Test of two prediction methods for minimum and maximum values of gait kinematics and kinetics data over a range of speeds

BackgroundMinimum and maximum values of gait kinematics and kinetics data are commonly used to quantitatively describe a walking pattern.Research questionThe purposes of this study were to determine the effect of speed on the minimum and maximum values of gait kinematics and kinetics variables and to test two prediction methods for the estimation of these minimum and maximum values at different gait speeds.MethodsAn open dataset with the data of 24 healthy adults (age: 27.6 ± 4.4 years, height: 171.1 ± 10.5 cm, body mass: 68.4 ± 12.2 kg) walking on a treadmill at eight gait speeds was employed in this study. The minimum and maximum angles and moments of the hip, knee, and ankle joints were extracted from speed-dependent prediction curves solely for the minimum and maximum values (PEAK method) and from speed-dependent prediction curves for the entire gait cycle (CYCLE method). The overall error, computed as the root-mean-square error (RMSE), for the minimum and maximum values predicted by these two methods were compared with the experimental true values.ResultsThe RMSEs for the joint angles were PEAK: 3.86 ± 1.21°, CYCLE: 3.88 ± 1.18° and for the joint moments were PEAK: 0.129 ± 0.052 Nm/kg, CYCLE: 0.131 ± 0.052 Nm/kg.SignificanceThe two prediction methods tested can be used to estimate the minimum and maximum values of biomechanical gait variables at a certain speed.     

Gait kinematics & kinetics at three walking speeds in individuals with chronic ankle instability and ankle sprain copers

BackgroundIndividuals with CAI have demonstrated a more inverted foot position during walking when compared to a healthy control group. Copers are individuals who have had an ankle sprain but learn to cope and return to pre-injury levels of function and may be a better comparison group than healthy controls because they have had the same initial injury.Research questionA controlled laboratory study was performed to simultaneously analyze differences in lower extremity walking gait kinematics, kinetics, and surface electromyography (EMG) between individuals with CAI and copers at a preferred walking speed (PWS), 120% preferred walking speed (120WS), and standardized walking speed (SWS) of 1.34 m/s.MethodsThirty-six (18 coper, 18 CAI) physically active individuals participated. Three-dimensional kinematics and kinetics at the ankle, knee, and hip and EMG amplitude for fibularis longus, tibialis anterior, medial gastrocnemius, and gluteus medius muscles were analyzed. Ten consecutive strides from each speed were analyzed using statistical parametric mapping (SPM). A 2 × 3 group by speed ANOVA and post-hoc t-tests were used to compare differences between the coper and CAI groups.ResultsThe CAI group had more ankle inversion at IC (PWS: MD = 4.2°, d = 1.08; 120WS: MD = 5.0°, d = 1.28; SWS: MD = 6.6°, d = 1.37) and greater peak inversion throughout swing at all three walking speeds (PWS: MD = 4.2°, d = 0.89; 120WS: MD = 4.4°, d = 0.91; SWS: MD = 6.2°, d = 1.21). The CAI group had greater peak hip adduction during swing (PWS: MD = 4.5°, d = 0.96; 120WS: MD = 4.1°, d = 1.04; SWS: MD = 3.6°, d = 0.98).SignificanceThe CAI group demonstrated greater ankle inversion at IC and during the swing phase and greater peak hip adduction during the swing phase compared to the copers. As the speed increased, ankle inversion in the CAI group also increased which could be linked to greater risk of recurrent sprains. Therefore, modeling gait training programs after the coper mechanics may be advantageous.     

