Treadmill training improves fitness reserve in chronic stroke patients.

OBJECTIVE: To investigate the hypothesis that treadmill training will improve peak fitness, while lowering the energy cost of hemiparetic gait in chronic stroke patients. DESIGN: Noncontrolled exercise intervention study with repeated-measures analysis. SETTING: Hospital-based senior exercise research center. PARTICIPANTS: Twenty-three patients (mean age +/- standard deviation [SD] 67 +/- 8 yr) with chronic hemiparetic gait after remote (>6 mo) ischemic stroke. INTERVENTION: Three 40-minute sessions of treadmill exercise weekly for 6 months. MAIN OUTCOME MEASURES: Peak exercise capacity (VO2peak) and rate of oxygen consumption during submaximal effort treadmill walking (economy of gait) by open circuit spirometry and ambulatory workload capacity before and after 3 and 6 months of training. RESULTS: Patients who completed 3 months of training (n = 21) increased their VO2peak +/- SD from 15.4 +/- 2.9 mL x kg(-1) x min(-1) to 17.0 +/- 4.4 mL x kg(-1) x min(-1) (p <.02) and lowered their oxygen demands of submaximal effort ambulation from 9.3 +/- 2 mL x kg(-1) x min(-1) to 7.9 +/- 1.5 mL x kg(-1) x min(-1) (p =.002), which enabled them to perform the same constant-load treadmill task using 20% less of their peak exercise capacity (62.3% +/- 17.2% vs 49.9% +/- 19.3%, p <.002). Gains in VO2peak and economy of gait plateaued by 3 months, while peak ambulatory workload capacity progressively increased by 39% (p <.001) over 6 months. CONCLUSIONS: Treadmill training improves physiologic fitness reserve in chronic stroke patients by increasing VO2peak while lowering the energy cost of hemiparetic gait, and increases peak ambulatory workload capacity. These improvements may enhance functional mobility in chronic stroke patients.     

Submaximal exercise in persons with stroke: test-retest reliability and concurrent validity with maximal oxygen consumption

OBJECTIVE: To establish the test-retest reliability and concurrent validity with maximum oxygen consumption (VO2max) for 3 submaximal exercise tests in persons with chronic stroke: (1) submaximal treadmill test, (2) submaximal cycle ergometer test, and (3) 6-minute walk test (6MWT). DESIGN: Prospective study using a convenience sample. SETTING: Free-standing tertiary rehabilitation center. PARTICIPANTS: A volunteer sample of 12 community-dwelling individuals who had a stroke with moderate motor deficits. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Heart rate, blood pressure, and oxygen consumption (VO2) were assessed during the exercise tests. RESULTS: Test-retest reliability was good to excellent for the exercise tests (maximal and submaximal tests). VO2 for all submaximal measures related to VO2max (r range, .66-.80). Neither the 6MWT distance, self-selected gait speed, nor hemodynamic measures related to VO2max. CONCLUSION: The VO2 measures of the submaximal exercise tests had excellent reliability and good concurrent validity with VO2max. Submaximal exercise tests may be a method by which to monitor the effects of interventions after a screening test (eg, symptom-limited graded exercise test, dobutamine stress echocardiograph).     

Exercise testing and training in a cancer rehabilitation program: the advantage of the steep ramp test

OBJECTIVE: To compare the short maximal exercise capacity test (steep ramp test) with the submaximal test to determine the most appropriate exercise test in cancer rehabilitation. DESIGN: A prospective study in which a submaximal test, a maximal short exercise capacity test (steep ramp test), and a maximal oxygen consumption test (Vo(2)max test) were performed before and after an 18-week training program. Vo(2)max testing, the criterion standard for the measurement of physical capacity, was compared with the submaximal test and the steep ramp test. SETTING: Community hospital and physiotherapy. PARTICIPANTS: Thirty-seven cancer survivors (10 men, 27 women) treated with chemotherapy. The subjects' mean age +/- standard deviation (SD) was 48+/-11 years. INTERVENTION: An 18-week training program including strength training, interval aerobic training, and home-based activities (endurance). MAIN OUTCOME MEASURES: Estimated Vo(2)max (submaximal test) and maximal workload (steep ramp test) were assessed during the exercise tests and compared with the results of the Vo(2)max test. RESULTS: A paired t test showed a significant improvement in Vo(2)max (+13%, P<.001) and maximal workload (+19%, P<.001) after the training program. This improvement was confirmed in the steep ramp test (maximal workload, +13%, P<.001) but not in the submaximal test (estimated Vo(2)max, +4%, P=.192). Pearson correlation quantified only a moderate correlation between the Vo(2)max test and the submaximal test and a high correlation between the Vo(2)max test and the steep ramp test. Intraclass correlation determined the test-retest reliability of the submaximal test (.873) and the steep ramp test (.996). A linear regression model (Vo(2)max, 6.7; steep ramp Wmax, +356.7) was estimated to predict Vo(2)max from the steep ramp test outcome, implying a prediction margin of +/-2 SDs (616 mL/min). CONCLUSIONS: The submaximal test proved to be invalid, whereas the steep ramp test seems to be a practicable, reliable, and valid test for the assessment of the training dose. The steep ramp test can be regularly repeated during the training program, providing information needed to readjust the training dose according to the progress made.     

