Mechanical energy of walking of stroke patients

One-year retention of gait speed improvement in stroke survivors after treatment with a wearable home-use gait device

Background

Gait impairments after stroke are associated with numerous physical and psychological consequences. Treatment with the iStride® gait device has been shown to facilitate improvements to gait function, including gait speed, for chronic stroke survivors with hemiparesis. This study examines the long-term gait speed changes up to 12 months after treatment with the gait device.

Methods

Eighteen individuals at least one-year post-stroke completed a target of 12, 30-minute treatment sessions with the gait device in their home environment. Gait speed was measured at baseline and five follow-up sessions after the treatment period: one  week, one  month, three months, six months, and 12 months. Gait speed changes were analyzed using repeated-measures ANOVA from baseline to each follow-up time frame. Additional analysis included comparison to the minimal clinically important difference (MCID), evaluation of gait speed classification changes, and review of subjective questionnaires.

Results

Participants retained an average gait speed improvement >0.21 m/s compared to baseline at all post-treatment time frames. Additionally, 94% of participants improved their gait speed beyond the MCID during one or more post-treatment measurements, and 88% subjectively reported a gait speed improvement.

Conclusion

Treatment with the gait device may result in meaningful, long-term gait speed improvement for chronic stroke survivors with hemiparetic gait impairments.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03649217, identifier NCT03649217.

Does Accelerometry at the Centre of Mass Accurately Predict the Gait Energy Expenditure in Patients with Hemiparesis?

BACKGROUND

The aim of this study was to compare energy expenditure (EE) predicted by accelerometery (EEAcc) with indirect calorimetry (EEMETA) in individuals with hemiparesis.

METHODS

Twenty-four participants (12 with stroke and 12 healthy controls) performed a six-minute walk test (6MWT) during which EEMETA was measured using a portable indirect calorimetry system and EEACC was calculated using Bouten's equation (1993) with data from a three-axis accelerometer positioned between L3 and L4.

RESULTS

The median EEMETA was 9.85 [8.18;11.89] W·kg-1 in the stroke group and 5.0 [4.56;5.46] W·kg-1 in the control group. The median EEACC was 8.57 [7.86;11.24] W·kg-1 in the control group and 8.2 [7.05;9.56] W·kg-1 in the stroke group. The EEACC and EEMETA were not significantly correlated in either the control (p = 0.8) or the stroke groups (p = 0.06). The Bland-Altman method showed a mean difference of 1.77 ± 3.65 W·kg-1 between the EEACC and EEMETA in the stroke group and -2.08 ± 1.59 W·kg-1 in the controls.

CONCLUSIONS

The accuracy of the predicted EE, based on the accelerometer and the equations proposed by Bouten et al., was low in individuals with hemiparesis and impaired gait. This combination (sensor and Bouten's equation) is not yet suitable for use as a stand-alone measure in clinical practice for the evaluation of hemiparetic patients.

Thigh and Shank, Kinetic and Potential Energies during Gait Swing Phase in Healthy Adults and Stroke Survivors

Background/Problem. Given the treatment-resistant gait deficits after stroke and known elevated energy cost of gait after stroke, it is important to study the patterns of mechanical energies of the lower limb segments. There is a dearth of information regarding mechanical energies specifically for the thigh and shank across the gait cycle. Therefore, the purpose of the current work was to characterize the following: (1) relative patterns of oscillation kinetic energy (KE) and potential energy (PE) within lower limb segments and across lower limb segments in healthy adults during the swing phase at chosen and slow gait speeds; (2) KE and PE swing phase patterns and values for stroke survivors versus healthy adults walking at slow speed; and (3) KE and PE patterns during the swing phase for two different compensatory gait strategies after stroke,. Methods. This was a gait characterization study, a two-group, parallel-cohort study of fourteen stroke survivors with gait deficits, walking at <0.4 m/s and eight adults with no gait deficits. For testing, the eight healthy adults walked at their chosen speed, and then at the imposed slow speed of <0.04 m/s. We used a standard motion capture system and calculation methods to acquire, calculate, and characterize oscillation patterns of KE and PE of the limb segments (thigh and shank) across the gait cycle. Results. In healthy adults, we identified key energy conservation mechanisms inherent in the interactions of KE and PE, both within the thigh and shank segments and across those limb segments, partially explaining the low cost of energy of the normal adult chosen speed gait pattern, and the underlying mechanism affording the known minimal set of activated muscles during walking, especially during the early swing phase. In contrast, KE was effectively absent for both healthy adults at imposed slow walking speed and stroke survivors at their very slow chosen speed, eliminating the normal conservation of energy between KE and PE within the thigh and across the thigh and shank. Moreover, and in comparison to healthy adult slow speed, stroke survivors exhibited greater abnormalities in mechanical energies patterns, reflected in either a compensatory stepping strategy (over-flexing the hip) or circumducting strategy (stiff-legged gait, with knee extended throughout the swing phase). Conclusions and contribution to the field. Taken together, these findings support targeted training to restore normal balance control and normal activation and de-activation coordination of hip, knee, and ankle muscles, respectively (agonist/antagonist at each joint), so as to eliminate the known post-stroke abnormal co-contractions; this motor training is critical in order to release the limb to swing normally in response to mechanical energies and afford the use of conservation of KE and PE energies within the thigh and across thigh and shank.

Investigating the underlying biomechanical mechanisms leading to falls in long-term ankle-foot orthosis and functional electrical stimulator users with chronic stroke

BACKGROUND

Ankle-foot-orthoses (AFOs) and functional electrical stimulators (FES) are commonly prescribed to treat foot-drop in individuals with stroke. Despite well-established positive impacts of AFO and FES devices on balance and gait, AFO and FES-users still fall at a high rate.

OBJECTIVE

The objective of this study was to investigate 1) the underlying biomechanical mechanisms leading to a fall in long-term AFO and FES-users with chronic stroke and 2) the impacts of AFOs and FES devices on fall outcomes and compensatory stepping response of long-term users with chronic stroke.

METHODS

Fall outcomes as well as kinematics and kinetics of compensatory stepping response of 42 individuals with chronic stroke (14 AFO-users, 10 FES-users, 18 Non-users) were evaluated during trip-like treadmill perturbations. AFO and FES-users were evaluated with and without their device.

RESULTS

Chronic AFO and FES-users fell 2.50 and 2.77 times more than Non-users. The most robust differences between AFO/FES-users and Non-users were 1) Reduced capacity to stabilize the trunk through reduction in forward whole-body angular momentum and 2) diminished capability to prepare and generate a second step using the paretic leg. Provocatively, the removal of AFO and FES devices did not decease/increase falls or change kinematics.

