Decreased Stride Length Research Articles

Gait and risk of falls associated with frontal cognitive functions at different stages of Alzheimer's disease

ABSTRACT The decline in frontal cognitive functions contributes to alterations of gait and increases the risk of falls in patients with dementia, a category which included Alzheimer's disease (AD). The objective of the present study was to compare the gait parameters and the risk of falls among patients at different stages of AD, and to relate these variables with cognitive functions. This is a cross-sectional study with 23 patients with mild and moderate AD. The Clinical Dementia Rating was used to classify the dementia severity. The kinematic parameters of gait (cadence, stride length, and stride speed) were analyzed under two conditions: (a) single task (free gait) and (b) dual task (walking and counting down). The risk of falls was evaluated using the Timed Up-and-Go test. The frontal cognitive functions were evaluated using the Frontal Assessment Battery (FAB), the Clock Drawing Test (CDT) and the Symbol Search Subtest. The patients who were at the moderate stage suffered reduced performance in their stride length and stride speed in the single task and had made more counting errors in the dual task and still had a higher fall risk. Both the mild and the moderate patients exhibited significant decreases in stride length, stride speed and cadence in the dual task. Was detected a significant correlation between CDT, FAB, and stride speed in the dual task condition. We also found a significant correlation between subtest Similarities, FAB and cadence in the dual task condition. The dual task produced changes in the kinematic parameters of gait for the mild and moderate AD patients and the gait alterations are related to frontal cognitive functions, particularly executive functions.

Abstract 3101: Post-ischemic Development and Resolution of Infarct and Behavioral Deficits Induced by Permanent Middle Cerebral Artery Occlusion in Middle-aged Rats: A Progesterone Dose-response Study

BACKGROUND: There is currently no safe, effective, widely applicable post-stroke treatment for ischemic stroke, especially when treatment is delayed beyond a few hours. Our group and others have shown progesterone (PROG) to be beneficial after brain injury in several injury models. A systematic pre-clinical PROG dose-response study in ischemic stroke models is lacking. Since focal pMCAO models better simulate the typical human stroke injury without reperfusion, our study sought to determine PROG's dose-response effects on behavioral performance after pMCAO. We used a clinically relevant, middle-aged rat model and long-term sensory, motor, and cognitive outcome measures. METHODS: Male Sprague-Dawley rats (12 months old) underwent pMCAO by electrocoagulation or sham operation. At 1h post-pMCAO, the animals were given an intraperitoneal injection of one of three doses of PROG (8, 16, or 32 mg/kg), followed by subcutaneous injections 6h post-injury and then once every 24h for the next 7 days. The dose was tapered over the final 2 treatments. Behavioral recovery was evaluated at repeated intervals for locomotor activity, grip strength, rotarod performance, sensory neglect, gait impairment and spatial navigation learning and memory. Rats were killed at 22 days post-stroke and brains perfused for evaluation of infarct volume. RESULTS: Repeated measures ANOVA showed significant group ( F (4,88) = 17.15, p <0.001) effects in grip strength, significant group ( F (4,41) = 3.5, p < 0.05) and time ( F (4,164) = 2.6, p < 0.05) effects on rotarod, significant group ( F (4,41) = 2.94, p < 0.05) effects on latency to remove sticky paper from the affected contralateral forepaw, and significant group ( F (4,41) = 14.63, p < 0.0001) effects on total distance traveled. The best recovery in grip strength, rotarod and sensory neglect was seen in the 8mg/kg PROG group. In spatial learning memory, percent time spent in the platform quadrant of the MWM showed that progesterone improved performance ( F (4, 40) =2.7, p <0.05). Automated, computer-assisted, gait assessment showed that PROG significantly improved gait deficits in the affected limb. Significant decreases in stride length, print area and swing speed were observed. Both 8mg/kg ansd 16mg/kg of PROG treatment produced significant attenuation in infarct volume compared to the vehicle-alone group ( F (3, 19) = 4.38, p < 0.05). CONCLUSION: All doses of PROG improved functional deficits in a clinically relevant model of stroke. The 8mg/kg dose was optimal in improving motor, sensory and memory function. PROG shows pre-clinical promise as a potential therapeutic agent and should be examined for safety and efficacy in a clinical trial for ischemic stroke.

