Bracing the trunk and neck in young adults leads to a more aged-like gait

Older individuals typically walk at slower speeds, with shorter step lengths, greater step widths and spend a larger proportion of the gait cycle in double stance. Changes in neck and trunk mobility may underlie some of the changes in walking seen with increasing age. Consequently, this study was designed to assess whether externally increasing trunk/neck stiffness in young adults leads to similar changes in gait pattern observed with aging. Twelve young adults (20–29 years), sixteen old adults (60–69 years) and fifteen older adults (70–79 years) walked across a 20′ pressure sensitive GAITRite© instrumented walkway at their preferred speed. The young adults also walked under three bracing conditions: (1) Neck braced, (2) Trunk braced, and (3) Neck and Trunk braced. The results revealed that the old and older age groups walked significantly slower, with a shorter step length and with a narrower base of support (p’s < 0.05) compared to the young adults. In young adults, combined neck and trunk bracing led to reduced walking speed, shorter step length, wider base of support and a larger proportion of the gait cycle spent in double stance (p’s < 0.05). The walking speed and step length of older adults remained less than fully braced young adults (p’s < 0.05). Overall these results indicate that artificially stiffening the trunk and neck of young individuals leads to systematic gait changes similar to aging. Consequently, age-related changes in mobility of the neck and torso may in part contribute to the decrements in walking seen for older adults.     

Dynamic stability of superior vs. inferior segments during walking in young and older adults

Active control of trunk motion is believed to enable humans to maintain stability during walking, suggesting that stability of the trunk is prioritized over other segments by the nervous system. We investigated if superior segments are more stable than inferior segments during walking and if age-related differences are more prominent in any particular body segments. Eighteen healthy older adults and 17 healthy young adults walked on a treadmill for two trials of 5 min each at their preferred speed. 3D kinematics of the trunk, pelvis, and left thigh, shank, and foot were recorded. Local divergence exponents and maximum Floquet multipliers (FM) were calculated to quantify each segment's responses to small inherent perturbations during walking. Both older and younger adults walked with similar preferred walking speeds (p = 0.86). Local divergence exponents were larger in inferior segments (p < 0.001), and larger in older adults (p < 0.001). FM was larger in the superior segments (p < 0.001), and larger in older adults (p < 0.001). The age-associated difference in local divergence exponents was larger for trunk motion (interaction p = 0.02). Thus, superior segments exhibited less local instability but greater orbital instability. Trunk motion was more sensitive to age-associated differences in dynamic stability during gait. Trunk motion should be considered in studying age-related deterioration of gait.     

Sleep quality is associated with walking under dual-task,but not single-task performance

ObjectivesThe objective of this study was to assess the relationship between sleep behavior and gait performance under single-task (ST) and dual-task (DT) walking conditions in community- dwelling older adults.MethodsWalking under ST and DT conditions was evaluated in 34 community-dwelling older adults, 64.7% women, mean age 71.5 (SD ± 5.8). Gait-speed and gait-variability data were collected using the OPAL wearable sensors of the Mobility Lab. Sleep behavior (sleep efficiency [SE] and sleep latency [SL]) was assessed using actigraphy, over 5 consecutive nights.ResultsLower SE was associated with decreased gait speed and increased stride-length variability during DT (rs = 0.35; p = 0.04; rs = −0.36; p = 0.03, respectively), whereas longer SL was associated with increased stride-length variability during DT (rs = 0.38; p = .03). After controlling for age and cognition, SE accounted for 24% and 33% of the variability in stride length and stride time. No associations were found between sleep and gait measures under ST walking.ConclusionsLower SE is associated with decreased gait speed and increased gait variability under DT conditions that are indicative of an increased risk for falls in older adults. Our findings support clinical recommendations to incorporate the evaluation of sleep quality in the context of risk assessment for falls.     