SIGNIFICANCE

It is well-established that AFOs/FES devices have a positive impact on static balance and decrease community falls by increasing toe clearance thus preventing trips/stumbles. However, our results suggest that once a trip occurs, these devices do not adequately assist recovery of balance. Specifically, current AFO and FES devices do not assist with second step generation or trunk control. Future studies should explore new devices or training paradigms that target enhancing trunk control and paretic compensatory stepping to decrease falls in this population.

A Conceptual Blueprint for Making Neuromusculoskeletal Models Clinically Useful

The ultimate goal of most neuromusculoskeletal modeling research is to improve the treatment of movement impairments. However, even though neuromusculoskeletal models have become more realistic anatomically, physiologically, and neurologically over the past 25 years, they have yet to make a positive impact on the design of clinical treatments for movement impairments. Such impairments are caused by common conditions such as stroke, osteoarthritis, Parkinson’s disease, spinal cord injury, cerebral palsy, limb amputation, and even cancer. The lack of clinical impact is somewhat surprising given that comparable computational technology has transformed the design of airplanes, automobiles, and other commercial products over the same time period. This paper provides the author’s personal perspective for how neuromusculoskeletal models can become clinically useful. First, the paper motivates the potential value of neuromusculoskeletal models for clinical treatment design. Next, it highlights five challenges to achieving clinical utility and provides suggestions for how to overcome them. After that, it describes clinical, technical, collaboration, and practical needs that must be addressed for neuromusculoskeletal models to fulfill their clinical potential, along with recommendations for meeting them. Finally, it discusses how more complex modeling and experimental methods could enhance neuromusculoskeletal model fidelity, personalization, and utilization. The author hopes that these ideas will provide a conceptual blueprint that will help the neuromusculoskeletal modeling research community work toward clinical utility.

Mechanical and energetic determinants of impaired gait following stroke: segmental work and pendular energy transduction during treadmill walking

Systems biology postulates the balance between energy production and conservation in optimizing locomotion. Here, we analyzed how mechanical energy production and conservation influenced metabolic energy expenditure in stroke survivors during treadmill walking at different speeds. We used the body center of mass (BCoM) and segmental center of mass to calculate mechanical energy production: external and each segment's mechanical work (W_seg). We also estimated energy conservation by applying the pendular transduction framework (i.e. energy transduction within the step; R_int). Energy conservation was likely optimized by the paretic lower-limb acting as a rigid shaft while the non-paretic limb pushed the BCoM forward at the slower walking speed. W_seg production was characterized by greater movements between the limbs and body, a compensatory strategy used mainly by the non-paretic limbs. Overall, W_seg production following a stroke was characterized by non-paretic upper-limb compensation, but also by an exaggerated lift of the paretic leg. This study also highlights how post-stroke subjects may perform a more economic gait while walking on a treadmill at preferred walking speeds. Complex neural adaptations optimize energy production and conservation at the systems level, and may fundament new insights onto post-stroke neurorehabilitation.

This article has and associated First Person interview with the first author of the paper.

Summary: Walking after a stroke may be energetically consuming. Here, we show how compensations and asymmetries may contribute to increasing the amount of work needed to walk following a stroke.

Reproducibility of Different Methodologies to Calculate Oxygen Consumption and Oxygen Cost During Walking in Chronic Stroke Survivors

OBJECTIVE

The most common methods to calculate energy costs are based on measured oxygen uptake during walking a standardized distance or time. Unfortunately, it is unclear which method is most reliable to determine energy cost of walking in stroke survivors. The objective of this study was to evaluate the 3 most commonly used methods for calculating oxygen consumption and -cost by assessing test-retest reliability and measurement error in community dwelling chronic stroke survivors during a 6 Minute Walk Test.

METHODS

In this secondary analysis of a longitudinal study, reproducibility of the outcome of walking distance, walking speed, oxygen consumption and oxygen cost from 3 methods (Kendall's tau, assumed steady-state and total walking time oxygen consumption) were determined using Intraclass Correlation Coefficient, Standard Error of Measurement and Smallest Detectable Change.

RESULTS

20 from the 31 participants successfully performed the 6 minute walk test-retest within a timeframe of 1 month. Within the 2 tests the reproducibility of walking distance and walking speed was high. The 3 methods to determine reproducibility for oxygen cost and oxygen consumption were considered good (Kendall's tau), good (assumed steady-state) and excellent (total walking time).

CONCLUSIONS

The method using oxygen consumption and -cost over the total walking time resulted in the highest reproducibility considering the Intraclass Correlation Coefficient, its 95% Confidence Interval, and smaller absolute differences.

Gait kinematics and physical function that most affect intralimb coordination in patients with stroke

BACKGROUND

Disturbed lower limb coordination is thought to limit gait ability in patients with stroke. However, the relationship of lower limb coordination with gait kinematics and physical function has not yet been clarified.

OBJECTIVE

The purpose of the study was to clarify the gait kinematic and physical function variables that most affect intralimb coordination by using the continuous relative phase (CRP) between the thigh and shank.

METHODS

Fifteen participants with stroke were enrolled in this study. Kinematic and kinetic measurements were recorded during gait at preferred speeds. CRP was defined as the difference between the thigh and shank phase angles.

RESULTS

Stepwise analysis revealed that non-paretic CRP during the propulsive phase was a determinant of gait speed. The paretic knee extension and flexion angles were determinants of the CRP during the propulsive phase in the non-paretic limb. Stepwise analysis showed that the paretic knee extension angle was a determinant of the CRP during the propulsive phase in the paretic limb. Stepwise analysis revealed that the paretic knee extensor muscle strength was a determinant of the CRP during the propulsive phase in both limbs.

CONCLUSIONS

Our study indicates that improvement in knee movement during the stance phase may improve coordination.

Experimental estimation of energy absorption during heel strike in human barefoot walking

Metabolic energy expenditure during human gait is poorly understood. Mechanical energy loss during heel strike contributes to this energy expenditure. Previous work has estimated the energy absorption during heel strike as 0.8 J using an effective foot mass model. The aim of our study is to investigate the possibility of determining the energy absorption by more directly estimating the work done by the ground reaction force, the force-integral method. Concurrently another aim is to compare this method of direct determination of work to the method of an effective foot mass model. Participants of our experimental study were asked to walk barefoot at preferred speed. Ground reaction force and lower leg kinematics were collected at high sampling frequency (3000 Hz; 1295 Hz), with tight synchronization. The work done by the ground reaction force is 3.8 J, estimated by integrating this force over the foot-ankle deformation. The effective mass model is improved by dropping the assumption that foot-ankle deformation is maximal at the instant of the impact force peak. On theoretical grounds it is clear that in the presence of substantial damping that peak force and peak deformation do not occur simultaneously. The energy absorption results, due the vertical force only, corresponding to the force-integral method is similar to the results of the improved application of the effective mass model (2.7 J; 2.5 J). However the total work done by the ground reaction force calculated by the force-integral method is significantly higher than that of the vertical component alone. We conclude that direct estimation of the work done by the ground reaction force is possible and preferable over the use of the effective foot mass model. Assuming that energy absorbed is lost, the mechanical energy loss of heel strike is around 3.8 J for preferred walking speeds (≈ 1.3 ^m/_s), which contributes to about 15–20% of the overall metabolic cost of transport.

