Joint kinetics during Tai Chi gait and normal walking gait in young and elderly Tai Chi Chuan practitioners

BACKGROUND: Tai Chi Chuan is becoming a popular exercise among elders. This study measured the inter-segmental forces and moments at the lower extremity joints during a Tai Chi gait as compared to those during normal walking gait, in both apparently healthy young and elderly Tai Chi Chuan practitioners. METHODS: Three-dimensional inter-segmental joint reaction force and moment were computed using the Inverse Dynamic Approach based on the kinematics and ground reaction force measurements in a laboratory setting in six young (two females, mean age 28; SD 6 years) and six elderly (five females, mean age 72; SD 8 years) subjects who had previous training of Yang style Tai Chi Chuan. FINDINGS: The results showed significant gait differences in both age groups, with significantly smaller peak compressive forces, larger peak shear forces in the ankle, knee and hip joints, and larger peak moments in the knee and hip joints during Tai Chi gait as compared to normal gait. Moreover, the peak shear force was oriented more in the medial-lateral direction at the ankle and knee joints, and the peak moment was in the frontal plane at the knee and hip joints. The results also showed significant age differences, with significantly smaller peak shear forces in all three joints in the elderly group than in the young group during Tai Chi gait. INTERPRETATION: Tai Chi gait has an increased shear force and frontal plane torque at lower extremity joints than normal gait. The shear force at all three lower extremity joints during Tai Chi gait is lower in the elderly subjects than young subjects. This data suggest that, in Tai Chi Chuan training, elderly people with degenerative joint diseases in the lower extremity should use caution when practicing Tai Chi Chuan.     

Peripheral arterial disease affects the frequency response of ground reaction forces during walking

Background

Walking is problematic for patients with peripheral arterial disease. The purpose of this study was to investigate the frequency domain of the ground reaction forces during walking to further elucidate the ambulatory impairment of these patients.

Methods

Nineteen bilateral peripheral arterial disease patients and nineteen controls were included in this study. Subjects were matched for age and gait speed. Participants walked over a force plate sampling at 600 Hz. PAD patients were tested before (pain-free condition) after the onset of claudication symptoms (pain). We calculated median frequency, frequency bandwidth, and frequency containing 99.5% of the signal for the vertical and anterior–posterior ground reaction forces.

Findings

Our results showed reduced median frequency in the vertical and anterior–posterior components of the ground reaction forces between the control group and both peripheral arterial disease conditions. We found reduced frequency bandwidth in the anterior–posterior direction between controls and the peripheral arterial disease pain-free condition. There were no differences in median frequency or bandwidth between peripheral arterial disease pain-free and pain conditions, but an increase in the frequency content for 99.5% of the signal was observed in the pain condition.

Interpretation

Reduced frequency phenomena during gait in peripheral arterial disease patients compared to velocity-matched controls suggests more sluggish activity within the neuromotor system. Increased frequency phenomena due to pain in these patients suggest a more erratic application of propulsive forces when walking. Frequency domain analysis thus offers new insights into the gait impairments associated with this patient population.     

Age and gender differences in the control of vertical ground reaction force by the hip,knee and ankle joints

[Purpose] This study examined the relationships between joint moment and the control of the vertical ground reaction force during walking in the elderly and young male and female individuals. [Subjects and Methods] Forty elderly people, 65 years old or older (20 males and 20 females), and 40 young people, 20 to 29 years old (20 males and 20 females), participated in this study. Joint moment and vertical ground reaction force during walking were obtained using a 3D motion analysis system and force plates. Stepwise linear regression analysis determined the joint moments that predict the amplitude of the vertical ground reaction force. [Results] Knee extension moment was related to the vertical ground reaction force in the young males and females. On the other hand, in the elderly females, hip, ankle, and knee joint moments were related to the first peak and second peak forces, and the minimum value of vertical ground reaction force, respectively. [Conclusion] Our results suggest that the young males and females make use of the knee joint moment to control of the vertical ground reaction force. There were differences between the elderly and the young females with regard to the joints used for the control of the vertical ground reaction force.Key words: Elderly people, Vertical ground reaction force, Lower extremity joint moment     

