Lang, Catherine E. PT, PhD; MacDonald, Jillian R.; Gnip, Christopher DPT
Over the past decade, data generated from animal models of stroke have led to new insights into how the brain responds and how it may recover from injury.1,2 In many of these studies, animals show complete recovery at a functional level with perhaps minor changes in movement strategies (for example, see Nudo et al3 and Friel et al4). In contrast, about 50% of people with hemiparesis continue to have considerable movement dysfunction long after their stroke.5–7 Two factors may help explain the persistent movement dysfunction in humans compared to animals. In animals, the induced lesions are small and discrete, while in humans, the lesions are larger. Second, there are differences in the relative importance of various descending motor pathways in the animal models versus humans with the animals retain the ability to use one of several redundant descending pathways (eg, rubrospinal tract) for compensatory movement control.8–12 A third reason, which may be more amenable to change, could be the amount of practice experienced in the animal models versus the amount of practice experienced by humans during rehabilitation.
Paradigms designed to investigate neural plasticity in animal models often require the “subject” to engage in hundreds of repetitions of practice. To examine how learning a motor skill alters cortical representation, rats performed 400 repetitions of a reaching task per day13 and monkeys performed 600 repetitions of a pellet retrieval task per day.14 In stroke models, to reverse the detrimental changes due to a cortical lesion, monkeys performed 600 repetitions of a pellet retrieval task per day.3 Similarly, studies designed to investigate motor learning in humans also employ large amounts of practice. To examine interactions between feedback and motor adaptation in humans, healthy adults performed 300 repetitions of a reaching task.15 To assess the effects of explicit feedback on skill learning after stroke, people with stroke performed 500 movements in a serial reaction time task.16 While clinical experience suggests that people engage in far fewer repetitions during rehabilitation, we have been unable to find data to support or refute this assumption.
Studies of rehabilitation intensity typically measure intensity as the duration or frequency of therapy sessions.17 These measures provide information about the amount of minutes and/or days per week of therapy service provided. Although these measures are useful for billing purposes and for obtaining a global picture of the amount of therapy or therapeutic activity, measures of duration and frequency do not provide information about how many repetitions of specific movements occurred in a session. Given the contemporary clinical belief that more practice is better,17 it is important to determine how much practice actually occurs during physical therapy (PT) and occupational therapy (OT).
The purpose of this study was to examine the amount of practice occurring during PT and OT sessions for people with hemiparesis post-stroke. Using observational methodology, we counted the number of repetitions of various activities during rehabilitation sessions. Both PT and OT sessions were observed because rehabilitation to improve movement is addressed by both disciplines in our community. Our goal was not to determine the optimal amount of practice but simply to describe the amount of practice that currently occurs. These data are important to gather because they will serve as a starting point for comparisons with animal models of stroke, with human studies of motor learning, and with innovative forms of movement therapy developed in the future.
The study protocol was approved by the Washington University Human Studies Committee. Due to the observational methodology, a waiver of written consent was granted. Each therapist, whose treatment sessions were observed, gave verbal consent to participate at the beginning of the study. Each patient who was observed gave verbal consent to participate at the beginning of each treatment session.
We observed 36 treatment sessions, 16 PT sessions and 20 OT sessions. Treatment sessions were observed at the Neurological Day Treatment and Outpatient Clinic of the Rehabilitation Institute of St. Louis during a three-month period. This setting was chosen because it is an environment in which therapy can be delivered with minimal influences from medical complications (ie, patients are healthy enough to be living at home) and patients typically have greater endurance to participate compared with the inpatient rehabilitation setting. Inclusion criteria for sessions were as follows: (1) the therapist providing the treatment was a licensed physical therapist, physical therapist assistant, occupational therapist, or certified occupational therapist assistant, (2) the patient participating in the treatment had hemiparesis due to stroke, and (3) the session was addressing motor problems related to the stroke. Exclusion criteria for sessions were as follows: (1) the individual providing treatment was an aide, technician, or student, (2) the session was an initial or discharge evaluation, (3) the session was addressing nonmotor (eg, cognitive or attention) problems, and/or (4) the session was addressing equipment fitting (eg, wheelchair, splints, orthotics).