Clinical-oriented Three-dimensional Gait Analysis Method for Evaluating Gait Disorder

Three-dimensional gait analysis (3DGA) is shown to be a useful clinical tool for the evaluation of gait abnormality due to movement disorders. However, the use of 3DGA in actual clinics remains uncommon. Possible reasons could include the time-consuming measurement process and difficulties in understanding measurement results, which are often presented using a large number of graphs. Here we present a clinician-friendly 3DGA method developed to facilitate the clinical use of 3DGA. This method consists of simplified preparation and measurement processes that can be performed in a short time period in clinical settings and intuitive results presentation to facilitate clinicians' understanding of results. The quick, simplified measurement procedure is achieved by the use of minimum markers and measurement of patients on a treadmill. To facilitate clinician understanding, results are presented in figures based on the clinicians' perspective. A Lissajous overview picture (LOP), which shows the trajectories of all markers from a holistic viewpoint, is used to facilitate intuitive understanding of gait patterns. Abnormal gait pattern indices, which are based on clinicians' perspectives in gait evaluation and standardized using the data of healthy subjects, are used to evaluate the extent of typical abnormal gait patterns in stroke patients. A graph depicting the analysis of the toe clearance strategy, which depicts how patients rely on normal and compensatory strategies to achieve toe clearance, is also presented. These methods could facilitate implementation of 3DGA in clinical settings and further encourage development of measurement strategies from the clinician's point of view.

Towards Total Energy Shaping Control of Lower-Limb Exoskeletons

Current robotic exoskeletons enforce fixed reference joint patterns during gait rehabilitation. These control methods aim to replicate normative joint kinematics but do not facilitate learning patient-specific kinematics. Trajectory-free control methods for exoskeletons are required to promote user control over joint kinematics. Our prior work on potential energy shaping provides virtual body-weight support through a trajectory-free control law, but altering only the gravitational forces does not assist the subject in accelerating/decelerating the body forward. Kinetic energy is velocity dependent and thus shaping the kinetic energy in addition to potential energy can yield greater dynamical changes in closed loop. In this paper, we generalize our previous work to achieve underactuated total energy shaping of the human body through a lower-limb exoskeleton. By shaping the fully-actuated part of the body's mass matrix, we satisfy the matching condition for different contact phases and obtain trajectory-free control laws. Simulations of a human-like biped demonstrate speed regulation in addition to body-weight support, indicating the potential clinical value of this control approach.

Muscle Synergies Facilitate Computational Prediction of Subject-Specific Walking Motions

Researchers have explored a variety of neurorehabilitation approaches to restore normal walking function following a stroke. However, there is currently no objective means for prescribing and implementing treatments that are likely to maximize recovery of walking function for any particular patient. As a first step toward optimizing neurorehabilitation effectiveness, this study develops and evaluates a patient-specific synergy-controlled neuromusculoskeletal simulation framework that can predict walking motions for an individual post-stroke. The main question we addressed was whether driving a subject-specific neuromusculoskeletal model with muscle synergy controls (5 per leg) facilitates generation of accurate walking predictions compared to a model driven by muscle activation controls (35 per leg) or joint torque controls (5 per leg). To explore this question, we developed a subject-specific neuromusculoskeletal model of a single high-functioning hemiparetic subject using instrumented treadmill walking data collected at the subject's self-selected speed of 0.5 m/s. The model included subject-specific representations of lower-body kinematic structure, foot-ground contact behavior, electromyography-driven muscle force generation, and neural control limitations and remaining capabilities. Using direct collocation optimal control and the subject-specific model, we evaluated the ability of the three control approaches to predict the subject's walking kinematics and kinetics at two speeds (0.5 and 0.8 m/s) for which experimental data were available from the subject. We also evaluated whether synergy controls could predict a physically realistic gait period at one speed (1.1 m/s) for which no experimental data were available. All three control approaches predicted the subject's walking kinematics and kinetics (including ground reaction forces) well for the model calibration speed of 0.5 m/s. However, only activation and synergy controls could predict the subject's walking kinematics and kinetics well for the faster non-calibration speed of 0.8 m/s, with synergy controls predicting the new gait period the most accurately. When used to predict how the subject would walk at 1.1 m/s, synergy controls predicted a gait period close to that estimated from the linear relationship between gait speed and stride length. These findings suggest that our neuromusculoskeletal simulation framework may be able to bridge the gap between patient-specific muscle synergy information and resulting functional capabilities and limitations.

The effect of a slider shoe on hemiplegic gait

Objective: To assess the effect of a slider shoe on the gait speed and energy efficiency of hemiplegic gait.

Design: A–B–A single-case design to compare walking with and without the slider shoe. Results were assessed graphically using the 2SD method.

Setting: Stroke unit of an NHS general hospital in the UK.

Subjects: Four acute stroke patients undergoing gait rehabilitation.

Intervention: Walking practice with and without a slider shoe worn over the real shoe of the weak leg.

Main outcome measures: Gait speed (10-m walk test) and energy efficiency (Physiological Cost Index).

Results: All subjects showed an improvement in speed and efficiency when wearing the slider shoe compared with the baseline phase (A1). Three subjects showed a sustained improvement in efficiency and two showed a sustained improvement in speed in the second baseline phase (A2).

Conclusion: A slider shoe may improve the speed and efficiency of hemiplegic gait for people in the early stages of gait rehabilitation. Further investigation is warranted.

Functional electrical stimulation through direct 4-channel nerve stimulation to improve gait in multiple sclerosis: a feasibility study

Background

Gait dysfunction due to lower limb central paralysis, frequently involving drop foot, is a common cause of disability in multiple sclerosis and has been treated with transcutaneous functional electrical stimulation (FES). We provide here the first report of 4-channel semi-implantable FES of the peroneal nerve which has been successfully used for rehabilitation in patients following stroke.

Methods

FES was implemented via a 4-channel semi-implantable closed-loop system (ActiGait®, ©Ottobock), generating dorsiflexion in drop foot. Walking distance, gait symmetry (temporospatial gait analyses, Vicon Motion Systems®), gait velocity (10 m walking test) and quality of life (SF-36 questionnaire) were measured to evaluate the therapeutic benefit of this system in two patients with progressive MS.

