This study investigated the relationship of lower extremity joint torques and weight-bearing symmetry to sit-to-stand (STS) performance in individuals with chronic stroke. A motion analysis system and two force plates measured STS duration and weight-bearing symmetry (determined by ground reaction forces) during three self-paced and three fast-paced conditions. An isokinetic dynamometer measured maximum concentric joint torques of the paretic and nonparetic ankle, knee, and hip, which were normalized by body mass. Pearson correlations indicated that (a) paretic ankle dorsiflexion and knee extension torques related to the duration of the self-paced STS condition (r = −0.450, −0.716, respectively), (b) paretic ankle dorsiflexion, plantar flexion, and knee extension torques related to the duration of the fast-paced STS condition (r = −0.466, −0.616, −0.736, respectively), and (c) greater weight-bearing symmetry related to faster STS performance for both self-paced and fast-paced STS conditions (r = −0.565, −0.564, respectively) (p < 0.05). This evidence suggests that paretic muscle strength and the ability to load the paretic limb are important factors underlying the ability to rise from a chair in individuals with chronic stroke.
PMID: 16139747 CAMSID: cams1870
Stroke; Sit-to-stand; Torque; Weight-bearing
Given the known sensorimotor deficits and asymmetric weight-bearing posture in stroke, the aim of this study was to determine whether stroke affects the modulation of standing postural reflexes with varying weight-bearing load.
Ten individuals with chronic stroke and 10 healthy older adult controls were exposed to unexpected forward and backward platform translations while standing. Three different stance conditions were imposed: increased weight-bearing load, decreased weight-bearing load, and self-selected stance. Surface EMG from bilateral ankle dorsiflexors (tibialis anterior) and extensors (gastrocnemius) were recorded and the magnitude of background muscle activity (prior to the platform translation) and postural reflex onset latency and magnitude (75 ms following reflex onset) were determined.
Load modulation of ankle extensors was found in controls and individuals with stroke. Although controls demonstrated modulation of ankle dorsiflexors to different loads, individuals with stroke did not show this modulation. Further, load did not change the onset latency of postural reflexes of the individuals with stroke.
The delayed paretic muscle onset latencies in conjunction with impaired modulation of ankle dorsiflexor postural reflexes may contribute to the instability and frequent falls observed among individuals with stroke.
The results provide some insight into standing postural reflexes following stroke.
PMID: 15546787 CAMSID: cams2000
postural control; reflex; weight-bearing; cerebrovascular accident
Transcranial magnetic stimulation (TMS) non-invasively measures excitability of central motor pathways in humans and is used to characterize neuroplasticity after stroke. Using TMS to index lower extremity neuroplasticity after gait rehabilitation requires test-retest reliability. This study assesses the reliability of TMS-derived variables measured at bilateral quadriceps of chronic hemiparetic stroke survivors. Results support using measures of both paretic and nonparetic motor threshold, MEP latencies; and nonparetic MEP amplitudes. Implications for longitudinal research are discussed.
TMS; Lower extremity; stroke; reliability; quadriceps; paretic
Hemiparetic stroke leads to major skeletal muscle abnormalities, as illustrated by paretic leg atrophy, weakness, and spasticity. Furthermore, the hemiparetic limb muscle shifts to a fast-twitch muscle fiber phenotype with anaerobic metabolism. This study investigated whether skeletal muscle genes were altered in chronic hemiparetic stroke. The nonparetic leg muscle served as an internal control. We used Affymetrix microarray analysis to survey gene expression differences between paretic and nonparetic vastus lateralis muscle punch biopsies from 10 subjects with chronic hemiparetic stroke. Stroke latency was greater than 6 months. We found that 116 genes were significantly altered between the paretic and nonparetic vastus lateralis muscles. These gene differences were consistent with reported differences after stroke in areas such as injury and inflammation markers, the myosin heavy chain profile, and high prevalence of impaired glucose tolerance and type 2 diabetes. Furthermore, while many other families of genes were altered, the gene families with the most genes altered included inflammation, cell cycle regulation, signal transduction, metabolism, and muscle contractile protein genes. This study is an early step toward identification of specific gene regulatory pathways that might lead to these differences, propagate disability, and increase vascular disease risk.
cell cycle; gene expression; hemiparetic stroke; inflammation; metabolism; microarray; muscle contraction; rehabilitation; skeletal muscle; transcription factors; vastus lateralis
Task-oriented therapies such as treadmill exercise can improve gait velocity after stroke, but slow velocities and abnormal gait patterns often persist, suggesting a need for additional strategies to improve walking.
