Effect of Breast Reconstruction on Kinematics and Performance during Upper Limb-Focused Functional Tasks.

BACKGROUND: Breast reconstruction after curative breast cancer surgery is becoming increasingly common. There is evidence to suggest that these surgeries have negative effects on shoulder function, but to date there have been no investigations of shoulder biomechanics during functional tasks in this group. The purpose of this study was to define and compare upper limb motion of patients with breast cancer who underwent mastectomy only or mastectomy with reconstruction with a control group without cancer during a range of work-related functional tasks. METHODS: Ninety-five women participated: 25 controls, 25 patients with breast cancer who received a mastectomy only, and 45 patients with breast cancer who received a mastectomy with reconstruction (implant, latissimus dorsi flap, or deep inferior epigastric artery perforator flap). Motion of the torso, humeri, and scapulae were tracked during arm-focused functional tasks, involving reaching, dexterity, and lifting overhead, and joint angles were calculated. Mean, maximum, and minimum angles were calculated and compared among groups using one-way analyses of variance ( p < 0.05). RESULTS: The reconstruction group had significantly different kinematics than the other two groups. Throughout task performance, patients who had reconstruction had increased scapular posterior tilt and increased humeral external rotation. These findings are consistent with reconstruction surgical procedures and may highlight muscle pattern alterations that interfere with co-contraction, stability, and functional task performance. CONCLUSIONS: The findings suggest that breast reconstruction surgery influences functional task performance. Scapular and humeral kinematics may indicate movement pattern differences that are important to address in rehabilitation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

The effect of peripheral arterial disease and intermittent claudication on gait regularity and symmetry.

Peripheral arterial disease (PAD) affects 20-30% of older adults and is associated with intermittent claudication (IC), which is walking-induced pain. This study compared the regularity and symmetry of gait between healthy older adults and adults with PAD, and between IC and non-IC conditions in the PAD group. Eighteen control (70.7 ± 6.3 years) and 11 PAD participants (67.0 ± 10.1 years) walked overground at a continuous, self-selected speed. A waist-mounted accelerometer determined step time, stride time, gait speed and mediolateral (ML), vertical (V) and anteroposterior (AP) gait regularity (step/stride) and symmetry. Correlations between ankle-brachial index (ABI) scores and PAD gait regularity/symmetry were also investigated. PAD step and stride times were greater (p < 0.01), while gait speed, ML and AP step regularity and ML and V stride regularity were significantly less than the controls (p < 0.05). There were no significant differences in gait symmetry. Within the PAD group, post-IC step/stride time and speed increased and decreased, respectively, (p < 0.05), while post-IC step and stride regularity were significantly less in all three directions (p < 0.01). Similarly, ML and V post-IC gait asymmetry increased significantly (p < 0.05). ABI was significantly correlated with pre-and post-IC vertical stride regularity (p < 0.01), and with pre- and post-IC ML gait symmetry (p < 0.05). The results demonstrate that gait regularity decreases as a result of PAD and IC. The association between gait regularity/symmetry and ABI should be investigated further, as it may have clinical application to the assessment of PAD severity.

Sex differences in the regularity and symmetry of gait in older adults with and without knee osteoarthritis.

BACKGROUND: Three-dimensional (3D) motion measured at the lower back during walking can describe the regularity and symmetry of gait that may be related to osteoarthritis (OA) and functional status. However, gait speed and inherent sex differences, regardless of the presence of OA, may confound these measures. Therefore, there is a need to understand the effect of OA separately among males and females, without the confounding influence of gait speed. OBJECTIVE: To investigate the difference in 3D gait regularity and symmetry measures between gait speed-matched males and females with and without knee OA. METHOD: Gait regularity and symmetry were computed as autocorrelations of pelvic accelerations during treadmill walking in four groups of older adults: healthy asymptomatic females (AsymF; n = 44), healthy asymptomatic males (AsymM; n = 45), females diagnosed with knee OA (OAF; n = 44), and males diagnosed with knee OA (OAM; n = 45). Data were obtained from a larger research database, allowing for the matching of gait speed between groups. The main effect of OA, sex, and interaction effect between them was examined for the 3D gait regularity and symmetry measures at an alpha level of 0.05. RESULTS: There was no main effect of OA on any variable, but there was a significant main effect of sex on mediolateral and anteroposterior gait regularity measures. Specifically, females demonstrated significantly greater gait regularity, most notably in the mediolateral directions compared to males. CONCLUSION: Older adult females were found to display significantly greater mediolateral gait regularity as compared to males, regardless of the presence of OA. Further, this difference exists among matched gait speeds, suggesting it is not the result of gait speed. Overall, these results highlight the importance of sex-specific analyses and considering gait speed when examining gait acceleration patterns near the center of mass for both cross sectional and longitudinal gait assessments.