Sagittal plane loading response during gait in different age groups and in people with knee osteoarthritis

OBJECTIVE: To investigate the gait patterns and the sagittal ground reaction forces in different age groups and in people with knee osteoarthritis. DESIGN: Motion analysis and force platform data were collected for a total of 55 female subjects capable of independent ambulation. Subjects were divided into three groups consisting of the control group, the elderly group, and the osteoarthritis knee group. Gait parameters of walking velocity, cadence, step length, stride time, single- and double-support time, and sagittal ground reaction forces were obtained during comfortable walking speed. Gait analysis was performed in a tertiary hospital's gait laboratory. Variables were analyzed using a univariate repeated-measures analysis of variance. Statistical significance was set at a value of P < 0.05. RESULTS: The osteoarthritis knee group had slower walking velocity, lower cadence, and longer stride time as compared with the elderly and young control groups (P < 0.05). In ground reaction force studies, the first peak time, expressed in percentage of gait cycle, was significantly longer in the osteoarthritis knee group (20.8 +/- 3.2) as compared with the elderly (17.8 +/- 2.0) and young control groups (17.1 +/- 1.8, P < 0.01). The force during time of minimal midstance was larger in the osteoarthritis knee group (90.9 +/- 5.3) as compared with the elderly and young control groups (P < 0.05). The second peak force was significantly smaller in the osteoarthritis knee group as compared with the young control group (P < 0.01). The force change in the midfoot region in the osteoarthritis knee and elderly groups revealed more loading force onto the midfoot region during midstance as compared with the young control group (P < 0.01). CONCLUSION: Gait parameters in the elderly and osteoarthritis knee patients were characterized by slower walking velocity, lower cadence, shorter step length, longer stride time, and longer double-support time. Less heel contact and push-off forces were noticed in these two groups, with more loading force onto the midfoot during midstance.     

Multiple sclerosis affects the frequency content in the vertical ground reaction forces during walking

Background

Multiple sclerosis is a progressive neurological disease that results in a high incident of gait disturbance. Exploring the frequency content of the ground reaction forces generated during walking may provide additional insights to gait in patients with multiple sclerosis that could lead to specific tools for differential diagnosis. The purpose of this study was to investigate differences in the frequency content of these forces in an effort to contribute to improved clinical management of this disease.

Methods

Eighteen patients and eighteen healthy controls walked across a 10 meter long walkway. The anterior–posterior and vertical ground reaction forces generated during the stance phase of gait were evaluated in the frequency domain using fast Fourier transformation. T-tests were utilized for comparison of median frequency, the 99.5% frequency, and the frequency bandwidth between patients and healthy controls and also for comparisons between patients with mild and moderate severity.

Findings

Patients with multiple sclerosis had significantly lower 99.5% frequency (P = 0.006) and median frequency (P < 0.001) in the vertical ground reaction force. No differences were found in the anterior–posterior reaction force frequency content. There were no differences between patients with mild and moderate severity.

Interpretation

The lower frequency content suggests lesser vertical oscillation of the center of gravity. Lack of differences between severities may suggest presence of differences prior to currently established diagnosis timelines. Analysis of the frequency content may potentially serve to provide earlier diagnostic assessment of this debilitating disease.     

