STROKE IS A LEADING CAUSE of disability in adults.

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1 1258 Gait Outcomes After Acute Stroke Rehabilitation With Supported Treadmill Ambulation Training: A Randomized Controlled Pilot Study Inácio Teixeira da Cunha Jr, PT, PhD, Peter A. Lim, MD, Huma Qureshy, PT, MS, Helene Henson, MD, Trilok Monga, MD, Elizabeth J. Protas, PT, PhD ABSTRACT. da Cunha IT Jr, Lim PA, Qureshy H, Henson H, Monga T, Protas EJ. Gait outcomes after acute stroke rehabilitation with supported treadmill ambulation training: a randomized controlled pilot study. Arch Phys Med Rehabil 2002;83: From the School of Physical Therapy, Texas Woman s University, Houston, TX (da Cunha, Qureshy, Protas); Department of Physical Medicine and Rehabilitation (Lim, Henson, Monga) and Rehabilitation Research and Development Center of Excellence on Healthy Aging with Disabilities (da Cunha, Monga, Protas), Houston Veterans Affairs Medical Center, Houston, TX; and Singapore General Hospital, Singapore (Lim). Supported by the Rehabilitation Research and Development Center of Excellence on Healthy Aging with Disabilities, Houston Veterans Affairs Medical Center, and the Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (Brazil). Presented in part at the American Physical Therapy Association s annual conference, June 2000, Indianapolis, IN. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Elizabeth J. Protas, PT, PhD, 1130 John Freeman Blvd, Houston, TX 77030, eprotas@twu.edu /02/ $35.00/0 doi: /apmr Objective: To investigate gait outcomes with supported treadmill ambulation training (STAT) associated with regular rehabilitation in acute stroke survivors. Design: Randomized controlled trial, pilot study. Setting: Rehabilitation medicine service at a Veterans Affairs medical center. Participants: Seven acute stroke survivors assigned to regular intervention group and 6 patients assigned to STAT intervention. Interventions: Regular intervention consisted of 3 hours daily of physical therapy, kinesiotherapy, and occupational therapy. STAT group received regular rehabilitation with STAT substituted for usual gait training. Participants were tested at baseline, treated for an average of 3 weeks, and retested on discharge. The analysis of covariance procedure was used to test for differences between the 2 approaches. Main Outcome Measures: Functional Ambulation Category Scale, gait speed, walking distance, gait energy expenditure, and gait energy cost. Results: The small sample size did not generate enough power to detect significant differences in any variable. However, medium to large effect sizes of 0.7 and 1.16 standard deviation units were observed for gait energy cost and walk distance, respectively. Conclusions: This pilot study indicated that STAT is a safe, feasible, and promising intervention for acute stroke survivors. A larger trial is warranted for statistical relevance. Key Words: Ambulation; Cerebrovascular accident; Gait; Rehabilitation; Treadmill test by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation STROKE IS A LEADING CAUSE of disability in adults. There are approximately 3 million Americans with residual disability from stroke, which results in an estimated annual economic burden of more than $30 billion. 1 The average ageadjusted incidence rate of first strokes has been reported to be 114 per 100, Residual motor weakness, abnormal movement synergies, and spasticity result in altered gait patterns and contribute to poor balance, risk for falls, and increased energy expenditure during walking. The functional consequences of the primary neurologic deficits often predispose the stroke survivor to a sedentary lifestyle, which further limits the individual s activities of daily living (ADLs) and reduces cardiovascular reserves. Efforts to minimize the impact and to improve functional outcomes after a stroke thus pose an important challenge for rehabilitation professionals. The pattern of walking recovery among stroke survivors is quite variable. Wade et al, 3 discussing the pattern of gait recovery in the early phases postevent, showed that only 22% of the 45 patients who could not walk as a consequence of stroke were able to walk normally within 3 months of recovery. Friedman 4 showed that the sooner the stroke survivor attained the ability to ambulate, the more likely that independent walking would be reestablished. Among patients who initially were not ambulating, independent walking was not achieved during months 1 through 4 of recovery. Bach-y-Rita 5 reported that several studies established the association between reduced functional recovery with delay in initiating therapy in neurologic conditions, in both animal and humans studies. This further shows the need to start gait training with this population as soon as possible. Gait restoration requires different techniques and often demands considerable assistance from the therapist to help the patient support body weight and control balance. The rehabilitation of stroke survivors is both expensive and demanding, and the results vary. Conventional gait training alone often leads to an asymmetrical gait pattern in many stroke patients. 