Measurement of energy cost by the physiological cost index in walking after stroke

OBJECTIVE: To compare the Physiological Cost Index (PCI) with direct measurement of oxygen consumption (Vo(2)) as an estimate of energy cost in persons with stroke and healthy subjects. DESIGN: Test-retest on separate days. A comparison of 2 methods of measurement. Measurements with and without an orthosis. SETTING: A university hospital. PARTICIPANTS: A convenience sample of 20 persons with hemiparesis more than 6 months after stroke and 16 healthy subjects, ages 30 to 63 years. INTERVENTIONS: Five minutes of treadmill walking at self-selected speeds while recording Vo(2) levels and heart rates. Additional data was recorded for 11 of the stroke subjects with and without an ankle-foot orthosis. MAIN OUTCOME MEASURES: Vo(2) and the PCI. RESULTS: No significant differences were found in the PCI or Vo(2) between test and retest. Both PCI and Vo(2) per distance were higher for the stroke subjects compared with healthy subjects. PCI showed a larger dispersion than Vo(2) between test and retest. The regression analysis for PCI showed that the model including age, sex, group assignment, and Vo(2) could explain 53% of the variation. The PCI did not show a significant difference in walking with or without an orthosis, whereas Vo(2) differed significantly. CONCLUSIONS: The PCI showed limited reliability and validity as a measure of energy cost after stroke due to the extensive variability between test and retest.     

Assessing walking ability in subjects with spinal cord injury: validity and reliability of 3 walking tests

OBJECTIVE: To assess the validity and reliability of 3 timed walking tests (Timed Up & Go [TUG], 10-meter walk test [10MWT], 6-minute walk test) in subjects with spinal cord injury (SCI). DESIGN: Cross-sectional study and repeated assessments. SETTING: The SCI center of a university hospital in Switzerland. PARTICIPANTS: Validity was assessed by using the data of 75 patients with SCI, and reliability was determined with 22 patients with SCI. INTERVENTION: Patients performed the timed tests and the Walking Index for Spinal Cord Injury II (WISCI II) on the same day. Three measurements within 7 days were taken to assess reliability. MAIN OUTCOME MEASURES: The measures were scatterplots, correlation coefficients ( r ), and the Bland-Altman plot. Validity was determined in patients with different walking abilities. RESULTS: Overall, correlation of the 3 timed walking tests was excellent with each other (| r |>.88) and moderate with the WISCI II (| r |>.60). The correlation between the timed tests for patients with poor walking ability remained high (| r |>.70) but decreased in WISCI II (| r |<.35). High correlation coefficients ( r >.97) were found for intra- and interrater reliability. However, TUG and 10MWT reliability were negatively influenced by a poor walking function. CONCLUSIONS: The 3 timed tests are valid and reliable measures for assessing walking function in patients with SCI.     

Oxygen consumption during machine-assisted and unassisted walking: a pilot study in hemiplegic and healthy humans

OBJECTIVE: To determine whether a gait-training (GT) machine influenced walking time duration and oxygen consumption in hemiplegic patients. DESIGN: Repeated measures with comparison of 2 groups. SETTING: Physiology laboratories in a rehabilitation hospital. PARTICIPANTS: Seven patients with stroke-related hemiplegia (2 men, 5 women; age, 46+/-11y; time since stroke, 12+/-9wk) and 7 healthy subjects (3 men, 4 women; age, 30+/-7y). INTERVENTIONS: Floor walking (FW) and GT-assisted walking with and without 50% body-weight support (BWS). MAIN OUTCOME MEASURES: Walking time duration, oxygen consumption (Vo(2)), minute ventilation (V(E)), and heart rate. RESULTS: When the condition effect was analyzed independently from the group, mean Vo(2) was higher during FW than during the GT tests (post hoc analysis: FW vs GT, P=.017; FW vs GT+BWS, P<.002). When the groups were compared independently of the condition, the group with hemiplegia had a significantly shorter walking time duration (analysis of variance [ANOVA], P<.001) and a significantly higher Vo(2) as a percentage of baseline (ANOVA, P=.03), compared with the controls. Walking time duration was influenced by walking condition (ANOVA, P<.001; post hoc analysis: FW vs GT, P<.001; FW vs GT+BWS, P<.001). Ve was influenced by walking condition (ANOVA, P=.043; not significant in the post hoc analysis) and was higher in the group with hemiplegia (ANOVA, P=.02). Heart rate was not influenced by walking condition (P=.11). A group effect was found with heart rate in cycles per minute (P=.035) but not as a percentage of baseline. No interaction was found between the ANOVA group-effect factor and the ANOVA walking-condition effect factor. CONCLUSIONS: Compared with FW, GT assistance increased walking time duration and reduced Vo(2) in patients with severe hemiplegia.     