The variability of force platform data in normal and cerebral palsy gait

OBJECTIVE: To determine the natural variability and symmetry of force platform parameters in normal and cerebral palsy gait. DESIGN: Force platform data has been analysed using coefficient of variation, analysis of variances and symmetry index. BACKGROUND: It is important to establish the natural variability of force platform data so that changes in gait due to natural variability and those due to intervention can be determined. METHODS: Force platform data and walking speed were recorded in 15 normal volunteers and 11 children with cerebral palsy on 3 consecutive days. Five recordings were made of each leg on each day. RESULTS: The force platform parameters in both groups showed greater asymmetry in the horizontal plane. In the cerebral palsy group significant asymmetry was found in all 3 directions. The variation of the vertical ground reaction force peaks (Fz1 and Fz3) and of the anterior-posterior negative peak (Fy3) for both groups was low. Fz3 was the most reproducible force parameter. The other force parameters showed high variability and are not considered reliable measures of gait. The temporal parameters and the walking speed were reproducible measures. CONCLUSIONS: Only selected ground reaction force parameters showed acceptable stability and reproducibility. Therefore caution has to be taken in the selection of these parameters, when assessing the effects of any intervention on cerebral palsy gait.     

Harmonic analysis of force platform data in normal and cerebral palsy gait

BACKGROUND: Examination of force platform data during gait is usually carried out in the time domain and is limited to selected points on the force-time graphs. Harmonic analysis allows examination of the whole waveform and has a greater potential for assessing the effects of treatment options. Therefore, the objectives of this study were to show the benefits of using harmonic analysis to determine the variability and symmetry of force platform data in normal and cerebral palsy gait. METHODS: Harmonic analysis was carried out on the foot to ground reaction force data recorded from a group of cerebral palsy children and a matched control group when they walked at their preferred walking speed. Statistical tests were used to assess this frequency domain data and to validate the reconstructed force-time curves. FINDINGS: The differences in the frequency domain parameters between the cerebral palsy and control groups were significant. The mediolateral force was the most variable and asymmetric parameter in the control group. Cerebral palsy gait was more variable and more asymmetric than normal gait. INTERPRETATION: This study has shown that the force platform data derived from clinical gait analysis can reveal more useful information in the frequency domain than the limited time domain information commonly used for analysing this type of data.     

Vertical ground reaction force shape is associated with gait parameters, timed up and go, and functional reach in elderly females.

OBJECTIVE: The aim of this study was to evaluate the relationship between knee pain and various indicators of the combined performance of the lower extremity (including gait parameters, functional performance such as timed up and go, and functional reach test) and to determine whether the classification of vertical ground reaction forces correlates with gait parameters and functional performance. SUBJECTS AND METHODS: Simultaneous analysis of gait, time-distance parameters and vertical ground reaction force. Timed up and go, and functional reach test were examined in 130 elderly women. The vertical component of the ground reaction force was grouped into 2 categories: M-shaped and non-M-shaped. RESULTS: No significant association was found between knee pain and timed up and go, functional reach test, or gait parameters in elderly female participants. There were significant differences between subjects with M- and non-M-shaped vertical ground reaction forces with regard to timed up and go, functional reach test and Japan Orthopaedic Association score. There were also significant differences between the 2 groups (M shaped and non-M-shaped) in gait parameters. CONCLUSION: Evaluation of the vertical ground reaction force to determine its shape may be a useful and simple tool in the analysis of gait and functional performance.     

Postural control in patients with Down syndrome

Purpose. To assess postural control in individuals with Down syndrome.

Method. Sixty young adults with Down syndrome were assessed and compared to 10 non-handicapped young. The subjects were asked to stay on a force platform for 30 seconds. Postural control was evaluated in two conditions: open and closed eyes. The kinetic data carried out from the force platform (i.e., ground reaction forces and Center of Pression (COP) displacements) were both evaluated in time domain and in frequency domain.

Results. Patients with Down syndrome are characterized by instable postural control. In particular the data evaluation in frequency domain underlined for Down syndrome subjects versus control group an increase in frequency oscillation both in anterior-posterior and in medio-lateral direction, that are confirmed in time domain analysis only for medio-lateral direction. In DS no changes are evident between eyes open and eyes closed condition.

Conclusion. This study finds that subjects with Down syndrome included in this research demonstrate that deficits in postural control system that may provide a partial explanation for function balance problems that are common in these subjects.     