Postoperative Foot and Ankle Kinematics in Rheumatoid Arthritis

Introduction Rheumatoid arthritis (RA) is a systemic autoimmune disease that can cause weakening and destruction of various joints of the foot and may result in pain and deformity. This clinical presentation can cause eventual loss of function, shoe-wear difficulties, and altered gait patterns. Purpose The goal of this prospective study was to quantify changes in temporal-spatial parameters and multisegmental foot and ankle kinematics in a group of patients with RA of the forefoot following surgery. Methods Three-dimensional (3-D) motion analysis was conducted preoperatively and postoperatively using a 15-camera Vicon Motion Analysis System (Vicon Motion Systems, Inc.; Lake Forest, CA) on 14 feet in 13 patients with forefoot RA. The Milwaukee foot model was used to characterize segmental kinematics and temporal-spatial parameters. Preoperative and postoperative data were compared using paired nonparametric methods; comparisons with normative data were performed using unpaired nonparametric methods. Results Preoperatively, the hallux was in a valgus position, the forefoot was abducted and in valgus, and range of motion was limited in various phases in all segments. Walking speed and stride length were decreased and stance prolonged when compared with normal controls. Postoperatively, the hallux alignment was restored to normal but a limited range of motion remained. Kinematics also demonstrated forefoot valgus and tibial internal rotation compared with the control population. Comparisons to healthy ambulators also showed decreased stride lengths and prolonged stance phase durations. Conclusion Surgery effectively restored alignment and weight-bearing capacity of the rheumatoid feet. Temporal-spatial parameters and kinematics, however, were not restored to control values, but rather were consistent with first metatarsophalangeal joint fusion effects. The altered mechanics after surgery demonstrate the importance of quantitative assessment in understanding the geometric and kinematic effects of surgical realignment with implications for postoperative rehabilitation and gait training.

A Comparison Of Treadmill And Overground Walking In Obese Women

Several reports that have compared the kinematic differences between treadmill (TM) and overground (OG) walking in healthy subjects. Studies on temporal aspects of gait in lean, healthy individuals typically report increased stride frequency and decreased stride length as the main difference between the two walking modalities. Findings are varied for differences in peak joint angles but trend towards minimal differences in peak values. Obese individuals display markedly different kinematics relative to lean individuals and are often not experienced TM walkers. The dimensions of standard laboratory TMs may also constrain limb excursions or elicit the need for increased stability. PURPOSE: To compare selected kinematic parameters of TM and OG walking in obese women. METHODS: 12 obese women (28.7 ± 9.1 years; 36.7 ± 6.4 kg·m-2; 45.6 ± 5.1% body fat) walked OG and on a TM at their preferred OG walking speed (1.37 ± 0.14 m·s-1). Kinematic measures on the TM were recorded after 6 minute of walking. Measured kinematic variables across 5 strides included stride length, stride frequency, stance time, and peak sagittal and frontal plane hip, knee, and ankle joint angles during the stance phase of the gait cycle. Paired T-tests were calculated to assess statistical significance (α = 0.05). RESULTS: Obese women had significantly greater stance time on the TM than during OG walking (p=0.01). Peak knee flexion during stance was greater on the TM (p<0.01) while ankle dorsiflexion during midstance (p=0.05) and ankle eversion range of motion (p<0.01) were significantly greater during OG walking. There were no significant differences between conditions for stride frequency, stride length, peak hip flexion, hip extension, hip range of motion, hip abduction, knee adduction, ankle plantar flexion during midstance, or peak ankle eversion during stance (p>0.05). CONCLUSIONS: Obese women display different kinematics on the TM relative to OG walking. In addition, the differences found in this study do not match reports from similar studies on lean individuals. The greater limb dimensions of the obese population potentially necessitate that different strategies be used for forward locomotion on a TM compared to OG. The results of this study indicate that several kinematic measures recorded on a TM do not replicate OG walking in obese adults.