Determinants of walking function after stroke: differences by deficit severity

OBJECTIVES: To investigate the relationship of cardiovascular fitness (Vo(2)peak), neurologic deficits in balance and leg strength, and body composition to ambulatory function after stroke and to determine whether these relationships differ between those with milder versus more severe gait deficits. DESIGN: Cross-sectional correlation study. SETTING: Outpatient clinic of an academic medical center. PARTICIPANTS: Seventy-four people (43 men, 31 women; mean age +/- standard deviation, 64+/-10y) with chronic hemiparetic stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Thirty-foot (9.1-m) walk velocity, 6-minute walk distance, Vo(2)peak, Berg Balance Scale score, bilateral quadriceps eccentric torque, total and regional lean mass, and percentage of fat mass. RESULTS: Short-distance walking correlated significantly with cardiovascular fitness, balance, paretic leg strength, nonparetic leg strength, percentage of body fat, and paretic lean mass but not with nonparetic lean mass. Long-distance walking correlated significantly with cardiovascular fitness, balance, paretic leg strength, nonparetic leg strength, and paretic lean mass but not with percentage of body fat or nonparetic lean mass. Stepwise regression showed that cardiovascular fitness, balance, and paretic leg strength were independently associated with long-distance walking (r(2)=.60, P<.001). Variance in long-distance walking was largely explained by balance for those who walked more slowly (<.48m/s) for short distances (r(2)=.42, P<.001) and by cardiovascular fitness for those who walked more quickly (>.48m/s) for short distances (r(2)=.26, P=.003). CONCLUSIONS: Short-distance walking after stroke is related to balance, cardiovascular fitness, and paretic leg strength. Long-distance walking ability differs by gait deficit severity, with balance more important in those who walk more slowly and cardiovascular fitness playing a greater role in those who walk more quickly. Improved understanding of the factors that predict ambulatory function may assist the design of individualized rehabilitation strategies across the spectrum of gait deficit severity in those with hemiparetic stroke.     

Validity and reliability of the modified shuttle walk test in patients with chronic obstructive pulmonary disease

OBJECTIVES: (1) To examine the concurrent criterion validity of the modified shuttle walk test (MSWT) by using the 6- (6MWT) and 12-minute walk test (12MWT), (2) to examine the concurrent criterion validity of the estimated maximum oxygen uptake (Vo2max) of the MSWT with actual Vo2max, and (3) to determine test-retest reliability of the MSWT in patients with chronic obstructive pulmonary disease (COPD). DESIGN: Validation study. SETTING: Outpatient pulmonary rehabilitation program. PARTICIPANTS: Thirty clinically stable adults with COPD. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects were randomly assigned to receive either the 6MWT and 12MWT or the MSWT first. The MSWT was repeated 1 week later (N = 30). Estimated Vo2max was calculated, and actual Vo2max was conducted by using the Jones test. Validity of the MSWT was assessed by comparing endurance scores and Vo2max with results from the 6MWT and 12MWT and Jones test, respectively. RESULTS: There was a moderately high correlation between the MSWT and the 6MWT and 12MWT at initial testing (.82 and .74, respectively). Correlation between estimated and actual Vo2max was r equal to .68. Test-retest reliability for the entire sample was high (intraclass correlation coefficient, .88). Results remained quite stable across severity, age, and sex subgroups. CONCLUSIONS: The MSWT is a standardized externally paced submaximal endurance walking test. The results indicate that the MSWT has high concurrent validity and test-retest reliability for patients with COPD.     

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.     