Dynamic joint stiffness of the ankle in chronic ankle instability patients

BackgroundWhile Individuals with chronic ankle instability (CAI) exhibit altered ankle joint movement and moments during stance phase of gait, the interaction or dynamic joint stiffness (DJS) between these is not fully understood. Little attention has been placed on DJS during gait, limiting our understanding of how the most common dynamic task during daily life could affect cartilage loading.Research questionDo Individuals with CAI exhibit altered ankle DJS and mechanical energy exerted at the ankle joint during stance phase of gait?MethodsEighty-four physically active individuals, consisting of 42 individuals with CAI (12 M and 30 F) and 42 control (12 M and 30 F) participants were recruited in this study. Three-dimensional gait analysis was conducted. The sagittal ankle joint angle and moment during stance phase of walking gait were obtained. Stance phase was divided into three sub-phases: controlled plantarflexion, controlled dorsiflexion, and powered plantarflexion. Ankle DJS was represented by the slope of the joint moment plotted as a function of the joint angle. The coefficient of determination was calculated to determine how accurately data fit a linear model. Net work was calculated by the difference between work produced and absorbed. Further, sex specific exploratory analyses of DJS and work between individuals with and without CAI were conducted.ResultsLower DJS during the controlled plantarflexion (CPF) sub-phase, work produced, and net work was found in the CAI group. Males with CAI exhibited lower ankle moment changes during controlled dorsiflexion (CDF) sub-phase and work absorbed. Females with CAI exhibited lower ankle moment changes during CPF and CDF sub-phases, lower DJS during the CPF sub-phase, and lower net work.SignificanceIndividuals with CAI have alterations in DJS and work relative to uninjured controls. Females with CAI showed greater DJS related alterations, relative to controls, than their male CAI counterparts.     

Normative Achilles and patellar tendon shear wave speeds and loading patterns during walking in typically developing children

BackgroundMotion analysis is commonly used to evaluate joint kinetics in children with cerebral palsy who exhibit gait disorders. However, one cannot readily infer muscle-tendon forces from joint kinetics. This study investigates the use of shear wave tensiometry to characterize Achilles and patellar tendon forces during gait.Research QuestionHow do Achilles and patellar tendon wave speed and loading modulate with walking speed in typically developing children?MethodsTwelve typically developing children (9–16 years old) walked on an instrumented treadmill with shear wave tensiometers over their Achilles (n = 11) and patellar (n = 9) tendons. Wave speeds were recorded at five leg length-normalized walking speeds (very slow to very fast). Achilles and patellar tendon moment arms were measured with synchronized ultrasound and motion capture. The tendon wave speed-load relationship was calibrated at the typical walking speed and used to estimate tendon loading at other walking speeds.ResultsCharacteristic Achilles and patellar tendon wave speed trajectories exhibited two peaks over a gait cycle. Peak Achilles tendon force closely aligned with peak ankle plantarflexor moment during pushoff, though force exhibited less modulation with walking speed. A second peak in late swing Achilles loading, which was not evident from the ankle moment, increased significantly with walking speed (p < 0.001). The two peaks in patellar tendon loading occurred at 12 ± 1% and 68 ± 6% of the gait cycle, matching the timing of peak knee extension moment in early stance and early swing. Both patellar tendon load peaks increased significantly with walking speed (p < 0.05).SignificanceThis is the first study to use shear wave tensiometry to characterize Achilles and patellar tendon loading during gait in children. These data could serve as a normative comparison when using tensiometry to identify abnormal tendon loading patterns in individuals who exhibit equinus and/or crouch gait.     

Gait biofeedback and impairment‐based rehabilitation for chronic ankle instability

