and mobility tasks in those with MS. Research Question: What are the effects of non-specific axial loading via weighted vests on walking and turning in those with MS.MethodsTwelve participants with MS and eleven age- and gender-matched healthy controls participated in a cross-sectional study. All participants completed five trials of continuous walking with turns wearing weighted vests at 0%, 2%, 4%, 5%, and then 0% of their body weight. Gait parameters were measured using wireless inertial sensors. A 2 (group) x 5 (vest weight) multivariate analysis of variance (MANOVA) was performed to determine any significant differences between groups and across weighted vests for each gait variable. Post-hoc analysis and paired t-tests with corresponding effect sizes were also conducted.ResultsA significant between groups main effect was found for group (F (6100) = 14.74, p = .000) in multiple gait parameters (p < 0.05), although no significant main effect was found for weighted vest. Within group analyses indicated significantly increased cadence and gait speed across varying weighted vests for both MS and control groups (p < 0 >05). Increased vest weight from 0%PRE to 2% also had large effect on shortening double support time and increasing stride length in the MS group.SignificanceThis study provided preliminary evidence that non-specific axial loads of varying weights appear to improve certain gait parameters. As such, this modality may offer mobility benefit and serve as an accessible home-based intervention alternative aimed at improving walking in individuals with MS.     

The effect of a home-based stretching exercise on the ground reaction force generation and absorption during walking in individuals with plantar fasciitis

ObjectivesThis study aimed to investigate effect of a home-based stretching exercise program in individuals with plantar fasciitis (PF) and to compare its effect on ground reaction force (GRF)-time variables between mild, moderate, and severe pain subgroups and between before and after in each subgroup.DesignA single cohort with pre-and post-test.InterventionsTwenty individuals with PF received 3 weeks of home-based stretching exercise for calf and plantar fascia.Main outcome measuresGRF-time variables included force and time at; first peak (F1 and TF1), valley (F2 and TF2), second peak (F3 and TF3) in vertical, breaking (F4 and TF4) and propulsive (F5 and TF5) forces, first peak (F6 and TF6) and second peak lateral (F7 and TF7) forces. Additionally, worst pain was assessed at before and after exercise.ResultsSignificant reductions were seen in F2, TF2, TF3, TF5 and worst pain after exercise (P < 0.05) in individuals with PF. No differences were seen between three subgroups. For within subgroup analysis, only mild subgroup showed significant changes in F2, TF2, F4, TF6, and TF7 after exercise (P < 0.05).ConclusionA home-based stretching exercise was effective in reducing pain and some GRF-time variables, with the most noticeable response seen in mild subgroup.     

Ground reaction force adaptation during cross-slope walking on railroad ballast

Background: Walking on railroad ballast is a unique challenge for railroad workers and contributes to a large number of falls and slips. However, the characteristics of ground reaction force (GRF) when walking on ballast combined with a cross-slope condition are poorly understood.Research question: How does the magnitude and temporal distribution of GRF change during walking on railroad ballast combined with a cross-slope condition?Methods: Eight experienced railroad workers walked with their self-selected speed on three surfaces (mainline ballast, walking ballast and no ballast) in both a level and cross-slope (7°) condition. The magnitude and time of occurrence of selected key features of the GRF were extracted from the force plate. A two-factor repeated measures ANOVA was used to determine the effect of surface and cross-slope condition.Results: The minimum anteroposterior GRF and the first peak of the normal GRF occurred earlier on mainline ballast and walking ballast than no ballast. The maximum anteroposterior GRF was smaller, but the first peak of the normal GRF was larger on walking ballast compared with no ballast. Additionally, the asymmetrically mediolateral GRFs were observed between upslope limb and downslope limb in the cross-slope condition, which were also significantly different from the level condition.Significance: Ballast combined with a cross-slope condition posed a higher requirement for dynamic control to prevent downslope slippage and body instability, which could increase the fall risk for railroad workers. Future studies should investigate interventions to improve dynamic balance and reduce foot slippage on ballast.     