The role of vision in obese and normal-weight children's gait control

Previous research has suggested that perceptual-motor difficulties may account for obese children's lower motor competence; however, specific evidence is currently lacking. Therefore, this study examined the effect of altered visual conditions on spatiotemporal and kinematic gait parameters in obese versus normal-weight children. Thirty-two obese and normal-weight children (11.2±1.5 years) walked barefoot on an instrumented walkway at constant self-selected speed during LIGHT and DARK conditions. Three-dimensional motion analysis was performed to calculate spatiotemporal parameters, as well as sagittal trunk segment and lower extremity joint angles at heel-strike and toe-off. Self-selected speed did not significantly differ between groups. In the DARK condition, all participants walked at a significantly slower speed, decreased stride length, and increased stride width. Without normal vision, obese children had a more pronounced increase in relative double support time compared to the normal-weight group, resulting in a significantly greater percentage of the gait cycle spent in stance. Walking in the DARK, both groups showed greater forward tilt of the trunk and restricted hip movement. All participants had increased knee flexion at heel-strike, as well as decreased knee extension and ankle plantarflexion at toe-off in the DARK condition. The removal of normal vision affected obese children's temporal gait pattern to a larger extent than that of normal-weight peers. Results suggest an increased dependency on vision in obese children to control locomotion. Next to the mechanical problem of moving excess mass, a different coupling between perception and action appears to be governing obese children's motor coordination and control.

Postural Control in Multiple Sclerosis: Implications for Fall Prevention

People with multiple sclerosis (MS) often have poor postural control, which likely underlies their increased risk of falls. Based on several studies of balance and gait in MS, it appears that the primary mechanisms underlying the observed changes are slowed somatosensory conduction and impaired central integration. This review of the published research on balance, gait, and falls in people with MS demonstrates that people with MS have balance impairments characterized by increased sway in quiet stance, delayed responses to postural perturbations, and a reduced ability to move toward their limits of stability. These impairments are likely causes of falls in people with MS and are consistent with the reduced gait speed, as well as decreased stride length, cadence, and joint movement, observed in most studies of gait in MS. Based on these findings, we identify several factors that may be amenable to intervention to prevent falls in people with MS.

Does stride length influence metabolic cost and biomechanical risk factors for knee osteoarthritis in obese women?

Background Obesity is the primary modifiable risk factor for knee osteoarthritis. The goal of this study was to develop a walking protocol for obese individuals that supported weight loss while minimizing biomechanical risk factors for knee osteoarthritis. We tested the hypotheses that walking with short, quick strides at a preferred walking speed requires more energy expenditure in obese women and reduces biomechanical risk factors for knee osteoarthritis at foot–ground impact relative to walking at the preferred stride length. Methods Ten obese (BMI = 33.09(4.22) kg/m 2) and 10 healthy-weight (BMI = 22.66(0.86) kg/m 2) women volunteered. V ˙ O 2 was measured while subjects walked on a treadmill at their preferred walking speed at a preferred stride length and a 15% shortened stride length (increased stride frequency). Peak impact shock, peak external knee adduction moment, and knee adduction angular impulse were measured during the two gait conditions. Findings Decreasing stride length 15% significantly increased metabolic cost by 4.6% ( P < 0.01; effect size = 0.24) and decreased the adduction angular impulse ( P = 0.046; effect size = 0.203), but did not significantly affect the adduction moment ( P = 0.196; effect size = 0.100) or impact shock ( P = 0.698; effect size = 0.605). Interpretation The small, but significant, increase in metabolic cost when walking with short, quick steps may be beneficial for weight reduction or maintenance in obese populations. The results of this study suggest that a 15% decrease in stride length is not sufficient to decrease the peak values of two of the biomechanical variables that may predispose obese women to knee osteoarthritis but does elicit benefits over the course of a stride.