Effects of different frequencies of rhythmic auditory cueing on the stride length,cadence, and gait speed in healthy young females

[Purpose] The aim of this study was to explore the effects of different frequencies of rhythmic auditory cueing (RAC) on stride length, cadence, and gait speed in healthy young females. The findings of this study might be used as clinical guidance of physical therapy for choosing the suitable frequency of RAC. [Subjects] Thirteen healthy young females were recruited in this study. [Methods] Ten meters walking tests were measured in all subjects under 4 conditions with each repeated 3 times and a 3-min seated rest period between repetitions. Subjects first walked as usual and then were asked to listen carefully to the rhythm of a metronome and walk with 3 kinds of RAC (90%, 100%, and 110% of the mean cadence). The three frequencies (90%, 100%, and 110%) of RAC were randomly assigned. Gait speed, stride length, and cadence were calculated, and a statistical analysis was performed using the SPSS (version 17.0) computer package. [Results] The gait speed and cadence of 90% RAC walking showed significant decreases compared with normal walking and 100% and 110% RAC walking. The stride length, cadence, and gait speed of 110% RAC walking showed significant increases compared with normal walking and 90% and 100% RAC walking. [Conclusion] Our results showed that 110% RAC was the best of the 3 cueing frequencies for improvement of stride length, cadence, and gait speed in healthy young females.Key words: Rhythmic auditory cueing, Frequency, Gait speed     

Differences in gait parameters between healthy subjects and persons with moderate and severe knee osteoarthritis: A result of altered walking speed?

Background

While knee osteoarthritis has been shown to affect a multitude of kinematic, kinetic and temporo-spatial gait parameters, few investigations have examined the effect of increasing levels of radiographic osteoarthritis severity on these gait parameters. Fewer still have investigated the effect of walking speed on gait variables in persons with knee osteoarthritis. The objective of this study was to investigate the influence of walking speed on biomechanical variables associated with joint loading in persons with varying severities of medial compartment knee osteoarthritis.

Methods

Twenty-one persons with moderate osteoarthritis (Kellgren–Lawrence score 2–3) and 13 persons with severe osteoarthritis (Kellgren–Lawrence score of 4) participated. Twenty-two persons without knee pain or radiographic evidence of arthritis comprised a healthy control group. Sagittal plane kinetics, knee adduction moment, sagittal plane knee excursion, ground reaction forces and knee joint reaction forces were calculated from three-dimensional motion analysis at 1.0 m/s, self-selected and fastest tolerable walking speeds. Differences were analyzed using multivariate analysis of variance and multivariate analysis of covariance with speed as a covariate.

Findings

Persons with knee osteoarthritis showed significantly lower knee and ankle joint moments, ground reaction forces, knee reaction force and knee excursion when walking at freely chosen speeds. When differences in walking speed were accounted for in the analysis, the only difference found at all conditions was decreased knee joint excursion.

Interpretation

Compared to a healthy control group, persons with knee OA demonstrate differences in joint kinetics and kinematics. Except for knee excursion, these differences in gait parameters appear to be a result of slower freely chosen walking speeds rather than a result of disease progression.     

Comparison of Hip and Low Back Loads between Normal Gait,Axillary Crutch Ambulation and Walking with a Hands-free Crutch in a Healthy Population

BackgroundInstead of using axillary crutches, using a hands-free crutch (HFC) has been associated with higher functional outcome scores. However, hip and back pain have been reported as side effects.Purpose/HypothesisThe purpose of this study was to compare range of motion and joint reaction forces at the hip and low back between HFC walking, normal walking, and standard crutch walking. It was hypothesized that hip joint reaction forces and low back joint reaction forces would be higher with HFC walking compared with normal walking and axillary crutch walking.Study DesignControlled Laboratory StudyMethodsUsing 3D motion analysis and force plates, kinematics and ground reaction forces were measured in 12 healthy subjects during gait, crutch ambulation and HFC walking. Gait speed, hip and trunk range of motion, and hip and low back reaction forces, were compared using repeated-measures ANOVA.ResultsGait speed during HFC ambulation was reduced 33% compared to crutch ambulation (P<0.001) and 44% compared to normal gait (p<0.001). Hip range of motion was reduced during both crutch conditions compared to gait (p<0.001). Trunk range of motion was greatest during HFC walking compared to both gait and crutch ambulation (p<0.001). Peak hip joint reaction force during HFC walking was 11% lower than during gait (p=0.026) and 30% lower than during crutch walking (p<0.001). Peak low back reaction force during HFC walking was 18% higher than during gait (p=0.032) but not different than during crutch walking.ConclusionHip joint reaction forces during HFC walking did not exceed those during gait or axillary crutch ambulation. However, a reduction in hip motion using the HFC was associated with increases in trunk motion and low-back loading. These could be a cause for reports of low-back pain accompanying HFC usage.Level of EvidenceLevel 3     

Effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force

[Purpose] The purpose of this study was to investigate the effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force. [Subjects] The subjects of this study were 30 young adult males, who were divided into a Nordic walking group of 15 subjects and a walking group of 15 subjects. [Methods] To analyze the spatiotemporal parameters and ground reaction force during walking in the two groups, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for them between Nordic walking and walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. To determine the pole for Nordic walking, each subject’s height was multiplied by 0.68. We then measured the spatiotemporal gait parameters and ground reaction force. [Results] Compared with the walking group, the Nordic walking group showed an increase in cadence, stride length, and step length, and a decrease in stride time, step time, and vertical ground reaction force. [Conclusion] The results of this study indicate that Nordic walking increases the stride and can be considered as helping patients with diseases affecting their gait. This demonstrates that Nordic walking is more effective in improving functional capabilities by promoting effective energy use and reducing the lower limb load, because the weight of the upper and lower limbs is dispersed during Nordic walking.Key words: Nordic walking, Ground reaction force, Spatiotemporal gait parameters     

Gait pattern classification of healthy elderly men based on biomechanical data

OBJECTIVES: To distinguish the gait patterns of young subjects from those of elderly men using three-dimensional (3D) gait data, to determine if elderly subjects displayed other than a typical gait pattern, and to identify which parameters best describe them. DESIGN: Nonrandomized study in which video and force plate data were collected at the subject's own free walking speed and used in a 3D inverse dynamic model. Cluster analysis was chosen to identify the gait families, and analyses of variance were performed to determine which parameters were different. SETTING: A gait laboratory. PARTICIPANTS: The sample of convenience involved a single but mixed group consisting of 16 able-bodied elderly subjects (mean age, 62yrs) and 16 able-bodied young subjects aged between 20 and 35 years. MAIN OUTCOME MEASURES: Phasic and temporal gait parameters, as well as the 3D muscle powers developed in the joints of the right lower limb during the gait cycle. RESULTS: The walking patterns in elderly subjects were found to be different from those of the young adults. Three elderly gait families or groups forming a specific gait pattern were identified, and differences were found in the phasic and temporal parameters as well as in 6 peak muscle powers. Four of the peak powers occurred in the sagittal plane, and half of them were related to the hip. CONCLUSIONS: Biomechanical parameters can be used to classify the gait patterns of young and elderly men using cluster analysis rather than age alone. The muscle powers in elderly subjects are perturbed throughout the gait cycle and not only at push-off. It appears that the plane in which the peak powers occurred was related to their occurrence in the gait cycle. Variability in the gait patterns of elderly subjects could reflect natural adaptations or compensations. These should not be indicative of a deficient gait or be misconstrued as some age-related pathology.     