Time-integrated propulsive and braking impulses do not depend on walking speed

BackgroundEnhancing propulsion during walking is often a focus in physical therapy for those with impaired gait. However, there is no consensus in the literature for assessing braking and propulsion. Both are typically measured from the anterior-posterior ground reaction force (AP-GRF). While normalization of AP-GRF force by bodyweight is commonly done in the analysis, different methods for AP-GRF time axis normalization are used.Research questionDoes walking speed affect propulsion and/or braking, and how do different methods for calculating propulsion and braking impact the conclusion, in both healthy adults and those with lower limb impairment?MethodsWe investigated three different analysis methods for assessing propulsion. 1. BW-TimeIntegration: Bodyweight (BW) normalized time integration of AP-GRF (units of BWs). 2. BW-%StanceIntegration: BW normalized AP-GRF is resampled to percent stance phase prior to integration (units of BW%Stance). 3. BW-Peak: BW normalized peak force (units of BW). We applied these methods to two data sets. One data set included AP-GRFs from trials of slow, self-selected, and fast walking speeds for 203 healthy controls (HCs); a second data set included subjects with lower limb orthopedic injuries.ResultsUsing the BW-TimeIntegration method, we found no effect of walking speed on propulsion for HCs. Time integration over the longer stance phase of slower walking balanced the lower magnitude AP-GRFs of slower walking, resulting in a time-integrated impulse that was the same regardless of walking speed. In contrast, the other two methods that are not time integration methods found that propulsion increased with walking speed. Similarly, in the gait pathology data set, differences in results were found depending on the analysis method used.SignificanceFor many gait studies concerning propulsion and/or braking, the impulse measure used should be related to the body’s change of momentum, necessitating an analysis method with a time integration of the AP-GRF.     

Influence of the environment on cognitive-motor interaction during walking in people living with and without multiple sclerosis

BackgroundMotor and cognitive impairments are highly prevalent in people with multiple sclerosis (pwMS). The current theoretical frameworks of cognitive-motor interaction (CMI) suggest that the environment can influence both motor and cognitive performance during walking. However, the relationship between increasing environmental demands and CMI in pwMS remains to be elucidated.Research questionWhat is the impact of increased environmental demands on CMI during walking in people living with and without MS?MethodsTwenty pwMS and 20 age-matched healthy adults (HA) participated in this cross-sectional study. Participants (age = 57.6 ± 7.8 years) performed four walks (baseline walking (BW), obstacle walking (OW), narrow walking (NW), and narrow with obstacles (NO)) in single-task and dual-task (serial-7 subtraction test) conditions. The dual-task costs (DTC) of gait (% change in walking time) and cognition (% change in correctly verbalized utterances) were calculated to quantify CMI. Secondary outcomes included physiological profile assessment (PPA), measures of cognition and falls efficacy scale international (FES-I).ResultsMixed-factor ANOVAs revealed no main effect of task (F = 1.71, p = 0.196) and group (F = 0.71, p = 0.406) on DTC of gait, while there were significant main effects of both task (F = 23.75, p < 0.001) and group (F = 6.53, p = 0.015) on DTC of cognition. Simple main effects revealed that pwMS had a significantly higher DTC of cognition during BW (+37.6 %, p=0.013), NW (+34.2 %, p=0.014) and NO (+49 %, p=0.016) compared to HA. Additionally, DTC of cognition increased during the more environmentally demanding conditions compared to BW (range: +28.4 % to +54.2 %, all p-values<0.01) in both pwMS and HA. Only DTCs of cognition were significantly correlated with PPA and FES-I.SignificanceThe study findings suggest that CMI may be influenced by the individual/environment at levels above those described by the more mechanistic theories of attention.     

Relationship between foot sensation and standing balance in patients with multiple sclerosis

The aims of the present study were to investigate the relationship between the foot sensations and standing balance in patients with Multiple Sclerosis (MS) and find out the sensation, which best predicts balance. Twenty-seven patients with MS (Expanded Disability Status Scale 1-3.5) and 10 healthy volunteers were included. Threshold of light touch-pressure, duration of vibration, and distance of two-point discrimination of the foot sole were assessed. Duration of static one-leg standing balance was measured. Light touch-pressure, vibration, two-point discrimination sensations of the foot sole, and duration of one-leg standing balance were decreased in patients with MS compared with controls (p < 0.05). Sensation of the foot sole was related with duration of one-leg standing balance in patients with MS. In the multiple regression analysis conducted in the 27 MS patients, 47.6% of the variance in the duration of one-leg standing balance was explained by two-point discrimination sensation of the heel (R² = 0.359, p = 0.001) and vibration sensation of the first metatarsal head (R² = 0.118, p = 0.029). As the cutaneous receptors sensitivity decreases in the foot sole the standing balance impairs in patients with MS. Two-point discrimination sensation of the heel and vibration sensation of the first metatarsal head region are the best predictors of the static standing balance in patients with MS. Other factors which could be possible to predict balance and effects of sensorial training of foot on balance should be investigated.     