We did not collect demographic information on the individual patients or therapists who were observed due to restrictions imposed by the waiver of written consent. During the 36 sessions, several patients were observed more than once. Which sessions, patients, and therapists were observed depended on whether the treatment session was scheduled during the time the observers were available. Aggregate demographic information on the clinic population of people with stroke and aggregate information about the treating therapists were obtained from the facility. Patients seen in this clinic ranged in age from 25 to 90 years. Approximately half of the clinic patients are African American and the other half are white. About 60% of the clinic patients receive Medicare, 15% receive Medicaid, and the remaining 25% of clinic patients have various commercial insurance policies or are uninsured. There were two physical therapists, two physical therapy assistants, four occupational therapists, and one certified occupational therapy assistant employed in the clinic during the observation period. The range of experience of the therapists and therapy assistants was four to 20 years. Therapists had their professional degrees from a variety of nearby and distant institutions.
Observations were done by two professional-level physical therapy students (J.R.M., C.G.). Before data collection, the observers were trained to watch and record movement using an observation manual and form designed for this study (see descriptions below). Training occurred over a two-month period before data collection and involved (1) developing an instruction manual that provided specific definitions for movement categories and units of repetition, (2) multiple meetings to discuss and refine definitions, (3) collecting pilot data to test the definitions for categories and units of repetition, and (4) revisions of the instruction manual. After training, the reliability between the two observers was tested by having them simultaneously observe and collect data from the same treatment session. Interrater reliability (ICC3,1) between the two raters was 0.99 (p < 0.001) for this session. Intrarater reliability could not be evaluated because the same observer could not observe the same sessions twice without videotapes (not allowed under the waiver of written consent).
The repertoire of activities that could potentially be observed during PT and OT is enormous. Activities that could be observed were therefore divided into six categories: (1) upper extremity movements, (2) lower extremity movements, (3) gait, (4) stair climbing, (5) transfers, and (6) balance activities. These broad categories were selected based on lists of activities that patients perform in rehabilitation.18,19 The chosen categories were the most parsimonious way to divide the variety of activities for the purpose of determining the number of repetitions. The following definitions of movements and units of repetition were used to record the observations.
An upper extremity movement was defined as any movement made at any segment(s) of the hemiparetic upper extremity. A lower extremity movement was defined as any movement made at any segment(s) of the hemiparetic lower extremity. The categories of upper and lower extremity movements were further subdivided into (1) active-exercise movements, (2) passive-exercise movements, (3) purposeful movements, and (4) sensory activities.
An active-exercise movement was defined as any movement where the patient was instructed to move the limb from an initial resting position through a specific motion and return it to the resting position. The active-exercise movement subcategories included therapeutic exercises such as flexion and extension of the shoulder, abduction and adduction of the hip, or any other rotation of one or more joints from either the upper extremity or the lower extremity. An active-exercise movement repetition was counted as a movement from initial resting position to final resting position. If the active-exercise movement was assisted by the therapist in some manner (eg, assistance to obtain the last 25% of the range of motion), it was still counted as an active-exercise movement. The active-exercise movement repetitions were summed to obtain the number of upper extremity and lower extremity repetitions per session.
A passive-exercise movement was defined as any movement at the patient's joint(s) made by the therapist or another outside source, without any effort by the patient. The passive-exercise movement subcategories included passive range of motion exercises and stretching exercises performed by the therapist. A passive-exercise movement repetition was counted as a movement from initial resting position to final resting position. The passive-exercise movement repetitions were summed to obtain the number of upper extremity and lower extremity repetitions per session.