Predicting the oxygen cost of walking in hemiparetic stroke patients

Objective

To verify the relation between spontaneous walking speed (Sfree) and oxygen cost of walking at Sfree (Cwfree) in post-stroke hemiparetic patients and to test the validity of a prediction model to estimate Cwfree based on Sfree.

Quantitative assessment of the stops walking while talking test in the elderly

OBJECTIVE: To examine whether trunk sway and walking speed differ between elderly "stoppers" and "nonstoppers" during a shorter version of the stops walking while talking (SWWT) test-an observational assessment of impaired dual-task performance-and during a normal walking trial. DESIGN: The original SWWT test was administered on the way to the test room (over a distance of 150m). Then, subjects were asked to walk 2 trials of 8m while wearing a trunk sway measuring device strapped firmly to their lower back. For the first 8-m trial, no questions were asked (control trial). During the second 8-m trial, subjects were asked an easy question (What is your age?) after walking 2m. SETTING: Long-stay geriatric care unit in Switzerland. PARTICIPANTS: Seventeen institutionalized elderly (16 women, 1 man; mean age, 86.3y; range, 79-93y). Subjects had to be able to walk at least 150m and to understand simple questions. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The amplitude of trunk sway angle and angular velocity in the forward-backward (pitch) and side-to-side (roll) directions and the duration of each trial were compared between the two 8-m walking trials with and without a question among subjects who did and did not come to a complete stop. RESULTS: In the original SWWT test, 4 persons stopped walking while talking, compared with 8 persons who stopped in the short (8-m) walking trial when a question was asked. Persons who stopped during the 8-m trial when a question was asked had significantly longer walking durations (by 19s) and larger trunk roll angular displacements (by 5.5 degrees ) during trials, both with and without a question. For both stoppers and nonstoppers, duration was longer during the trial when a question was asked. CONCLUSION: A fixed and brief walking distance, coupled with a single sudden question, provided an effective method of identifying subjects who stop walking while talking. These subjects are those who have slower walking speeds and more unstable trunk control in the roll plane even under normal walking conditions. Our findings support the predictive capabilities of a brief SWWT test for the unstable and fall-prone elderly, as well as the usefulness of objective trunk sway measures to identify gait instabilities.     

The effects of prosthetic foot design on physiologic measurements, self-selected walking velocity, and physical activity in people with transtibial amputation

OBJECTIVE: To investigate the physiologic differences during multispeed treadmill walking and physical activity profiles for the Otto Bock C-Walk foot (C-Walk), Flex-Foot, and solid ankle cushion heel (SACH) foot in people with transtibial amputation. DESIGN: A repeated-measures design with 3 prostheses. SETTING: Research laboratory. PARTICIPANTS: Eight men with unilateral transtibial amputation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Physiologic responses (energy expenditure, gait efficiency, exercise intensity, rating of perceived exertion [RPE]) during multispeed treadmill walking (53.64, 67.05, 80.46, 93.87, 107.28 m/min) test were analyzed with 2-way repeated-measures analysis of variance (ANOVA). One-way ANOVA was employed to analyze foot-type differences for self-selected walking velocity (SSWV), and steps per day (daily activity). Analysis of covariance was used to analyze foot-type differences with SSWV as the covariable for the physiologic measurements. RESULTS: The C-Walk had a trend of improved physiologic responses compared with the SACH; however, no foot-type differences were statistically significant. Compared with the C-Walk and SACH, the Flex-Foot showed no significant differences in energy expenditure and gait efficiency, but significantly lower percentage of age-predicted maximum heart rate and RPE values. CONCLUSIONS: The energy storing-releasing feet appeared to have certain trends of improved gait performance compared with the SACH; however, not many objective foot-type differences were significantly noted. Further studies with a larger sample size are suggested.     