Locomotion et maladie de Huntington

In Huntington's disease (HD), perturbed locomotion occurs early in the course of the disease and presents numerous clinical features. The gait disorders in HD might best be defined as a timing disorder; however, hypokinesia (i.e. a decrease in stride length) also plays an important role in disturbed locomotion as HD progresses. Gait impairments are particularly important because they lead to an increased risk of falls. Falls risk factors and consequences depend on the stage of the disease. A satisfactory therapeutic strategy for gait impairments is a serious challenge: the use of a metronome during gait in HD patients does not effectively improve their gait. Attention deficits in HD may be a major determinant of this failure. The effect of antichoreic medications on gait is still controversial because of the absence of specific evaluation of these medications on gait disturbances.

Effects of Stride Length and Running Mileage on a Probabilistic Stress Fracture Model

The fatigue life of bone is inversely related to strain magnitude. Decreasing stride length is a potential mechanism of strain reduction during running. If stride length is decreased, the number of loading cycles will increase for a given mileage. It is unclear if increased loading cycles are detrimental to skeletal health despite reductions in strain. To determine the effects of stride length and running mileage on the probability of tibial stress fracture. Ten male subjects ran overground at their preferred running velocity during two conditions: preferred stride length and 10% reduction in preferred stride length. Force platform and kinematic data were collected concurrently. A combination of experimental and musculoskeletal modeling techniques was used to determine joint contact forces acting on the distal tibia. Peak instantaneous joint contact forces served as inputs to a finite element model to estimate tibial strains during stance. Stress fracture probability for stride length conditions and three running mileages (3, 5, and 7 miles x d(-1)) were determined using a probabilistic model of bone damage, repair, and adaptation. Differences in stress fracture probability were compared between conditions using a 2 x 3 repeated-measures ANOVA. The main effects of stride length (P = 0.017) and running mileage (P = 0.001) were significant. Reducing stride length decreased the probability of stress fracture by 3% to 6%. Increasing running mileage increased the probability of stress fracture by 4% to 10%. Results suggest that strain magnitude plays a more important role in stress fracture development than the total number of loading cycles. Runners wishing to decrease their probability for tibial stress fracture may benefit from a 10% reduction in stride length.

Gait adaptations to simultaneous cognitive and mechanical constraints

Previous studies have shown that walking is not a purely automatic motor task but places demands on sensory and cognitive systems. We set out to investigate whether complex walking tasks, as when walking down a steeper gradient while performing a concurrent cognitive task, would demand gait adaptation beyond those required for walking under low-challenge conditions. Thirteen healthy young individuals walked at their self-selected speed on a treadmill at different inclinations (0, -5 and -10%). Gait spatio-temporal measures, pelvis angular excursion, and sacral centre of mass (CoM) motion were acquired while walking or while walking and performing a mental tracking task. Repeated-measures ANOVAs revealed that decreasing treadmill inclination from 0 to -10% resulted in significant decreased walking speed (P < 0.001), decreased stride length (P < 0.001), increased pelvis tilt (P = 0.006) and obliquity variability (P = 0.05), decreased pelvis rotation (P = 0.02), and increased anterio-posterior (A-P) CoM displacement (P = 0.015). Compared to walking alone, walking under dual-task condition resulted in increased step width (P < 0.001), and increased medio-lateral (M-L) CoM displacement (P = 0.039) regardless of inclination grade, while sagittal plane dynamics did not change. Findings suggest that gait adapts differently to cognitive and mechanical constraints; the cognitive system is more actively involved in controlling frontal than sagittal plane gait dynamics, while the reverse is true for the mechanical system. Finally, these findings suggest that gait adaptations maintain the ability to perform concurrent tasks while treadmill walking in healthy young adults.