A purposeful movement was defined as any movement that accomplishes or attempts to accomplish a specific and usually functional goal or any movement that simulates a specific functional task. The purposeful movement subcategories included a broad range of movements such as fastening a button, reaching for a cone, buttering a slice of bread, or putting on a shoe. Purposeful movements were quantified by counting the number of repetitions of the whole task, where one repetition was considered completion of the specified task (eg, the button was placed through the buttonhole, the cone was reached and grasped). Because they were not privy to the therapist's thought process, the observers were occasionally challenged to initially determine what purposeful movement was occurring. To address this situation, observers also counted the number of repetitions of each subunit for some purposeful movements, where one subunit was considered an easily discernible part of the whole task. For example, if the task (unknown to the observer) was to butter a slice of bread and the patient was observed taking the bread from the bag, slicing the butter, and then spreading the butter on the bread, one whole unit and three subunits were recorded. Additionally, when looking at the whole task, any rest break longer than 10 seconds without any movement resulted in the observer counting another subunit. By recording the subunits, we ensured that the observer would not miss any of the treatment because of trying to decide what task was occurring and how to record it. After the observation session, the observer would refer to the instruction manual on hand and make a decision as to whether the data on the tasks or the subtasks should be recorded. For the majority of instances, the number of repetitions of the whole task (eg, buttering a slice of bread) was used. An example of when the count of subunits was used as the number of repetitions was when a person was building a toy structure and the subunits counted were the addition of each toy piece to the structure. The number of repetitions was summed across activities to obtain the number of purposeful movements per session.
A sensory activity was defined as any activity that was for the purpose of receiving sensory or proprioceptive stimulation. The sensory category included activities such as weight-bearing through the affected arm while standing, stroking over the muscle belly, and massage. Sensory activities were quantified by counting the number of episodes of the activity, where one episode was a single period of time doing that activity. For example, one period of bearing weight through the affected arm was counted as one repetition. If the therapist or patient stopped the activity or took a rest break longer than 10 seconds, an additional unit of activity was recorded. The number of repetitions was summed across activities to obtain the number of sensory activities per session.
Repetitions for gait were quantified two ways. First, the number of gait episodes was counted, where a gait episode was considered one period of instructed walking. Additional gait episodes were counted if the patient rested for longer than 20 seconds or the therapist stopped the patient to adjust or modify his or her gait pattern. Second, the number of steps per gait episode was counted. The number of steps was summed across gait episodes to obtain the total number of steps per session. We note that gait and stairs (see next paragraph) are the main “purposeful movements” of the lower extremities. We categorized them separately because they required counting with different units of measure, which may not be directly comparable (ie, steps versus repetitions).
Repetitions for stair climbing were also quantified two ways. First, the number of stair episodes was counted, where a stair episode was considered one period of instructed stair climbing. Additional stair episodes were counted if the patient rested for longer than 20 seconds, took more than 10 walking steps before reaching another stair step, or the therapist stopped the patient to adjust or modify his or her stair-climbing behavior. Second, the number of stairs per stair episode was counted. The number of stairs was summed across stair episodes to obtain the total number of stairs per session.
A transfer was defined as any change in position or surface made by the patient under direction and instruction of the therapist. An example of a change in position is moving from sitting to supine on a treatment mat. An example of a change of surface is moving from sitting in a wheelchair to sitting on the toilet. Transfers were counted if the therapist was providing specific therapeutic instruction about the transfer before, during, or after the movement or the therapist was monitoring and attending to the movement. Transfers were not counted if the transfer was simply a direction to position the patient in preparation for the next activity without therapist attention. For example, a sit-supine change in position was not counted when a therapist said “Please lie down so we can go over your home exercise program.” The number of transfers (regardless of type) was counted to obtain the number of transfers per session.
A balance activity was defined as any activity where the patient worked on balance in standing, sitting, or quadruped under the direction and instruction of the therapist. An example of a balance activity was having the patient sit on the mat in front of a mirror in an attempt to maintain midline sitting. Each episode was counted as one balance activity. Additional balance activities were counted if the patient rested longer than 20 seconds or the activity was changed (eg, removal of the mirror). The number of balance activities was counted to obtain the number of balance activities per session.
In all categories and subcategories, repetitions were included when the patient made an attempt, regardless of whether the movement was successful or unsuccessful. Attempts were included because our purpose was to record the number of instructed activities performed in a given time period, not to measure the success of any given patient in completing a given task. A recorded repetition therefore does not always mean a movement or task was completed, but means a substantial effort was made toward accomplishing that specific movement or task. An example of where a substantial effort is counted as a repetition is when a patient is instructed to transfer from a wheelchair to a mat. If the patient leans forward and puts weight through his or her legs, struggles but is unable to complete the transfer, returns to the wheelchair, and rests, then one transfer repetition was recorded. Subsequently, if the patient attempts a second time, struggles but returns to the wheelchair again, a second transfer is counted. Finally, on the third try, if the patient completes the transfer and successfully makes it to the mat, this was counted as the third transfer. Thus, the numbers of repetitions counted here may be considered an overestimate of the number of successful repetitions completed.