The Effect of Breathing Laterality on Hip Roll Kinematics in Submaximal Front Crawl Swimming.

The purpose of this study was to determine the effect of breathing laterality on hip roll kinematics in submaximal front crawl swimming. Eighteen elite competitive swimmers performed three 100 m front crawl trials at a consistent sub-maximal speed (70% of seasonal best time) in a 25 m pool. Each trial was performed with one of three different breathing conditions: (1) unilateral breathing (preferred side), (2) bilateral breathing (alternating left/right-side every 3 strokes) and (3) simulated non-breathing using a swim snorkel. A waist-mounted triaxial accelerometer was used to determine continuous hip roll angle throughout the trial, from which peak hip roll angles (Ó¨) and average angular velocities (ω) were calculated. Two-way repeated measures ANOVAs were used to identify significant main effects for laterality (preferred vs. non-preferred breathing sides) and condition (unilateral, bilateral and snorkel breathing) for both Ó¨ and ω. Peak hip roll to the preferred side was significantly greater (p < 0.001) in the unilateral condition, while ω to the non-preferred side was significantly greater in the unilateral (p < 0.01) and bilateral (p < 0.04) conditions. Significant same-side differences were also found between the different breathing conditions. The results demonstrate that breathing laterality affects hip roll kinematics at submaximal speeds, and that unilateral and snorkel breathing are associated with the least and most symmetric hip roll kinematics, respectively. The findings show that a snorkel effectively balances and controls bilateral hip rotation at submaximal speeds that are consistent with training, which may help to minimize and/or correct roll asymmetries that are the result of unilateral breathing.

Long-range correlations and stride pattern variability in recreational and elite distance runners during a prolonged run.

BACKGROUND: Although movement variability and long-range correlations (LRCs) have been assessed in relation to neuropathology and aging during walking, to date only a few studies have investigated these aspects in subjects of different skill levels during prolonged overground running. RESEARCH QUESTION: What effect does skill level and run duration have on different stride parameters, measures of variability and long-range correlations? METHODS: Using a between-subject repeated measures design, we assessed stride mechanics, variability and LRCs in recreational and elite runners over the course of a continuous exhaustive run. All subjects ran at a fixed, pre-determined running speed relative to their maximal performance. Stride parameters were continually recorded using a single foot-mounted inertial measurement unit. It was hypothesized that a significant reduction in the strength of the LRCs would occur over the course of the run and that the observed changes would be more pronounced in the group of recreational runners. RESULTS: Runners maintained a consistent stride length (SL), stride time (ST) and contact time (CT) during the run, while peak impact acceleration increased. Across groups, long-range correlations significantly decreased over the course of the run, while the magnitude of the variability remained constant. LRCs did not differ significantly between groups. SIGNIFICANCE: This is the first study to simultaneously investigate the effects of prolonged running and skill level on a range of stride parameters as well as stride-to-stride variability. Generally, long-range correlations were shown to be sensitive to run duration, while the magnitude of the variability did not differ between earlier and later stages of the run. The lack of a group effect on LRCs supports the idea that the mechanisms responsible for the emergence of temporal patterns in the stride pattern are not influenced by skill level.

Body roll differences in freestyle swimming between swimmers with and without shoulder pain.

Several studies have identified body roll as an important variable that affects shoulder pain due to its potential to modify upper limb kinematics. This study aimed to investigate potential differences in body roll between swimmers with and without shoulder pain. Twenty-four competitive swimmers participated in the study, 12 with unilateral shoulder pain and 12 without. Body roll was measured using two tri-axial accelerometers, one at the shoulder and one at the hip, during three trials of 100 m front crawl swimming at three different speeds. The results showed no significant difference in peak body roll angle between groups for the breathing side at the shoulders or hips. However, for the non-breathing side, swimmers with shoulder pain rolled significantly less at the hips (49º vs 57º, p = 0.018, r = 0.931) while no significant difference was found at the shoulders. These findings suggest that a potential relationship between hip rotation and shoulder pain may exist, such that hip roll is diminished to the non-breathing side in swimmers with unilateral shoulder pain. Given that a cause-effect relationship cannot be inferred from this cross-sectional study, future studies should attempt to identify the mechanisms that link body roll to the aetiology and pathomechanics of shoulder pain.