Effects of age and physical activity status on redistribution of joint work during walking

During walking older adults rely less on ankle and more on hip work than young adults. Disproportionate declines in plantarflexor strength may be a mechanism underlying this proximal work redistribution. We tested the hypothesis that proximal redistribution is more apparent in older compared to young adults and in sedentary compared to active individuals over multiple walking speeds. We recruited 18 young (18–35 yrs) and 17 older (65–80 yrs) physically active and sedentary adults. Participants completed five trials at four walking speeds as marker positions and ground reaction forces were collected. Sagittal plane net joint moments were computed using inverse dynamics. Instantaneous joint powers for the ankle, knee, and hip were computed as products of net joint moments and joint angular velocities. Positive joint work was computed by integrating hip, knee, and ankle joint powers over time in early, mid, and late stance, respectively. Relative joint work was expressed as a percentage of total work. Isokinetic strength of lower limb flexor and extensor muscles was measured. Older adults had lower relative ankle (p = 0.005) and higher relative hip (p = 0.007) work than young adults for multiple speeds. Non-significant trends (p < 0.10) indicating sedentary participants had lower relative ankle (p = 0.068) and higher relative hip work (p = 0.087) than active adults were observed. Age-related differences in plantarflexor strength were not disproportionate compared to strength differences in knee and hip musculature. Age influenced proximal work redistribution over multiple walking speeds. Physical activity status showed a similar trend for proximal work redistribution, but failed to reach statistical significance.     

The influence of divided attention on walking turns: Effects on gait control in young adults with and without a history of low back pain

The cognitive control of gait is altered in individuals with low back pain, but it is unclear if this alteration persists between painful episodes. Locomotor perturbations such as walking turns may provide a sensitive measure of gait adaptation during divided attention in young adults. The purpose of this study was to investigate changes in gait during turns performed with divided attention, and to compare healthy young adults with asymptomatic individuals who have a history of recurrent low back pain (rLBP). Twenty-eight participants performed 90° ipsilateral walking turns at a controlled speed of 1.5 m/s. During the divided attention condition they concurrently performed a verbal 2-back task. Step length and width, trunk-pelvis and hip excursion, inter-segmental coordination and stride-to-stride variability were quantified using motion capture. Mixed-model ANOVA were used to examine the effect of divided attention and group, and interaction effects on the selected variables. Step length variability decreased significantly with divided attention in the healthy group but not in the rLBP group (post-hoc p = 0.024). Inter-segmental coordination variability was significantly decreased during divided attention (main effect of condition p < 0.000). There were small but significant reductions in hip axial and sagittal motion across groups (main effect of condition p = 0.044 and p = 0.040 respectively), and a trend toward increased frontal motion in the rLBP group only (post-hoc p = 0.048). These findings suggest that the ability to switch attentional resources during gait is altered in young adults with a history of rLBP, even between symptomatic episodes.     

Cognitive motor interference during dual-task gait in essential tremor

BackgroundFunctional ambulation requires concurrent performance of motor and cognitive tasks, which may create interference (degraded performance) in either or both tasks. People with essential tremor (ET) demonstrate impairments in gait and cognitive function. In this study we examined the extent of interference between gait and cognition in people with ET and controls during dual-task gait.MethodsWe tested 62 controls and 151 ET participants (age range: 72–102). ET participants were divided into two groups based on median score on the modified Mini Mental State Examination. Participants walked at their preferred speed, and performed a verbal fluency task while walking. We analyzed gait velocity, cadence, stride length, double support time, stride time, step width, step time difference, coefficient of variation (CV) of stride time and stride length.ResultsVerbal fluency performance during gait was similar across groups (p = 0.68). Velocity, cadence and stride length were lowest whereas step time difference (p = 0.003), double support time (p = 0.009), stride time (p = 0.002) and stride time CV (p = 0.007) were highest for ET participants with lower cognitive scores (ETp-LCS), compared with ET participants with higher cognitive scores (ETp-HCS) and controls. ETp-LCS demonstrated greatest interference for double support time (p = 0.005), step time difference (p = 0.013) and stride time coefficient of variation (p = 0.03).ConclusionsETp-LCS demonstrated high levels of cognitive motor interference. Gait impairments during complex tasks may increase risk for falls for this subgroup and underscore the importance of clinical assessment of gait under simple and dual-task conditions.     