At times we observed the therapist working on two skills at once with the patient. In these instances, repetitions in both activities were recorded. An example of this is when the therapist asked the patient to sit unsupported on the edge of the mat to address balance but then also asked him or her to practice tying a shoe with both hands in his or her lap. The observer would record repetitions for the sitting balance activities and record repetitions for the upper extremity purposeful movements.
For each treatment session, observers positioned themselves in locations where they could adequately see and hear the therapist and patient, but where they would be least distracting. Therapists were instructed not to offer rationales or explanations to the observer during the treatment session. Likewise, observers were instructed not to participate in any way during the session. It is possible that the act of being observed changed the therapist's or the patient's behavior, but we have no way of determining this. Observers documented the category and subcategory of each activity and the number of repetitions of each activity on the form. Write-in areas were available to make additional notes about any observations and to record the specific activities observed in each category. Additional information recorded on the form included the type of therapy (PT or OT), the type of therapist providing the therapy, and the duration of the session in minutes.
Statistica software (Softstat Inc., Tulsa, OK) was used for data management and analyses. Data were normally distributed as determined by Kolmogorov-Smirnov tests. Descriptive statistics were generated for each category and subcategory. For the upper extremity movement categories, 95% confidence intervals (CI) of the means were compared to see whether there were differences between the number of repetitions for active-exercise, passive-exercise, and purposeful movements. CIs of the means were also used to compare numbers of repetitions in other categories.
Across the 16 PT and 20 OT sessions observed, the average session duration was 36 ± 14 minutes. Time was recorded from the point where therapeutic intervention began to when it ended. Thus, this value is not a representation of the time scheduled per patient nor is it necessarily a representation of the full time spent with the patient. We report this value because it provides a context in which to appreciate the number of repetitions observed.
Descriptive statistics for each category or subcategory are shown in Table 1. The values include the percentage and number of sessions in which each category or subcategory was observed, and the mean, standard deviation (SD), standard error (SE), and 95% CI for the number of repetitions of that category or subcategory, averaged over the sessions when it occurred. Examples of common movements observed are provided in Table 2. Upper extremity movements were observed in 24 of the 36 sessions compared with lower extremity movements, which were only observed in 12 of the 36 sessions. We anticipated that lower extremity movement repetitions would be small because we counted gait and stairs in separate categories. The number of repetitions of upper extremity purposeful movement was smaller (95% CI = 5.4–18.6) than the number of repetitions for upper extremity active-exercise (95% CI = 20.1–57.5) and passive-exercise (95% CI = 20.2–47.5) movements. Note that for the upper and lower extremity movement subcategories, the average number of repetitions is the sum of all the repetitions observed. This means that the number of repetitions observed is not for a single activity, but usually for several activities. For example, for one session with 12 repetitions of upper extremity purposeful movement, two repetitions of removing a jacket, two repetitions of removing a shirt, and eight repetitions of reaching-to-grasp cones were observed. Upper extremity and lower extremity sensory activities were also observed, although in fewer sessions than the other upper and lower extremity subcategories.
When measured in steps, gait had the highest number of repetitions of all the categories and subcategories (95% CI, steps: = 117–466). When measured in episodes however, the number of repetitions for gait (95% CI, episodes = 2.2–5.5) was closer to the number of repetitions for the other upper and lower extremity, stairs, transfer, and balance categories. Stairs, occurring in five of 36 sessions, included practice on stairs in the gym area and also in a hallway stairwell. Transfers were observed more frequently (27/36) than any other activity. Transfer training may not have been the primary focus of a treatment, but specific training was often integrated as patients moved from one position to another. Transfer training was observed in multiple settings including the therapy gym, the therapy kitchen, and the bathroom. Balance was observed in five of 36 sessions and included activities such as practice balancing in different positions, in front of a mirror, and also with manual resistance from the therapist.