6,7 More recently, a new technology was developed to provide gait training in patients with neurologic dysfunction. It consists of a suspension system to which the patient is connected so that weight shifting, balance, and stepping can be controlled while walking is facilitated by a treadmill. 7,8 Several studies 7-10 have shown promising outcomes and the feasibility of supported treadmill ambulation training (STAT) compared with regular physical therapy in chronic stroke patients. People with neurologic conditions can improve gait by either treadmill ambulation with non body-weight support or with body-weight support (BWS). 8,9,11-15 The degree of locomotor recovery has been shown to be significantly related to the training used in patients with neurologic conditions. 8,16,17 Some studies involving animals with spinal cord injury have shown that a near-normal walking pattern can be achieved after a

2 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha 1259 period of locomotor training in which support for the hindquarters and stepping on a treadmill is provided Most studies, however, have focused on using new training strategies in individuals with chronic conditions. There is a need to examine gait and functional outcomes of BWS during more acute and subacute recovery after a stroke. Gait training is often delayed during the early rehabilitation process because gait is thought to require preparation such as improved strength, balance, and coordination before the initiation of this more complex and demanding activity. However, by using the suspension system with the treadmill may compensate for these early deficits present with acute and subacute stroke survivors, allowing timely intervention. Therefore, we propose to use this new approach to provide early gait training with acute stroke patients, which consists of STAT combined with conventional rehabilitation for achieving functional ambulation. The goal of this study was to conduct a pilot study of STAT during inpatient rehabilitation of acute stroke survivors. It was hypothesized that the STAT group would show more extensive improvement in gait outcomes compared with regular rehabilitative care alone. The gait outcomes analyzed were gait ability, gait speed, walking distance, gait energy expenditure, and gait energy cost. METHODS Participants Fifteen stroke survivors were recruited from a sample of convenience among the stroke patients admitted to the Rehabilitation Medicine Service at the Veterans Affairs Medical Center (VAMC), in Houston, TX. Participants had a recent ( 6wk poststroke) unilateral stroke based on the clinical evaluation. They were recruited to participate in this study after meeting specific inclusion criteria and voluntarily signing an informed consent agreement. This pilot study was approved by the Institutional Review Board for Human Subject Research for Baylor College of Medicine and Affiliated Hospitals and the Human Subjects Review Committee of Texas Woman s University. Patients entered the study regardless of gender or race, although, as anticipated, men are more prevalent in this facility. The inclusion criteria were (1) history and clinical presentation (hemiparesis) of recent stroke ( 6wk postevent); (2) a significant gait deficit as evidenced by a gait speed of 36m/min (0.6m/s) or less, and a score of 0, 1, or 2 on the Functional Ambulation Category (FAC) Scale (needs assistance); (3) sufficient cognition to participate in the training: a Mini-Mental State Exam (MMSE) score of 21 or higher; (4) ability to stand with or without assistance and to take at least 1 or more steps with or without assistance; and (5) stable medical condition to allow participation with testing protocol and intervention. The exclusion criteria were (1) patients with any comorbidity or disability other than stroke (ie, amputation, spinal cord lesion) that would preclude gait training; (2) recent myocardial infarction ( 4wk) or cardiac bypass surgery with complications; (3) any uncontrolled health condition for which exercise is contraindicated, such as consistent, uncontrolled diabetes (blood sugar levels, 250mg/dL), or persistent, uncontrolled hypertension ( 190/110mmHg); (4) significant lower-extremity degenerative joint disease that would interfere with gait training; (5) body weight over 110kg, because the harnesses would not fit individuals over this body weight; (6) cognitive impairment (MMSE score, 21); and (7) history of bilateral cerebrovascular accident. Measurements Descriptive details of the subjects such as age, height, weight, side and location of lesion, and number of days since the stroke were recorded. Each patient was also characterized according to cognitive impairment and stroke-related impairment. Cognitive impairment was evaluated by the MMSE, a brief, valid, and reliable instrument. 