Our purpose was to analyze the effects of 4 weeks of visual gait biofeedback (GBF) and impairment‐based rehabilitation on gait biomechanics and patient‐reported outcomes (PROs) in individuals with chronic ankle instability (CAI). Twenty‐seven individuals with CAI participated in this randomized controlled trial (14 received no biofeedback (NBF), 13 received GBF). Both groups received 8 sessions of impairment‐based rehabilitation. The GBF group received visual biofeedback to reduce ankle frontal plane angle at initial contact (IC) during treadmill walking. The NBF group walked for equal time during rehabilitation but without biofeedback. Dependent variables included three‐dimensional kinematics and kinetics at the ankle, knee, and hip, electromyography amplitudes of 4 lower extremity muscles (tibialis anterior, fibularis longus, medial gastrocnemius, and gluteus medius), and PROs (Foot and Ankle Ability Measure Activities of Daily Living (FAAM‐ADL), FAAM‐Sport, Tampa Scale of Kinesiophobia (TSK), and Global Rating of Change (GROC)). The GBF group significantly decreased ankle inversion at IC (MD:‐7.3º, g = 1.6) and throughout the entire stride cycle (peak inversion: MD:‐5.9º, g = 1.2). The NBF group did not have significantly altered gait biomechanics. The groups were significantly different after rehabilitation for the FAAM‐ADL (GBF: 97.1 ± 2.3%, NBF: 92.0 ± 5.7%), TSK (GBF: 29.7 ± 3.7, NBF: 34.9 ± 5.8), and GROC (GBF: 5.5 ± 1.0, NBF:3.9 ± 2.0) with the GBF group showing greater improvements than the NBF group. There were no significant differences between groups for kinetics or electromyography measures. The GBF group successfully decreased ankle inversion angle and had greater improvements in PROs after intervention compared to the NBF group. Impairment‐based rehabilitation combined with visual biofeedback during gait training is recommended for individuals with CAI.     

Spring-like Ankle Foot Orthoses reduce the energy cost of walking by taking over ankle work

In patients with central neurological disorders, gait is often limited by a reduced ability to push off with the ankle. To overcome this reduced ankle push-off, energy-storing, spring-like carbon-composite Ankle Foot Orthoses (AFO) can be prescribed. It is expected that the energy returned by the AFO in late stance will support ankle push-off, and reduce the energy cost of walking. In 10 patients with multiple sclerosis and stroke the energy cost of walking, 3D kinematics, joint power, and joint work were measured during gait, with and without the AFO. The mechanical characteristics of the AFO were measured separately, and used to calculate the contribution of the AFO to the ankle kinetics. We found a significant decrease of 9.8% in energy cost of walking when walking with the AFO. With the AFO, the range of motion of the ankle was reduced by 12.3°, and the net work around the ankle was reduced by 29%. The total net work in the affected leg remained unchanged. The AFO accounted for 60% of the positive ankle work, which reduced the total amount of work performed by the leg by 11.1% when walking with the AFO. The decrease in energy cost when walking with a spring-like energy-storing AFO in central neurological patients is not induced by an augmented net ankle push-off, but by the AFO partially taking over ankle work.     

Individuals with multiple sclerosis redistribute positive mechanical work from the ankle to the hip during walking

Individuals with multiple sclerosis (MS) typically walk slower, have reduced cadences and shorter step lengths. While these spatiotemporal gait alterations have been thought to be due to decreased power generation at the ankle, the distribution of mechanical work across the ankle, knee and hip joints during walking is not well understood. By quantifying the mechanical work at each joint, the compensatory mechanisms utilized by individuals with MS to maintain gait speed may be better understood. Fifteen subjects with MS (EDSS: 4.4 ± 1.0) and fifteen healthy age-matched control subjects completed a three-dimensional gait analysis. The net mechanical work at the ankle, knee and hip joints was quantified for the stance phase of gait. Our results found that the less impaired leg of the subjects with MS generated a similar amount of mechanical work as the control group; however, the ankle joint produced less positive mechanical work, and the hip joint generated more positive mechanical work. Additionally, the less impaired leg of the subjects with MS and the leg of the control group generated more positive work than the more impaired leg of the subjects with MS. These outcomes suggest that individuals with MS may adopt a hip compensatory strategy with their less impaired leg during gait due to the limited amount of mechanical work generated at the ankle.     