To determine the effects of a 6-week visually guided, impedance controlled, ankle robotics intervention on paretic ankle motor control and gait function in chronic stroke.
This was a single-arm pilot study with a convenience sample of 8 stroke survivors with chronic hemiparetic gait, trained and tested in a laboratory. Subjects trained in dorsiflexion–plantarflexion by playing video games with the robot during three 1-hour training sessions weekly, totaling 560 repetitions per session. Assessments included paretic ankle ranges of motion, strength, motor control, and overground gait function.
Improved paretic ankle motor control was seen as increased target success, along with faster and smoother movements. Walking velocity also increased significantly, whereas durations of paretic single support increased and double support decreased.
Robotic feedback training improved paretic ankle motor control with improvements in floor walking. Increased walking speeds were comparable with reports from other task-oriented, locomotor training approaches used in stroke, suggesting that a focus on ankle motor control may provide a valuable adjunct to locomotor therapies.
stroke; rehabilitation; anklebot; ankle robot; hemiparetic gait
What are the neuroplastic mechanisms that allow some stroke patients to regain high quality control of their paretic leg, while others do not? One theory implicates ipsilateral corticospinal pathways projecting from the non-lesioned hemisphere. We devised a new transcranial magnetic stimulation protocol to identify ipsilateral corticospinal tract conductivity from the non-lesioned hemisphere to the paretic limb in chronic stroke patients. We also assessed corticospinal tract degeneration using diffusion tensor imaging and used an ankle tracking task to assess lower limb motor control. We found greater tracking error during antiphase bilateral ankle movement for patients with strong conductivity from the non-lesioned hemisphere to paretic ankle than those with weak or no conductivity. These findings suggest that, instead of assisting motor control, contributions to lower limb motor control from the non-lesioned hemisphere of some stroke survivors may be maladaptive.
lower extremity; neuroplasticity; TMS; DTI; stroke
After unilateral total knee arthroplasty (TKA), rehabilitation specialists often constrain knee angles or foot positions during sit-to-stand, to encourage increased weight bearing through the operated limb. Biomechanical studies often constrain limb position during sit-to-stand in an effort to reduce variability. Differences between self-selecting or constraining position are unknown in persons after TKA. Twenty-six subjects with unilateral TKA participated in motion analysis. Subjects performed the sit-to-stand using a self-selected position (ssSTS); next, trials were collected in a constrained condition (ccSTS), where both knees were positioned with the tibia vertical, perpendicular to the floor. Repeated measures ANOVA (limb × condition) assessed differences between limbs and between conditions. Subjects used greater hip flexion bilaterally during ccSTS (91°) compared to ssSTS (87°; p=0.001) and knee flexion on the non-operated limb was greater during ssSTS (84°) compared to ccSTS (82°; p=0.018). The ccSTS resulted in larger extensor moments on the non-operated limb at the hip (ssSTS -0.473, ccSTS -0.521; p=0.021) and knee (ssSTS -0.431, ccSTS -0.457; p=0.001) compared to the operated limb. The ccSTS exacerbated the asymmetries at the hip and knee compared to ssSTS, and did not improve use of the operated limb. Reliance on the non-operated limb may put them at risk for progression of osteoarthritis in other joints of the lower extremities.
sit-to-stand; total knee arthroplasty; altered movement pattern
A greater percent loss of concentric versus eccentric muscle torque (i.e., relative eccentric muscle torque preservation) has been reported in the paretic limb of individuals with stroke and has been attributed to hypertonia and/or co-contractions. Stroke provides a unique condition for examining mechanisms underlying eccentric muscle preservation because both limbs experience similar amounts of general physical activity, but the paretic side is impaired directly by the brain lesion.