21,22 We used a cutoff score of 21 on the MMSE, based on the report by Small et al, 23 to avoid cognitive impairments that would preclude participation in the study. The National Institutes of Health (NIH) Stroke Scale was used to characterize the patient s impairment. This scale has been validated and its reliability is good The NIH Stroke Scale, and the MMSE were used for descriptive purposes. Gait Parameters Gait was assessed by means of 5 measures as follows. Gait ability. Gait ability function was rated by using the FAC Scale. 27,28 Participants were rated according to the personnel support needed for gait, regardless of use of an assistive device according to the following 6-point scale: 0, patient cannot walk or requires help of 2 or more people; 1, patient requires firm continuous support from 1 person who helps with carrying weight and with balance; 2, patient needs continuous or intermittent support of 1 person to help with balance or coordination; 3, patient requires verbal supervision or stand-by help from 1 person without physical contact; 4, patient can walk independently on level ground, but requires help on stairs, slopes, or uneven surfaces; and 5, patient can walk independently. The measure was rated by an investigator and based on the participant s ability to walk. The patient was asked to stand up and to take some steps if possible. If he/she could ambulate, his/her ability to walk was assessed while walking 15m. 16 Assessment of FAC Scale interrater reliability has generated a coefficient of Gait speed. Gait speed was evaluated by timing a 5-m walk with a stopwatch. Speed was calculated in meters per second. The subject was asked to stand and walk as fast as possible on a measured walkway for 5m, with any assistive device necessary and while being guarded by and provided whatever assistance needed by a physical therapist. The walking speed was measured twice, and the average of 2 trials was recorded as definitive data to clarify the averaged measure of gait speed. If the patient could not walk 5m continuously, his speed was computed as zero. The reliability of gait speed measured with a stopwatch in persons with gait impairments is excellent. 29 Walking distance. Walking distance was evaluated by recording the distance covered in 5 minutes (gait endurance). The participants walked back and forth over a distance of 5m, and a stopwatch was used to time a total of 5 minutes. The floor surface was marked at 1-m intervals, and the distance was recorded accordingly. Subjects were asked to walk as fast and as far as possible. It was anticipated that, for the initial test, some participants might be unable to walk for 5 minutes. For these subjects, the following adaptation was used. The subject used the parallel bars with appropriate orthotic devices. The participant was encouraged to do whatever was possible during the 5 minutes, such as a combination of standing and taking only a few steps in the parallel bars. The distance covered for those steps was recorded as the initial 5-minute walk endurance. If the subject was unable to do even that, a zero was recorded for the initial test. We selected a 5-minute period to evaluate endurance rather than 6 to 12 minutes because we

3 1260 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha anticipated serious initial gait compromise. The validity and reliability of the 5-minute walk test are excellent. 30 Gait energy expenditure. Gait energy expenditure was the oxygen consumed during the 5-minute walk. It was evaluated by adding the oxygen consumption (V O2 ) each minute in milliliters per kilogram of body mass observed over the 5-minute walk (Walking Distance Test). Before the walk, the subject was fitted with a portable gas analyzer (KB1-C system) a to obtain the value of oxygen consumption during this task, through indirect calorimetry. This is a lightweight, portable system that consists of a facemask for collecting expired air, sensors for analyzing oxygen and carbon dioxide content of expired air, a heart rate monitor, a battery pack, and a transmitter worn by the subject. A receiving unit received and stored the transmitted data. These data were downloaded into a computer to calculate values for oxygen consumption, minute ventilation, and respiratory exchange ratio. The gas analyzers were calibrated with room air and a sample of known gas, and the flowmeter was calibrated by moving a known volume of air through the flowmeter with a calibration syringe according to the manufacturer s instructions. The machine was calibrated before testing each subject. The validity of the KB1-C system was tested against the traditional computer-based metabolic measurement cart to evaluate oxygen consumption by using 12 subjects who performed maximal graded exercise tests on a treadmill. 