Accelerometry-Based Step Count Validation for Horse Movement Analysis During Stall Confinement.

Quantitative tracking of equine movement during stall confinement has the potential to detect subtle changes in mobility due to injury. These changes may warn of potential complications, providing vital information to direct rehabilitation protocols. Inertial measurement units (IMUs) are readily available and easily attached to a limb or surcingle to objectively record step count in horses. The objectives of this study were: (1) to compare IMU-based step counts to a visually-based criterion measure (video) for three different types of movements in a stall environment, and (2) to compare three different sensor positions to determine the ideal location on the horse to assess movement. An IMU was attached at the withers, right forelimb and hindlimb of six horses to assess free-movement, circles, and figure-eights recorded in 5 min intervals and to determine the best location, through analysis of all three axes of the triaxial accelerometer, for step count during stall confinement. Mean step count difference, absolute error (%) and intraclass correlation coefficients (ICCs) were determined to assess the sensor's ability to track steps compared to the criterion measure. When comparing sensor location for all movement conditions, the right-forelimb vertical-axis produced the best results (ICC = 1.0, % error = 6.8, mean step count difference = 1.3) followed closely by the right-hindlimb (ICC = 0.999, % error = 15.2, mean step count difference = 1.8). Limitations included the small number of horse participants and the lack of random selection due to limited availability and accessibility. Overall, the findings demonstrate excellent levels of agreement between the IMU's vertical axis and the video-based criterion at the forelimb and hindlimb locations for all movement conditions.

Test-Retest Reliability and the Effects of Walking Speed on Stride Time Variability During Continuous, Overground Walking in Healthy Young Adults.

Studies have investigated the reliability and effect of walking speed on stride time variability during walking trials performed on a treadmill. The objective of this study was to investigate the reliability of stride time variability and the effect of walking speed on stride time variability, during continuous, overground walking in healthy young adults. Participants completed: (1) 2 walking trials at their preferred walking speed on 1 day and another trial 2 to 4 days later and (2) 1 trial at their preferred walking speed, 1 trial approximately 20% to 25% faster than their preferred walking speed, and 1 trial approximately 20% to 25% slower than their preferred walking speed on a separate day. Data from a waist-mounted accelerometer were used to determine the consecutive stride times for each trial. The reliability of stride time variability outcomes was generally poor (intraclass correlations: .167-.487). Although some significant differences in stride time variability were found between the preferred walking speed, fast, and slow trials, individual between-trial differences were generally below the estimated minimum difference considered to be a real difference. The development of a protocol to improve the reliability of stride time variability outcomes during continuous, overground walking would be beneficial to improve their application in research and clinical settings.

Brain gray matter volume associations with gait speed and related structural covariance networks in cognitively healthy individuals and in patients with mild cognitive impairment: A cross-sectional study.

INTRODUCTION: Gait speed is slower in patients with mild cognitive impairment (MCI) compared to cognitively healthy individuals (CHI). We examined the patterns of brain gray matter (GM) volume association and covariance with gait speed in CHI and in patients with MCI. METHODS: A total of 96 CHI and 99 patients with MCI were recruited in this cross-sectional study. Brain GM volumes measured with voxel-based morphometry and self-paced gait speed were used as outcomes. RESULTS: The right middle frontal and precentral gyri volumes were positively associated with gait speed in CHI and covariated with frontal cortex. Striatum (i.e. left putamen and bilateral caudate nuclei) volumes were positively associated with gait speed in patients with MCI and covariated with striatal structures. CONCLUSIONS: Two different patterns of brain GM volume association and covariance with gait speed were found and involving frontal cortex in CHI and the striatum in patients with MCI.

Motoric cognitive risk syndrome, incident cognitive impairment and morphological brain abnormalities: Systematic review and meta-analysis.