Trunk sway during walking among older adults: Norms and correlation with gait velocity

The aim of this study was to establish quantitative norms for trunk sway during walking for older male and female ambulatory adults at different age groups (65–70, 71–75, 76–80, ≥81). We also assessed the relationship between dynamic trunk sway and gait velocity in older individuals with clinically normal or abnormal gaits. Trunk sway in medio-lateral (roll) and antero-posterior (pitch) planes was measured using a body-mounted gyroscope (SwayStar) during walking on a 4.5 m long instrumented walkway. Of the 284 older adults (mean age 76.8, 54.6% women) in this sample, the mean ± SD value of roll and pitch angles were 6.0 ± 2.0° and 6.7 ± 2.2° respectively. Older women showed significantly greater trunk sway in both roll and pitch angles than older men (p < 0.01). In both men and women, there was no significant association of roll angle with age although gait velocity decreased with increasing age. The relationship between roll angle and gait velocity was U-shaped for the overall sample. Among the subgroup with clinically normal gait, increased roll angle was associated with increased gait velocity (p < 0.001). However, there was no significant relationship between roll angle and gait velocity among the subgroup with abnormal gait. Therefore, the relationship between medio-lateral trunk sway and gait velocity differs depending on whether gait is clinically normal.We conclude that trunk sway during walking should be interpreted with consideration of both gait velocity and presence of gait abnormality in older adults.     

The association between fear of falling and gait variability in both leg and trunk movements

The aim of this study was to explore whether FoF was associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Ninety-three elderly people participated in this study. Each participant was categorized into either Fear or No-Fear group on the basis of having FoF. The participants walked 15 m at their preferred speed. The wireless motion recording sensor units were attached to L3 spinous process and right posterior surface of heel during gait. Gait velocity, stride time and stride length were calculated. Variability in lower limb movements was represented by coefficient of variation (CV) of stride time. Trunk variability was represented by autocorrelation coefficients (AC) in three directions (vertical: VT, mediolateral: ML and anteroposterior: AP), respectively. Gait parameters were compared between groups, and further analyses were performed using generalized linear regression models after adjustment of age, sex, fall experience, height, weight, and gait velocity. Although gait velocity, mean stride time and stride length did not differ significantly between groups, stride time CV and all ACs were significantly worse in the Fear group after adjustment for variables, even including gait velocity (stride time CV: p = 0.003, β = −0.793; AC-VT: p = 0.011, β = 0.053; AC-ML: p = 0.044, β = 0.075; AC-AP: p = 0.002, β = 0.078). Our results suggest that fear of falling is associated with variability in both leg and trunk movements during gait in community-dwelling elderly. Further studies are needed to prove a causal relationship.     

Trunk sway during walking among older adults: Norms and correlation with gait velocity

The aim of this study was to establish quantitative norms for trunk sway during walking for older male and female ambulatory adults at different age groups (65–70, 71–75, 76–80, ≥81). We also assessed the relationship between dynamic trunk sway and gait velocity in older individuals with clinically normal or abnormal gaits. Trunk sway in medio-lateral (roll) and antero-posterior (pitch) planes was measured using a body-mounted gyroscope (SwayStar) during walking on a 4.5 m long instrumented walkway. Of the 284 older adults (mean age 76.8, 54.6% women) in this sample, the mean ± SD value of roll and pitch angles were 6.0 ± 2.0° and 6.7 ± 2.2° respectively. Older women showed significantly greater trunk sway in both roll and pitch angles than older men (p < 0.01). In both men and women, there was no significant association of roll angle with age although gait velocity decreased with increasing age. The relationship between roll angle and gait velocity was U-shaped for the overall sample. Among the subgroup with clinically normal gait, increased roll angle was associated with increased gait velocity (p < 0.001). However, there was no significant relationship between roll angle and gait velocity among the subgroup with abnormal gait. Therefore, the relationship between medio-lateral trunk sway and gait velocity differs depending on whether gait is clinically normal.We conclude that trunk sway during walking should be interpreted with consideration of both gait velocity and presence of gait abnormality in older adults.     