The purpose of this study was to determine 1) whether eccentric preservation also exists in the nonparetic limb and 2) the relationship of eccentric or concentric torque preservation with physical activity in stroke. We hypothesized that the nonparetic muscles would demonstrate eccentric muscle preservation, which would suggest that non-neural mechanisms may also contribute to its relative preservation.
Eighteen stroke and 18 healthy control subjects (age and sex matched) completed a physical activity questionnaire. Maximum voluntary concentric and eccentric joint torques of the ankle, knee and hip flexors and extensors were measured using an isokinetic dynamometer at 30°/s for the paretic and nonparetic muscles. Relative concentric and eccentric peak torque preservation were expressed as a percentage of control subject torque.
Relative eccentric torque was higher (more preserved) than relative concentric torque for paretic, as well as nonparetic muscles. Physical activity correlated with paretic (r=0.640, p=0.001) and nonparetic concentric torque preservation (r=0.508, p=0.009), but not with eccentric torque preservation for either leg.
The relative preservation of eccentric torque in the nonparetic muscles suggest a role of non-neural mechanisms and could also explain the preservation observed in other chronic health conditions. Loss of concentric, but not eccentric muscle torque was related to physical inactivity in stroke.
PMID: 19516167 CAMSID: cams1776
strength; rehabilitation; force; CVA
Total reaching range of motion (work area) diminishes as a function of shoulder abduction loading in the paretic arm in individuals with chronic hemiparetic stroke. This occurs when reaching outward against gravity or during transport of an object.
This study implements 2 closely related impairment-based interventions to identify the effect of a subcomponent of reaching exercise thought to be a crucial element in arm rehabilitation.
A total of 14 individuals with chronic moderate to severe hemiparesis participated in the participant-blinded, randomized controlled study. The experimental group progressively trained for 8 weeks to actively support the weight of the arm, up to and beyond, while reaching to various outward targets. The control group practiced the same reaching tasks with matched frequency and duration with the weight of the arm supported. Work area and isometric strength were measured before and after the intervention.
Change scores for work area at 9 loads were calculated for each group. Change scores were significantly larger for the experimental group indicating a larger increase in work area, especially shoulder abduction loads equivalent to those experienced during object transport. Changes in strength were not found within or between groups.
Progressive shoulder abduction loading can be utilized to ameliorate reaching range of motion against gravity. Future work should investigate the dosage response of this intervention, as well as test whether shoulder abduction loading can augment other therapeutic techniques such as goal-directed functional task practice and behavioral shaping to enhance real-world arm function.
Stroke; Upper extremity; Shoulder loading; Biomechanics; Rehabilitation; Muscle strength; Robotics
The Motricity Index was used to measure strength in upper and lower extremities after stroke. The weighted score based on the ordinal 6 point scale of Medical Research Council was used to measure maximal isometric muscle strength. There is dearth of articles dealing with the reliability of this method. Therefore, the aim of this study was to determine the test retest reliability of Motricity Index strength assessments for paretic lower limb in 20 chronic stroke patients with one week interval.
In a cross sectional study, intrarater reliability of lower extremity Motricity Index strength assessments with one week interval were measured.
The SPSS 18 was used for analysis of data. Two-way random-consistency model of ICC was used for assessment of test-retest reliability. The ICC values showed high reliability of strength measurement of Motricity Index (ICC=0.93).
The Motricity Index can be a reliable instrument for measuring the strength of involved lower extremity when assessment is done by one rater following chronic stroke.
Reliability; Motricity Index; Hemiparesis; Chronic stroke
Clinical observations of the flexion synergy in individuals with chronic hemiparetic stroke describe coupling of shoulder, elbow, wrist, and finger joints. Yet, experimental quantification of the synergy within a shoulder abduction (SABD) loading paradigm has focused only on shoulder and elbow joints. The paretic wrist and fingers have typically been studied in isolation. Therefore, this study quantified involuntary behavior of paretic wrist and fingers during concurrent activation of shoulder and elbow.