Results

Walking distance increased from 517 to 1884 m in Patient 1 and from 52 to 506 m in Patient 2. Gait velocity did not change significantly in Patient 1 and increased from 0.6 to 0.8 m/s in Patient 2. Maximum deviations of center of mass from the midline to each side changed significantly after 3 months of stimulation compared to baseline, decreasing from 15 to 12 mm in Patient 1 and from 47 to 37 mm in Patient 2. Both patients experienced reduced pain and fatigue and benefits to quality of life. Adverse events did not occur during the observation period.

Conclusion

We conclude that implantable 4-channel FES systems are not only feasible but present a promising new alternative for treating central drop foot in MS patients.

Cardiovascular Health and Fitness After Stroke

Stroke patients have profound cardiovascular and muscular deconditioning, with metabolic fitness levels that are about half those found in age-matched sedentary controls. Physical deconditioning, along with elevated energy demands of hemiparetic gait, define a detrimental combination termed diminished physiological fitness reserve that can greatly limit that can greatly limit performance of activities of daily living. The physiological features that underlie worsening metabolic fitness in the chronic phase of stroke include gross muscular atrophy, altered muscle molecular phenotype, increased intramuscular area fat, elevated tissue inflammatory markers, and diminished peripheral blood flow dynamics. Epidemiological evidence further suggests that the reduced cardiovascular fitness and secondary biological changes in muscle may propagate components of the metabolic syndrome, conferring added morbidity and mortality risk. This article reviews some of the consequences of poor fitness in chronic stroke and the potential biological underpinnings that support a rationale for more aggressive approaches to exercise therapy in this population.

Energy flow analysis of the lower extremity during gait in persons with chronic stroke

BACKGROUND

A decline in walking capacity and high energy cost can limit mobility following stroke. Mechanical energy exchange between lower limb and trunk segments can reflect gait inefficiencies, but reveals little about active energy flow between adjacent segments through muscle actions. This study evaluated mechanical energy expenditures (MEEs) during walking in stroke and healthy groups to understand movement control and explore the impact of walking speed on mechanical energy exchanges.

METHODS

Thirteen adults with hemiparesis and six healthy controls walked at self-selected speed. Power curves for each lower limb joint were segmented into concentric and eccentric sources of muscle power and transfer/no-transfer modes to calculate MEEs during stance.

FINDINGS

MEEs were lower in the stroke group on the affected side compared to the less affected side and compared to controls. Specifically, the affected plantarflexors transferred less energy distally via concentric action in late stance compared to the less affected side. However, the stroke group generated greater energy at the ankle in the absence of transfer compared to controls. Less concentrically transferred energy through midstance and absorbed in late stance was evident by the knee extensors bilaterally in stroke. At the hip, the total energy (no transfer) was reduced on the affected side. Classifying stroke subjects by walking speed (<.6m/s, >.6m/s) revealed disruptions in harnessing energy through motion and transfer energy across segments in the slower group.

INTERPRETATION

The limited ability of those with stroke to exploit intersegmental energy transfer to optimize efficiency may limit endurance and functional independence.

Which type of cane is the most efficient, based on oxygen consumption and balance capacity, in chronic stroke patients?

Canes are widely prescribed as walking aids, but little is known about the effects of canes on the physiological cost of walking. The purpose of this study was to investigate the differences in oxygen consumption associated with the gaits of hemiplegic patients in terms of balance capacity according to the type of cane used. Twenty-nine patients with chronic stroke were divided into poor-balance (n=15) and relatively-better-balance groups (n=14) based on a cutoff score of 49 on the Berg balance scale (BBS). Each patient completed three consecutive days of walking with a randomly assigned singlepoint cane, quad cane, or hemi-walker. We measured the oxygen expenditure and oxygen cost using a portable gas analyzer and heart rate during a 6-min walk test (6MWT) and a 10-m walk test (10MWT). The oxygen expenditure, gait endurance, and gait velocity were higher with the single-point cane (p<0.01) than with any of the other cane types, and the oxygen costs were lower (p<0.01) with the single-point cane among the patients with relatively better balance. The oxygen cost for the quad cane was lower (p<0.01) than that found for any the other cane types among the patients with relatively poor balance. Our study revealed that single-point canes require less oxygen use at a given speed and permits greater speed at the same oxygen consumption for hemiplegic patients with good balance. Walking aids with a greater base support may be more suitable than those with a smaller base support for patients with relatively poor balance. However, our conclusions are only preliminary because of the small sample size (KCT0001076).

Cardiovascular response during submaximal underwater treadmill exercise in stroke patients

Objective

To evaluate the cardiovascular response during head-out water immersion, underwater treadmill gait, and land treadmill gait in stroke patients.

Methods

Ten stroke patients were recruited for underwater and land treadmill gait sessions. Each session was 40 minutes long; 5 minutes for standing rest on land, 5 minutes for standing rest in water or on treadmill, 20 minutes for treadmill walking in water or on land, 5 minutes for standing rest in water or on treadmill, and 5 minutes for standing rest on land. Blood pressure (BP) and heart rate (HR) were measured during each session. In order to estimate the cardiovascular workload and myocardial oxygen demand, the rate pressure product (RPP) value was calculated by multiplying systolic BP (SBP) by HR.

Results

SBP, DBP, mean BP (mBP), and RPP decreased significantly after water immersion, but HR was unchanged. During underwater and land treadmill gait, SBP, mBP, DBP, RPP, and HR increased. However, the mean maximum increases in BP, HR and RPP of underwater treadmill walking were significantly lower than that of land treadmill walking.

Conclusion

Stroke patients showed different cardiovascular responses during water immersion and underwater gait as opposed to standing and treadmill-walking on land. Water immersion and aquatic treadmill gait may reduce the workload of the cardiovascular system. This study suggested that underwater treadmill may be a safe and useful option for cardiovascular fitness and early ambulation in stroke rehabilitation.

A randomized comparison of energy consumption when using different canes, inpatients after stroke

Objectives:

To investigate the differences in oxygen consumption associated with gait in hemiplegic patients according to the type of cane they use.

Design:

A randomized crossover design.

Setting:

University hospital-based rehabilitation center, Korea.

Subjects:

Thirty consecutive patients (mean ± SD age, 56.3 ± 3.2 years) with chronic stroke, 17 (56.7%) males and 13 (43.3%) females.

Interventions:

At approximately the same time of day for three consecutive days, each participant completed a walk with one of three randomly assigned types of canes: a single-point cane, a quad cane, and a hemi-walker.

Main outcome measure:

Energy expenditure (O2 rate, mL/kg/min), energy cost (O2 cost, mL/kg/m), and heart rate (HR) via a portable gas analyzer, a 10-meter walk test (10MWT), and a 6-minute walk test (6MWT).