31 A Pearson correlation coefficient of 0.9 was reported. 31 The reliability of this system was tested with 11 subjects during 2 trials of 4 submaximal workloads and 1 maximal workload, and the intraclass correlation coefficients reported ranged from.78 to Gait energy cost. Gait energy cost refers to the amount of oxygen consumed per unit distance traveled during the 5-minute walk. Gait cost (mlo 2 kg 1 m 1 ) was obtained by dividing gait energy expenditure (mlo 2 kg 1 min 5 )bythe walking distance (m). Lower scores indicate better performance on this variable. Procedures After randomization by using random numbers to preassign subjects based on recruitment order, 2 groups were obtained: a group undergoing regular rehabilitation care at the Houston VAMC, and a second group undergoing regular rehabilitation care with STAT. Regular rehabilitation in this facility consists of daily sessions of physical therapy, kinesiotherapy, and occupational therapy. The usual amount of time is 3 hours daily, consisting of 1 hour for each type of therapy. Physical therapy focused on strengthening, function, and mobility activities, including gait training. The objectives of kinesiotherapy were to increase strength and endurance, while occupational therapy intervention related to ADLs. The STAT group received the same interventions as in the regular intervention group, but without the usual gait training. For the STAT group, STAT was substituted for the usual gait training. Only stair climbing, locomotion on uneven surface, and training on how to handle walking devices were allowed during regular intervention for the subjects in the STAT group. With STAT, there was an overhead harness b consisting of a thoracic belt that attached around the hips and chest and 2 thigh straps with anterior and posterior attachments to the thoracic band. This harness was fastened snugly to the subject to minimize upward shifting and attached to the BWS system. The BWS system has a suspension mechanism that indicated the amount of weight being supported. c Training started with support of up to 30% of body weight and was progressively decreased as the participants acquired the capability of greater self-support. The exact amount of BWS was determined by the therapist based on observing support required to facilitate proper trunk and limb alignment as well as transfer of weight onto the hemiparetic limb. As the protocol progressed, the percentages of BWS were decreased, aiming for zero BWS, so that the subject would be training with full body weight at faster speeds. BWS was decreased as much as possible while still allowing the hemiparetic limb to support weight during stance phase with less than 15 of knee flexion. The therapist followed the rule of reducing BWS as quickly as possible and/or increasing treadmill speed. The BWS was reassessed during every training session, and a daily log sheet was kept to record gait speed, amount of support, and cardiovascular responses. The treadmill d used for training allowed walking to be initiated for a speed as slow as.01m/s and to be increased by increments of.01m/s. The initial speed and progression were determined by the therapist. Speed was increased when a usual step length occurred at a higher speed. The patient was checked for progression during every training session. Subjects were trained daily (Monday through Friday), for 20 minutes, up to discharge from the rehabilitation unit. Measurements of blood pressure were performed before, during, and after completing each training session. Missing more than 3 consecutively scheduled visits for medical reasons or inability to participate resulted in the patient being dropped from the study. Statistical Analysis Descriptive statistics were used to characterize demographics and to establish initial scores on the MMSE and the NIH Stroke Scale. Independent t tests were used to compare differences between group means. Nonparametric (Wilcoxon) tests were conducted for variables recorded in ordinal scales (MMSE, NIH Stroke Scale). Analysis of covariance (ANCOVA) with the pretest score as the covariate was used to determine differences in the clinical outcomes measured across the 2 groups. The gait ability scale was reported in ordinal data; therefore, the raw scores were ranked, and the ANCOVA was conducted based on the ranks by using the baseline ranks as the covariates. 33 Because this was a pilot study, we were interested in determining effect sizes for the measures. The effect sizes were calculated by the difference between the adjusted means of the STAT group and regular group divided by the averaged standard deviation (SD) at baseline. 