Eight individuals with chronic moderate-to-severe hemiparesis and four controls participated. Isometric wrist/finger and thumb flexion forces and wrist/finger flexor and extensor electromyograms (EMG) were measured at two positions when lifting the arm: in front of the torso and at maximal reaching distance. The task was completed in the ACT3D robotic device with six SABD loads by paretic, non-paretic, and control limbs.
Considerable forces and EMG were generated during lifting of the paretic arm only, and they progressively increased with SABD load. Additionally, the forces were greater at the maximal reach position than at the position front of the torso.
Flexion of paretic wrist and fingers is involuntarily coupled with certain shoulder and elbow movements.
Activation of the proximal upper limb must be considered when seeking to understand, rehabilitate, or develop devices to assist the paretic hand.
Although healthy individuals have less force production capacity during bilateral muscle contractions compared to unilateral efforts, emerging evidence suggests that certain aspects of paretic upper limb task performance after stroke may be enhanced by moving bilaterally instead of unilaterally. We investigated whether the bilateral movement condition affects grip force differently on the paretic side of people with post-stroke hemiparesis, compared to their non-paretic side and both sides of healthy young adults.
Within a single session, we compared: 1) maximal grip force during unilateral vs. bilateral contractions on each side, and 2) force contributed by each side during a 30% submaximal bilateral contraction.
Healthy controls produced less grip force in the bilateral condition, regardless of side (- 2.4% difference), and similar findings were observed on the non-paretic side of people with hemiparesis (- 4.5% difference). On the paretic side, however, maximal grip force was increased by the bilateral condition in most participants (+11.3% difference, on average). During submaximal bilateral contractions in each group, the two sides each contributed the same percentage of unilateral maximal force.
The bilateral condition facilitates paretic limb grip force at maximal, but not submaximal levels.
In some people with post-stroke hemiparesis, the paretic limb may benefit from bilateral training with high force requirements.
stroke; upper extremity; interhemispheric inhibition; bilateral deficit; strength; human
Although slow and insufficient muscle activation is a hallmark of hemiparesis post-stroke, movement speed is rarely emphasized during upper extremity rehabilitation. Moving faster may increase intensity of task-specific training, but positive and/or negative effects on paretic-limb movement quality are unknown.
To determine whether moving quickly instead of at a preferred speed either enhances or impairs paretic limb task performance after stroke.
Sixteen people with post-stroke hemiparesis and 11 healthy controls performed reach-grasp-lift movements at their preferred speed and as fast as possible, using palmar and 3-finger grip types. We measured durations of the reach and grasp phases, straightness of the reach path, thumb-index finger separation (aperture), efficiency of finger movement, and grip force.
As expected, reach and grasp phase durations decreased in the fast condition in both groups, showing that participants were able to move more quickly when asked. When moving fast, the hemiparetic group had reach durations equal to those of healthy controls moving at their preferred speed. Movement quality also improved. Reach paths were straighter and peak apertures were greater in both groups in the fast condition. The group with hemiparesis also showed improved efficiency of finger movement. Differences in peak grip force across speed conditions did not reach significance.
People with hemiparesis are able to move faster than they choose to, and when they do, movement quality is improved. Simple instructions to move faster could be a cost-free and effective means of increasing rehabilitation intensity after stroke.
hemiparesis; speed; kinematics; upper extremity; motor control; reach-to-grasp
The objective of this study was to compare the neuromuscular function of the paretic and non-paretic plantar flexors (i.e. soleus, gastrocnemius medialis, lateralis) in chronic stroke patients. It was hypothesized that the contractile rate of force development (RFD) and neural activation, assessed by electromyogram (EMG) and V-waves normalized to the M-wave, and voluntary activation (twitch interpolation) would be reduced during plantar flexor maximum voluntary isometric contraction and that the evoked muscle twitch properties would be reduced in the paretic limb. Ten chronic stroke survivors completed the study. The main findings were that the paretic side showed deteriorated function compared to the non-paretic leg in terms of (1) RFD in all analyzed time windows from force onset to 250 ms, although relative RFD (i.e. normalized to maximum voluntary force) was similar; (2) fast neural activation (for most analyzed time windows), assessed by EMG activity in time windows from EMG onset to 250 ms; (3) V-wave responses (except for gastrocnemius medialis); (4) voluntary activation; (5) the evoked peak twitch force, although there was no evidence of intrinsic muscle slowing; (6) EMG activity obtained at maximal voluntary force. In conclusion, this study demonstrates considerable neuromuscular asymmetry of the plantar flexors in chronic stroke survivors. Effective rehabilitation regimes should be investigated.