Test-retest reliability and minimal detectable change of ankle kinematics and spatiotemporal parameters in MS population

BackgroundMany people with multiple sclerosis (pwMS) experience walking impairments often including foot drop, evident as either reduced dorsiflexion at initial contact and/or at the swing phase of the gait cycle. To measure even subtle differences in ankle kinematics, 3D gait analysis is considered a ‘gold’ standard. However, the psychometric properties of ankle kinematics in the MS population have not yet been examined.ObjectiveThe aim of the study was to examine test-retest relative and absolute reliability of sagittal ankle kinematics and spatiotemporal parameters in two groups of pwMS with different levels of walking impairment.MethodsTwo groups of pwMS underwent 3D gait analysis on two occasions 7–14 days apart. Group A consisted of 21 (14 female) people with Expanded Disability Status Scale (EDSS) 1–3.5 and group B consisted of 28 participants (14 female) with EDSS 4-6. The Intraclass Correlation Coefficient (ICC_2,2), standard error of measurement (SEM) and minimal detectable change (MDC_95%) were calculated for peak dorsiflexion (DF) in swing, ankle angle at initial contact (IC), gait profile score (GPS), walking speed, cadence and step length.ResultsBoth groups presented ‘excellent’ ICC values (>0.75) for DF in swing, IC and step length of most and least affected limbs, walking speed and cadence, with GPS for both limbs exhibiting ‘fair’ to ‘good’ ICCs (0.489–0.698). The MDC_95% values for all ankle kinematic parameters in group A were lower (1.9°–4.2°) than those in group B (2.2°–7.7°).ConclusionThe present results suggest that ankle kinematic and spatiotemporal parameters derived from 3D gait analysis are reliable outcome measures to be used in the MS population. Further, this study provides indices of reliability that can be applied to both clinical decision making and in the design of studies aimed at treating foot drop in people with MS.     

Method for characterization of dynamic ankle stiffness in patients with spasticity

BackgroundDynamic ankle stiffness has been quantified as the slope of the ankle joint moment-angle curve over the gait interval of the second rocker, defined explicitly as the period of the gait cycle from the first relative maximum plantar flexion in early stance to maximum dorsiflexion in midstance. However, gastrocnemius spasticity may interfere with the second ankle rocker in patients with spasticity. This gait disruption results in stiffness calculations which are misleading. Current dynamic stiffness metrics need to be modified.Research QuestionThe main goal of this study was to develop and test a new method to better evaluate dynamic ankle stiffness in individuals with pathologic gait who lack a second rocker interval.MethodsTwenty unimpaired ambulators (10/20 female, 26.7 ± 5.0 years, BMI: 23.2 ± 2.2) and 9 individuals with cerebral palsy (5/9 female, 5.7 ± 1.7 years, BMI: 14.6 ± 2.1, GMFCS Levels: I – 2, II – 5, III - 2) participated in this study. Dynamic ankle stiffness was evaluated using the previous kinematic method, defined by the interval of maximum plantar flexion to maximum dorsiflexion angle in midstance, and the proposed kinetic method, defined by the interval from the maximum dorsiflexion moment to first peak plantar flexion moment. Stiffness was quantified as the linear slope between the sagittal plane ankle angle and moment. Method differences were explored using an equivalence test (α = 0.05).Results and SignificanceThere was equivalence between the methods for unimpaired ambulators (p = 0.000) and a lack of equivalence for patients with spasticity (p = 0.958). The new method was successfully applied to all 9 pediatric ambulators with CP and demonstrated increased stiffness in patients with spasticity as compared to the previous method. The ability to objectively calculate ankle stiffness in pathologic gait is critical for determining change associated with clinical intervention.     