Last, a large amount of variance existed in the number of repetitions observed for each category and subcategory. The variance can be appreciated by the SDs given in Table 1. We note that the variance in the number of repetitions was accompanied by variation in the activities performed (Table 2), even within a single treatment session. On average, 7.1 ± 4.3 (range, 1–17) different activities were observed in each session.
Our results show that the number of repetitions observed during PT and OT for people with hemiparesis post stroke is relatively small, with the exception being gait steps. The number of repetitions of upper extremity purposeful movements was smaller than the number of passive- or active-exercise movements. Considerable variability in the number of repetitions and the type of activities performed was seen both within and across observed sessions.
Repetitions in Therapy Versus in Animal Plasticity and Human Motor Learning Studies
We found that the number of repetitions performed during therapy sessions in a single outpatient and day treatment neurology clinic was an order of magnitude lower than the numbers of repetitions performed in animal plasticity and human motor learning studies (see Introduction).3,13–15,20 The category of gait steps was the exception to this, where we observed an average of 292 steps. This number of steps is somewhat low compared to estimates of 600 to 1800 steps performed by spinal cats during daily 20- to 30-minute treadmill sessions.21,22 Data on the numbers of repetitions cited in the Introduction and in this Discussion are drawn largely from studies of upper extremity movements. To date, the number of steps necessary to induce neuroplastic changes and promote optimal ambulatory function has not been studied in an animal (or human) model of stroke. It remains to be determined, therefore, whether the number of gait steps observed here is any closer to optimal than that observed for the upper extremity. Below, we consider three factors that may explain the disparity seen between the animal plasticity and human motor learning studies and our own observations: (1) expectations regarding the capacity to practice, (2) the delivery of skilled therapeutic intervention, and (3) the need to practice multiple movements.
First, there may be a discrepancy in the expectations for the amount of practice. In animal plasticity studies, expectations for the number of repetitions are high and consequently experiments are designed to ensure that the high expectations are met. This is accomplished by requiring the animals to perform repetitions in order to receive their daily intake of food or liquid. In human motor learning studies, expectations for the number of repetitions are also high. Experiments are designed to motivate the subject to complete hundreds of repetitions, often via engaging video games and/or by providing monetary rewards. Additionally, the ability to achieve larger numbers of repetitions may be facilitated by time limits requiring subjects to perform repetitions or sets of repetitions quickly to earn the rewards. Expectations for the number of repetitions in therapy are likely not as high for therapists or for people with hemiparesis. In a busy clinic, a therapist may be focused on accomplishing a certain number of activities with each patient and not consider how many repetitions a patient could make. People with hemiparesis receiving therapy may presume that the therapist is already pushing them to perform an adequate number of repetitions. Our data on the low number of repetitions currently seen in therapy lend support for the emerging robotic23–26 and virtual reality27–29 movement therapies. These technologies may make it easier to increase the expectations regarding the number of repetitions and to increase the motivation to execute those repetitions.
A second explanation for the small number of repetitions observed may be the delivery of skilled therapeutic intervention. In animal plasticity and human motor learning studies, the subject often practices with only knowledge of results feedback (success or failure, typically provided immediately from a computer screen). Thus, a large number of repetitions may be completed quickly. In contrast, during physical and occupational therapy sessions, the therapist may be constantly assessing and subsequently modifying the treatment technique within the session, and providing feedback to improve performance. Teaching by the therapist and learning by the patient may take increased amounts of time compared with the more rote repetition. Furthermore, if the patient is receiving PT or OT, it is likely that he or she has difficulty performing one or more essential tasks. The more complicated or difficult the essential task is, the more time it may take the patient to achieve a repetition of it.
A third explanation for the small number of repetitions observed may be the realistic need to practice many movements during rehabilitation. Our data indicate that therapists are practicing an average of seven different activities during each session. In animal plasticity and human motor learning studies, subjects typically practice a single movement (eg, reach, retrieve pellet from a well). Because a goal of rehabilitation is to assist people in moving about in the real world, a larger number and a greater variety of movements need to be practiced during the course of a single therapy session. Practice of multiple movements is particularly important given that functional training on one movement does not often generalize to improved performance on other movements.30,31 Additionally, most people with stroke have numerous impairments, activity limitations, and participation restrictions. Therapists often select multipronged treatment approaches where some therapeutic activities address impairments, some therapeutic activities address activity limitations and participation restrictions, and some therapeutic activities address all areas.