34 RESULTS Between February 1999 to June 2000, about 50 stroke survivors admitted to the rehabilitation unit at the VAMC Houston were screened. Fifteen men fulfilled the criteria and voluntarily agreed to participate in this study. However, 2 participants were dropped from the study (one from the STAT intervention because he did not complete at least 9 STAT sessions; one from the regular intervention because of pulmonary complications). Seven participants were randomly assigned to regular intervention, and 6 patients were assigned to the experimental group (STAT intervention). Table 1 depicts information on demographics, level of cognition (MMSE), impairment (NIH Stroke Scale), number of days since the stroke, and hours of rehabilitation each group received. All participants had cerebrovascular accidents documented clinically; computerized tomography or magnetic resonance imaging results were also noted. Table 2 summarizes information on type of lesion, location, comorbidities, and medications for all participants. The 2 groups had no significant differences in demographics, impairment, and cognition or in the number of days since the

4 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha 1261 Table 1: Sample Characteristics Regular (n 7) STAT (n 6) Mean SD Min Max Mean SD Min Max P Age (y) Height (cm) Weight (kg) MMSE * NIH Stroke Scale * Days since stroke Hours of rehabilitation * Nonparametric procedure (Wilcoxon) used for statistical significance. stroke. Although this was not significant, the regular intervention group had more variability in age, weight, and the time since the stroke. A mean score of less than 6 on the NIH Stroke Scale for both groups revealed that the subjects were moderately impaired, which, according to Adams et al, 35 predicts good chance of recovery. A mean MMSE score over 25 for both groups suggests that the participants had no major dementia. The mean number of days from the onset of symptoms until entry into rehabilitation was 2 weeks for both groups; thus, the patients were within an acute phase of recovery. Despite the randomization, the clinical outcomes revealed that the STAT group tended to start off with slightly better scores in all gait parameters, thus requiring the use of the pretest scores as covariates. Table 3 depicts information on individual scores for each variable analyzed. Table 4 shows the means and SDs, and 95% confidence intervals for both groups, pre- and postinterventions. The ANCOVAs did not show any statistically significant differences between the 2 interventions, for any of the dependent variables analyzed. Although the statistical analysis performed on the gait ability scores was based on the variability of the ranks, a meaningful interpretation should be based on the raw FAC scores. The preand postmedian scores for both groups were equal, that is, 1 and 3, respectively, for both regular and STAT interventions (table 3). This means that, in general, the participants in both groups required firm continuous support from 1 person to help with walking and with balance at the beginning of rehabilitation. Both groups improved similarly at the end of the intervention, attaining a median score of 3 in the FAC Scale, which shows that participants required verbal supervision or stand-by help from 1 person without physical contact by discharge. After intervention, the STAT group had 5 participants who scored 2 or more (needs continuous or intermittent support of 1 person to help with balance or coordination), and only one who still scored 0 (patient cannot walk or requires help of 2 or more people). In the regular group, 4 subjects scored 2 or more, but 3 still scored 0 after intervention. Two patients in the regular group could not walk 5m continuously on the pretest and scored zero on this variable. One subject walked 5m but had to rest 3 times to cover this distance and the other walked just 1m. Therefore, the variability in the initial gait speed in the regular intervention group was higher, and had a mean value of.12.15m/s. The pretest gait speed for the regular intervention group was a third less than that of the STAT group (.37.25m/s). After intervention, the STAT group attained a mean speed of.59.29m/s compared with.27.23m/s for the regular group (table 4). This generated a moderate effect size of 0.4 SDs units. 34 The initial walking distance for both groups was also quite different. The STAT group covered about 64m (or 4.6 times) more than the regular group ( m vs m, respectively; fig 1). After the interventions, this difference in distance increased to approximately 110m between the 2 groups ( m vs m, accordingly) (table 4). The variability remained high for both groups, especially for the regular group. The walk distance results for the STAT intervention, when compared to the regular intervention, generated a large effect size of 1.16 SD units. 