Multiple sclerosis influences the precision of the ankle plantarflexon muscular force production

ObjectiveTo quantify the precision of the steady-state isometric control of the ankle plantarflexors musculature of individuals with multiple sclerosis (MS), and to evaluate if the precision is related to the mobility impairments.MethodsIndividuals with MS and healthy adults performed a submaximal steady-state isometric contraction with the ankle plantarflexors. The coefficient of variation was used to assess the amount of variability or error in the precision of the torques generated by the ankle plantarflexor musculature. The participants also walked across a digital mat at their preferred and fast-as-possible walking speeds, which recorded their spatiotemporal gait kinematics.ResultsThe individuals with MS: (1) had reduced maximal voluntary torques at the ankle, (2) a greater amount of variability in the precision of the isometric ankle torques, (3) altered and more variable spatiotemporal gait kinematics, and (4) a greater amount of variability in the isometric ankle torques were related to a slower walking speed and cadence, shorter step length and a greater amount of gait variability.ConclusionsThese results further fuels the impression that a reduction in control of the ankle joint musculature may be a key factor in the mobility and balance impairments seen in individuals with MS.     

Midfoot and ankle motion during heel rise and gait are related in people with diabetes and peripheral neuropathy

BackgroundMidfoot and ankle movement dysfunction in people with diabetes mellitus and peripheral neuropathy (DMPN) is associated with midfoot deformity and increased plantar pressures during gait. If midfoot and ankle motion during heel rise and push-off of gait have similar mechanics, heel rise performance could be a clinically feasible way to identify abnormal midfoot and ankle function during gait.Research questionIs midfoot and ankle joint motion during a heel rise associated with midfoot and ankle motion at push-off during gait in people with DMPN?MethodsSixty adults with DMPN completed double-limb heel rise, single-limb heel rise, and walking. A modified Oxford multi-segment foot model (forefoot, hindfoot, shank) was used to analyze midfoot (forefoot on hindfoot) and ankle (hindfoot on shank) sagittal angle during heel rise and gait. Pearson correlation was used to test the relationship between heel rise and gait kinematic variables (n = 60). Additionally, we classified 60 participants into two subgroups based on midfoot and ankle position at peak heel rise: midfoot and ankle dorsiflexed (dorsiflexed; n = 23) and midfoot and ankle plantarflexed (plantarflexed; n = 20). Movement trajectories of midfoot and ankle motion during single-limb heel rise and gait of the subgroups were examined.ResultsPeak double-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.49 and r = 0.40, respectively). Peak single-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.63 and r = 0.54, respectively). The dorsiflexed subgroup, identified by heel rise performance showed greater midfoot and ankle dorsiflexion during gait compared to the plantarflexed subgroup (mean difference between subgroups: midfoot 3°, ankle 3°).SignificancePeople with DMPN who fail to plantarflex the midfoot and ankle during heel rise have difficulty plantarflexing the midfoot and ankle during gait. Utilizing a heel rise task may help identify midfoot and ankle dysfunction associated with gait in people with DMPN.     

Lower extremity joint moments throughout gait at two speeds more than 4 years after ACL reconstruction

BackgroundLong-term gait adaptations after anterior cruciate ligament reconstruction (ACLR) have been reported. However, it is still unclear if they persist more than 4 years after surgery and if they are affected by gait speed.Research question: To investigate differences between groups, legs and walking speeds for ankle, knee and hip joint moments in three planes throughout the stance phase of gait.MethodsReconstructed participants (n = 20 males, 32.5 years, 5.5 years post-ACLR) and healthy controls (n = 20 males, 30.6 years) took part in the study. Gait analysis was performed in two different speeds (self-selected and 30% faster). Sagittal, frontal and transverse plane external moments were measured for ankle, knee and hip and compared throughout the stance phase using 95% confidence intervals. Significant differences were established as a consecutive 5% of gait cycle in which 95% confidence interval did not overlap.ResultsThe reconstructed leg did not demonstrate higher joint moments; there were largely no differences while there was lower knee external rotation moment compared to the non-preferred leg of the control group. Higher joint moments were observed during fast speed walking on sagittal plane for knee and hip moments in both groups, and in the frontal and transverse plane for ankle moments.SignificanceGait kinetics appear to be largely normalized at a minimum of 4 years after ACLR. Faster walking speed increase lower extremity joint moments.     