Physiological responses to body weight--supported treadmill exercise in healthy adults

Hoffman MD, Donaghe HE. Physiological responses to body weight–supported treadmill exercise in healthy adults.

Objective

To determine whether the relationships of heart rate, rating of perceived exertion (RPE), and ground reaction forces (GRFs) with oxygen consumption rate (V?o₂) during treadmill exercise are altered by partial body weight support (BWS) via lower-body positive pressure.

Design

Repeated-measures design.

Setting

Exercise physiology laboratory.

Participants

Healthy, active adults (N=12); mean age ± SD, 45.1±12.6 years.

Interventions

Not applicable.

Main Outcome Measures

V?o₂, heart rate, RPE, and GRFs were measured during walking and running at 3 levels (0%, 25%, 50%) of BWS. Before exercise, standing heart rate and blood pressure were measured under each BWS condition.

Results

Standing heart rates were 7 beats/min lower (P<.05) and systolic blood pressures were 10mmHg higher (P<.001) at 50% BWS compared with 0% BWS, but mean blood pressure while standing and the relationship of heart rate with V?o₂ during walking and running were not altered by BWS. While walking, the RPE at a V?o₂ of 10 mL · kg^–1 · min^–1 was statistically lower (P<.05) at 0% BWS compared with 25% and 50% BWS (mean values, 7 vs 8 points), but RPE was not different among conditions while running at a V?o₂ of 25 mL · kg^–1 · min^–1. Peak normal GRFs at specified V?o₂ levels and RPE values were reduced (P<.05) with increasing BWS for walking and running.

Conclusions

Because partial BWS does not alter the relationship of heart rate with V?o₂ during exercise and has minimal effect on the relationship of RPE with V?o₂, training heart rate and RPE values do not appear to require adjustment with partial BWS. Reduced GRFs at specified V?o₂ levels from partial BWS suggest that there are important clinical applications of this technology.     

The assessment of walking capacity using the walking index for spinal cord injury: self-selected versus maximal levels

OBJECTIVES: To assess (1) the frequency and magnitude of differences between self-selected and maximal walking capacity following spinal cord injury (SCI) by using the Walking Index for Spinal Cord Injury (WISCI) and (2) how these levels differ in efficiency and velocity. DESIGN: Prospective cohort. SETTING: Academic medical center. PARTICIPANTS: Fifty people with chronic incomplete SCI. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects ambulated at the level used in the community (self-selected WISCI) and the highest level possible (maximal WISCI). Velocity (in m/s), Physiological Cost Index (PCI), and Total Heart Beat Index (THBI) were calculated. Differences were compared using the paired t test (parametric) or Wilcoxon signed-rank test (nonparametric). RESULTS: For 36 subjects, maximal WISCI was higher than self-selected WISCI; 21 subjects showed an increase of 3 levels or more. Ambulatory velocity was higher for self-selected WISCI compared with maximal WISCI (.68 m/s vs .56 m/s, P<.001). PCI and THBI at self-selected WISCI were lower than at maximal WISCI (PCI, 0.99 beats/m vs 1.48 beats/m, P<.001; THBI, 3.39 beats/m vs 4.75 beats/m, P<.001). CONCLUSIONS: Many people with chronic SCI are capable of ambulating at multiple levels. For these people, ambulation at self-selected WISCI was more efficient as evidenced by greater velocity and decreased PCI and THBI. The findings have implications for assessing walking capacity within the context of clinical trials.     