BACKGROUND: Motoric cognitive risk syndrome (MCR) is a pre-dementia stage, which associates slow walking speed with subjective cognitive impairment (SCI). MCR's clinical utility for the prediction of dementia and its pathophysiology are unclear. The aim of this systematic review and meta-analysis is to examine the association of MCR with incident cognitive impairment, cognitive performance and brain structures. METHODS: A systematic search was conducted using the Medical Subject Heading terms "Walking" and "Cognition disorders" combined with the terms "Subjective cognitive impairment", "Subjective cognitive decline" and "Motoric cognitive risk". A total of 11 studies were included in the systematic review and meta-analysis: 3 studies had dementia as the outcome, 3 studies had cognitive performance as the outcome, 4 studies had brain structures as the outcome and one study examined the incidence of both major neurocognitive disorders and cognitive impairment. RESULTS: MCR was found to be associated with incident cognitive impairment (pooled hazard ratio (HR) = 1.70, 95% CI, 1.46-1.98 with P-value <0.001) and dementia (pooled HR = 2.50, 95% CI, 1.75-2.39 with P-value <0.001). MCR was also found to be associated with low grey matter volume involving the premotor and the prefrontal cortex, and lacunar lesions in the frontal lobe. No significant association was found with white matter abnormalities. CONCLUSION: MCR predicts cognitive impairment and dementia, suggesting that it may be used as a screening syndrome for dementia in a primary care setting. Its significant association with both low grey matter volume and lacunar lesions makes its pathophysiology unclear and suggests multiple pathways.

Association of Motoric Cognitive Risk Syndrome with Cardiovascular Disease and Risk Factors: Results from an Original Study and Meta-Analysis.

BACKGROUND: Motoric cognitive risk (MCR) syndrome, a recently described pre-dementia syndrome, has been associated with cardiovascular disease and their risk factors (CVDRF). OBJECTIVE: To determine whether MCR syndrome was associated with CVDRF in French community-dwelling older adults, and to quantitatively evaluate, with a systematic review and meta-analysis, the association of MCR syndrome with CVDRF. METHODS: Based on a cross-sectional design, 238 older adults without dementia were selected from the French GAIT study. An English and French systematic Medline and Embase search (without limiting date of publication) was also conducted in February 2017 using the terms "motoric cognitive risk syndrome" OR "motoric cognitive risk" OR "motoric risk". The systematic review and meta-analysis included 8 studies. CVDRF were defined as cardiovascular diseases, hypertension, diabetes, stroke, obesity and abnormal waist-hip ratio (WHR). RESULTS: The prevalence of MCR syndrome in the current original study was 16.8%. MCR syndrome was associated with abnormalWHR(Odds ratio [OR] >2.8 with p < 0.020) and high blood pressure (OR >2.5 with p < 0.025). Of the 202 originally identified abstracts, 7 (3.5%) were selected for the systematic review. The meta-analysis showed that all pooled OR were significant with a p-value <0.001 (OR = 1.41 for cardiovascular diseases, 1.21 for hypertension, 1.44 for diabetes, 2.05 for stroke, and 1.34 for obesity). When pooling all CVDRF, the overall OR was 1.38 (95% CI, 1.33-1.45) with p-value <0.001. CONCLUSION: MCR syndrome is significantly associated with CVDRF. These findings suggest that a vascular mechanism may underlie the pathophysiology of MCR syndrome.

Stride length determination during overground running using a single foot-mounted inertial measurement unit.

From a research perspective, detailed knowledge about stride length (SL) is important for coaches, clinicians and researchers because together with stride rate it determines the speed of locomotion. Moreover, individual SL vectors represent the integrated output of different biomechanical determinants and as such provide valuable insight into the control of running gait. In recent years, several studies have tried to estimate SL using body-mounted inertial measurement units (IMUs) and have reported promising results. However, many studies have used systems based on multiple sensors or have only focused on estimating SL for walking. Here we test the concurrent validity of a single foot-mounted, 9-degree of freedom IMU to estimate SL for running. We employed a running-specific, Kalman filter based zero-velocity update (ZUPT) algorithm to calculate individual SL vectors with the IMU and compared the results to SLs that were simultaneously recorded by a 6-camera 3D motion capture system. The results showed that the analytical procedures were able to successfully identify all strides that were recorded by the camera system and that excellent levels of absolute agreement (ICC(3,1) = 0.955) existed between the two methods. The findings demonstrate that individual SL vectors can be accurately estimated with a single foot-mounted IMU when running in a controlled laboratory setting.