The effect of visual targeting on ground reaction force and temporospatial parameters of gait

BACKGROUND: Visual targeting has been cited as a confounding factor for gait analysis in which measures of ground reaction force and plantar pressure are obtained. OBJECTIVE: To investigate the effect of visual targeting on temporospatial and kinetic aspects of gait when small targets, such as pressure platforms, have to be used. DESIGN: A within subjects repeated measure design was used to measure step parameters and ground reaction forces of 11 healthy volunteers. METHODS: Subjects were required to walk over a 10 m walkway at a self-selected pace. A 30x24 cm(2) target area was superimposed over a hidden Kistler force plate (60x90 cm(2)) mounted at the midpoint of the walkway. Step parameters and ground reaction forces were measured with and without the presence of the target. Ground reaction forces were analysed within the time-domain. RESULTS: Subjects used visual control strategies when approaching targets of similar dimensions to a pressure platform. These strategies were manifested by an increase in the variability of the step length onto the target (P<0.05). However, targeting was observed to have no affect on the magnitude, timing and variability of ground reaction forces when measured within the time-domain and averaged over five trials (P>0.05). CONCLUSIONS: Visual control strategies employed while walking toward a target area have no affect on ground reaction force parameters when measured within the time-domain. RELEVANCE: These findings demonstrate that targeting a 30x24 cm(2) target does not affect ground reaction force parameters, when a gait protocol that fine-tunes the start position is employed. The findings are relevant to gait research in which small force or pressure platforms are used to assess gait kinetics.     

Kinetic alterations independent of walking speed in elderly fallers

OBJECTIVES: To determine if joint kinetic gait alterations in fallers persist when they attempt to walk at a faster speed that is more comparable with nonfallers' comfortable walking speed. DESIGN: Retrospective, case-control study. Stereophotogrammetric and force platform data were collected. SETTING: A gait laboratory. PARTICIPANTS: Sixteen elderly subjects who had at least 2 falls in the last 6 months from an unclear cause and 23 elderly subjects with no history of repeated falls. MAIN OUTCOME MEASURES: Differences in all major peak joint kinetic (moment and power) values during the gait cycle between elderly nonfallers walking at comfortable speed and elderly fallers walking at (1) comfortable and (2) fast speed. RESULTS: Statistically significant differences present at both comfortable and fast walking speeds were present in 4 sagittal plane parameters. There was an increase in peak external hip flexion moment in stance, a reduction in peak hip extension moment, a reduction in knee flexion moment in preswing, and a reduction in knee power absorption in preswing. CONCLUSION: The presence and persistence of 4 specific alterations in sagittal plane joint kinetics at both comfortable and fast walking speeds imply specific intrinsic pattern differences and allow for new insights into the mechanics of gait in elderly people who fall. The presence of these alterations also suggests they may serve as potential identifiable markers to detect those who may be at risk for falls.     

Determination of the effectiveness of materials in attenuating high frequency shock during gait using filterbank analysis

OBJECTIVE: To develop an accurate method for quantifying the frequency content of the ground reaction force transient. DESIGN: Repeated measures design comparing the impact severity during walking with different insole materials. BACKGROUND: The body experiences a brief but sizeable impact upon heel strike during walking. This impact transient is believed to result in musculoskeletal injuries. It is important to accurately quantify this impact as a step towards decreasing the risk of injury. METHODS: Seven subjects walked barefoot at their normal cadence across a force platform, while insole materials (Spenco, Microcel-puff, and Plastazote) were placed on the surface of the force platform. A filterbank program was developed to determine the percent root mean square in 10 Hz frequency bands from zero to 400 Hz. Analysis focused on the impact transient contained in a 20 ms window after heel contact. RESULTS: The high frequency (>60 Hz) power was significantly larger in the barefoot condition compared to the insole conditions. The barefoot condition also resulted in significantly higher initial peak forces and force loading rates. CONCLUSIONS: The frequency content of the ground reaction force can be effectively quantified using a filterbank approach. Shoe insole materials can reduce the initial peak force, force loading rate, and frequency content of the impact transient in walking. The frequency content of the initial ground reaction force extends up to 400 Hz in some footwear conditions. RELEVANCE: The new filterbank procedure illustrates that the vertical ground reaction force in walking has a higher frequency content than previously thought. This signal requires high sampling rates to avoid aliasing, and appropriate signal processing algorithms, such as filter banks, for analysis.     