Visuomotor adaptation of voluntary step initiation in older adults

It has been suggested that feedforward planning of gait and posture is diminished in older adults. Motor adaptation is one mechanism by which feedforward commands can be updated or fine-tuned. Thus, if feedforward mechanisms are diminished in older adults, motor adaptation is also likely to be limited. The purpose of the study was to compare the ability of healthy older versus young adults in generating a voluntary stepping motor adaptation in response to a novel visual sensory perturbation. We recorded stepping movements from 18 healthy older and 18 young adults during baseline and adaptation stepping blocks. During baseline, the stepping target remained stationary; in adaptation, a visual perturbation was introduced by shifting the target laterally during mid-step. We compared adaptation between groups, measured by improvements in endpoint accuracy and movement duration. Older adults adapted stepping accuracy similarly to young adults (accuracy improvement: 29.7 ± 27.6% vs. 37.3 ± 22.9%, older vs. young group respectively, p = 0.375), but showed significant slowness during movement. Thus older adults were able to achieve accuracy levels nearly equivalent to younger adults, but only at the expense of movement speed, at least during the early adaptation period (movement duration: 1143.7 ± 170.6 ms vs. 956.0 ± 74.6 ms, p < 0.001). With practice, however, they were able to reduce movement times and gain speed and accuracy to levels similar to young adults. These findings suggest older adults may retain the ability for stepping adaptations to environmental changes or novel demands, given sufficient practice.     

Dynamic instability during post-stroke hemiparetic walking

Falls and fall-related injuries cause extremely costly and potentially fatal health problems in people post-stroke. However, there is no global indicator of walking instability for detecting which individuals will have increased risk of falls. The purposes of this study were to directly quantify walking stability in stroke survivors and neurologically intact controls and to determine which stability measures would reveal the changes in walking stability following stroke. This study thus provided an initial step to establish objective measures for identifying potential fallers. Nine post-stroke individuals and nine controls walked on a treadmill at four different speeds. We computed short-term local divergence exponent (LDE) and maximum Floquet multiplier (maxFM) of the trunk motion, average and variability of dynamic margins of stability (MOS) and step spatiotemporal measures. Post-stroke individuals demonstrated larger short-term LDE (p = 0.002) and maxFM (p = 0.041) in the mediolateral (ML) direction compared to the controls but remained orbitally stable (maxFM < 1). In addition, post-stroke individuals walked with greater average step width (p = 0.003) but similar average ML MOS (p = 0.154) compared to the controls. Post-stroke individuals also exhibited greater variability in all MOS and step measures (all p < 0.005). Our findings indicate that post-stroke individuals walked with greater local and orbital instability and gait variability than neurologically intact controls. The results suggest that short-term LDE of ML trunk motion and the variability of MOS and step spatiotemporal measures detect the changes in walking stability associated with stroke. These stability measures may have the potential for identifying those post-stroke individuals at increased risk of falls.     

Backward compared to forward over ground gait retraining have additional benefits for gait in individuals with mild to moderate Parkinson’s disease: A randomized controlled trial

Over ground gait retraining in the reverse direction has shown to be beneficial for neurological rehabilitation, but has not yet been investigated in Parkinson’s disease (PD). Backwards walking (BW) might be a useful training alternative to improve PD gait and possibly reduce fall risk during complex multi-directional daily activities. The primary aim was to compare the effect of an eight-week forward (FWG) and backwards (BWG) gait retraining program on gait parameters in PD individuals. Twenty-nine participants (aged 71.0 ± 8.8 years; UPDRS-III 38.1 ± 12.3; H&Y 2.7 ± 0.5) were randomly assigned to either the control (FWG; n = 14) or experimental group (BWG; n = 15). Baseline measures included disease severity (UPDRS III), global cognition (MoCA) and depression (PHQ-9). Outcome measures were selected gait variables on the 10m-instrumented-walk-test (i10mWT) assessed before and after the interventions. Both groups improved usual gait speed (FWG: p = 0.03, d = 0.35; BWG: p < 0.01, d = 0.35) and height-normalized gait speed (FWG: p = 0.04, d = 0.35; BWG: p < 0.01, d = 0.57). Additionally, the BWG demonstrated improved cadence (p < 0.01, d = 0.67) and stride length (SL; p = 0.02, d = 0.39). Both interventions were effective to improved gait speed sufficiently to independently navigate in the community.     