Results:

Energy expenditure, gait endurance, and gait velocity for a single-point cane were higher ( p<0.001 or p=0.005) than for any other type of cane. Energy cost (0.5 ± 0.2 mL/kg/m vs. 0.6 ± 0.2 mL/kg/m vs. 0.6 ± 0.2 ml/kg/m, respectively, p=0.001) was lower for the single-point cane, except for HR ( p ≥ 0.05) after the Bonferroni correction (0.05/5=0.01).

Conclusions:

A single-point cane requires less oxygen use at a given speed, or permits greater speed for the same oxygen consumption.

Change in the Mechanical Energy of the Body Center of Mass in Hemiplegic Gait after Continuous Use of a Plantar Flexion Resistive Ankle-foot Orthosis

[Purpose] The aim of this study was to investigate the changes in mechanical energy due to continuous use of a plantar flexion resistive ankle-foot orthosis (AFO) of subjects with chronic hemiplegia. [Subjects and Methods] The subjects were 5 hemiplegic patients using AFOs without a plantar flexion resistive function in their daily lives. We analyzed the gait of the subjects using a 3D motion capture system under three conditions: patients’ use of their own AFOs; after being fitted with a plantar flexion resistive AFO; and after continuous use of the device. The gait efficiency was determined by calculating the mutual exchange of kinetic and potential energy of the center of mass. [Results] An increased exchange rate of the kinetic and potential energy was found for all subjects. A larger increase of energy exchange was shown on the non-paralyzed side, and after continuous use of the plantar flexion resistive AFO. [Conclusion] We found that continuous use of a plantar flexion resistive AFO increased the rate of mutual exchange between kinetic energy and potential energy. The change in the rate was closely related to the role of the non-paretic side, showing that the subjects needed a certain amount of time to adapt to the plantar flexion resistive AFO.

Effects on foot external rotation of the modified ankle-foot orthosis on post-stroke hemiparetic gait

Objective

To evaluate the effects of heel-opened ankle foot orthosis (HOAFO) on hemiparetic gait after stroke, especially on external foot rotation, and to compare the effects of HOAFO with conventional plastic-AFO (pAFO) and barefoot during gait.

Methods

This cross-over observational study involved 15 hemiparetic patients with external rotation of the affected foot. All subjects were able to walk independently, regardless of their usual use of a single cane, and had a less than fair-grade in ankle dorsiflexion power. Each patient was asked to walk in three conditions with randomized sequences: 1) barefoot, 2) with a pAFO, and 3) with an HOAFO. Their gait patterns were analyzed using a motion analysis system.

Results

Fifteen patients consisted of nine males and six females. On gait analysis, hip and foot external rotation were significantly greater in pAFO (-3.35° and -23.68°) than in barefoot and HOAFO conditions (p<0.05). Wearing an HOAFO resulted in significant decreases in hip (0.78°, p=0.04) and foot (-17.99°, p<0.01) external rotation compared with pAFO; although there was no significant difference between HOAFO and barefoot walking. Walking speed and percentage of single limb support were significantly greater for HOAFO than in barefoot walking.

Conclusion

HOAFO was superior to pAFO in reducing hip and foot external rotation during the stance phase in patients with post-stroke hemiparesis. HOAFO may, therefore, be useful in patients with excessive external rotation of the foot during conventional pAFO.

Guiding task-oriented gait training after stroke or spinal cord injury by means of a biomechanical gait analysis

To recover the ability to walk is one of the most important goals of persons recovering from a stroke or spinal cord injury (SCI). While a task-oriented approach to gait training is recommended, randomized controlled trials or meta-analyses comparing different methods of delivering training have failed in general to demonstrate the superiority of one approach over the other. The large variations in the mean outcome gait measures reported in these studies reflect, at least in part, the heterogeneity of the sensorimotor impairments underlying the gait disability as well as variations in the therapeutic response. The purpose of this chapter is to demonstrate that biomechanical gait analysis can reveal information pertinent to the selection of a task-oriented approach to enhance gait training as well as the therapeutic response that clinical evaluations alone cannot provide. We first briefly review locomotor impairments underlying the gait disability after stroke and SCI as well as the effects of selected technological task-oriented gait training interventions. We then give examples that demonstrate the use of gait analysis to pinpoint underlying impairments that can guide the choice of sensorimotor therapy and then immediately identify responders to the intervention. Such an individualized approach should promote therapeutic efficacy while leading over time to the identification of clinical indices to guide therapy when gait analysis is not feasible. Given the requirements of a gait analysis laboratory and the qualified personnel to capture and interpret the data, future studies will need to demonstrate the feasibility of the technological proposed approach and assess the costs and benefits for the health care system.

Adherence to a home-based exercise program for individuals after stroke

BACKGROUND

Although aerobic training (AT) and resistance training (RT) have been shown to improve functional abilities in patients post stroke, few patients participate, with many doing so for only a short duration.

PURPOSE

To retrospectively identify factors that affect adherence to a home-based exercise program adapted for stroke patients in a cardiac rehabilitation program during and after program completion.

METHODS

Fourteen participants (age 63 ± 3 years, 37 ± 34 months post stroke) attended the rehabilitation center on a weekly (24 weeks) and then monthly (2 months) basis. Patients were required to complete 4 AT and 1 to 2 RT sessions away from the center each week. A 16-item survey exploring adherence to home-based workouts was administered.

RESULTS

Seven patients were currently participating (mean time in program, 19.4 ± 8 weeks) and 7 had graduated (mean of 32.8 ± 28 weeks post graduation) from the program. Current participants had higher adherence than graduated participants to AT (100% vs 76%; P < .01) and RT (100% vs 55%; P < .01). The most common factors motivating participants were to improve overall health, improve functional abilities, and enhance confidence and to reduce musculoskeletal issues. The most common factors preventing workouts were lack of motivation, musculoskeletal issues, and fatigue. There was a negative correlation between age and adherence to AT in the graduated group.

CONCLUSION

Adherence to home-based exercise is superior during participation in an organized group program, with decline after graduation.

Enhancing physical activity and brain reorganization after stroke

It is becoming increasingly clear that, if reorganization of brain function is to be optimal after stroke, there needs to be a reorganisation of the methods used in physical rehabilitation and the time spent in specific task practice, strength and endurance training, and aerobic exercise. Frequency and intensity of rehabilitation need to be increased so that patients can gain the energy levels and vigour necessary for participation in physical activity both during rehabilitation and after discharge. It is evident that many patients are discharged from inpatient rehabilitation severely deconditioned, meaning that their energy levels are too low for active participation in daily life. Physicians, therapists, and nursing staff responsible for rehabilitation practice should address this issue not only during inpatient rehabilitation but also after discharge by promoting and supporting community-based exercise opportunities. During inpatient rehabilitation, group sessions should be frequent and need to include specific aerobic training. Physiotherapy must take advantage of the training aids available, including exercise equipment such as treadmills, and of new developments in computerised feedback systems, robotics, and electromechanical trainers. For illustrative purposes, this paper focuses on the role of physiotherapists, but the necessary changes in practice and in attitude will require cooperation from many others.