H-reflex; Neural drive; Brain infarction; Cerebrovascular accident; Rehabilitation
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.
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.
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).
Our results suggest that for these subjects the added inertia and friction of this backdriveable robot did not significantly alter their gait pattern.
Due to motor and sensory deficits in individuals with stroke, we proposed that they must compensate for these impairments during standing with greater dependence on vision. In addition, we hypothesized that asymmetric weight-bearing, which occurs following stroke, is related to increased postural sway and those with greater asymmetry will have greater reliance on vision. Twenty-eight individuals with stroke and 28 healthy older adult controls stood quietly with eyes open or closed on a force platform while postural sway was quantified by centre of pressure measures and weight-bearing asymmetry was calculated from vertical ground reaction forces. To determine the influence of vision on postural sway, a visual ratio (eyes open/eyes closed) was calculated for the sway measures. The results demonstrated that individuals with stroke had greater visual dependence for the control of postural sway velocity in the medial-lateral, but not anterior-posterior direction, compared to controls. Further, we found that greater asymmetry was moderately related to increased medial-lateral sway for the individuals with stroke. Contrary to predictions, those individuals with stroke with mild asymmetry had greater visual dependence than those with more severe asymmetry.
PMID: 16399522 CAMSID: cams1869
postural control; cerebrovascular accident; balance
The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for twenty persons with chronic stroke and ten healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the non-paretic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task.
PMID: 16014786 CAMSID: cams2416
Upper extremity; arm; motor control; biomechanics; EMG; rehabilitation
The ability to extend the elbow following stroke depends on the magnitude and direction of torques acting at the shoulder. The mechanisms underlying this link remain unclear. The purpose of this study was to evaluate whether the effects of shoulder loading on elbow function were related to weakness or its distribution in the paretic limb. Ten subjects with longstanding hemiparesis performed movements with the arm either passively supported against gravity by an air bearing, or by activation of shoulder muscles. Isometric maximum voluntary torques at the elbow and shoulder were measured using a load cell. The speed and range of elbow extension movements were negatively impacted by actively supporting the paretic limb against gravity. However, the effects of gravity loading were not related to proximal weakness or abnormalities in the elbow flexor–extensor strength balance. The findings support the existence of abnormal descending motor commands that constrain the ability of stroke survivors to generate elbow extension torque in combination with abduction torque at the shoulder.
gravity; kinematics; muscle weakness; reaching; stroke
The purposes of this study were to compare the gait initiation task between individuals with chronic stroke and age-matched healthy controls, to determine whether the observed differences between groups could be attributed to the presence of a stroke or to differences in gait initiation speed, and to establish the gait initiation variables that relate with a faster gait initiation speed. All subjects initiated gait at their preferred speed, while control subjects were also asked to initiate gait at a speed that was comparable to the stroke group. It was found that while many temporal and kinetic differences were observed between the two groups, most were simply due to differences in gait initiation speed. Two variables that remained different when speed was controlled were the magnitude of the antero-posterior impulse generated by the paretic limb when it was used as either the leading or trailing limb. Kinetic parameters of the trailing limb (i.e. peak antero-posterior force and impulse) were also found to correlate with the gait initiation speed for the non-paretic lead limb condition. The results suggest that the propulsive function of the paretic limb when used as the trailing limb is a key area to address in the rehabilitation of gait initiation for individuals with stroke.
PMID: 16488149 CAMSID: cams1868
cerebrovascular accident; gait speed; kinetics
To determine retention of motor changes 3 months after participation in a regimen comprised of mental practice combined with repetitive task specific training (MP + RTP).