Altered vision destabilizes gait in older persons

This study assessed the effects of dim light and four experimentally induced changes in vision on gait speed and footfall and trunk parameters in older persons walking on level ground. Using a quasi-experimental design, gait characteristics were assessed in full light, dim light, and in dim light combined with manipulations resulting in reduced depth vision, double vision, blurred vision, and tunnel vision, respectively. A convenience sample of 24 home-dwelling older women and men (mean age 78.5 years, SD 3.4) with normal vision for their age and able to walk at least 10 m without assistance participated. Outcome measures were gait speed and spatial and temporal parameters of footfall and trunk acceleration, derived from an electronic gait mat and accelerometers. Dim light alone had no effect. Vision manipulations combined with dim light had effect on most footfall parameters but few trunk parameters. The largest effects were found regarding double and tunnel vision. Men increased and women decreased gait speed following manipulations (p = 0.017), with gender differences also in stride velocity variability (p = 0.017) and inter-stride medio-lateral trunk acceleration variability (p = 0.014). Gender effects were related to differences in body height and physical functioning. Results indicate that visual problems lead to a more cautious and unstable gait pattern even under relatively simple conditions. This points to the importance of assessing vision in older persons and correcting visual impairments where possible.     

Gait variability and disability in multiple sclerosis

Gait variability is clinically relevant in some populations, but there is limited documentation of gait variability in persons with multiple sclerosis (MS). This investigation examined average and variability of spatiotemporal gait parameters in persons with MS and healthy controls and subsequent associations with disability status. 88 individuals with MS (age 52.4 ± 11.1) and 20 healthy controls (age 50.9 ± 8.7) performed two self-paced walking trials on a 7.9-m electronic walkway to determine gait parameters. Disability was indexed by the Expanded Disability Status Scale (EDSS) and ranged between 2.5 and 6.5. Gait variability was indexed by standard deviation (SD) and coefficient of variation (CV = SD/mean) of step time, step length, and step width. Average gait parameters were significantly correlated with EDSS (ρ = 0.756–0.609) and were significantly different in individuals with MS compared to controls (p ≤ 0.002). Also, step length (p < 0.001) and step time (p < 0.001) variability were both significantly greater in MS compared to controls. EDSS was positively correlated with step length variability and individuals with MS who used assistive devices to walk had significantly greater step length variability than those who walked independently (p's < .05). EDSS was correlated with step time and length variability even when age was taken into account. Additionally, Fisher's z test of partial correlations revealed that average gait parameters were more closely related to disability status than gait variability in individuals with MS. This suggests that focusing on average gait parameters may be more important than variability in therapeutic interventions in MS.     

Foot-related pain and disability and spatiotemporal parameters of gait during self-selected and fast walking speeds in people with gout: A two-arm cross sectional study