Understanding gait control in post-stroke: implications for management

The role of the brain in post-stroke gait is not understood properly, although the ability to walk becomes impaired in more than 80% of post-stroke patients. Most, however, regain some ability to walk with either limited mobility or inefficient, asymmetrical or unsafe gait. Conventional intervention focuses on support of weak muscles or body part by use of foot orthosis and walking aids. This review provides an overview of available evidence of neuro-kinesiology & neurophysiology of normal and post-stroke gait. The role of the spinal cord has been explored, more in animals than humans. Mammalian locomotion is based on a rhythmic, "pacemaker" activity of the spinal stepping generators. Bipedal human locomotion is different from quadripedal animal locomotion. However, knowledge derived from the spinal cord investigation of animals, is being applied for management of human gait dysfunction. The potential role of the brain is now recognized in the independent activation of muscles during walking. The brain modifies the gait pattern during the complex demands of daily activities. Though the exact role of the motor cortex in control of gait is unclear, available evidence may be applied to gait rehabilitation of post-stroke patients.

The effect of an arm sling on energy consumption while walking in hemiplegic patients: a randomized comparison

Objective: To evaluate the effect of an arm sling on gait speed and energy efficiency of patients with hemiplegia.

Design: A randomized crossover design.

Setting: A rehabilitation department of a university hospital.

Subjects: Thirty-seven outpatients with hemiplegia were included in this study.

Interventions: All patients walked on a 20-m walkway twice on the same day, randomly with and without an arm sling, at a self selected speed.

Main measures: The heart rate, gait speed, oxygen cost and oxygen rate were measured on all patients. We analysed all values with and without an arm sling and also compared them after all patients being stratified according to demographic and clinical characteristics.

Results: When we compared the heart rate between walking with (90.7 ± 17.2 beats/min) and without (91.2 ± 18.6 beats/min) the arm sling, it was significantly decreased while walking with the arm sling. When we compared the gait speed between walking with (32.8 m/min) and without (30.1 m/min), it was significantly increased with the arm sling walking. The O₂ rate in hemiplegic patients walking with the arm sling was significantly decreased by 7%, compared to walking without arm sling (5.8 mL/kg min and 6.2 mL/kg min, respectively). The O₂ cost in hemiplegic patients walking without arm sling was significantly 1.4 times greater than walking with it (0.2 mL/kg m and 0.3 mL/kg m, respectively).

Conclusion: An arm sling can be used to improve the gait efficiency.

Effect of AFO design on walking after stroke: impact of ankle plantar flexion contracture

This study was conducted to compare the effects of three ankle-foot orthosis (AFO) designs on walking after stroke and determine whether an ankle plantar flexion contracture impacts response to the AFOs. A total of 30 individuals, ranging from 6-215 months post-stroke, were tested in four conditions: shoes only (SH), dorsi-assist/dorsi-stop AFO (DA-DS), plantar stop/free dorsiflexion AFO (PS), and rigid AFO (Rigid). Kinematics, kinetics, and electromyographic (EMG) activity were recorded from the hemiparetic lower extremity while participants walked at a self-selected pace. Gait parameters were compared between conditions and between participants with and without a moderate ankle plantar flexion contracture. All AFOs increased ankle dorsiflexion in swing and early stance. Anterior tibialis EMG was reduced only in the PS AFO. Both PS and Rigid AFOs restricted ankle plantar flexion and increased knee flexion in loading. Peak ankle dorsiflexion in stance and soleus EMG intensity were greatest in the PS AFO. The Rigid AFO tended to restrict dorsiflexion in stance and knee flexion in swing only in participants without a plantar flexion contracture. Individuals without a contracture benefit from an AFO that permits dorsiflexion mobility in stance and those with quadriceps weakness may more easily tolerate an AFO with plantar flexion mobility in loading.

Effects of unilateral robotic limb loading on gait characteristics in subjects with chronic stroke

Background

Hemiparesis after stroke often leads to impaired ankle motor control that impacts gait function. In recent studies, robotic devices have been developed to address this impairment. While capable of imparting forces to assist during training and gait, these devices add mass to the paretic leg which might encumber patients' gait pattern. The purpose of this study was to assess the effects of the added mass of one of these robots, the MIT's Anklebot, while unpowered, on gait of chronic stroke survivors during overground and treadmill walking.

Methods

Nine chronic stroke survivors walked overground and on a treadmill with and without the anklebot mounted on the paretic leg. Gait parameters, interlimb symmetry, and joint kinematics were collected for the four conditions. Repeated-measures analysis of variance (ANOVA) tests were conducted to examine for possible differences across four conditions for the paretic and nonparetic leg.

Results

The added inertia and friction of the unpowered anklebot had no statistically significant effect on spatio-temporal parameters of gait, including paretic and nonparetic step time and stance percentage, in both overground and treadmill conditions. Noteworthy, interlimb symmetry as characterized by relative stance duration was greater on the treadmill than overground regardless of loading conditions. The presence of the unpowered robot loading reduced the nonparetic knee peak flexion on the treadmill and paretic peak dorsiflexion overground (p < 0.05).

Conclusions

Our results suggest that for these subjects the added inertia and friction of this backdriveable robot did not significantly alter their gait pattern.

Physiological cost of walking in those with chronic fatigue syndrome (CFS): a case-control study

PURPOSE

To examine the physiological cost of walking in subjects with chronic fatigue syndrome (CFS) and a matched control group, walking at their preferred and at matched walking speeds.

METHODS

Seventeen people with CFS and 17 matched-controls participated in this observational study of physiological cost during over-ground gait. Each subject walked for 5 min at their preferred walking speed (PWS). Controls then walked for 5 min at the same pace of their matched CFS subject. Gait speed and oxygen uptake, gross and net were measured and oxygen uptake was expressed per unit distance ambulated. CFS subjects completed the CFS-Activities and Participation Questionnaire (CFS-APQ).

RESULTS

At PWS the CFS group walked at a slower velocity of 0.84 +/- 0.21 m s(-1) compared to controls with a velocity of 1.19 +/- 0.13 m s(-1) (p < 0.001). At PWS both gross and net oxygen uptake of CFS subjects was significantly less than controls (p = 0.023 and p = 0.025 respectively). At matched-velocity both gross and net physiological cost of gait was greater for CFS subjects than controls (p = 0.048 and p = 0.001, respectively).

CONCLUSION

The physiological cost of walking was significantly greater for people with CFS compared with healthy subjects. The reasons for these higher energy demands for walking in those with CFS have yet to be fully elucidated.