MRI- and MRS-derived hippocampal correlates of quantitative locomotor function in older adults

Gait measures have been shown to predict cognitive decline and dementia in older adults. Investigation of the neurobiology associated with locomotor function is needed to elucidate this relationship with cognitive abilities. This study aimed to examine magnetic resonance imaging (MRI; hippocampal volume)- and proton magnetic resonance spectroscopy (MRS; N-acetylaspartate to creatine (NAA/Cr) ratios)-derived hippocampal correlates of quantitative gait function (swing time (seconds), stride length (cm), and stride length variability (standard deviation)) in a subset of 48 nondemented older adults (24 males; mean age = 81 years) drawn from the Einstein Aging Study, a community-based sample of individuals over the age of 70 residing in Bronx, New York. Linear regression analyses controlling for age were used to examine hippocampal volume and neurochemistry as predictors of gait function. We found that stride length was associated with hippocampal volume ( β = 0.36, p = 0.03; overall model R 2 = 0.33, p = 0.01), but not hippocampal neurochemistry ( β = 0.09, p = 0.48). Stride length variability was more strongly associated with hippocampal NAA/Cr ( β = − 0.38, p = 0.01; overall model R 2 = 0.14, p = 0.04) than hippocampal volume ( β = − 0.33, p = 0.08). Gait swing time was not significantly related to any neuroimaging measure. These relationships remained significant after accounting for memory and clinical gait impairments. These findings suggest that nondemented older adults exhibit increased stride length variability that is associated with lower levels of hippocampal neuronal metabolism, but not hippocampal volume. Conversely, decreased stride length is associated with smaller hippocampal volumes, but not hippocampal neurochemistry. Distinct neurobiological hippocampal substrates may support decreased stride length and increased stride length variability in older adults.

Soccer Fatigue, Sprinting and Hamstring Injury Risk

The aim of this study was to investigate the effect of a multi-directional soccer-specific fatigue protocol on sprinting kinematics in relation to hamstring injury risk. Nine semi-professional soccer players (Mean +/- SD: Age: 21.3 +/- 2.9 year; Height 185.0 +/- 8.7 cm; Body Mass 81.6 +/- 6.7 kg) completed the SAFT(90); a multi-directional, intermittent 90 min exercise protocol representative of soccer match-play. The 10m sprint times and three-dimensional kinematic data were recorded using a high-speed motion capture system (Qualisys Track Manager) every 15 min during the SAFT(90). A significant time dependent increase was observed in sprint time during the SAFT(90) (P<0.01) with a corresponding significant decrease in stride length (P<0.01). Analysis of the kinematic sprint data revealed significantly reduced combined maximal hip flexion and knee extension angle, indicating reduced hamstring length, between pre-exercise and half-time (P<0.01) and pre-exercise and full-time (P<0.05). These findings revealed that the SAFT(90) produced time dependent impairments in sprinting performance and kinematics of technique which may result from shorter hamstring muscle length. Alterations in sprinting technique may have implications for the increased predisposition to hamstring strain injury during the latter stages of soccer match-play.

Striatal dopamine level contributes to hydroxyl radical generation and subsequent neurodegeneration in the striatum in 3-nitropropionic acid-induced Huntington's disease in rats

We tested the hypothesis that dopamine contributes significantly to the hydroxyl radical ( OH)-induced striatal neurotoxicity caused by 3-nitropropionic acid (3-NP) in a rat model of Huntington's disease. Dopamine (10–100 μM) or 3-NP (10–1000 μM) individually caused a significant increase in the generation of hydroxyl radical ( OH) in the mitochondria, which was synergistically enhanced when the lowest dose of the neurotoxin (10 μM) and dopamine (100 μM) were present together. Similarly, systemic administration of l-DOPA (100–250 mg/kg) and a low dose of 3-NP (10 mg/kg) potentiated OH generation in the striatum, and the rats exhibited significant decrease in stride length, a direct indication of neuropathology. The pathology was also evident in striatal sections subjected to NeuN immunohistochemistry. The significant changes in stride length, the production of striatal OH and neuropathological features due to administration of a toxic dose of 3-NP (20 mg/kg) were significantly attenuated by treating the rats with tyrosine hydroxylase inhibitor α-methyl- p-tyrosine prior to 3-NP administration. These results strongly implicate a major contributory role of striatal dopamine in increased generation of OH, which leads to striatal neurodegeneration and accompanied behavioral changes, in 3-NP model of Huntington's disease.