Intensity and daily reliability of the six-minute walk test in moderate chronic heart failure patients

OBJECTIVE: To assess the intensity and daily reliability of the six-minute walk test (6MWT) in patients with moderate chronic heart failure (CHF). DESIGN: Evaluation of testing protocol. SETTING: Hospitalized care. PARTICIPANTS: CHF patients under optimal drug treatment (CHF-D, n=12) or optimal drug treatment plus multisite cardiac pacing (CHF-P, n=12). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak values of oxygen uptake (VO2) and heart rate during a symptom-limited, treadmill exercise test and VO2, heart rate, and distance during 2 6MWT sessions (morning and afternoon). The 6MWT intensity was estimated by the ratio (%) of VO2 and heart rate values measured at the end of this test in relation to the respective peak values obtained during the treadmill exercise test. RESULTS: Subjects' VO2 and heart rate during the 6MWT were lower (P<.001) and were about 90% of the peak values (VO2: CHF-D, 90.5%+/-11.1%; CHF-P, 93.0%+/-13.2%; heart rate: CHF-D, 90.6%+/-6.6%; CHF-P, 91.4%+/-9.6%). The distance walked during both 6MWT sessions did not differ significantly, with low coefficients of variation (< or =2.0%) and high intraclass correlation coefficients (> or =.98). In CHF-D only, the patients' VO2 and heart rate were significantly (P<.01, P<.05, respectively) higher during the afternoon session. CONCLUSIONS: Despite an intensity significantly lower but close to that of the symptom-limited exercise test, the 6MWT was well tolerated in both CHF groups. In these populations, the 6MWT is reliable on a daily basis, for the distance walked. However, for assessing VO2 and heart rate values in CHF-D patients, the 6MWT must always be performed at the same time of day.     

Equations for estimating the oxygen cost of walking in stroke patients: Systematic review

ObjectiveTo report all equations that can potentially be used to estimate the oxygen cost of walking (Cw) without using a respiratory gas exchange analyzer and to provide the level of reliability of each equation.Data sourcesWebline, Medline, Scopus, ScienceDirect, Bielefeld Academic Search Engine (BASE), and Wiley Online Library databases from 1950 to August 2019 with search terms related to stroke and oxygen cost of walking.MethodsThis systematic review was reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the methodological quality of included studies was determined with the Critical Appraisal Skills Programme (CASP).ResultsWe screened 2065 articles, and 33 were included for full-text analysis. Four articles were included in the data synthesis (stroke individuals = 184). Analysis reported 4 equations estimating Cw that were developed from logistic regression equations between Cw and self-selected walking speed. The equations differed in several methodological aspects (characteristics of individuals, type of equation, Cw reference measurement methods). The Compagnat et al. study had the highest quality (CASP score = 9/9).ConclusionsThis literature review highlighted 4 equations for estimating Cw from self-selected walking speed. Compagnat et al. presented the best quality parameters, but this work involved a population restricted to individuals with hemispheric stroke sequelae.     

行走受损问卷在2型糖尿病患者中应用的信效度评价

目的 评价中文版行走受损问卷(WIQ)在2型糖尿病患者行走能力评估中的信效度.方法 纳入2型糖尿病患者126例,以中文版WIQ问卷、简明健康调查问卷(SF-36)及6 min步行试验(6MWT)为研究工具行资料收集,用信度分析、相关分析、两样本t检验等统计方法评价量表信效度.结果 WIQ量表总的Cronbach's α系数为0.867;WIQ量表的距离、速度、爬梯维度评分及总评分与6 min行走距离(6MWD)相关;WIQ总评分与SF-36测量相同概念反映躯体健康的4个维度评分相关;不同年龄组间WIQ各维度及总评分比较差异显著.结论 中文版WIQ问卷信效度较好,简单、可靠、实用,可用于评估2型糖尿病患者的行走能力.     