Activation of the Large-Conductance, Voltage, and Ca2+- Activated K+ (BK) Channel in Acute Spinal Cord Injury in the Wistar Rat Is Neuroprotective.

Context/Objectives: Spinal cord injury (SCI) results in significant neuronal and glial cell death resulting in impaired neurological and motor function. Uncontrolled Ca2+ entry results in excitotoxicity and cell death. In this study, we examine the use of a BK channel activator, Isopimaric acid (ISO), as a neuroprotective agent post-SCI as this channel is involved in regulating Ca2+ entry. Design:By using a 25-g clip compression at the T6 level, we generated a SCI event in wistar rats. At 1 h post-injury we administered ISO (BK channel activator), the BK channel inhibitor iberiotoxin (IbTx), or a vehicle control for 4 weeks via mini osmotic pump (pump capacity). For 8 weeks post-injury, gait analysis of motor function was performed. At the end of 8 weeks, the extent of myelination in the spinal cord was assessed in addition to the electrophysiological profile. Results:Our immunohistological data suggests that ISO treatment leads to an increase or preservation of myelinated axonal tracts. This was further supported by our electrophysiological studies which demonstrate higher compound action potential amplitudes and speed of transmission in ISO-treated animals compared to inj-non-treated. Finally, treatment with ISO significantly improved motor function in our test model. Conclusion: In conclusion, activation of the BK channel during acute SCI may be a novel therapeutic target for acute SCI.

Guidelines for Assessment of Gait and Reference Values for Spatiotemporal Gait Parameters in Older Adults: The Biomathics and Canadian Gait Consortiums Initiative.

Background: Gait disorders, a highly prevalent condition in older adults, are associated with several adverse health consequences. Gait analysis allows qualitative and quantitative assessments of gait that improves the understanding of mechanisms of gait disorders and the choice of interventions. This manuscript aims (1) to give consensus guidance for clinical and spatiotemporal gait analysis based on the recorded footfalls in older adults aged 65 years and over, and (2) to provide reference values for spatiotemporal gait parameters based on the recorded footfalls in healthy older adults free of cognitive impairment and multi-morbidities. Methods: International experts working in a network of two different consortiums (i.e., Biomathics and Canadian Gait Consortium) participated in this initiative. First, they identified items of standardized information following the usual procedure of formulation of consensus findings. Second, they merged databases including spatiotemporal gait assessments with GAITRite® system and clinical information from the "Gait, cOgnitiOn & Decline" (GOOD) initiative and the Generation 100 (Gen 100) study. Only healthy-free of cognitive impairment and multi-morbidities (i.e., ≤ 3 therapeutics taken daily)-participants aged 65 and older were selected. Age, sex, body mass index, mean values, and coefficients of variation (CoV) of gait parameters were used for the analyses. Results: Standardized systematic assessment of three categories of items, which were demographics and clinical information, and gait characteristics (clinical and spatiotemporal gait analysis based on the recorded footfalls), were selected for the proposed guidelines. Two complementary sets of items were distinguished: a minimal data set and a full data set. In addition, a total of 954 participants (mean age 72.8 ± 4.8 years, 45.8% women) were recruited to establish the reference values. Performance of spatiotemporal gait parameters based on the recorded footfalls declined with increasing age (mean values and CoV) and demonstrated sex differences (mean values). Conclusions: Based on an international multicenter collaboration, we propose consensus guidelines for gait assessment and spatiotemporal gait analysis based on the recorded footfalls, and reference values for healthy older adults.

Association Between Falls and Brain Subvolumes: Results from a Cross-Sectional Analysis in Healthy Older Adults.