Repetitions of Upper Extremity Purposeful Movements
The number of repetitions of upper extremity purposeful movements was about one third the numbers of repetitions of active- or passive-exercise movements. This observation of what actually occurs during therapy sessions is inconsistent with current teaching that practice of purposeful movements is an integral part of improving functional status.32 One reason for the lower number of purposeful movement repetitions may be that the amount of time to perform one purposeful movement is generally longer than the amount of time to perform one active- or passive-exercise movement. For example, it may take a person with hemiparesis 10 minutes to fasten 10 buttons (counted as 10 reps), yet it may take less than three minutes to perform 10 repetitions of a finger flexion exercise. Thus, the difference in the numbers of repetitions in these categories may mean that a similar duration of time was devoted to each category, but within that time, more repetitions of active- and passive- exercise movements could be completed.
Another reason why we observed more active-exercise movements than purposeful movements may be the therapist's goals for treatment. Anecdotal comments by the observed therapists after completion of this project indicated that they devoted considerable therapy time to implementing and establishing home exercise programs because the number of therapy visits was limited by third-party payers. The home exercise programs consisted mainly of movements that fell into our active- or passive-exercise categories. We speculate that a method to simultaneously increase the number of purposeful activities during therapy and establish a regularly executed home exercise program would be to use purposeful movements as the specific home exercises. For example, instead of executing straight plane shoulder range of motion exercises, people with hemiparesis could reach and grasp objects from various shelves in their kitchen.
We were surprised by the quantity of passive-exercise movements observed. Upper extremity passive-exercise movements were observed in 47% of all sessions and 75% of sessions in which upper extremity movement problems were addressed. The number of repetitions of passive-exercise movements was similar to the number of repetitions of active-exercise movements. Presumably, the passive-exercise movements were employed to maintain or increase range of motion and/or to minimize abnormalities in muscle tone, such as spasticity. With a limited number of therapy visits and a limited amount of time for each visit, therapists must question whether passive activities addressing impairments such as spasticity are warranted given the large fluctuations in tone within a single individual33 and the lack of evidence linking spasticity to functional movement performance.34,35
Several limitations restrict the generalizability of our findings. First, we used a nonparticipant observational methodology with a waiver of written consent to collect these data. This prevented us from obtaining subject-specific information about our sample, ie, we could not collect demographic and stroke-specific information such as age, race, lesion type, lesion onset, or stroke severity. We had to rely on aggregate information from the facility about the population of therapists and the populations of patients. Thus, our data provide insight into how much practice occurs for an unidentified population of people with hemiparesis post-stroke in a single outpatient setting. Future studies are needed to determine (1) whether the data collected here can be generalized to other clinical settings and (2) whether beyond these general findings, there are interesting and clinically relevant differences in amount of practice between various subpopulations of people with hemiparesis and across various clinical settings.
Second, we had to divide the enormous range of possible movements into categories and subcategories. Although we chose the simplest method we could at the time, a variety of other categorization schemes are possible. Within each category, we had to define a single repetition of an activity. For some activities, such as active elbow flexion exercises or gait, the number of repetitions was relatively easy to define. For other activities, defining the number of repetitions was difficult, especially in the purposeful movement subcategories. Other factors that limited our ability to count repetitions included some instances where one activity was counted as a repetition in two categories simultaneously (see example in Methods) and some instances where the goal of the movement or activity was not clear and had to be determined by the observer. It is possible that our chosen definitions and categorizations resulted in slightly underestimating or overestimating the number of repetitions that occurred. Even if we consider our counts as underestimations, the true numbers of repetitions would still remain an order of magnitude lower than the number of repetitions in animal plasticity and human motor learning studies. Future studies to test the generalizability of our results in other outpatient clinics, other settings, and/or other patient populations could use the same categorization scheme because we did not encounter any major problems. Categories for counting repetitions of wheelchair propulsion or other specialty areas may need to be added for specific settings or specific populations.