Reliability and validity of the six-minute arm test for the evaluation of cardiovascular fitness in people with spinal cord injury

OBJECTIVES: To design a submaximal arm ergometry test (six-minute arm test [6-MAT]), for persons with spinal cord injury (SCI) and to determine the test-retest reliability and concurrent validity of this test. DESIGN: Prospective, exploratory, methodologic study. To determine test-retest reliability, subjects completed the 6-MAT on 2 days, separated by 1 week. Validity was determined by comparing 6-MAT results with peak oxygen consumption (VO2peak). SETTING: Tertiary rehabilitation center. PARTICIPANTS: Thirty subjects with SCI (mean age, 36.3y; 83% male). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects were evaluated on the 6-MAT and a VO2peak test. RESULTS: All subjects were able to complete the 6-MAT. Test-retest reliability of steady-state oxygen consumption (VO2) and heart rate during the 6-MAT were excellent (intraclass correlation coefficient [ICC], .81; 95% confidence interval [CI], .58-.92; ICC=.90; 95% CI, .75-.96, respectively). The correlation between VO2peak and 6-MAT VO2 was excellent (r=.92) and the correlations between VO2peak and 6-MAT heart rate (r=.63) and VO2peak and 6-MAT power output (r=.73) were good. CONCLUSIONS: This study showed that the 6-MAT has acceptable values for test-retest reliability and validity. The 6-MAT should be further tested for responsiveness to enhance its use as a clinical tool.     

Predicting oxygen uptake for men and women with moderate to severe chronic obstructive pulmonary disease

OBJECTIVE: To develop regression equations for estimating peak oxygen consumption (Vo(2)) for men and women with moderate to severe chronic obstructive pulmonary disease (COPD) from the 6-minute walk test (6MWT). DESIGN: Multivariate analysis of patient pulmonary function and exercise gas exchange indices to 2 outcomes for the 6MWT (distance ambulated, calculated work [6M(WORK)]). SETTING: A university hospital and clinics. PARTICIPANTS: A total of 124 patients (90 men 34 women; age range, 45\N81y), from the community, with moderate to very severe COPD. Forced expiratory volume in 1 second (FEV(1)) ranged from.70 to 2.79L/min, forced vital capacity (FVC) ranged from 1.73 to 5.77L, and FEV(1)/FVC ranged from 24% to 69%. All patients were in stable condition at the time of testing and were on a stable drug regimen. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Pulmonary function testing was completed according to American Thoracic Society criteria. Cycle ergometry with gas exchange, by using a ramp protocol, was completed. The 6MWT was done in the hospital corridor, with distances recorded after each minute. Work capacity by each method was reduced from the normal predicted. RESULTS: Peak oxygen uptake (Vo(2)) averaged 1184+/-302mL/min for men and 860+/-256mL/min for women (58%, 68% of predicted, respectively). Ventilatory reserve was limited at an achieved peak ventilation (Ve) of 79.9%+/-19.1% of predicted. Borg scores for dyspnea and leg fatigue were equivalent for each test modality, with leg fatigue being slightly higher for each gender. 6M(WORK) for the 6MWT was the strongest independent predictor of peak Vo(2) (r=.81, P<.0001), whereas that for distance ambulated was correlated at r equal to.54 (P<.0001). This is a 36% improvement in the variance accounted for by the application of 6M(WORK) as the outcome for the 6MWT. Generalized regression modeling was then used to develop equations for the estimation of peak Vo(2) for the 6MWT. Additional variables included in the model were diffusing capacity of lung for carbon dioxide, FVC, maximal inspiratory pressure, weight (in kilograms), and age, with their appropriate interactions. This derived regression model accounted for 79% on the variance for estimation of peak Vo(2) in the patients studied. CONCLUSION: Peak Vo(2) can be estimated for men and for women by using the generalized equations presented. The calculation of 6M(WORK) is an improvement over distance ambulated as the 6MWT outcome. These data build on the existing body of knowledge for the 6MWT and extend its application for patients with COPD. Knowledge of the peak Vo(2) can be used for patient assessment, serial monitoring, evaluating disability, and as a common index of function across modalities. The calculation of 6M(WORK) outperformed distance ambulated and is easily converted to other indices of caloric expenditure that are commonly used in the laboratory and clinical settings.     