How is walking speed related to muscle strength? A study of healthy persons and persons with late effects of polio

OBJECTIVES: To evaluate the relationship between walking speed and muscle strength in the lower extremities in healthy persons and in persons with late effects of polio and to compare the models for these relationships. DESIGN: Retrospective analysis. SETTING: University hospital department. PARTICIPANTS: An urban sample of 144 healthy men and women (age range, 40-79 y) and 234 (146 women, 88 men) subjects with late polio. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Muscle strength in the lower extremities was measured and combined into an index. Walking speed for spontaneous and maximal walking was measured. A nonlinear regression model was developed. RESULTS: Evidence was provided for the nonlinear relationship between walking speed and strength. A specific strength threshold could not be identified. The asymptote of this curve for maximal walking was 2.57 m/s in the healthy group and 2.02 m/s in the subjects with late effects of polio. A high body mass index (>25 kg/m2) lowered the asymptote. CONCLUSIONS: It is important to prevent strength decrease that approaches the critical level where a further reduction affects walking speed more evidently. The difference in the relationship between muscle strength and walking speed for the 2 groups studied may partly depend on biomechanic imbalance between muscle groups.     

Effects of different baggage carrying methods on walking while wearing an arm sling in simulated hemiplegic stroke patients

[Purpose] We aimed to clarify the effects of different baggage carrying methods on the movement of the trunk and pelvis while walking with an arm sling in simulated hemiplegic stroke patients. [Participants and Methods] The participants were 14 healthy young adults. Measurements were obtained using a three-dimensional motion analysis device in the following order: normal walking, walking with an arm sling on the upper left limb, walking with baggage on the right side, vertical walking, and diagonal walking. The range of motion of the trunk and pelvis during one walking cycle was analyzed. [Results] The range of motion of the lateral tilt of the pelvis significantly differed between normal and vertical walking, as well as between normal walking and diagonal walking. A significant difference was observed in the range of movement in pelvic rotation during the three walking cycles—walking with baggage, vertical walking, and diagonal walking. The range of movement in pelvic rotation was seemingly smaller under other conditions compared to that in normal walking. [Conclusion] It was shown that walking with restrictions on the upper limbs, such as wearing an arm sling or carrying baggage, may impose slight restrictions on the lateral tilt as well as on the rotation of the pelvis.     

Walking while talking: effect of task prioritization in the elderly

OBJECTIVE: To examine the effect of 2 instructions on the same walking while talking (WWT) task on task prioritization by nondisabled subjects. DESIGN: Cross-sectional survey with within subject comparisons. SETTING: Community-based sample. PARTICIPANTS: Older adults (N=189; mean age, 80.2+/-4.9y), who did not meet criteria from the Diagnostic and Statistical Manual, Fourth Edition, for dementia and were able to independently perform activities of daily living. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Verbal and gait measures on the same WWT task with 2 different instructions: paying attention to both talking and walking (WWT-C) and paying attention only to talking (WWT-T). RESULTS: Task prioritization effects were seen on walking but not on talking. Compared with their baseline normal walking velocity (without talking), subjects slowed down more on WWT-T (median change, 28.3%) than WWT-C (median change, 26.4%). Comparing the 2 WWT conditions, velocity and cadence was slower during WWT-T compared with WWT-C, with longer stride length. Verbal output was not significantly different on the 2 conditions. CONCLUSIONS: Changing instructions while maintaining the same cognitive and motor tasks on WWT in older adults result in task prioritization effects.     

早期康复治疗对急性脑血管意外偏瘫患者下肢运动功能的影响

目的 研究早期康复治疗对急性脑血管意外偏瘫患者下肢运动及上不行能力的影响。方法 随机选择68例脑血管意外（CVA）患者,分康复治疗组（37例）和常规治疗对照组（31例）。按照Bobath技术和Carr的运动再学习原理对康复组患者进行早期综合的康复治疗,平均治疗时间28d。采用Scandinavian中风量表(Scandinavian stroke scale,SSS)和Barthel指数量表进行运动和步行能力评价。结果 经康复治疗后偏瘫侧下肢运动及步行能力均明显提高,总的步行率达83.8％,较治疗前增加了51.4％。康复治疗组治疗前后和康复组与对照组治疗报比较有非常显著性意义（P＜0.01）。结论 早期康复治疗能促进脑血管意外偏送信患者下肢运动及步行能力的恢复,提高临床治疗效果。     