A third limitation to the generalizability of our data is the number of sessions observed. We observed 36 treatment sessions. Because some sessions were focused on addressing lower extremity movement problems (typically PT) and some sessions were focused on addressing upper extremity movement problems (typically OT), activities in each category and subcategory were not observed at every session. Part way through data collection after 20 sessions were observed, we did a preliminary analysis to get a general idea of the number of repetitions in each category and subcategory. At the end of data collection, our results from 36 sessions remained consistent with the results after 20 sessions. Although the possibility exists that observing more sessions would change the numbers of repetitions, we think it is unlikely that these changes would be substantial.
We found that the number of repetitions performed in therapy is relatively low, except for gait steps, and that upper extremity treatment may emphasize active and passive exercise over purposeful activities. Our intent was not to provide definitive values for the number of repetitions that occur in therapy, but to provide a starting point from which to compare and appreciate what occurs during therapy sessions for people with hemiparesis post-stroke to what occurs in studies of animal plasticity and human motor learning. For clinicians, our data will be useful for comparing the amount of practice they provide to their patients and useful for examining how and why they choose to practice particular movements. Finally, these data may encourage discussions within clinics and within and across professions regarding ways to facilitate larger numbers of repetitions during movement therapy. If future studies substantiate the importance of the amount of repetition currently suggested by the animal literature, then the current delivery of rehabilitation services will have to change.
The authors thank the therapists and people with hemiparesis for allowing us to observe their treatments. Salary support during this project was provided by NIH HD047669 (C.E.L.).
1. Nudo RJ, Plautz EJ, Frost SB. Role of adaptive plasticity in recovery of function after damage to motor cortex. Muscle Nerve. 2001;24:1000–1019.
2. Kleim JA, Jones TA, Schallert T. Motor enrichment and the induction of plasticity before or after brain injury. Neurochem Res. 2003;28:1757–1769.
3. Nudo RJ, Wise BM, SiFuentes F, Milliken GW. Neural substrates for the effects of rehabilitative training on motor recovery after ischemic infarct. Science. 1996;272:1791–1794.
4. Friel KM, Heddings AA, Nudo RJ. Effects of postlesion experience on behavioral recovery and neurophysiologic reorganization after cortical injury in primates. Neurorehabil Neural Repair. 2000;14:187–198.
5. Wade DT, Hewer RL. Functional abilities after stroke: measurement, natural history and prognosis. J Neurol Neurosurg Psychiatry. 1987;50:177–182.
6. Reding MJ, Potes E. Rehabilitation outcome following initial unilateral hemispheric stroke. Life table analysis approach. Stroke. 1988;19:1354–1358.
7. Jorgensen HS, Nakayama H, Raaschou HO, et al. Outcome and time course of recovery in stroke. Part I: Outcome. The Copenhagen Stroke Study. Arch Phys Med Rehabil. 1995;76:399–405.
8. Lang CE, Reilly KT, Schieber MH. Human voluntary motor control and dysfunction. In: Selzer ME, Clarke S, Cohen LG, et al., eds. Textbook of Neural Repair and Rehabilitation: Medical Rehabilitation. Vol. 2. Cambridge: Cambridge University Press; 2006:24–36.
9. Lawrence DG, Kuypers HG. The functional organization of the motor system in the monkey. I. The effects of bilateral pyramidal lesions. Brain. 1968;91:1–14.
10. Lawrence DG, Kuypers HG. The functional organization of the motor system in the monkey. II. The effects of lesions of the descending brain-stem pathways. Brain. 1968;91:15–36.
11. Nudo RJ, Masterton RB. Descending pathways to the spinal cord: a comparative study of 22 mammals. J Comp Neurol. 1988;277:53–79.
12. Lemon RN, Griffiths J. Comparing the function of the corticospinal system in different species: organizational differences for motor specialization? Muscle Nerve. 2005;32:261–279.
13. Kleim JA, Barbay S, Nudo RJ. Functional reorganization of the rat motor cortex following motor skill learning. J Neurophysiol. 1998;80:3321–3325.