Falls are a consequence of gait instability. Cortical and subcortical abnormalities have been associated with gait instability but not yet with falls. This study aims to compare the global and regional brain subvolumes between healthy older fallers and non-fallers. A total of 77 healthy older individuals (23 fallers and 54 non-fallers, 69.8 ± 3.5 years; 45.5 % female) were included in this study using a cross-sectional design. Based on an a priori hypothesis, the following brain subvolumes were quantified from three-dimensional T1-weighted MRI using FreeSurfer software: total white matter abnormalities, total white matter, total cortical and subcortical gray matter, hippocampus, motor cortex, somatosensory cortex, premotor cortex, prefrontal cortex and parietal cortex volumes. Gait performances were also recorded. Age, sex, body mass index, comorbidities, use of psychoactive drugs, far-distance visual acuity, lower-limb proprioception, depressive symptoms and cognitive scores (Mini-Mental State Examination, Frontal Assessment Battery) were used as covariates. Fallers have more frequently depressive symptoms (P = 0.048), a lower far distance visual acuity (P = 0.026) and a higher coefficient of variation of stride time (P = 0.008) compared to non-fallers. There was a trend to greater subvolumes for the somatosensory cortex (P = 0.093) and the hippocampus (P = 0.060) in the falls group. Multiple logistic regressions showed that subvolumes of the somatosensory cortex and the hippocampus (P < 0.042) were increased in fallers compared to non-fallers, even after adjustment for clinical and brain characteristics. The greater subvolumes of the somatosensory cortex and hippocampus reported in fallers compared to non-fallers suggests a possible brain compensatory mechanism involving spatial navigation and integration of sensory information.

Accelerometer-Based Step Regularity Is Lower in Older Adults with Bilateral Knee Osteoarthritis.

Purpose: To compare the regularity and symmetry of gait between a cohort of older adults with bilateral knee osteoarthritis (OA) and an age and sex-matched control group of older adults with healthy knees. Methods: Fifteen (8 females) older adults with knee OA (64.7 ± 6.7 years) and fifteen (8 females) pain-free controls (66.1 ± 10.0 years) completed a 9-min. walk at a self-selected, comfortable speed while wearing a single waist-mounted tri-axial accelerometer. The following gait parameters were compared between the two groups according to sex: mean step time, mean stride time, stride and step regularity (defined as the consistency of the stride-to-stride or step-to-step pattern) and the symmetry of gait (defined as the difference between step and stride regularity) as determined by an unbiased autocorrelation procedure that analyzed the pattern of acceleration in the vertical, mediolateral and anteroposterior directions. Results: Older adults with knee OA displayed significantly less step regularity in the vertical (p < 0.05) and anteroposterior (p < 0.05) directions than controls. Females with knee OA were also found to have significantly less mediolateral step regularity than female controls (p < 0.05), whereas no difference was found between males. Conclusion: The results showed that the regularity of the step pattern in individuals with bilateral knee OA was less consistent compared to similarly-aged older adults with healthy knees. The findings suggest that future studies should investigate the relationship between step regularity, sex and movement direction as well as the application of these methods to the clinical assessment of knee OA.

Accelerometer-based determination of gait variability in older adults with knee osteoarthritis.

Knee osteoarthritis (KOA) can affect the spatiotemporal (ST) aspects of gait as well as the variability of select ST parameters based on standard linear measures of variability (e.g., standard deviation (SD) and coefficient of variation). Non-linear measures (e.g., fractal scaling index (FSI) and sample entropy) can be more sensitive to changes in gait variability, and have been used to quantify differences in the stride patterns of patients with Parkinson's disease and the motion of ACL-deficient knees. However, the effect of KOA on the dynamic complexity of the stride pattern has not been investigated. Therefore, the purpose of this study was to investigate the effect of KOA on gait variability (linear and non-linear measures) in a group of older adults, and to compare these results to a healthy control group. Participants walked for 10min with a tri-axial accelerometer placed at the lower back. Mean and SDs of stride time and step time as well as the FSI for the entire series of stride times were calculated for each participant. Participants with KOA had significantly greater mean stride time (p=0.031) and step time (p=0.024) than control group participants. While stride and step time variability (SD) were greater in the KOA group, the differences were not significant, nor was the difference in the FSI. Low statistical power (ß=0.40 and 0.30 for stride and step time SD, respectively) combined with the confounding effects of walking speed and heterogeneous KOA severity likely prevented significant differences from being found.

Anti-Dementia Drugs, Gait Performance and Mental Imagery of Gait: A Non-Randomized Open-Label Trial.