Gluteus medius dysfunction in females with chronic ankle instability is consistent at different walking speeds

BackgroundPatients with chronic ankle instability often present with altered gait mechanics compared to ankle sprain copers. There is increasing evidence to suggest proximal neuromuscular alterations contribute to the injury etiology, however little is known about how these changes manifest during gait. The purpose of this study was to investigate ipsilateral gluteus maximus and medius functional activity ratios throughout treadmill walking at three speeds (preferred, 120% preferred, and 1.35 m per second) in chronic ankle instability patients compared to copers.Methods28 females (14 chronic ankle instability, 14 copers) walked at the three gait speeds in randomized order. Ground reaction forces and 10-s gluteal ultrasound clips were simultaneously recorded. Clips were reduced using ground reaction forces to extract 55 measurement frames. Normalized gluteal thickness measures were used to determine functional activity ratios. 2 × 3 analyses of variance were run to assess group and speed effects on gluteal outcomes throughout walking using statistical parametric mapping. Post-hoc t-tests, mean differences, and Cohen's d effect sizes were assessed for significant findings (P ≤ .05).FindingsThe chronic ankle instability group had significantly decreased gluteus medius activity throughout the entire gait cycle when compared to the coper group, independent of gait speed (P < .001, mean differences: 0.10–0.18; d: 1.00–3.17). There were no significant group or speed main effects, nor an interaction for gluteus maximus activity.InterpretationGluteal dysfunction throughout walking was identified in chronic ankle instability. The coper group remained within healthy reference muscle activity ranges, suggesting that proximal muscle activation alterations are associated chronic ankle impairments.     

Reproducibility of loading measurements with skin-mounted accelerometers during walking

OBJECTIVE: To examine reproducibility of load measurements with skin-mounted accelerometers (SMAs) during walking. DESIGN: Reliability study. SETTING: A motion analysis laboratory. PARTICIPANTS: Ten healthy young men. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Two triaxial accelerometers were fixed to the subjects' skin above and below the knee joint. The subjects walked barefoot at their preferred speed and at a constant speed (1.3m/s, +/-5%) in a gait laboratory and along a corridor. The same protocol was repeated over 2 days. Initial peak acceleration (IPA), peak-to-peak (PP) acceleration, and maximal and average acceleration transient rates (ATRs) were calculated. The coefficient of variation (CV) and Pearson linear correlation coefficient were calculated to measure reproducibility of SMA load measurements. RESULTS: IPA and PP acceleration had good interday repeatability (CV <15%). The repeatability of average ATR and maximal ATR parameters was generally not acceptable. The loading variables obtained from ground reaction forces and SMA measurements during gait revealed high linear correlations, indicating that with SMA measurements it is possible to predict certain ground reaction force loading parameters. CONCLUSIONS: SMAs are practical for use in clinical environments to collect acceleration data that may be used to estimate joint loads.     

Ground reaction forces during level ground walking with body weight unloading

Background:

Partial body weight support (BWS) systems have been broadly used with treadmills as a strategy for gait training of individuals with gait impairments. Considering that we usually walk on level ground and that BWS is achieved by altering the load on the plantar surface of the foot, it would be important to investigate some ground reaction force (GRF) parameters in healthy individuals walking on level ground with BWS to better implement rehabilitation protocols for individuals with gait impairments.

Objective:

To describe the effects of body weight unloading on GRF parameters as healthy young adults walked with BWS on level ground.

Method:

Eighteen healthy young adults (27±4 years old) walked on a walkway, with two force plates embedded in the middle of it, wearing a harness connected to a BWS system, with 0%, 15%, and 30% BWS. Vertical and horizontal peaks and vertical valley of GRF, weight acceptance and push-off rates, and impulse were calculated and compared across the three experimental conditions.

Results:

Overall, participants walked more slowly with the BWS system on level ground compared to their normal walking speed. As body weight unloading increased, the magnitude of the GRF forces decreased. Conversely, weight acceptance rate was similar among conditions.

Conclusions:

Different amounts of body weight unloading promote different outputs of GRF parameters, even with the same mean walk speed. The only parameter that was similar among the three experimental conditions was the weight acceptance rate.