Metabolic cost of extremely slow walking in cardiac patients: implications for exercise testing and training

To assess metabolic cost of extremely slow walking, nine patients with coronary heart disease (means age, 56.1 yr) underwent multistage treadmill testing using standard open circuit calorimetry techniques. Heart rate, blood pressure, minute ventilation, and oxygen uptake in METS (1MET = 3.5 ml/kg/min) were determined at rest and at six submaximal work loads: 0.8, 1.0, 1.5, 2.0, 3.0 and 3.5mph, 0% grade. The oxygen uptake versus walking speed (0.8 to 3.5mph) relationship was y = 0.2064 (x)2 + 0.0180 (x) + 1.7260 (y = METS and x = speed in mph), r = 0.99. Results indicate that low-level exercise test protocols employing work loads between 0.8 and 2.0 mph impose similar metabolic and cardiac demands. Extremely slow walking approximates 2METS and may impose metabolic loads sufficient for exercise training in select patients with coronary heart disease.     

Walking with a rollator and the level of physical intensity in adults 75 years of age or older

OBJECTIVE: To determine whether walking with a rollator by persons 75 years of age or older is of sufficient intensity to improve aerobic fitness. DESIGN: A cross-sectional cohort study. SETTING: University movement laboratory. PARTICIPANTS: Fifteen subjects 75 years of age or older (mean age, 83.7 y) who could only walk by using a rollator. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: During 6 minutes of self-paced treadmill walking using a rollator at a mean walking speed of 0.6 m/s, oxygen uptake (Vo2), carbon dioxide production, and heart rate were determined. Respiratory exchange ratio (RER) and energy expenditure were calculated. The energy expenditure was expressed as the number of metabolic equivalents (METS), the percentage of estimated maximal Vo2 (Vo2max), the percentage of estimated Vo2max reserve, and the percentage of estimated maximal heart rate. RESULTS: Mean Vo2 was .718 L/min. Mean RER was .93 (95% confidence interval [CI], .89-.97). Thirteen participants showed an RER below 1.0, which indicates a negligible contribution of anaerobic expenditure. Walking with a rollator required a mean of 2.8 (95% CI, 2.4-3.2) METS, 71.9% of Vo2max (95% CI, 65.2%-78.6%), 50.5% (95% CI, 39.4%-61.5%) of Vo2 reserve, and 75.2% (95% CI, 67.6%-82.8%) of estimated maximal heart rate. CONCLUSIONS: For people 75 years of age or older, walking with a rollator is an activity of moderate to high level of intensity, with the capacity of improving aerobic fitness.     

Influence of walking speed on lower limb muscle activity and energy consumption during treadmill walking of hemiparetic patients.

OBJECTIVE: To identify the relationship between treadmill speed and energy consumption and lower limb muscle activity in ambulatory hemiparetic patients. DESIGN: Experimental cohort. SETTING: Inpatient rehabilitation clinic. PARTICIPANTS: Twenty-four ambulatory hemiparetic subjects. INTERVENTION: Subjects walked harness-secured on the treadmill with no body-weight support at self-reported (V SAS), slow (V SAS - 25%), and fast (V SAS + 25%) speed. MAIN OUTCOME MEASURES: Assessment of basic, limb-dependent cycle parameters, lower limb muscle activity, and energy consumption. RESULTS: Cadence (r = .75), stride length (r = .78), relative double-support duration (r = .31), mean muscle activity of the paretic tibialis anterior (r = .12), gastrocnemius (r = .37), vastus lateralis (r =.19), rectus femoris (r = .31), and biceps femoris (r = .45) muscles, as well as heart rate (r = .54), correlated positively with treadmill speed. Mean maximum heart rate was 131 beats/min. Energy (r = -.67) and cardiac cost (r = -.55) correlated negatively with gait speed (ie, patients walked more efficiently at faster velocities). The qualitative muscle activation pattern analysis revealed earlier (more normal) onset of activation of gastrocnemius, vastus lateralis, biceps femoris, and gluteus medius. CONCLUSIONS: Patients should try to walk fast on the treadmill, thereby facilitating relevant weight-bearing muscles and improving gait efficiency.     

Step training with body weight support: effect of treadmill speed and practice paradigms on poststroke locomotor recovery