Construct validity of the walk ratio as a measure of gait control in people with multiple sclerosis without mobility aids

Ambulatory limitations are a key component of disability in people with multiple sclerosis (PwMS). Various tools are employed to assess walking performance in PwMS; however, no ideal measure has as yet been attained. In this situation, a walk ratio might be more advantageous compared with other gait measures. The walk ratio, a simple index for describing temporal and spatial co-ordination, denotes the relationship between step length and cadence during walking. Hence, the primary objective of this study was to determine the relationship between the walk ratio and measures of other theoretically related constructs. The walk ratio was studied using the GAITRite™ system (CIR Systems, Inc. Havertown, USA). The study group included 229 PwMS (143 women) and a mean disease duration of 5.8 (SD = 7.1) years. The walk ratio score of the total sample was 5.3 (SD = 0.8). Significant differences based on the expanded disability status scale (EDSS) scores (F = 11.616, P < 0.001) were observed between the neurological disability subgroups. Scores of the very mild (EDSS 0–2.0), mild (EDSS 2.5–4.0) and moderate (EDSS 4.5–5.5) groups were 5.5 (SD = 0.7), 5.2 (SD = 0.7), 4.9 (SD = 0.9), respectively. In terms of fall status, the MS fallers demonstrated a significant lower walk ratio compared to the MS non-fallers; 5.1 (SD = 0.8) vs. 5.5 (SD = 0.7); P < 0.001. Modest significant correlation scores were found between walk ratio and ambulation tests. Scores were slightly higher in the short walking tests, timed 25-foot walk and timed up and go tests (Pearson's rho = 0.369, 0.364) compared to the 6 and 2-min walk time tests (Pearson's rho = 0.344, 0.308). Collectively, the current study supports the construct validity of the walk ratio index in PwMS without mobility aids.     

The effect of visual field manipulations on standing balance control in people with multiple sclerosis

BackgroundMultiple sclerosis (MS) is associated with an increased risk of falls, degeneration of sensory organization, and possible increased reliance on vision for balance control.Research questionThe aim of this study was to assess differences in standing postural control between people with MS and age and sex matched controls during medial-lateral (ML) oscillations of the visual field, with and without blinders to the lower periphery.MethodsTen persons with MS (mean age 54.0 ± 5.3 years) and ten age and sex matched controls (mean age: 56.3 ± 6.0 years) participated in this study. Balance control was assessed while participants stood in a Christie Cave system while wearing stereoscopic glasses that projected an immersive forest scene. Visual conditions consisted of 2 m ML visual oscillations of the scene at five frequencies (0.0, 0.3, 0.6, 0.7 and 0.8 Hz) with and without blinders to block the lower periphery.Results and significanceThe results demonstrated that, in comparison to controls, participants with MS had a significantly larger center of pressure sway in both the ML and AP direction to ML visual oscillations. Additionally, participants with MS and controls both increased center of pressure frequency content to the visual oscillation frequency, while participants with MS also increased relative power at the visual oscillation frequency in the AP direction. Blinders of lower periphery reduced the percent power at the visual oscillation frequency in both groups and reduced overall sway in participants with MS during visual oscillations. Overall, results indicate that postural balance is sensitive to visual feedback in people with MS. The elicited AP sway to ML visual oscillation could reflect errors in visual processing for the control of balance, and decreased sway in response to blocking vision of the lower peripheral field could indicate an increased reliance on visual cues to maintain balance.     

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BackgroundFalls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations.Research questionDoes a relationship exist between gait variability, falls and the energy cost of gait in PwMS?MethodsThis cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test.ResultsThirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls.SignificanceWe demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.     