Effects Of Reducing Stride Length And Shoe Stiffness On The Probability Of Tibial Stress Fracture

The fatigue life of bone is inversely related to strain magnitude. Potential mechanisms of strain reduction during running include decreasing stride length and shoe midsole stiffness. However, if stride length is decreased the number of loading cycles will increase for a given mileage. It is unclear if increased loading cycles are detrimental to skeletal health despite reductions in strain. PURPOSE: To determine if reducing stride length or midsole stiffness decreases the probability of tibial stress fracture. METHODS: Nine male subjects ran overground at their preferred running velocity during three conditions: preferred stride length (PSL), -10%PSL, and PSL with compliant midsole (PSLcomp). Force platform and kinematic data were collected concurrently. A combination of experimental and musculoskeletal modeling techniques were used to determine joint contact forces acting on the distal tibia. Peak instantaneous joint contact forces served as inputs to a finite element model to estimate the maximum tibial strains during stance. Stress fracture probability for each condition was determined using Taylor's model of damage, repair, and adaptation. Differences in stress fracture probability were compared between conditions using a repeated measures ANOVA with Tukey's post-hoc tests. RESULTS: The probability of stress fracture during -10%PSL was 25% lower than PSL (p<0.01) and 28% lower than PSLcomp (p<0.01). This was due to an overall reduction in tibial strain magnitudes during -10%PSL. No difference in stress fracture probability was observed between PSL and PSLcomp. CONCLUSION: These results suggest that strain magnitude plays a more important role in stress fracture development than the total number of loading cycles. Runners wishing to decrease their probability for tibial stress fracture may benefit from a 10% reduction in stride length. This conclusion is specific to the parameters investigated in this study and may not apply to different velocities, stride lengths, and mileages. Although decreasing midsole stiffness was not an effective way to reduce tibial strains and subsequently the probability of stress fracture, no attempt was made to incorporate strain rates into the model. Midsole stiffness can influence the rate of loading and bone microdamage increases proportionately to strain rate.

Clinical factors associated with a conservative gait pattern in older male veterans with diabetes

BackgroundPatients with diabetes and peripheral neuropathy are at higher risk for falls. People with diabetes sometimes adopt a more conservative gait pattern with decreased walking speed, widened base, and increased double support time. The purpose of this study was to use a multivariate approach to describe this conservative gait pattern.MethodsMale veterans (mean age = 67 years; SD = 9.8; range 37–86) with diabetes (n = 152) participated in this study from July 2000 to May 2001 at the Veterans Affairs Medical Center, White River Junction, VT. Various demographic, clinical, static mobility, and plantar pressure measures were collected. Conservative gait pattern was defined by visual gait analysis as failure to demonstrate a heel-to-toe gait during the propulsive phase of gait.ResultsPatients with the conservative gait pattern had lower walking speed and decreased stride length compared to normal gait. (0.68 m/s v. 0.91 m/s, p < 0.001; 1.04 m v. 1.24 m, p < 0.001) Age, monofilament insensitivity, and Romberg's sign were significantly higher; and ankle dorsiflexion was significantly lower in the conservative gait pattern group. In the multivariate analysis, walking speed, age, ankle dorsiflexion, and callus were retained in the final model describing 36% of the variance. With the inclusion of ankle dorsiflexion in the model, monofilament insensitivity was no longer an independent predictor.ConclusionOur multivariate investigation of conservative gait in diabetes patients suggests that walking speed, advanced age, limited ankle dorsiflexion, and callus describe this condition more so than clinical measures of neuropathy.

