The bilateral movement condition facilitates maximal but not submaximal paretic-limb grip force in people with post-stroke hemiparesis

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: The bilateral condition facilitates paretic limb grip force at maximal, but not submaximal levels. SIGNIFICANCE: In some people with post-stroke hemiparesis, the paretic limb may benefit from bilateral training with high force requirements

Upper-limb activity in adults: Referent values using accelerometry

The goal of physical rehabilitation following upper extremity (UE) impairment is functional restoration of the UE for use in daily activities. Because capacity for UE function may not translate into real-world activity, it is important that assessment of real-world UE activity be used in conjunction with clinical measures of capacity. Accelerometry can be used to quantify duration of UE activity outside of the clinic. The purpose of this study was to characterize hours of UE activity and potential modifying factors of UE activity (sedentary activity, cognitive impairment, depressive symptomatology, additive effects of comorbidities, cohabitation status, and age). Seventy-four community dwelling adults wore accelerometers on bilateral wrists for 25 hours and provided information on modifying factors. Mean hours of dominant UE activity was 9.1 ± 1.9 hours and the ratio of activity between the non-dominant and dominant UEs was 0.95 ± 0.06. Decreased hours of dominant UE activity was associated with increased time spent in sedentary activity. No other factors were associated with hours of dominant UE activity. These data can be used to help clinicians establish outcome goals for patients, given pre-impairment level of sedentary activity, and to track progress during rehabilitation of the UEs

Scapular and humeral movement patterns of people with stroke during range-of-motion exercises

BACKGROUND AND PURPOSE: Range-of-motion (ROM) exercises may contribute to hemiparetic shoulder pain, but the underlying mechanisms are unknown. This study examined scapular and humeral movement patterns in people with hemiparesis post stroke as they performed commonly prescribed ROM exercises. METHODS: Using kinematic techniques, we studied 13 people with hemiparesis, both with and without pain, as they performed three commonly prescribed ROM exercises: person-assisted ROM, self-assisted ROM, and cane-assisted ROM. Their data were compared to a group of 12 matched control subjects performing scapular plane shoulder elevation using mixed model ANOVAs. Correlation analyses were used to examine the relationship between participants’ ratings of pain and kinematic data. RESULTS: The hemiparetic group had mild pain at rest that increased during the performance of the exercises. During shoulder elevation, humeral external rotation in the hemiparetic group was decreased in all three ROM exercises compared to the control group. Scapular upward rotation in the hemiparetic group was decreased for the person-assisted ROM exercise only. No differences in scapular tilt were found between groups. The extent of movement abnormalities was not related to pain severity. DISCUSSION AND CONCLUSIONS: People with hemiparesis had altered scapular and humeral movement patterns and increased shoulder pain when performing the ROM exercises. These data can assist clinicians in making decisions regarding which exercises to prescribe to preserve shoulder motion and prevent contractures in this population

Comparison of unilateral versus bilateral upper extremity task performance after stroke

BACKGROUND: Previous studies have suggested that practicing functional tasks bilaterally instead of unilaterally may improve paretic limb performance after stroke. OBJECTIVE: The purposes of this study were to determine whether the bilateral movement condition alters paretic limb performance of a functional task in people with post-stroke hemiparesis, and to identify specifically which parameters of performance may be affected. METHODS: In this single-session study, we examined immediate effects of the bilateral vs. unilateral movement condition on performance of a reach-grasp-lift-release task at preferred-speed in 16 people with mild to moderate post-stroke hemiparesis and in 12 healthy controls. Performance was quantified using motion analysis variables, including durations of the reach and grasp phases, reach path straightness, maximum thumb-index finger aperture, efficiency of finger movement, peak grip force, and timing of release. RESULTS: We found no evidence of immediate improvement in paretic-limb performance in the bilateral condition. In both groups, release timing occurred later when participants moved bilaterally instead of unilaterally, possibly representing a divided-attention effect. Other variables did not differ across conditions. CONCLUSIONS: Our findings suggest little immediate impact of the bilateral condition on motor performance of a reach-grasp-lift-release task at preferred speed, in people with mild to moderate hemiparesis

Using dual tasks to test immediate transfer of training between naturalistic movements: A proof-of-principle study

Theories of motor learning predict that training a movement reduces the amount of attention needed for its performance (i.e. more automatic). If training one movement transfers, then the amount of attention needed for performing a second movement should also be reduced, as measured under dual task conditions. The purpose of this study was to test whether dual task paradigms are feasible for detecting transfer of training between two naturalistic movements. Immediately following motor training, subjects improved performance of a second untrained movement under both single and dual task conditions. Subjects with no training did not. Improved performance in the untrained movement was likely due to transfer, and suggests that dual tasks may be feasible for detecting transfer between naturalistic actions

Relationships between accelerometry and general compensatory movements of the upper limb after stroke