Post-sprain versus post-fracture post-traumatic ankle osteoarthritis: Impact on foot and ankle kinematics and kinetics

BackgroundCommon etiologies for post-traumatic ankle osteoarthritis are ankle fractures and chronic ankle instability. As the nature of trauma is different for these two etiologies, it might be expected that the two subtypes of post-traumatic ankle osteoarthritis would display different foot mechanics during gait.Research questionThe objective of this exploratory cross-sectional study was to compare the foot kinematics and kinetics of patients suffering from post-fracture ankle osteoarthritis with those of patients suffering from post-sprain ankle osteoarthritis.MethodsTwenty-nine subjects with end-stage post-traumatic ankle osteoarthritis and fifteen asymptomatic control subjects participated in this study. All patients suffered from post-traumatic ankle osteoarthritis secondary to ankle-related fracture (Group 1; n = 15) or to chronic ankle instability (Group 2; n = 14). A four-segment kinematic and kinetic foot model was used to calculate intrinsic foot joint kinematics and kinetics during gait. Vector field statistical analysis MANOVA was used to assess differences between groups for the entire three-component intrinsic foot joint angles and moments.ResultsMANOVA showed significant differences between the groups. Post-hoc analyses suggested that the differences between post-fracture ankle osteoarthritis group and controls were caused by a combination of less adducted Shank-Calcaneus position and less plantarflexion at this joint. Post-hoc analyses also suggested that both pathological groups exhibited a decreased plantarflexion moment for Shank-Calcaneus, Chopart, Lisfranc joints compared to controls. Analyses of both pathological groups versus controls for power suggested lower Shank-Calcaneus and Lisfranc power generation during pre-swing phase.SignificanceNo significant differences were found between the two pathological groups in this exploratory study. Alterations in foot kinematics and kinetics were mainly found about the dorsi-/plantarflexion axis during the pre-swing phase of the stance phase for both pathological groups compared to controls. Observed differences were not limited to the painful ankle joint, but seem also to have affected the kinetics of the neighbouring foot joints.     

Altered neuromuscular control and ankle joint kinematics during walking in subjects with functional instability of the ankle joint

BACKGROUND: The ankle joint requires very precise neuromuscular control during the transition from terminal swing to the early stance phase of the gait cycle. Altered ankle joint arthrokinematics and muscular activity have been cited as potential factors that may lead to an inversion sprain during the aforementioned time periods. However, to date, no study has investigated patterns of muscle activity and 3D joint kinematics simultaneously in a group of subjects with functional instability compared with a noninjured control group during these phases of the gait cycle. PURPOSE: To compare the patterns of lower limb 3D joint kinematics and electromyographic activity during treadmill walking in a group of subjects with functional instability with those observed in a control group. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional angular velocities and displacements of the hip, knee, and ankle joints, as well as surface electromyography of the rectus femoris, peroneus longus, tibialis anterior, and soleus muscles, were recorded simultaneously while subjects walked on a treadmill at a velocity of 4 km/h. RESULTS: Before heel strike, subjects with functional instability exhibited a decrease in vertical foot-floor clearance (12.62 vs 22.84 mm; P < .05), as well as exhibiting a more inverted position of the ankle joint before, at, and immediately after heel strike (1.69 degrees , 2.10 degrees , and -0.09 degrees vs -1.43 degrees , -1.43 degrees , and -2.78 degrees , respectively [minus value = eversion]; P < .05) compared with controls. Subjects with functional instability were also observed to have an increase in peroneus longus integral electromyography during the post-heel strike time period (107.91%.millisecond vs 64.53%.millisecond; P < .01). CONCLUSION: The altered kinematics observed in this study could explain the reason subjects with functional instability experience repeated episodes of ankle inversion injury in situations with only slight or no external provocation. It is hypothesized that the observed increase in peroneus longus activity may be the result of a change in preprogrammed feed-forward motor control.     