A robust machine learning enabled decomposition of shear ground reaction forces during the double contact phase of walking

BackgroundDynamic analyses of walking rely on the 3D ground reaction forces (GRF) under each foot, while only the resultant force of both limbs may be recorded on a single-belt instrumented treadmill or when both feet touch the same force platform.Research questionThis study aims to develop a robust decomposition of the shear GRF to complete the most accurate decomposition of the vertical GRF [8].MethodsA retrospective study of 374 healthy adults records (age: 22.8 ± 2.6 years, speed: 1.34 ± 0.28 m/s) and of 434 patient records (age: 21.3 ± 17.8 years, speed: 0.64 ± 0.19 m/s) were used in a machine learning process to develop a robust predictive model to decompose the fore-aft GRF. The lateral GRF was decomposed by resolving the equilibrium of transverse moments around the center of pressure.ResultsA predictive linear model of the fore-aft GRF under the back foot every 5% of the double contact phase was obtained from 2 predictors: the total fore-aft GRF and the vertical GRF under the back foot. Each predictor uses a time series of 31 samples before and during the double contact. The model performs accurately in healthy (median[IQR] error of 3.0[2.2–4.1]%) and in clinical gaits (7.7[4.7–13.4]%). The error in lateral GRF decomposition is of 5.7[3.9–10.2]% in healthy gaits and of 12.0[7.2–19.2]% in patients under the back foot and about half of that under the front foot.SignificanceThe decomposition of shear GRFs achieved in this study supports the mechanics of walking. It provides outstanding accuracy in healthy gait and also applies to neurologic and orthopedic disorders. Together with the vertical GRF decomposition [8], this approach for the shear components paves the way for robust single limb GRF determination on a single-belt instrumented treadmill or when both feet touch the same force platform in normal and clinical gait analysis.     

Anticipatory postural adjustment during gait initiation in multiple sclerosis patients: A systematic review

BackgroundMultiple sclerosis (MS) causes balance and walking disorders. Gait initiation is the complex transition between standing and walking and is characterized by two distinct phases: the anticipatory postural adjustment (APA) phase followed by the execution of the first step phase.Research aimTo determine alterations in the APA during gait initiation in patients with MS.MethodsA systematic search was conducted in May 2018. The search was carried out by the use of the following databases: PubMed, Web of Science and the Cochrane Library. The following keywords were used: MS, gait initiation, step initiation, and postural adjustment(s). Outcomes of interest were the variables generally used to assess APA, including electromyography, force-plate data, or video-based data, duration of APA, and length of first step. The Ottawa scale was used to assess the quality of the studies.ResultsEight case-control studies were included; one was a transverse study. A total of 215 MS patients and 116 healthy subjects were included with ages ranging from 22 to 76 years old. In MS patients, Expanded Disability Status Scale (EDSS) scores ranged from 0 to 7. APA CoP displacements were smaller in the anteroposterior axis. Four studies evaluated muscle activation during APA. The latencies of all muscles were delayed, and smaller magnitudes of muscle activity during APA were found, even in the early stage of disease. The first step was shorter in MS patients than in healthy patients. No previous study has reported joint movement or trunk inclination during gait initiation.SignificanceThis review illustrates the gap in knowledge of APA alterations in MS patients. APA assessment in the early stage of MS could be an interesting measure to characterize balance, dynamic control and risk of fall for such patients.     

Gait deficits in people with multiple sclerosis: A systematic review and meta-analysis

BackgroundMultiple Sclerosis (MS) results in postural instability and gait abnormalities which are associated with accidental falls.ObjectiveThis systematic review and meta-analysis aims to quantify the effect of MS on gait to inform the development of falls prevention interventions.MethodsA systematic literature search identified case-control studies investigating differences in gait variables between people with MS and healthy controls. Meta-analysis examined the effect of MS on gait under normal and fast paced conditions.ResultsForty-one studies of people with Expanded Disability Status Scale (EDSS) 1.8 to 4.5 were included, of which 32 contributed to meta-analysis. A large effect of MS was found on stride length (Standardised Mean Difference, SMD = 1.27, 95% CI{0.93, 1.61}), velocity (SMD = 1.12, 95% CI{0.85, 1.39}), double support duration (SMD = 0.85, 95% CI{0.51, 1.2}), step length (SMD = 1.15, 95% CI{0.75, 1.5})and swing phase duration (SMD = 1.23, 95% CI{0.06, 2.41}). A moderate effect was found on step width and stride time with the smallest effect found on cadence (SMD = 0.43, 95% CI{0.14, 0.72}). All effect sizes increased for variables investigated under a fast walking pace condition (for example the effect on cadence increased to SMD = 1.15, 95% CI{0.42, 1.88}).ConclusionsMS has a significant effect on gait even for those with relatively low EDSS. This effect is amplified when walking at faster speeds suggesting this condition may be more beneficial for assessment and treatment. No studies investigated the association between these deficits and falls. Further investigation relating to the predictive or protective nature of these deficits in relation to falls is warranted.     