Prospective, blinded, cohort, pre-post study
Outpatient rehabilitation hospital
Twenty-one individuals in the chronic stage of stroke (mean age = 66.1 ± 8.1 years; age range = 56 to 76 years; mean time since stroke at study enrollment = 58.7 months; range 13 to 129 months) exhibiting mild to moderate impairments of hand function.
All individuals had been randomly assigned to receive a 10-week regimen comprised of MP emphasizing paretic upper extremity use during valued activities. Directly after each of these sessions, subjects were administered audiotaped MP. We assessed this group’s paretic upper extremity motor levels before, after, and 3 months after intervention.
MAIN OUTCOME MEASURES
The upper extremity section of the Fugl-Meyer Assessment of Sensorimotor Impairment (FM), the Action Research Arm test (ARAT), the Arm Motor Ability test (AMAT), and Box and Block test (BB).
None of the scores significantly changed from the period directly after intervention to the 3-month post testing period (FM: t = 0.817; ARAT: t = 0.923; AMAT:t = 0.898, t = 0.818, and t = 0.967 for the functional ability, quality of movement, and time scales, respectively; BB: t = 0.892).
Changes in paretic upper extremity movement realized through MP + RTP participation are retained 3 months after the intervention has concluded. This is the first study examining retention of motor changes after MP + RTP participation, and one of only a few studies examining long retention of motor changes following any intervention targeting stroke-induced hemiparesis.
Introduction. Improvement of postural stability is an important goal during poststroke rehabilitation. Since weight-bearing asymmetry (WBA) towards the nonparetic leg is common, training of weight-bearing symmetry has been a major focus in post-stroke balance rehabilitation. It is assumed that restoration of a more symmetrical weight distribution is associated with improved postural stability. Objective. To determine to what extent WBA is associated with postural instability in people after stroke. Methods. Electronic databases were searched (Cochrane, MEDLINE, EMBASE, and CINAHL) until March 2012. Main Eligibility Criteria. (1) Participants were people after stroke. (2) The association between WBA and postural stability was reported. Quality of reporting was assessed with the STROBE checklist and a related tool for reporting of confounding. Results. Nine observational studies met all criteria. Greater spontaneous WBA was associated with higher center of pressure (COP) velocity and with poorer synchronization of COP trajectories between the legs (two and one studies, resp.). Evidence for associations between WBA and performance on clinical balance tests or falls was weak. Conclusion. Greater WBA after stroke was associated with increased postural sway, but the current literature does not provide evidence for a causal relationship. Further studies should investigate whether reducing WBA would improve postural stability.
The purpose of this study was to establish the test-retest reliability and concurrent validity with maximal oxygen uptake (VO2max) for three submaximal exercise tests in individuals with chronic stroke: 1) submaximal treadmill test, 2) submaximal cycle ergometer test and 3) six minute walk test (6MWT).
Prospective study using a convenient sample
Freestanding tertiary rehabilitation centre
12 community-dwelling individuals who have had a stroke with moderate motor deficits; volunteer sample
Main Outcome Measures
Heart rate (HR), blood pressure (BP) and oxygen uptake (VO2) were assessed during the exercise tests.
Test-retest reliability was good to excellent for the exercise tests (maximal and submaximal tests). VO2 for all submaximal measures related to VO2max (r=0.66 to 0.80). Neither the 6MWT distance, self-selected gait speed or hemodynamic measures related to VO2max.
The VO2 measures of the submaximal exercise tests had excellent reliability and good concurrent validity with VO2max. Submaximal exercise tests may be one potential method of monitoring effects of interventions following a screening test (e.g., symptom-limited graded exercise test, dobutamine stress echocardiograph).
PMID: 14970978 CAMSID: cams1873
Cerebrovascular accident; Exercise test; Outcome assessment; Rehabilitation
Self-selected walking speed has been used to stratify persons post-stroke to predict functional walking status and changes in status have been used to define clinical meaningfulness in rehabilitation trials. However, this stratification was validated primarily using self-report questionnaires.
This study aims to validate the speed-based classification system with quantitative measures of walking performance.