14. Nudo RJ, Milliken GW, Merzenich MM. Use-dependent alterations of movement representations in primary motor cortex of adult squirrel monkeys. J Neurosci. 1996;16:785–807.
15. Fine MS, Thoroughman KA. Motor adaptation to single force pulses: sensitive to direction but insensitive to within-movement pulse placement and magnitude. J Neurophysiol. 2006;96:710–720.
16. Boyd L, Winstein C. Explicit information interferes with implicit motor learning of both continuous and discrete movement tasks after stroke. J Neurol Phys Ther. 2006;30:46–59.
17. Kwakkel G. Impact of intensity of practice after stroke: issues for consideration. Disabil Rehabil. 2006;28:823–830.
18. Bode RK, Heinemann AW, Semik P, et al. Patterns of therapy activities across length of stay and impairment levels: peering inside the “black box” of inpatient stroke rehabilitation. Arch Phys Med Rehabil. 2004;85:1901–1908.
19. Pedretti LW, Early MB. Occupational Therapy: Practice Skills for Physical Dysfunction, 5th ed. St. Louis: Mosby; 2001:463–506.
20. Nudo RJ, Milliken GW. Reorganization of movement representations in primary motor cortex following focal ischemic infarcts in adult squirrel monkeys. J Neurophysiol. 1996;75:2144–2149.
21. Chau C, Barbeau H, Rossignol S. Early locomotor training with clonidine in spinal cats. J Neurophysiol. 1998;79:392–409.
22. de Leon RD, Hodgson JA, Roy RR, et al. Locomotor capacity attributable to step training versus spontaneous recovery after spinalization in adult cats. J Neurophysiol. 1998;79:1329–1340.
23. Hesse S, Schmidt H, Werner C, Bardeleben A. Upper and lower extremity robotic devices for rehabilitation and for studying motor control. Curr Opin Neurol. 2003;16:705–710.
24. Lum PS, Burgar CG, Shor PC, et al. Robot-assisted movement training compared with conventional therapy techniques for the rehabilitation of upper-limb motor function after stroke. Arch Phys Med Rehabil. 2002;83:952–959.
25. Volpe BT, Krebs HI, Hogan N. Robot-aided sensorimotor training in stroke rehabilitation. Adv Neurol. 2003;92:429–433.
26. Patton JL, Stoykov ME, Kovic M, et al. Evaluation of robotic training forces that either enhance or reduce error in chronic hemiparetic stroke survivors. Exp Brain Res. 2006;168:368–383.
27. Merians AS, Jack D, Boian R, et al. Virtual reality-augmented rehabilitation for patients following stroke. Phys Ther. 2002;82:898–915.
28. Holden MK. Virtual environments for motor rehabilitation: review. Cyberpsychol Behav. 2005;8:187–219.
29. Sanchez RJ, Liu J, Rao S, et al. Automating arm movement training following severe stroke: functional exercises with quantitative feedback in a gravity-reduced environment. IEEE Trans Neural Syst Rehabil Eng. 2006;14:378–389.
30. Shimada H, Uchiyama Y, Kakurai S. Specific effects of balance and gait exercises on physical functioning among the frail elderly. Clin Rehabil. 2003;17:472–479.
31. Winstein CJ, Gardner ER, McNeal DR, et al. Standing balance training: effect on balance and locomotion in hemiparetic adults. Arch Phys Med Rehabil. 1989;70:755–762.
32. Shumway-Cook A, Woollacott MH. Motor Control: Theory and Practical Applications, 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2001:26–49.
33. Schmit BD, Dewald JP, Rymer WZ. Stretch reflex adaptation in elbow flexors during repeated passive movements in unilateral brain-injured patients. Arch Phys Med Rehabil. 2000;81:269–278.
34. Wagner JM, Lang CE, Sahrmann SA, et al. Relationships between sensorimotor impairments and reaching deficits in acute hemiparesis. Neurorehabil Neural Repair. 2006;20:406–416.
35. Sahrmann SA, Norton BJ. The relationship of voluntary movement to spasticity in the upper motor neuron syndrome. Ann Neurol. 1977;2:460–465.