34 The amount of oxygen consumed during the 5-minute walk test (gait energy expenditure) was similar compared with the Table 2: Subject Characteristics Subject Group Type of Injury Location Comorbidity Medication 1 Reg Ischemic R internal capsulae HTN 2, 4 2 Reg Ischemic R basal ganglia HTN, NIDDM, CAD 1, 4 3 Reg Ischemic L internal capsulae HTN, NIDDM, CAD, COPD 7 4 Reg Ischemic L cerebral hemisphere and thalamus HTN, NIDDM 1, 2, 3, 4, 6 5 Reg Ischemic R temporal lobe cortex HTN, PVD, NIDDM 1, 2, 5 6 Reg Ischemic L frontal lobe HTN 1, 2, 3, 4 7 Reg Ischemic R subcortical HTN 1, 2, 3, 7 8 STAT Ischemic Brainstem HTN 1, 2, 4 9 STAT Ischemic L cerebellar cortex HTN, NIDDM 1, 2, 3, 4, 7 10 STAT Hemorrhagic L thalamic HTN, 1, 3, 4 11 STAT Ischemic L pontine HTN 4 12 STAT Ischemic L frontal lobe HTN, NIDDM 1, 3, 6 13 STAT Ischemic L pontine HTN 4 Abbreviations: Reg, controls; R, right; L, left; HTN, hypertension; NIDDM, non insulin-dependent diabetes mellitus; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; PVD, peripheral vascular disease; 1, -blockers; 2, diuretics; 3, angiotensin-converting enzyme inhibitors; 4, calcium channel-blockers; 5, nitrates; 6, antiarrhythmic; 7, other.

5 1262 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha Table 3: Individual Scores for Each Outcome Variable Before and After Interventions GS (m/s) WD (m) GEE (mlo 2 kg 1 min 5 ) GEC (mlo 2 kg 1 m 1 ) Subject Group Pre Post Pre Post Pre Post Pre Post Pre Post 1 Reg Reg Reg Reg Reg Reg Reg STAT STAT STAT STAT STAT STAT Abbreviations: GS, gait speed; WD, walking distance; GEE, gait energy endurance; GEC, gait energy cost; FAC, functional ambulation category. FAC distance covered by each group. The energy expenditure observed in this test was only 1.2 times more in the STAT group compared with the regular intervention at baseline ( mLO 2 kg 1 min 5 vs mLO 2 kg 1 min 5, respectively) (table 4). After intervention, the STAT group had an energy expenditure of mLO 2 kg 1 min 5, whereas the regular group had mLO 2 kg 1 min 5, also 1.2 times higher in the STAT group (table 4). This indicates that the effort to perform the walk test was comparatively higher for the regular group, mainly at the beginning of the study. A moderate effect size of 0.3 SD units was obtained with the gait energy expenditure. 34 The oxygen consumed per meter (gait energy cost) during the 5-minute walk was highly variable with the regular intervention group, especially at baseline ( mLO 2 kg 1 m 1 ), because there were 2 participants who, during the 5 minutes, were able to walk just 1 and 5m, respectively. Therefore, the difference between the 2 groups was notable, even though it failed to reach statistical significance. After intervention, the STAT group still showed lower gait energy costs per meter walked as compared with the regular group ( mlo 2 kg 1 m 1 vs mLO 2 kg 1 m 1, respectively) (table 4). The gait energy cost variable generated a large effect size of 0.7 SD units. 34 The regular intervention received a mean of hours of intervention, whereas the STAT group received hours, which was not statistically different (table 1). However, 1 subject in regular intervention received a total time of 108 hours of rehabilitation. Without this patient, the rehabilitation time in this group had a mean of hours of intervention, which is similar to the STAT group. This showed that we were able to equalize the time of intervention between the 2 groups so that time spent in therapy could not be considered a confounding factor. DISCUSSION Using the STAT for early gait training with acute stroke survivors in this pilot study yielded promising results. STAT is feasible and safe to use with stroke survivors even during acute rehabilitation. The sample studied constituted individuals with sequelae who could benefit from a rehabilitative intervention. At baseline, the NIH Stroke Scale and the FAC Scale scores did not differ for the 2 groups, although the performance-based gait tests showed that the groups were not similar, despite randomization. FAC Scale scores were able to detect changes after both interventions but had less discrimination when contrasted with the gait parameters. Consequently, the continuous variables used in this study to objectively characterize this population and to determine changes after intervention showed better discriminatory capabilities as compared with qualitative ordinal scales. Table 4: Gait Parameters Pre- and Postinterventions Regular (n 7) STAT (n 6) Mean SD 95% CI Mean SD 95% CI Ability Pre Post Speed (m/s) Pre to Post Distance (m) Pre Post Energy expenditure (mlo 2 kg 1 min 5 ) Pre Post Cost (mlo 2 kg 1 m 1 ) Pre to Post Abbreviations: CI, confidence interval.