Fifty-nine individuals with chronic post-stroke hemiparesis (greater than six months post-stroke) participated. Spatiotemporal and kinetic measures included: paretic propulsion (Pp); paretic step ratio (PSR); and the paretic pre-swing percentage (PPS). Additional measures included synergy (FM-S) portion of the Fugl-Meyer Assessment and the average number of steps/day in the home and community measured with a StepWatch Step Activity Monitor. Participants were stratified by self-selected gait speed into three groups (household ambulators: < 0.4 m/s; limited community ambulators: 0.4–0.8 m/s; and community ambulators: > 0.8 m/s). Group differences were analyzed using a Kruskal-Wallis H Test with Rank Sums Test post-hoc analyses.
Analyses demonstrated a main effect in all measures, but only steps/day and PPS demonstrated a significant difference between all three groups.
Classifying individuals post-stroke by self-selected walking speed is associated with home and community-based walking behavior as quantified by daily step counts. In addition, PPS distinguishes all three groups. Pp differentiates the moderate from the fast groups and may represent a contribution to mechanisms of increasing walking speed. Speed classification presents a useful yet simple mechanism to stratify those with post-stroke and may be mechanically linked to changes in PPS.
To determine the reliability of isokinetic concentric strength measures of both the hemiparetic and non-involved limbs for flexion and extension motions of the hip, knee, and ankle joints in individuals who have had a stroke.
Test-retest, repeated-measures intraobserver reliability design.
Tertiary rehabilitation center.
20 community-dwelling individuals who have had a stroke, with motor deficits ranging from 3 to 6 on the Chedoke-McMaster Stroke Assessment; volunteer sample.
Main Outcome Measures
Peak torque and average torque (ie, mean over the range of motion tested) from an ensemble-averaged (three trials) torque-angle curve during isokinetic concentric extension and flexion movements of the ankle, knee, and hip.
Although peak and average torque were significantly less for the hemiparetic limb compared with the non-involved limb, the intraclass correlation coefficients (ICCs) between the two test sessions were high (0.95–0.99 for peak torque, 0.88–0.98 for average torque) for both limbs for all 3 joints. However, there was a learning effect, as observed by the slightly greater values attained from the second test session.
Peak and average isokinetic torque can be used to assess reliably lower extremity strength in persons with chronic stroke. Practice sessions may be required before the actual test to reduce the effect of learning.
PMID: 11887111 CAMSID: cams2410
cerebrovascular accident; rehabilitation; muscle; reproducibility of results
Prospective assessment of cardiovascular control in individuals with spinal cord injury (SCI) in response to active stand training. Cardiovascular parameters were measured at rest and in response to orthostatic challenge before and after training in individuals with clinically complete SCI. The goal of this study was to evaluate the effect of active stand training on arterial blood pressure and heart rate and changes in response to orthostatic stress in individuals with SCI. Measurements were obtained in individuals with SCI (n = 8) prior to and after 40 and 80 sessions of the standing component of a locomotor training intervention (stand LT). During standing, all participants wore a harness and were suspended by an overhead, pneumatic body weight support (BWS) system over a treadmill. Trainers provided manual facilitation as necessary at the trunk and legs. All individuals were able to bear more weight on their legs after the stand LT training. Resting arterial blood pressure significantly increased in individuals with cervical SCI after 80 training sessions. At the end of the training period, resting systolic blood pressure (BP) in individuals with cervical SCI in a seated position, increased by 24% (from 84 ± 5 to 104 ± 7 mmHg). Furthermore, orthostatic hypotension present in response to standing prior to training (decrease in systolic BP of 24 ± 14 mmHg) was not evident (decrease in systolic BP of 0 ± 11 mmHg) after 80 sessions of stand LT. Hemodynamic parameters of individuals with thoracic SCI were relatively stable prior to training and not significantly different after 80 sessions of stand LT. Improvements in resting arterial blood pressure and responses to orthostatic stress in individuals with clinically complete cervical SCI occurred following intensive stand LT training. These results may be attributed to repetitive neuromuscular activation of the legs from loading and/or conditioning of cardiovascular responses from repetitively assuming an upright posture.
cardiovascular control; orthostatic stress; spinal cord injury; stand training