Immediate effects of cane use on gait symmetry in individuals with subacute stroke

PURPOSE

In stroke rehabilitation, there is a lack of consensus regarding the effects of cane use on gait symmetry. This study aimed to evaluate the immediate effects on gait symmetry of ambulating with a standard cane and a quad cane among individuals with subacute stroke.

METHOD

A within-subject experimental design was used to evaluate symmetry in in-patients with subacute stroke during ambulation on a pressure-sensitive walkway for three task conditions: with no cane, with standard single-point cane, and with quad cane.

RESULTS

Fourteen patients were classified as symmetric (n = 5) or asymmetric (n = 9) based on their gait symmetry while walking without an aid. Overall, use of a standard cane during ambulation significantly improved symmetry in asymmetric patients (p = 0.028). In contrast, the use of a quad cane did not improve symmetry (p = 0.36). There was no effect on symmetry in symmetric patients with use of either a standard cane (p = 0.88) or a quad cane (p = 0.32).

CONCLUSIONS

These results indicate that the immediate effect of a standard cane is to improve symmetry in patients with subacute stroke who have asymmetric gait. Future studies are required to determine the long-term effects of canes on gait symmetry in this population.

Immediate and long-term functional impact of repetitive locomotor training as an adjunct to conventional physiotherapy for non-ambulatory patients after stroke

PURPOSE

The aim of the present study was to assess the heart rate intensity during gait training and to evaluate the relationship between heart rate intensity during gait training and walking ability of patients after stroke.

METHODS

We included non-ambulatory patients within six weeks after first stroke. Over four weeks patients were trained five times a week, with either 20 minutes of repetitive locomotor training and 25 min of physiotherapy (RLT-PT), or 45 min of PT alone. We assessed the heart rate intensity during training period. Additionally we assessed walking ability (Functional Ambulation Categories) and the rate of independent ability to perform activities of daily life (Barthel Index) at the end of study and six months and three years later on.

RESULTS

We included 30 patients in each group. Patients in RLT-PT group exercised longer in the HR target zone than in the PT group (16.1+/-11.8 min vs. 5.3+/-5.6 min, p<0.001). Higher heart rates were associated with independent walking at the end of study, at six months and at three years after the end of study (Fishers exact test, p=0.014, p=0.012 and p=0.017, respectively).

CONCLUSIONS

Higher heart rate intensities during gait-training of non-ambulatory post-stroke patients may improve walking function.

Pilot study of Lokomat versus manual-assisted treadmill training for locomotor recovery post-stroke

BACKGROUND

While manually-assisted body-weight supported treadmill training (BWSTT) has revealed improved locomotor function in persons with post-stroke hemiparesis, outcomes are inconsistent and it is very labor intensive. Thus an alternate treatment approach is desirable. Objectives of this pilot study were to: 1) compare the efficacy of body-weight supported treadmill training (BWSTT) combined with the Lokomat robotic gait orthosis versus manually-assisted BWSTT for locomotor training post-stroke, and 2) assess effects of fast versus slow treadmill training speed.

METHODS

Sixteen volunteers with chronic hemiparetic gait (0.62 +/- 0.30 m/s) post-stroke were randomly allocated to Lokomat (n = 8) or manual-BWSTT (n = 8) 3x/wk for 4 weeks. Groups were also stratified by fast (mean 0.92 +/- 0.15 m/s) or slow (0.58 +/- 0.12 m/s) training speeds. The primary outcomes were self-selected overground walking speed and paretic step length ratio. Secondary outcomes included: fast overground walking speed, 6-minute walk test, and a battery of clinical measures.

RESULTS

No significant differences in primary outcomes were revealed between Lokomat and manual groups as a result of training. However, within the Lokomat group, self-selected walk speed, paretic step length ratio, and four of the six secondary measures improved (p = 0.04-0.05, effect sizes = 0.19-0.60). Within the manual group, only balance scores improved (p = 0.02, effect size = 0.57). Group differences between fast and slow training groups were not revealed (p > or = 0.28).

CONCLUSION

Results suggest that Lokomat training may have advantages over manual-BWSTT following a modest intervention dose in chronic hemiparetic persons and further, that our training speeds produce similar gait improvements. Suggestions for a larger randomized controlled trial with optimal study parameters are provided.

Joint moment work during the stance-to-swing transition in hemiparetic subjects

Following stroke many individuals are left with neurological and functional deficits, including hemiparesis, which impair their ability to walk. Our previous work reported that propulsion of the paretic leg during pre-swing is impaired and may limit gait speed and knee flexion during swing. To elucidate the mechanism of this impairment, we assessed the mechanical work produced by the hip, knee, and ankle moments during pre-swing of the paretic limb in a group of stroke subjects and compared it with the work produced by non-disabled controls walking at similar speeds. Kinematic and kinetic gait data were collected from 23 hemiparetic and 10 control subjects. The hemiparetic subjects walked at their self-selected speeds. The controls walked at their self-selected and two or three slower speeds. Even when compared to controls walking at slow speeds, ankle plantarflexor work during pre-swing was greatly reduced (-0.136+/-0.062J/kg) in the hemiparetic subjects. Differences in hip (+0.006+/-0.020J/kg) and knee (+0.040+/-0.026J/kg) moment work partially offset the reduction in ankle work, but net joint moment work was still significantly reduced (-0.088+/-0.056J/kg). The reduction in work accounts for the low energy of the paretic limb at the stance-to-swing transition previously reported. Future investigation is needed to determine if targeted training of the plantarflexors in the paretic limb improves swing-phase function and locomotor performance in hemiparetic individuals.

Physiological evaluation of gait disturbances post stroke

A large proportion of stroke survivors have to deal with problems in mobility. Proper evaluations must be undertaken to understand the sensorimotor impairments underlying locomotor disorders post stroke, so that evidence-based interventions can be developed. The current electrophysiological, biomechanical, and imagery evaluations that provide insight into locomotor dysfunction post stroke, as well as their advantages and limitations, are reviewed in this paper. In particular, electrophysiological evaluations focus on the contrast of electromyographic patterns and integrity of spinal reflex pathways during perturbed and unperturbed locomotion between persons with stroke and healthy individuals. At a behavioral level, biomechanical evaluations that include temporal distance factors, kinematic and kinetic analyses, as well as the mechanical energy and metabolic cost, are useful when combined with electrophysiological measures for the interpretation of gait disturbances that are related to the control of the central nervous system or secondary to biomechanical constraints. Finally, current methods in imaging and transcranial magnetic stimulation can provide further insight into cortical control of locomotion and the integrity of the corticospinal pathways.