行走受损问卷在2型糖尿病外周动脉疾病患者中应用的信效度评价

目的评价中文版行走受损问卷在2型糖尿病外周动脉疾病患者行走能力评估中的信效度。方法纳入2型糖尿病患者126例,据踝肱指数(Ankle-Brachial Index,ABI)分为PAD组(ABI0.9,n=39)与非PAD组(ABI≥0.9,n=87),以中文版WIQ问卷、简明健康调查问卷(SF-36)及6min步行试验(Six-minute walk test,6MWT)为研究工具行资料收集,采用信度分析、相关分析、两样本t检验等统计学方法评价量表信效度。结果WIQ量表总的Cronbach’sα系数为0.91,组内相关系数(Intraclass correlation reliability,ICC)为0.89。PAD组WIQ量表的距离、速度、爬梯维度评分及总评分与6min行走距离(Six-minute walk distance,6MWD)相关(r=0.76、0.84、0.60、0.86,均P0.01)。PAD组WIQ各维度评分和总评分与SF-36生理功能(Physical Functioning,PF)、生理职能(Role-Physical,RP)维度评分相关(均P0.01)。校正年龄后,PAD组与非PAD组间WIQ各维度评分及总评分的差异有显著意义(均P0.01)。结论中文版行走受损问卷(WIQ)信效度较好,且简单、可靠、实用,可作为临床工具用于评估2型糖尿病外周动脉疾病患者的行走能力。     

Energy cost of the case Western reserve standing neuroprosthesis

OBJECTIVE: To determine the oxygen consumption of a person with C7 American Spinal Injury Association (ASIA) grade B tetraplegia using the Case Western Reserve/Veterans Administration (CWRU/VA) standing neuroprosthesis. DESIGN: Measure the oxygen consumption and carbon dioxide production of a person with C7 ASIA grade B tetraplegia at rest, standing in the parallel bars with the CWRU/VA system on, ambulating in the parallel bars, and transferring from a wheelchair to a mat with the system on. SETTING: University medical center. PARTICIPANT: A 26-year-old man with C7 ASIA grade B tetraplegia. The subject was a recipient of the CWRU/VA standing neuroprosthesis. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measurement of oxygen consumption and carbon dioxide production using a metabolic cart. RESULTS: Oxygen consumption of the subject was 1.22mL.kg(-1).min(-1) at rest. It was 4.7mL.kg(-1).min(-1) while standing in the parallel bars, 7.2mL.kg(-1).min(-1) while ambulating in the parallel bars, and 7.9mL.kg(-1).min(-1) when transferring from a wheelchair to a mat. CONCLUSIONS: Oxygen consumption of the subject when using the system is about 2 metabolic equivalent units, which is compatible with sustained use of the system for standing.     

The relation between walking capacity and clinical correlates in survivors of chronic spinal poliomyelitis

OBJECTIVES: To examine (1) common clinical measures that may influence walking performance in the six-minute walk test (6MWT) in people with chronic poliomyelitis and (2) the test-retest reliability of the 6MWT distance, lower-extremity muscle strength, balance, and balance confidence on separate trials. DESIGN: A prospective quasi-experimental study. SETTING: University-based postpolio clinic. PARTICIPANTS: Nineteen survivors of poliomyelitis (mean age, 62.2+/-1.9y; time since polio onset, 54.4+/-8.79y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: 6MWT distance, rate-pressure product (RPP), Physiological Cost Index (PCI), ratings of perceived exertion (RPE), pain, fatigue, strength, standing balance, balance confidence, limb-length discrepancy, and lung function. RESULTS: The 6MWT distance correlated with PCI, pretest pain, lower-extremity muscle strength, balance, balance confidence, corrected leg-length discrepancy, and lung function but not with RPP, RPE, posttest pain, or pretest and posttest fatigue. The PCI correlated with balance confidence and lung function. About 68% of the variance in 6MWT distance was accounted for by balance and pretest pain. The P value was set at .05. CONCLUSIONS: With stringent standardization of the 6MWT applied to survivors of poliomyelitis (a neuromuscular condition with a musculoskeletal component), reproducibility was high; hence, test validity and interpretation were enhanced. The 6MWT distance was useful in elucidating the relation between impairment and a functional activity-namely, walking-in survivors of poliomyelitis.