ObjectivesTo examine gait parameters in people with gout during different walking speeds while adjusting for body mass index (BMI) and foot-pain, and to determine the relationship between gait parameters and foot-pain and disability.MethodGait parameters were measured using the GAITRite™ walkway in 20 gout participants and 20 age- and sex-matched controls during self-selected and fast walking speeds. Foot-pain and disability was measured using the Manchester Foot Pain and Disability Index (MFPDI) which contains four domains relating to function, physical appearance, pain and work/leisure.ResultsAt the self-selected speed, gout participants demonstrated increased step time (p = 0.017), and stance time (p = 0.012), and reduced velocity (p = 0.031) and cadence (p = 0.013). At the fast speed, gout participants demonstrated increased step time (p = 0.007), swing time (p = 0.005) and stance time (p = 0.019) and reduced velocity (p = 0.036) and cadence (p = 0.009). For participants with gout, step length was correlated with total MFPDI (r = −0.62, p = 0.008), function (r = −0.65, p = 0.005) and physical appearance (r = −0.50, p = 0.041); stride length was correlated with total MFPDI (r = −0.62, p = 0.008), function (r = −0.65, p = 0.005) and physical appearance (r = −0.50, p = 0.041); and velocity was correlated with total MFPDI (r = −0.60, p = 0.011), function (r = −0.63, p = 0.007) and work/leisure (r = −0.53, p = 0.030).ConclusionGait patterns exhibited by people with gout are different from controls during both self-selected and fast walking speeds, even after adjusting for BMI and foot-pain. Additionally, gait parameters were strongly correlated with patient-reported functional limitation, physical appearance and work/leisure difficulties, while pain did not significantly influence gait in people with gout.     

Variability of gait,bilateral coordination,and asymmetry in women with fibromyalgia

PurposeTo analyze how fibromyalgia affected the variability, asymmetry, and bilateral coordination of gait walking at comfortable and fast speeds.Methods65 fibromyalgia (FM) patients and 50 healthy women were analyzed. Gait analysis was performed using an instrumented walkway (GAITRite system). Average walking speed, coefficient of variation (CV) of stride length, swing time, and step width data were obtained and bilateral coordination and gait asymmetry were analyzed.ResultsFM patients presented significantly lower speeds than the healthy group. FM patients obtained significantly higher values of CV_StrideLength (p = 0.04; p < 0.001), CV_SwingTime (p < 0.001; p < 0.001), CV_StepWidth (p = 0.004; p < 0.001), phase coordination index (p = 0.01; p = 0.03), and p_CV (p < 0.001; p = 0.001) than the control group, walking at comfortable or fast speeds. Gait asymmetry only showed significant differences in the fast condition.ConclusionFM patients walked more slowly and presented a greater variability of gait and worse bilateral coordination than healthy subjects. Gait asymmetry only showed differences in the fast condition. The variability and the bilateral coordination were particularly affected by FM in women. Therefore, variability and bilateral coordination of gait could be analyzed to complement the gait evaluation of FM patients.     

Perceptual-motor behaviour during a simulated pedestrian crossing

This study used a novel research paradigm to examine gait control during real-time between-person collision avoidance. Ten young adults (M = 20.1 ± 1.52 years) were required to walk across a six metre simulated pedestrian crossing, while avoiding a collision with one or two oncoming pedestrians. The potential for social interaction was manipulated by having the oncoming pedestrians walk with (2 MP) or without (2 P) looking at a mobile phone. Participants took longer to complete the crossing when avoiding a collision with two oncoming pedestrians (2 MP: M = 5.68 s; 2P: M = 5.74 s) in comparison with baseline (M = 4.96 s). Gait velocity decreased and was more variable when avoiding a collision during the 2 P condition, whilst the anterior-posterior separation distance between pedestrians and the participants at the initiation of peak mediolateral deviation was significantly smaller in 2 MP compared to 2 P. These findings offer preliminary understanding on how gait control may be adapted to changes in the availability of other persons’ gaze orientation information. Future work is needed to further understand how different adaptive behaviours emerge relative to other persons during pedestrian crossings.     