Muscular utilization of the plantarflexors, hip flexors and extensors in persons with hemiparesis walking at self-selected and maximal speeds

Gait performance secondary to a stroke is partially dependent on residual muscle strength. However, to pinpoint more precisely the mechanism of this relationship, biomechanical models, such as the muscular utilization ratio (MUR) that integrates both muscle strength and gait parameters into the concept of level of effort, are warranted. The aim of the present study was to evaluate the MUR of plantarflexors, hip flexors and extensor muscles during their concentric action in 17 chronic hemiparetic participants walking at self-selected and maximal speeds. Results revealed that peak MUR increased with gait speed. At self-selected speed (0.73+/-0.27 m/s), peak MUR values on the paretic side were 64% (+/-18.7), 46% (+/-27.6) and 33% (+/-25.6) for the plantarflexors, hip flexors and extensor muscles, respectively. At maximal speed (1.26+/-0.39 m/s), corresponding values were 77% (+/-23.6), 72% (+/-33.0) and 58% (+/-32.1). Peak MUR showed negative associations (-0.33<r>-0.68), although not all significant, with voluntary muscle strength. The results of this study indicated that the peak MUR increased with gait speed. The plantarflexors were the most used muscle group at self-selected speed, whereas at maximal speed the three muscle groups showed similar peak MUR values. This last finding suggested an important role of the hip muscles in reaching a faster speed. Lastly, because moderate associations were found between peak MUR values and the voluntary muscle strength of hip flexors and extensors, it can be concluded that the weakest paretic muscle groups show, in general, the highest level of effort during gait.

Exercise rehabilitation after stroke

Stroke is a leading cause of disability that results not only in persistent neurological deficits, but also profound physical deconditioning that propagates disability and worsens cardiovascular risk. The potential for exercise-mediated adaptations to improve function, fitness, and cardiovascular health after stroke has been underestimated: it represents an emerging arena in neurotherapeutics. To define the health rationale for cardiovascular (aerobic) exercise, we first outline the impact of debilitating secondary biological changes in muscle and body composition on fitness and metabolic health after stroke. We provide an overview of evidence-based advances in exercise therapeutics, with a focus on task-oriented models that combine a progressive aerobic conditioning stimulus with motor learning to improve multiple physiological domains that determine longitudinal outcomes after stroke. Although progress in development of safe and effective exercise strategies is advancing, fundamental questions regarding dose intensity, prescription to optimize central and peripheral neuromuscular adaptations, and the public health value of exercise in secondary stroke prevention remain unanswered. Key issues steering future research in exercise neurotherapeutics are discussed within the context of initiatives to facilitate translation to community-based studies, requisite for dissemination.

Metabolic Cost of Overground Gait in Younger Stroke Patients and Healthy Controls

PURPOSE

Locomotor impairment, such as that which may occur following a stroke, results in increased energy expenditure during walking. Previous research quantifying this increased metabolic demand has focused on older people; thus, the aim of this study was to investigate the physiological cost of walking in younger patients following stroke.

METHODS

Thirteen stroke patients (mean age of 40.7+/-10.0 yr) and 13 age- and sex-matched controls participated. Each subject walked for 5 min around an elliptical course (two cones set 9.5 m apart) at their own preferred walking speed (PWS). The percentage of expired oxygen was measured using a portable gas analyzer. Following a 5-min rest, the control subjects repeated the procedure, but at the PWS of the patient to whom they were matched.

RESULTS

The PWS of the stroke patients was significantly lower than that of the controls (P<0.001); however, there was no significant difference in terms of oxygen uptake (P=0.403). When the distance walked was considered, there was a statistically significant difference in oxygen uptake per unit of distance between the two groups (P<0.001) and also between the patients PWS and the controls walking at the PWS of the patients.

CONCLUSION

The high metabolic cost of walking would suggest that, even for younger stroke patients, early rehabilitation should consider aerobic evaluation and training with the aim of optimizing functional independence.

Gait differences between individuals with post-stroke hemiparesis and non-disabled controls at matched speeds

Treadmill walking was used to assess the consistent gait differences between six individuals with post-stroke hemiparesis and six non-disabled, healthy controls at matched speeds. The hemiparetic subjects walked on the treadmill at their comfortable speeds, while each control walked at the same speed as the hemiparetic subject with whom he or she was matched. Kinematic and insole pressure data were collected from multiple, steady-state gait cycles. A large set of gait differences found between hemiparetic and non-disabled subjects was consistent with impaired swing initiation in the paretic limb (i.e., inadequate propulsion of the leg during pre-swing, increased percentage swing time, and reduced knee flexion at toe-off and mid-swing in the paretic limb) and related compensatory strategies (i.e., pelvic hiking and swing-phase propulsion and circumduction of the paretic limb). Exaggerated positive work associated with raising the trunk during pre-swing and swing of the paretic limb, consistent with pelvic hiking, contributed to increased mechanical energetic cost during walking. A second set of gait differences found was consistent with impaired single limb support on the paretic limb (i.e., shortened support time on the paretic limb) and related compensatory strategies (i.e., exaggerated propulsion of the non-paretic limb during pre-swing to shorten its swing time). Other significant gait differences included asymmetry in step length and increased step width. We conclude that consistent gait differences exist between hemiparetic and non-disabled subjects walking at matched speeds. The differences provide insights, concerning hemiparetic impairment and related compensatory strategies, that are in addition to the observation of slow walking speed.

Gait deviations associated with post-stroke hemiparesis: improvement during treadmill walking using weight support, speed, support stiffness, and handrail hold

By comparing treadmill walking in hemiparetic and non-disabled individuals at matched speeds, Chen et al. [Chen G, Patten C, Kothari DH, Zajac FE. Gait differences between individuals with post-stroke hemiparesis and non-disabled controls at matched speeds. Gait Posture (2004)] identified gait deviations that were consistent with impaired swing initiation and single limb support in the paretic limb and related compensatory strategies. Treadmill training with harness support is a promising, task-oriented approach to restoring locomotor function in individuals with post-stroke hemiparesis. To provide a rationale for the proper selection of training parameters, we assessed the potential of body weight support, treadmill speed, support stiffness, and handrail hold to improve the identified gait deviations associated with hemiparesis during treadmill walking. In the six hemiparetic subjects studied, the adjustment of each training parameter was found to improve a specific set of the gait deviations. With increased body weight support or the addition of handrail hold, percentage single limb support time on the paretic limb increased and temporal symmetry improved. With increased treadmill speed, leg kinetic energy at toe-off in the paretic limb increased but remained low relative to values in the non-paretic limb. With increased support stiffness, the exaggerated energy cost associated with raising the trunk during pre-swing and swing of the paretic limb was improved. We conclude that the proper selection of training parameters can improve the gait pattern practiced by individuals with hemiparesis during treadmill training and may improve treatment outcome.