Limited remyelination in Theiler's murine encephalomyelitis due to insufficient oligodendroglial differentiation of nerve/glial antigen 2 (NG2)‐positive putative oligodendroglial progenitor cells

Limited remyelination is a key feature of demyelinating Theiler's murine encephalomyelitis (TME). It is hypothesized that a dysregulation of differentiation of oligodendroglial progenitor cells (OPCs) represents the main cause of insufficient regeneration in this model of multiple sclerosis. TME virus (TMEV)-infected SJL/J mice were evaluated by footprint analysis, light and electron microscopy, immunohistology, confocal immunofluorescence and RT-qPCR at multiple time points ranging from 1 h to 196 days post infection (dpi). Footprint analysis revealed a significantly decreased stride length at 147 and 196 dpi. Demyelination progressively increased from 14 towards 196 dpi. A mild amount of remyelination was detected at 147 and 196 dpi. Early onset axonal injury was detected from 14 dpi on. TMEV RNA was detectable throughout the observation period and markedly increased between 7 and 28 dpi. Intralesional nerve/glial antigen 2 (NG2)-positive OPCs were temporarily increased between 28 and 98 dpi. Similarly, a transient upregulation of NG2 and platelet-derived growth factor alpha-receptor mRNA was noticed. In contrast, intralesional 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-positive oligodendrocytes were decreased between 56 and 196 dpi. Although CNPase mRNA remained unchanged, myelin basic protein mRNA and especially its exon 2 containing splice variants were decreased. Glial fibrillary acidic protein (GFAP)-positive astrocytes and GFAP mRNA were increased in the late phase of TME. A mildly increased colocalization of both NG2/CNPase and NG2/GFAP was revealed at 196 dpi. Summarized, the present results indicated a dysregulation of OPC maturation as the main cause for the delayed and limited remyelination in TME. A shift of OPC differentiation from oligodendroglial towards astrocytic differentiation is postulated.

Comparison of three-dimensional lower extremity running kinematics of young adult and elderly runners

The objective of this study was to compare the three-dimensional lower extremity running kinematics of young adult runners and elderly runners. Seventeen elderly adults (age 67–73 years) and 17 young adults (age 26–36 years) ran at 3.1 m · s−1 on a treadmill while the movements of the lower extremity during the stance phase were recorded at 120 Hz using three-dimensional video. The three-dimensional kinematics of the lower limb segments and of the ankle and knee joints were determined, and selected variables were calculated to describe the movement. Our results suggest that elderly runners have a different movement pattern of the lower extremity from that of young adults during the stance phase of running. Compared with the young adults, the elderly runners had a substantial decrease in stride length (1.97 vs. 2.23 m; P = 0.01), an increase in stride frequency (1.58 vs. 1.37 Hz; P = 0.002), less knee flexion/extension range of motion (26 vs. 33°; P = 0.002), less tibial internal/external rotation range of motion (9 vs. 12°; P < 0.001), larger external rotation angle of the foot segment (toe-out angle) at the heel strike (−5.8 vs. −1.0°; P = 0.009), and greater asynchronies between the ankle and knee movements during running. These results may help to explain why elderly individuals could be more susceptible to running-related injuries.

Wearing the F-Scan mobile in-shoe pressure measurement system alters gait characteristics during running

This study investigated the influence of wearing an F-Scan mobile in-shoe pressure measurement system on running characteristics. Six subjects ran on a treadmill at three speeds (3.5 m s −1, 4.5 m s −1 and 5.4 m s −1) with and without wearing the F-Scan system while kinematic data were collected at 240 Hz using a motion capture system. Six gait cycles were selected for analysis, with touchdown and toe-off visually identified based on foot markers displacement. Spatio-temporal gait parameters including stride frequency, stride length, stride length relative to height, and stance time were determined. A 2 × 3 ANOVA with repeated measures ( α = 0.05) was performed to identify differences in each gait parameter between running with and without the F-Scan system at different speeds. Wearing the F-Scan system did not affect the stance time but lead to an increase in stride frequency ( P < 0.05) and a decrease in stride length ( P < 0.05) and relative stride length ( P < 0.05). As speed increased, stance time decreased while stride frequency, stride length and relative stride length increased (all P < 0.001). These results imply that wearing the F-Scan system alters gait characteristics and therefore data obtained may not represent those in a real life setting, at least in the case of running. One should take into account the potential risk of the movement of interest being altered when interpreting data obtained while subjects were wearing the F-Scan system. Future instrumentation should minimize the potential influence a measurement device may have on natural movement.