Capacity to increase walking speed is limited by impaired hip and ankle power generation in lower functioning persons post-stroke

It is well known that stroke patients walk with reduced speed, but their potential to increase walking speed can also be impaired and has not been thoroughly investigated. We hypothesized that failure to effectively recruit both hip flexor and ankle plantarflexor muscles of the paretic side limits the potential to increase walking speed in lower functioning hemiparetic subjects. To test this hypothesis, we measured gait kinematics and kinetics of 12 persons with hemiparesis following stroke at self-selected and fast walking conditions. Two groups were identified: (1) lower functioning subjects (n=6) who increased normalized walking speed from 0.52 leg lengths/s (ll/s, SEM: 0.04) to 0.72 ll/s (SEM: 0.03) and (2) higher functioning subjects (n=6) who increased walking speed from 0.88 ll/s (SEM: 0.04) to 1.4 ll/s (SEM 0.03). Changes in spatiotemporal parameters, joint kinematics and kinetics between self-selected and fast walking were compared to control subjects examined at matched walking speeds (0.35 ll/s (SEM: 0.03), 0.63 ll/s (SEM: 0.03), 0.92 ll/s (SEM: 0.04) and 1.4 ll/s (SEM: 0.04)). Similar to speed-matched controls, the higher functioning hemiparetic subjects increased paretic limb hip flexion power and ankle plantarflexion power to increase walking speed. The lower functioning hemiparetic subjects did not increase power generation at the hip or ankle to increase walking speed. This observation suggests that impaired ankle power generation combined with saturation of hip power generation limits the potential to increase walking speed in lower functioning hemiparetic subjects.     

Obese adults walk differently in shoes than while barefoot

BackgroundSome comparisons between walking gait of obese and non-obese adults have been made during barefoot conditions, and others while shod. Methodological differences, footwear conditions, and gait speed disparities among the research done on overweight individuals were the factors motivating the present study.Research questionThe present study was designed to compare gait kinematics and kinetics of obese adults between two footwear conditions (barefoot versus shod) at a set walking speed.MethodsTen obese (body mass index > 30 kg.m⁻²), but otherwise healthy adults (age = 26 ± 3 years, height = 1.79 ± 0.10 m, mass = 108.46 ± 13.25 kg) participated in this study. Ground reaction forces and 3D kinematic data were simultaneously collected as participants walked overground at 1.5 m.s⁻¹ in barefoot and shod conditions.ResultsWalking barefoot reduced ankle, knee, and hip ranges of motion, and stride length, stance time, and double support time were also reduced. Kinetic outcomes included smaller peak vertical and anterior-posterior ground reaction forces and knee joint moments while barefoot.SignificanceFootwear condition significantly influences key gait variables in obese adults. Conflicting conclusions from previous investigations of gait in obese adults may be a consequence of differing footwear conditions.     

Leg and lower limb dynamic joint stiffness during different walking speeds in healthy adults

BackgroundThe differences and relationship between joint stiffness and leg stiffness can be used to characterize the lower limb behavior during different walking speeds.Research questionThis study aimed to investigate the differences in whole leg and lower limb joint stiffness at different walking speeds and the interactions between leg and lower limb joint stiffness.MethodsTwenty-seven healthy adults, seventeen males (age: 19.6 ± 2.2 years, height: 176.0 ± 6.0 cm, mass: 69.7 ± 8.9 kg), and ten females (age: 19.1 ± 1.9 years, height: 164.0 ± 3.0 cm, mass: 59.6 ± 3.8 kg), were recruited. Dynamic leg and joint stiffness were calculated during eccentric loading from data recorded using 3D infrared motion analysis and force plates at slow, normal, and fast walking speeds. Differences in dynamic stiffness, joint angles and moments were explored between the walking speeds using Repeated Measures ANOVA with Sidak post-hoc tests. Correlations between leg, joint stiffness, and walking speed were also explored.ResultsThe results indicated that the leg dynamic stiffness is decreased by walking speed, however, hip and ankle joint stiffness were increased (p < 0.001) and knee stiffness was unaffected. Leg stiffness showed no correlation with hip, knee, or ankle stiffness. A positive significant correlation was seen between hip and ankle stiffness (p < 0.01) and between knee and ankle stiffness (p < 0.001), however, no correlation was seen between hip and knee stiffness.SignificanceThese results suggest leg stiffness is not associated with lower limb joint stiffness during eccentric loading. This provides new information on the responses of ankle, knee and hip joint stiffness to walking speed.     