BACKGROUND: Few studies have examined the effect of anti-dementia drugs (i.e., acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists) on gait performance. Past studies have focused on the stride time (i.e., gait cycle duration) but not on the mental imagery of gait. OBJECTIVES: To compare mental imagery of gait and spatiotemporal gait parameters in patients with dementia [i.e., Alzheimer's disease (AD) and non-AD] before and after the use of anti-dementia drugs (i.e., acetylcholinesterase inhibitors and memantine) and in controls (i.e., patients with dementia who did not take anti-dementia drugs). METHODS: A total of 112 patients (mean age 82.5 ± 4.2 years, 68.8 % female) with mild-to-moderate AD and non-AD dementia were included in this non-randomized open-label trial (n = 56 in the Intervention group, and n = 56 in the Control group matched for age, sex, and stage and type of dementia) nested in a cohort study (mean follow-up 238.5 ± 79.8 days). Mental imagery of gait was assessed with the actual and imagined Timed Up and Go tests (aTUG and iTUG) and the difference between aTUG and iTUG (i.e., delta-TUG). Spatiotemporal gait parameters were measured with the GAITRite(®) system during normal walking. RESULTS: Participants in the Intervention group had a longer iTUG time (p < 0.001) and a lower delta-TUG value (p = 0.001) at the follow-up compared with those in the Control group. There was a significant increase in iTUG (p = 0.001) and decrease in delta-TUG (p < 0.001) from baseline to the follow-up only in the Intervention group. Multiple linear regression showed that the use of anti-dementia drugs was associated with a longer iTUG time and a lower delta-TUG value (best performance, p < 0.002). CONCLUSIONS: Our findings showed an improvement in mental imagery of gait with the use of anti-dementia drugs, but no changes in actual gait performance. TRIAL REGISTRATION: NCT01315704.

The relationship between hippocampal volume and static postural sway: results from the GAIT study.

The role of the hippocampus in postural control, in particular in maintaining upright stance, has not been fully examined in normal aging. This study aims to examine the association of postural sway with hippocampal volume while maintaining upright stance in healthy older individuals. Seventy healthy individuals (mean age 69.7 ± 3.4 years; 41.4 % women) were recruited in this study based on cross-sectional design. Hippocampal volume (quantified from a three-dimensional T1-weighted MRI using semi-automated software), three center of pressure (COP) motion parameters (sway area, path length of anterior-posterior (AP) and medial-lateral (ML) displacement) while maintaining upright stance (eyes open and closed), and the relative difference between open and closed eye conditions were used as outcome measures. Age, sex, body mass index, lower limb proprioception, distance vision, 15-item geriatric depression scale score, total cranial volume, and white matter abnormalities were used as covariates. The sway area decreased from open to closed eye condition but this variation was non-significant (P = 0.244), whereas path length of AP and ML displacement increased significantly (P < 0.003). Increase in sway area from open to closed eyes was associated with greater hippocampal volume (ß -18.21; P = 0.044), and a trend for an association of increase in path length of AP displacement (P = 0.075 for open eyes and P = 0.071 for closed eyes) with greater hippocampal volume was reported. The hippocampus is involved in upright postural control in normal aging, such that an increase in sway area of COP motion from open to closed eyes is associated with greater hippocampal volume in healthy older adults.

Comparison of two alternative technical marker sets for measuring 3D pelvic motion during gait.

When using motion capture to measure pelvic motion, situations in which the anterior superior iliac spines (ASISs) or posterior superior iliac spines (PSISs) are obscured from view require that an alternative technical marker set be used to track the pelvis. The current study evaluated the accuracy and temporal similarity (i.e., cross-correlation) of two alternative pelvic models compared to the standard pelvic model during gait. The first alternative model used markers placed on the ASISs and iliac crests (ASIS-IC), while the second alternative model used markers placed on the PSISs and iliac crests (PSIS-IC). Both alternative models demonstrated an acceptable degree of accuracy in the sagittal, frontal, and transverse planes (root-mean-square error <1.4° in all planes). The temporal similarity between both alternative models and the standard model was "very strong" in the frontal and transverse planes. In the sagittal plane, the temporal similarity was also "very strong" for the PSIS-IC model and "strong" for the ASIS-IC model. Although statistically significant differences were found between the two alternative models for some of the variables, the practical significance of these findings is generally questionable considering the magnitude of the differences. These results suggest that both alternative models are suitable alternatives to the standard pelvic model for tracking pelvic motion. However, consideration would need to be paid to the spatial resolution and temporal resolution requirements, as well as the specific plane(s) of movement that are deemed most important, for a particular investigation if one of these alternative models is to be used.