Hip kinetics during gait are clinically meaningful outcomes in young boys with Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked genetic neuromuscular disorder characterized by progressive proximal to distal muscle weakness. The success of randomized clinical trials for novel therapeutics depends on outcome measurements that are sensitive to change. As the development of motor skills may lead to functional improvements in young boys with DMD, their inclusion may potentially confound clinical trials. Three-dimensional gait analysis is an under-utilized approach that can quantify joint moments and powers, which reflect functional muscle strength. In this study, gait kinetics, kinematics, spatial-temporal parameters, and timed functional tests were quantified over a one-year period for 21 boys between 4 and 8 years old who were enrolled in a multisite natural history study. At baseline, hip moments and powers were inadequate. Between the two visits, 12 boys began a corticosteroid regimen (mean duration 10.8 ± 2.4 months) while 9 boys remained steroid-naïve. Significant between-group differences favoring steroid use were found for primary kinetic outcomes (peak hip extensor moments (p = .007), duration of hip extensor moments (p = .007), peak hip power generation (p = .028)), and spatial-temporal parameters (walking speed (p = .016) and cadence (p = .021)). Significant between-group differences were not found for kinematics or timed functional tests with the exception of the 10 m walk test (p = .03), which improves in typically developing children within this age range. These results indicate that hip joint kinetics can be used to identify weakness in young boys with DMD and are sensitive to corticosteroid intervention. Inclusion of gait analysis may enhance detection of a treatment effect in clinical trials particularly for young boys with more preserved muscle function.     

Manipulating walking path configuration influences gait variability and six-minute walk test outcomes in older and younger adults

This study determined whether manipulations to walking path configuration influenced six-minute walk test (6MWT) outcomes and assessed how gait variability changes over the duration of the 6MWT in different walking path configurations. Healthy older (ODR) and younger (YNG) (n = 24) adults completed familiarisation trials and five randomly ordered experimental trials of the 6MWT with walking configurations of; 5, 10 and 15 m straight lines, a 6 m by 3 m rectangle (RECT), and a figure of eight (FIG8). Six-minute walk distance (6MWD) and walking speed (m.s⁻¹) were recorded for all trials and the stride count recorded for experimental trials. Reflective markers were attached to the sacrum and feet with kinematic data recorded at 100 Hz by a nine-camera motion capture system for 5 m, 15 m and FIG8 trials, in order to calculate variability in stride and step length, stride width, stride and step time and double limb support time. Walking speeds and 6MWD were greatest in the 15 m and FIG8 experimental trials in both groups (p < 0.01). Step length and stride width variability were consistent over the 6MWT duration but greater in the 5 m trial vs. the 15 m and FIG8 trials (p < 0.05). Stride and step time and double limb support time variability all reduced between 10 and 30 strides (p < 0.01). Stride and step time variability were greater in the 5 m vs. 15 m and FIG8 trials (p < 0.01). Increasing uninterrupted gait and walking path length results in improved 6MWT outcomes and decreased gait variability in older and younger adults.     

Trunk muscle action compensates for reduced quadriceps force during walking after total knee arthroplasty

Patients with total knee arthroplasty (TKA) frequently exhibit changes in gait biomechanics post-surgery, including decreased ranges of joint motion and changes in joint loading; however, the actions of the lower-limb muscles in generating joint moments and accelerating the center of mass (COM) during walking are yet to be described. The aim of the present study was to evaluate differences in lower-limb joint kinematics, muscle-generated joint moments, and muscle contributions to COM accelerations in TKA patients and healthy age-matched controls when both groups walk at the same speed. Each TKA patient was fitted with a posterior-stabilized total knee replacement and underwent patellar resurfacing. Three-dimensional gait analysis and subject-specific musculoskeletal modeling were used to determine lower-limb and trunk muscle forces and muscle contributions to COM accelerations during the stance phase of gait. The TKA patients exhibited a ‘quadriceps avoidance’ gait pattern, with the vasti contributing significantly less to the extension moment developed about the knee during early stance (p = 0.036). There was a significant decrease in the contribution of the vasti to the vertical acceleration (support) (p = 0.022) and forward deceleration of the COM (braking) (p = 0.049) during early stance; however, the TKA patients compensated for this deficiency by leaning their trunks forward. This significantly increased the contribution of the contralateral back extensor muscle (erector spinae) to support (p = 0.030), and that of the contralateral back rotators (internal and external obliques) to braking (p = 0.004). These findings provide insight into the biomechanical causes of post-operative gait adaptations such as ‘quadriceps avoidance’ observed in TKA patients.