OBJECTIVE: To investigate the effect of practice paradigms that varied treadmill speed during step training with body weight support in subjects with chronic hemiparesis after stroke. DESIGN: Randomized, repeated-measures pilot study with 1- and 3-month follow-ups. SETTING: Outpatient locomotor laboratory. PARTICIPANTS: Twenty-four individuals with hemiparetic gait deficits whose walking speeds were at least 50% below normal. INTERVENTION: Participants were stratified by locomotor severity based on initial walking velocity and randomly assigned to treadmill training at slow (0.5mph), fast (2.0mph), or variable (0.5, 1.0, 1.5, 2.0mph) speeds. Participants received 20 minutes of training per session for 12 sessions over 4 weeks. MAIN OUTCOME MEASURE: Self-selected overground walking velocity (SSV) was assessed at the onset, middle, and end of training, and 1 and 3 months later. RESULTS: SSV improved in all groups compared with baseline (P<.001). All groups increased SSV in the 1-month follow-up (P<.01) and maintained these gains at the 3-month follow-up (P=.77). The greatest improvement in SSV across training occurred with fast training speeds compared with the slow and variable groups combined (P=.04). Effect size (ES) was large between fast compared with slow (ES=.75) and variable groups (ES=.73). CONCLUSIONS: Training at speeds comparable with normal walking velocity was more effective in improving SSV than training at speeds at or below the patient's typical overground walking velocity.     

六分钟步行试验与摄氧量的相关性研究

背景:6 min步行试验是一种亚极量水平的运动试验,其操作简便、费用低廉,因而应用较广泛,然而将步行距离转换为最大运动能力是不易的.目的:课题组创新性地在6 min步行实验中引入做功的概念,将无线遥测呼吸气体分析仪同时应用于6 min步行试验和心肺运动试验,分析6 min步行试验中的距离、做功与峰值摄氧量与Bruce方案测得的最大摄氧量之间的相关性.设计、时间及地点:实验于2009-03/05在南京东南大学附属中大医院康复医学科完成.对象:健康受试者来自在中大医院康复医学科实习的学生,共25名,男14名,女11名;年龄(22.0±2.3)岁.方法:25名志愿者先按Bruce方案进行极量心肺运动试验,检测每位受试者极量运动时的最大摄氧量和无氧阈,再接受6 min步行试验,测量每位受试者的6 min步行距离、做功和峰值摄氧量.心肺运动试验和6 min步行试验均采用便携式K4b~2气体分析仪实时检测气体交换参数,以获得最大摄氧量和峰值摄氧量.主要观察指标:①摄氧量、心率、呼吸频率随时间的变化规律.②步行距离、做功、摄氧量、心率、呼吸频率的前后比较.③心肺运动试验中的最大摄氧量、无氧阈与6 min步行试验中的峰值摄氧量比较.④距离、做功与峰值摄氧量、最大摄氧量之间的相关性.结果:心肺运动试验测得的无氧阈与6 min步行试验测得的峰值摄氧量之间差异无显著性意义(P > 0.05).6 min步行距离与峰值摄氧量和最大摄氧量均无明显相关;6 min步行做功与峰值摄氧量呈线性相关(r=0.779 7,P < 0.001);6 min步行做功与最大摄氧量亦呈线性相关(r=0.894 1,P < 0.001).结论:6 min步行试验是一种无氧阈水平的运动试验.6 min步行做功既可反映受试者亚极量运动的能力,也能反映受试者极量运动的能力.     

Effects of circuit resistance training on fitness attributes and upper-extremity pain in middle-aged men with paraplegia

OBJECTIVE: To examine the effects of circuit resistance exercise (CRT) training on muscle strength, endurance, anaerobic power, and shoulder pain in middle-aged men with paraplegia. DESIGN: Repeated testing. SETTING: Academic medical center. PARTICIPANTS: Seven men (age range, 39-58y) with motor-complete paraplegia from T5 to T12 and confirmed shoulder pain occurring during daily activities. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects underwent a 4-month CRT program using alternating resistance maneuvers and high-speed, low-resistance arm exercise. One-repetition maximal force was measured before training and monthly thereafter. Pretraining and posttraining peak oxygen uptake (Vo(2)peak) was measured by graded arm testing. Anaerobic power was measured before and after training using a 30-second Wingate Anaerobic Test. Shoulder pain was self-evaluated by an index validated for people with spinal cord injury (Wheelchair Users Shoulder Pain Index [WUSPI]). RESULTS: Strength increases ranging from 38.6% to 59.7% were observed for all maneuvers (P range, .005-.008). Vo(2)peak increased after training by 10.4% (P=.01), and peak and average anaerobic power increased by 6% (P=.001) and 8.6% (P=.005), respectively. WUSPI scores +/- standard deviation were lowered from 31.9+/-24.8 to 5.7+/-5.9 (P=.008), with 3 of 7 subjects reporting complete resolution of shoulder pain. CONCLUSIONS: CRT improves muscle strength, endurance, and anaerobic power of middle-aged men with paraplegia while significantly reducing their shoulder pain.