Gait ground reaction force characteristics in deaf and hearing children

The link between gait parameters and hearing loss is not well understood. The objective of this study was to investigate the effects of the gait ground reaction forces, their time to peak, vertical loading rate, impulses and free moment during gait in deaf and hearing children. Thirty male children were equally divided into a healthy group and a group with hearing loss problems (Deaf group). Ground reaction forces were analyzed during barefoot walking. MANOVA test was used for between group comparisons. The significance level was set at p<0.05 for all analyses. Hearing loss was associated with increased propulsion lateral-medial ground reaction force (p=0.031), its time to peak (p=0.008), and lateral- medial impulse (p=0.018). Similar vertical reaction forces were observed in both groups (p>0.05). Positive peak of free moments in the healthy group was significantly greater than that in the deaf group (p=0.004). In conclusion, the results reveal that gait ground reaction force components in deaf children may have clinical values for rehabilitation of these subjects.     

Unplanned gait termination in individuals with multiple sclerosis

Despite the pervasive nature of gait impairment in multiple sclerosis (MS), there is limited information concerning the control of gait termination in individuals with MS. The purpose of this investigation was to examine unplanned gait termination with and without cognitive distractors in individuals with MS compared to healthy controls. Thirty-one individuals with MS and 14 healthy controls completed a series of unplanned gait termination tasks over a pressure sensitive walkway under distracting and non-distracting conditions. Individuals with MS were further broken down into groups based on assistive device use: (no assistive device (MS_noAD) n = 18; and assistive device (MS_AD) n = 13). Individuals with MS who walked with an assistive device (MS_AD: 67.8 ± 15.1 cm/s) walked slower than individuals without an assistive device (MS_noAD: 110.4 ± 32.3 cm/s, p < 0.01) and controls (120.0 ± 30.0 cm/s; p < 0.01). There was a significant reduction in velocity in the cognitively distracting condition (93.4 ± 32.1 cm/s) compared to the normal condition [108.8 ± 36.2 cm/s; F(1,43) = 3.4, p = 0.04]. All participants took longer to stop during the distracting condition (1.7±0.6 s) than the non-distracting condition (1.4 ± 0.4 s; U = 673.0 p < 0.01). After controlling for gait velocity, post-hoc analysis revealed the MS_AD group took significantly longer to stop compared to the control group (p = 0.05). Further research investigating the control of unplanned gait termination in MS is warranted.     

Correlates of dual task cost of standing balance in individuals with multiple sclerosis

Cognitive and balance dysfunction are common symptoms in individuals with multiple sclerosis (MS). Although traditionally seen as separate impairments, performing a concurrent cognitive task while maintaining an upright posture results in individuals with MS increasing their postural sway (i.e. dual task cost (DTC) of balance). However, the factors relating to this phenomenon are not clear. This investigation examined the demographic, clinical and cognitive correlates of DTC of balance in individuals with MS. Sixty-two persons with MS completed both quiet standing and dual task balance trials on a force platform. Additionally, they provided demographic information and performed clinical tests of balance, spasticity, fall risk and cognitive processing speed. Dual task cost was calculated as the percentage change in sway area from the baseline to dual task force platform conditions. Overall, there were no significant correlations between DTC of balance and any of the outcome measures in the entire sample. In contrast, postural sway in the baseline and dual task condition were found to correlate with disability, fall risk, balance performance, fatigue, cognitive processing speed and age. Secondary analysis revealed different correlates of DTC of balance in those with low versus high baseline sway. The results suggest that the change in standing balance with the simultaneous performance of cognitive task may only be informative in individuals with minimal balance dysfunction.     

Use of a tibial accelerometer to measure ground reaction force in running: A reliability and validity comparison with force plates

Objectives

The use of microsensor technologies to conduct research and implement interventions in sports and exercise medicine has increased recently. The objective of this paper was to determine the validity and reliability of the ViPerform as a measure of load compared to vertical ground reaction force (GRF) as measured by force plates.