BACKGROUND: Standardized assessments are used in rehabilitation clinics after stroke to measure restoration versus compensatory movements of the upper limb. Accelerometry is an emerging tool that can bridge the gap between in- and out-of-clinic assessments of the upper limb, but is limited in that it currently does not capture the quality of a person\u27s movement, an important concept to assess compensation versus restoration. The purpose of this analysis was to characterize how accelerometer variables may reflect upper limb compensatory movement patterns after stroke. METHODS: This study was a secondary analysis of an existing data set from a Phase II, single-blind, randomized, parallel dose-response trial (NCT0114369). Sources of data utilized were: (1) a compensatory movement score derived from video analysis of the Action Research Arm Test (ARAT), and (2) calculated accelerometer variables quantifying time, magnitude and variability of upper limb movement from the same time point during study participation for both in-clinic and out-of-clinic recording periods. RESULTS: Participants had chronic upper limb paresis of mild to moderate severity. Compensatory movement scores varied across the sample, with a mean of 73.7 ± 33.6 and range from 11.5 to 188. Moderate correlations were observed between the compensatory movement score and each accelerometer variable. Accelerometer variables measured out-of-clinic had stronger relationships with compensatory movements, compared with accelerometer variables in-clinic. Variables quantifying time, magnitude, and variability of upper limb movement out-of-clinic had relationships to the compensatory movement score. CONCLUSIONS: Accelerometry is a tool that, while measuring movement quantity, can also reflect the use of general compensatory movement patterns of the upper limb in persons with chronic stroke. Individuals who move their limbs more in daily life with respect to time and variability tend to move with less movement compensations and more typical movement patterns. Likewise, individuals who move their paretic limbs less and their non-paretic limb more in daily life tend to move with more movement compensations at all joints in the paretic limb and less typical movement patterns

Person-specific changes in motor performance accompany upper extremity functional gains after stroke

In animal models, hundreds of repetitions of upper extremity (UE) task practice promote neural adaptation and functional gain. Recently, we demonstrated improved UE function following a similar intervention for people after stroke. In this secondary analysis, computerized measures of UE task performance were used to identify movement parameters that changed as function improved. Ten people with chronic post-stroke hemiparesis participated in high-repetition UE task-specific training 3 times per week for 6 weeks. Before and after training, we assessed UE function with the Action Research Arm Test (ARAT), and evaluated motor performance using computerized motion capture during a reach-grasp-transport-release task. Movement parameters included the duration of each movement phase, trunk excursion, peak aperture, aperture path ratio, and peak grip force. Group results showed an improvement in ARAT scores (p = 0.003). Although each individual changed significantly on at least one movement parameter, across the group there were no changes in any movement parameter that reached or approached significance. Changes on the ARAT were not closely related to changes in movement parameters. Since aspects of motor performance that contribute to functional change vary across individuals, an individualized approach to upper extremity motion analysis appears warranted

Transfer of training between distinct motor tasks after stroke: Implications for task-specific approaches to upper-extremity neurorehabilitation

BACKGROUND: Although task-specific training is emerging as a viable approach for recovering motor function after stroke, there is little evidence for whether the effects of such training transfer to other functional motor tasks not directly practiced in therapy. OBJECTIVE: The purpose of the current study was to test whether training on one motor task would transfer to untrained tasks that were either spatiotemporally similar or different in individuals with chronic hemiparesis post-stroke. METHODS: Eleven participants with chronic mild-to-moderate hemiparesis following stroke completed five days of supervised massed practice of a feeding task with their affected side. Performance on the feeding task, along with two other untrained functional upper extremity motor tasks (sorting, dressing) was assessed before and after training. RESULTS: Performance of all three tasks improved significantly after training exclusively on one motor task. The amount of improvement in the untrained tasks was comparable, and was not dependent on the degree of similarity to the trained task. CONCLUSIONS: Because the number and type of tasks that can be practiced are often limited within standard stroke rehabilitation, results from this study will be useful for designing task-specific training plans to maximize therapy benefits

An accelerometry-based methodology for assessment of real-world bilateral upper extremity activity

BACKGROUND:The use of both upper extremities (UE) is necessary for the completion of many everyday tasks. Few clinical assessments measure the abilities of the UEs to work together; rather, they assess unilateral function and compare it between affected and unaffected UEs. Furthermore, clinical assessments are unable to measure function that occurs in the real-world, outside the clinic. This study examines the validity of an innovative approach to assess real-world bilateral UE activity using accelerometry. METHODS:Seventy-four neurologically intact adults completed ten tasks (donning/doffing shoes, grooming, stacking boxes, cutting playdough, folding towels, writing, unilateral sorting, bilateral sorting, unilateral typing, and bilateral typing) while wearing accelerometers on both wrists. Two variables, the Bilateral Magnitude and Magnitude Ratio, were derived from accelerometry data to distinguish between high- and low-intensity tasks, and between bilateral and unilateral tasks. Estimated energy expenditure and time spent in simultaneous UE activity for each task were also calculated. RESULTS:The Bilateral Magnitude distinguished between high- and low-intensity tasks, and the Magnitude Ratio distinguished between unilateral and bilateral UE tasks. The Bilateral Magnitude was strongly correlated with estimated energy expenditure (ρ = 0.74, p<0.02), and the Magnitude Ratio was strongly correlated with time spent in simultaneous UE activity (ρ = 0.93, p<0.01) across tasks. CONCLUSIONS:These results demonstrate face validity and construct validity of this methodology to quantify bilateral UE activity during the performance of everyday tasks performed in a laboratory setting, and can now be used to assess bilateral UE activity in real-world environments