6 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha 1263 Fig 1. Individual changes in walking distance. Each line represents a single participant. Abbreviations: WD1, initial walking distance; WD2, postintervention walking speed. There were no statistically significant results observed with any of the outcomes analyzed. However, for some of the variables, the effect size generated in this short intervention study was similar to or larger than the effect sizes for rehabilitation studies. Kwakkel et al 36 reported effect sizes of rehabilitation after stroke of.28,.37, and.10 SD units for variables including ADLs, neuromuscular capacity, and function, respectively. Ottenbacher and Barrett 37 reported a higher effect size with rehabilitation of.57 SD units. In our study, even though we had clinically significant effect sizes, the power to detect statistically significant changes with this preliminary study was low because of the small sample size. For example, for walking distance and gait energy costs, whose effect sizes were 1.16 and 0.7, respectively, the power was 50% and 20%. With gait speed and gait energy expenditure, in which the effect sizes were 0.4 and 0.3, respectively, the power to detect changes was even smaller ( 10%). Therefore, this pilot study warrants future studies with larger samples sizes. Gait speed in stroke survivors is quite variable, ranging from as low as.15m/s to over 1.0m/s. 3,38-40 Initial levels of gait speed have been correlated with recovery, 38,40,41 whereas discharge gait speed has been correlated with functional outcomes. 42 The reported range for walking speed recovery for stroke survivors was between.25 to.50m/s. 43 In our study, the initial gait speeds of m/s for the regular group and.36.25m/s for the STAT group suggested that our patients were substantially compromised, especially in the regular intervention group. The STAT group achieved a mean gait speed compatible with moderate community activities after a 3-week intervention, whereas the regular group achieved a gait speed compatible with unlimited household ambulation (.27.23m/s). 41,42 The change in gait speed between the 2 groups after intervention (.22m/s) was smaller than the differences observed between the 2 groups at baseline (.24m/s). This primarily shows how variable gait speed can be even in the early stages of rehabilitation. It may also reflect the fact that 3 subjects in the regular group had a gait speed equal to zero. However, the small effect size observed in this outcome after both interventions suggested that gait speed may not be the best measure for early stages of recovery after an acute stroke. The 5-minute walk test is primarily designed to measure endurance. It requires both some aerobic fitness and lower-limb strength. For acute stroke survivors, proper balance is also crucial for this test. The short initial distances in our study may reflect major deficits in these capacities. At baseline, there were differences between the 2 groups in terms of distance covered, with high variability, primarily in the regular group. However, the amount of oxygen consumed (gait energy expenditure) during this task was similar between the 2 groups. This indicates that the energy demand to perform the 5-minute walk was far higher in the regular group, which suggests that this group may have had less strength, aerobic fitness, and/or balance, and used more compensatory strategies. These differences are further supported by the gait energy cost when the amount of oxygen consumed per meter walked during the 5 minutes (gait energy cost) was much less in the STAT group. The gait energy expenditure for walking and gait energy costs in normal individuals (age range, 20 80y) is around 12.01mLO 2 kg 1 m 1 and.15 to.16mlo 2 kg 1 m 1,respectively. 44 For subacute (6wk poststroke) stroke survivors (average age, 54y), gait energy expenditure was reported to be 8.9mLO 2 kg 1 m 1, and gait energy cost was.34mlo 2 kg 1 m 1 at admission. 