IC-P3-232: MRI and MRS-derived hippocampal correlates of quantitative gait dysfunction in older adults

Background: Gait measures have been shown to predict cognitive decline and dementia in older adults independent of memory performance and other clinical variables. Investigation of the neurobiology associated with gait dysfunction is needed to elucidate this relationship. Neuroimaging has emerged as a powerful tool for the identification of brain morphometry and physiology associated with dementia risk factors. This study aimed to examine magnetic resonance imaging (MRI)and magnetic resonance spectroscopy (MRS)derived hippocampal correlates of gait function in a well-characterized sample of nondemented older adults. Methods: 4T MRI, 1H MRS, and quantitative gait evaluations were conducted in a subset of 48 nondemented older adults (24 males; mean age 81 years) drawn from the Einstein Aging Study, a community-based sample of individuals over the age of 70 residing in the Bronx, New York. Hippocampal volumes, hippocampal neurochemistry (Nacetyl-aspartate to creatine ratios), and quantitative gait measures (stride length, swing, and stride variability) were obtained in all participants. Gait measure selection was based on three gait domains identified in our prior research. Volumetrics were obtained by a single trained rater with high intrarater reliability (ICC 0.99). Results: Separate linear regression analyses controlling for age were used to examine hippocampal volume and neurochemistry as predictors of gait function (stride length, swing, and stride variability). Stride variability was associated with hippocampal neurochemistry ( -0.38, p 0.01; overall model R2 0.14, p 0.04), but not hippocampal volume ( -0.33, p 0.08). Conversely, stride length was associated with hippocampal volume ( 0.36, p 0.03; overall model R2 0.33, p 0.01), but not hippocampal neurochemistry ( 0.09, p 0.48). Gait swing was not significantly related to any neuroimaging measure. Conclusions: Nondemented older adults exhibit increased stride variability that is associated with lower levels of hippocampal neuronal metabolism as measured by MRS neurochemistry, but not hippocampal volume. Furthermore, decreased stride length is associated with smaller hippocampal volumes, but not hippocampal neurochemistry. If confirmed in larger samples, this pattern of results suggests that distinct neurobiological substrates may support decreased stride length and increased variability in older adults. Additional investigation is necessary to examine the longitudinal sequence of motor, cognitive, neurochemical and neuroanatomic changes in normal aging and dementia.

Beneficial effects of treadmill training in a cerebral palsy-like rodent model: Walking pattern and soleus quantitative histology

The aim of the present study was to investigate whether treadmill locomotor training could have beneficial effects on deficits consequent to perinatal anoxia, sensorimotor restriction or a combination of both. Fifty-six newborn male Wistar rats were divided into four groups: control, anoxic, sensorimotor-restricted and anoxic–sensorimotor-restricted. Rats were exposed to anoxia in the first two postnatal days (P0 and P1) and/or hind-limb sensorimotor restriction from P2 to P28 for 16 h/day. Control and experimental rats underwent treadmill training for three weeks (from P31 to P52). Body weight and walking patterns (stride length and foot angle) were measured weekly during treadmill locomotor training. Soleus muscle cross-sectional mean area and fiber density were measured using planar morphometry. Anoxia per se did not cause gait or muscle deficits. Body weight, stride length and soleus fiber cross-sectional mean area, however, were increased in trained anoxic rats. Sensorimotor-restricted animals, either with or without perinatal anoxia, showed deficits in body weight gain, decreased stride length, wider foot angle and soleus fiber atrophy. In the sensorimotor-restricted group, treadmill training improved body weight gain and stride length, and decreased the percentage of the atrophic fibers. However, in the anoxic–sensorimotor-restricted group, training improved stride length only. Three weeks of treadmill training were able to improve stride length in restricted and anoxic-restricted animals, although body weight deficit and the degree of degradation in muscle histology were reduced only in the restricted group.