Assessment of gait kinetics in post-menopausal women using tri-axial ankle accelerometers during barefoot walking

Background: Physical activity (PA) interventions, designed to increase exposure to ground reaction force (GRF) loading, are a common target for reducing fracture risk in post-menopausal women with low bone mineral density (BMD). Unfortunately, accurate tracking of PA in free-living environments and the ability to translate this activity into evaluations of bone health is currently limited.Research question: This study evaluates the effectiveness of ankle-worn accelerometers to estimate the vertical GRFs responsible for bone and joint loading in post-menopausal women at a range of self-selected walking speeds during barefoot walking.Methods: Seventy women, at least one year post-menopause, wore Actigraph GT3X + on both ankles and completed walking trials at self-selected speeds (a minimum of five each at fast, normal and slow walking) along a 30 m instrumented walkway with force plates and photocells to measure loading and estimate gait velocity. Repeated measures correlation analysis and step-wise mixed-effects modelling were performed to evaluate significant predictors of peak vertical GRFs normalized to body weight (pVGRFbw), including peak vertical ankle accelerations (pVacc), walking velocity (Vel_w) and age.Results: A strong repeated measures correlation of r = 0.75 (95%CI [0.71-0.76] via 1000 bootstrap passes) between pVacc and pVGRFbw was observed. Five-fold cross-validation of mixed-model predictions yielded an average mean-absolute-error (MAE[95%CI]) and root-mean-square-error (RMSE) rate of 5.98%[5.61–6.42] and 0.076 [0.069-0.082] with a more complex model (including Vel_w,) and 6.80%[6.37–7.54] and 0.087BW[0.081-0.095] with a simpler model (including only pVacc), when comparing accelerometer-based estimations of pVGRFbw to force plate measures of pVGRFbw. Age was not found to be significant.Significance: This study is the first to show a strong relationship among ankle accelerometry data and high fidelity lower-limb loading approximations in post-menopausal women. The results provide the first steps necessary for estimation of real-world limb and joint loading supporting the goals of accurate PA tracking and improved individualization of clinical interventions.     

Foot and ankle biomechanics during walking in older adults: A systematic review and meta-analysis of observational studies

BackgroundThe foot and ankle complex undergoes significant structural and functional changes with advancing age.Research questionThe objective of this systematic review and meta-analysis was to synthesize and critique the research literature pertaining to foot and ankle biomechanics while walking in young and older adults.MethodsElectronic databases (Web of Science, PubMed, Scopus and Embase) were searched from inception to April 2019 for cross-sectional studies which compared kinematics, kinetics and plantar pressure differences between young and older adults. Screening and data extraction were performed by two independent assessors, with disagreements resolved by consensus.ResultsA total of 39 articles underwent full-text screening, and 19 articles met the inclusion criteria and were included. Meta-analysis showed that older adults had less ankle joint plantar flexion (5 studies; weighted mean difference [WMD]: −5.15; 95 %CI: −6.47 to −3.83; P < 0.001) and less ankle joint power generation (6 studies; standardized mean difference [SMD]: −0.62; 95 %CI: −0.82 to −0.41; P < 0.001) during propulsion compared to young adults. These differences persisted in subgroup analyses comparing different walking speeds. Plantar pressure findings were highly variable due to differences in data collection protocols and meta-analysis was not possible.SignificanceOlder adults have unique foot and ankle kinematics and kinetics during walking characterized by reduced ankle joint plantarflexion and power generation during propulsion.