45 On discharge, the energy expenditure was 11.5mLO 2 kg 1 m 1, and the gait energy cost was.54mlo 2 kg 1 m If the gait energy expenditure observed in our study were averaged by the 5 minutes walked, at baseline, the regular and STAT groups would have an energy expenditure of 6.6 and 8.15mLO 2 kg 1 m 1, respectively. Our STAT group had similar baseline values compared with the previous report of energy expenditure, but expanded 2.5 times more gait energy cost than in a study by Hash 45 (.85 vs.34mlo 2 kg 1 m 1, respectively). This shows that immediately after a stroke, walking is performed with higher physiologic costs and less efficiently than normal walking. Thus, besides the impairment resulting from acute strokes, performance may be further compromised because of the high-energy demands frequently associated with compensatory strategies employed to walk. With the regular group, the increase in gait energy cost was primarily because of the fact that some patients could not walk, although they strove to perform this task during the 5-minute trial. After intervention, the regular group had an expenditure of 7.83mLO 2 kg 1 m 1, which is below the baseline value of the STAT group. The energy expenditure after intervention with the STAT group (9.7mLO 2 kg 1 m 1 ) was very similar to a previous report. 45 However, the cost per meter walked was lower. This indicates that after 3 weeks of the STAT intervention, the stroke survivors still had higher energy costs than normal walking for individuals without a stroke but lower energy costs than stroke patients who had undergone rehabilitation reported in the literature. Although the primary use of supported treadmill training is to restore gait function, it is possible that some aerobic training occurred during the 3 weeks of intervention. It is still unclear whether the improvement in energy use was because of recovery of motor function, aerobic training, or both. CONCLUSION This pilot study showed that STAT is a feasible and safe technique with which to perform gait training with individuals who survive strokes and undergo acute rehabilitation. Because the power of this study was low, it cannot be said that STAT is superior to regular training based on the clinical variables analyzed. The clinical outcome variables used revealed no

7 1264 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha significant differences between the samples studied. Clinically, the effect size obtained with the STAT intervention as compared with regular rehabilitation alone is quite promising. However, another trial, with a larger sample size, should be conducted to generate enough power to show statistical differences. Stratification of participants according to their initial gait speed is recommended because this outcome can be so variable at baseline. References 1. Gresham GE, Duncan PW, Stason WB, et al. Post-stroke rehabilitation. Clinical Practice Guideline No. 16. Rockville (MD): US Department of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research; May AHCPR Publication No Terent A. Stroke morbidity. In: Whisnant J, editor. Stroke: populations, cohorts, and clinical trials. Oxford: Butterworth-Heinemann; p Wade D, Wood V, Heller A, Maggs J, Hewer RL. Walking after stroke. 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8 GAIT OUTCOMES AND ACUTE STROKE REHABILITATION, da Cunha Hassid E, Rose D, Commisarow J, Guttry M, Dobkin B. Improved gait symmetry in hemiparetic stroke patients induced during body weight-supported treadmill stepping. J Neuro Rehabil 1997;11: Waters RL, Mulroy S. The energy expenditure of normal and pathologic gait. Gait Posture 1999;9: Hash D. Energetics of wheelchair propulsion and walking in stroke patients. Orthop Clin North Am 1978;9: Suppliers a. Aerosport, model KB1-C; MedGraphics, 350 Oak Grove Pkwy, St. Paul, MN b. Pneu-Weight Harness; Quinton Inc, Stair Master/Quinton, Willows Rd NE, Ste 100, Kirkland, WA c. Vigor Support System, 4915 Advance Wy, Stevensville, MI d. Woodway USA, W229 N591 Foster Ct, Waukesha, WI