Treadmill Walking In Patients Research Articles

Biomechanical Effects of Manipulating Preferred Cadence During Treadmill Walking in Patients With ACL Reconstruction.

Abnormal gait is common after anterior cruciate ligament reconstruction (ACLR) which may influence osteoarthritis risk in this population. Yet few gait retraining options currently exist in ACLR rehabilitation. Cueing cadence changes is a simple, low-cost method that can alter walking mechanics in healthy adults, but few studies have tested its effectiveness in an ACLR population. Here, we evaluated the acute effects of altering cadence on knee mechanics in patients 9 to 12 months post ACLR. Cueing larger steps will facilitate larger knee angles and moments, while cueing smaller steps would induce smaller knee angles and moments. Randomized cross-sectional design. Level 3. Twenty-eight patients with unilateral ACLR underwent gait assessments on a treadmill at preferred pace. Preferred walking gait was assessed first to obtain preferred cadence. Participants then completed trials while matching an audible beat set to 90% and 110% of preferred cadence in a randomized order. Three-dimensional sagittal and frontal plane biomechanics were evaluated bilaterally. Compared with preferred cadence, cueing larger steps induced larger peak knee flexion moments (KFMs) and knee extension excursions bilaterally (P < 0.01), whereas cueing smaller steps only reduced knee flexion excursions (P < 0.01). Knee adduction moments remain unchanged across conditions and were similar between limbs (P > 0.05). Peak KFMs and excursions were smaller in the injured compared with uninjured limb (P < 0.01). Frontal plane gait outcomes were unchanged across conditions suggesting acute cadence manipulations result in mainly sagittal plane adaptations. Follow-up studies using a longitudinal cadence biofeedback paradigm may be warranted to elucidate the utility of this gait retraining strategy after ACLR. Cueing changes in walking cadence can target sagittal plane knee loading and joint range of motion in ACLR participants. This strategy may offer high clinical translatability given it requires relatively minimal equipment (ie, free metronome app) outside of a treadmill.

Coactivation pattern in leg muscles during treadmill walking in patients suffering from intermittent claudication

BackgroundIn patients with peripheral arterial disease and presenting intermittent claudication (PAD-IC), the pain due to ischemia impacts gait parameters, particularly in cases of unilateral disease. Deterioration of gait parameters in a pathological context is frequently associated with increased coactivation (simultaneous activation of agonist and antagonist muscles around a joint). Research questionDoes unilateral PAD-IC affect the coactivation pattern during walking? Does the coactivation pattern change with increasing pain intensity? MethodWe evaluated symptomatic and asymptomatic legs in 17 subjects with unilateral PAD-IC and 16 without PAD-IC (control group), during walking. Tibialis anterior (TA) and gastrocnemius medialis (GM) electromyographic activity, and peaks of vertical ground reaction force were recorded in this prospective study. We analyzed the coactivation index (CI(GM/TA)) during three periods (pain-free, pain and maximum pain) and phases of the gait cycle. Statistical analysis was carried out using the ANOVA procedure. ResultsDuring single support, CI(GM/TA) increases in the symptomatic leg during the pain period (+28 %) and in the asymptomatic leg during the maximum pain period (+29 %). During second double support, CI(GM/TA) increases in the symptomatic leg only (+49 %). In these gait phases, pain elicits differences in CI(GM/TA) between legs (p < 0.05). Second peak force decreases in the symptomatic leg only (−9%) and is negatively correlated with CI(GM/TA) during the three periods (r = −0.57; −0.76 and −0.78 respectively, p < 0.05). No difference is found in the control group. SignificanceThe appearance and development of pain in the lower limbs is associated with a higher level of CI(GM/TA), revealing a compensatory gait pattern in PAD-IC patients. Optimal prevention, rehabilitation and re-training strategies for PAD-IC patients should take into consideration neuromuscular compensatory mechanisms between asymptomatic and symptomatic legs.

Discriminant validity and reproducibility of spatiotemporal and kinetic parameters during treadmill walking in patients with knee osteoarthritis

BackgroundInstrumented treadmills are potentially useful tools for the assessment of gait parameters in orthopaedic clinical settings, but their measurement properties remain uncertain. Research questionWhat is the discriminant validity and reproducibility of spatiotemporal and kinetic gait parameters measured by a pressure-instrumented treadmill at different speeds and inclinations in patients with knee osteoarthritis (KOA)? MethodsA total of 54 patients with unilateral KOA and 23 healthy controls took part in the study. Step length, single-limb support duration and ground reaction force were recorded during level and uphill walking at 3 and 4 km/h using a commercially-available treadmill instrumented with an integrated pressure platform. We examined discriminant validity (difference between involved and uninvolved side as well as against healthy controls) and test-retest reproducibility (reliability and agreement). ResultsSignificant side differences were observed for single-limb support duration and ground reaction force at touchdown in all conditions (P < 0.05). All the investigated gait parameters showed acceptable reliability and agreement, except step length at 4 km/h uphill. SignificanceWe conclude that the pressure-instrumented treadmill used in this study may have good clinical utility for quantitative gait analysis in patients with KOA under different experimental conditions.

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls

BackgroundImprovement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable. Research questionWhat is the test-retest reliability of six stability outcome measures during gait? MethodsPatients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoPAP) and medial-lateral (XCoM-CoPML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoPAP-angle) and medial-lateral (CoM-CoPML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects. ResultsThe ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoPAP (p = 0.008) and CoM-CoPAP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls. SignificanceBased on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoPML and CoM-CoPML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoPML and CoM-CoPML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.

Inflammation and Muscle Oxygen Saturation are Associated with Exercise Pressor Response in Peripheral Artery Disease

PURPOSE: To determine whether calf muscle oxygen saturation (StO2) and vascular biomarkers of inflammation and oxidative stress were associated with an exercise pressor response during treadmill walking in patients with symptomatic peripheral artery disease (PAD). METHODS: A total of 179 patients were characterized on demographic variables, comorbid conditions, cardiovascular risk factors, ankle/brachial index, peak walking time (PWT), claudication onset time (COT), and calf muscle oxygen saturation (StO2) during a graded maximal treadmill test. The exercise pressor response was measured as the change in blood pressure from rest to the end of the first 2-minute treadmill exercise work stage (2 mph, 0% grade). Patients were further characterized on endothelial effects of circulating factors present in the sera using a cell culture-based bioassay on primary human arterial endothelial cells, and on circulating inflammatory and vascular biomarkers. RESULTS: During the maximal treadmill test, patients experienced COT at 197±164 seconds (mean±SD) and PWT at 395±254 seconds. There was a wide range in the change in systolic blood pressure (-46 to 50 mm Hg) and in diastolic blood pressure (-23 to 38 mm Hg), with mean increases of 4.3 mm Hg and 1.4 mm Hg, respectively. In multiple regression analyses, significant predictors of systolic blood pressure included glucose (p<0.001) and insulin (p=0.039). The significant predictors of diastolic blood pressure included cultured endothelial cell apoptosis (p=0.019), the percentage drop in exercise calf muscle StO2 (p=0.023), high sensitivity C-reactive protein (p=0.032), and glucose (p=0.033). CONCLUSION: Higher levels in pro-inflammatory vascular biomarkers, impaired calf muscle StO2 during exercise, and elevated blood glucose were independently associated with greater exercise pressor response in patients with symptomatic PAD. The clinical implication is that exercise and nutritional interventions designed to improve inflammation, microcirculation, and glucose metabolism may ameliorate the exercise pressor response in patients with symptomatic PAD.

Influence of the amount of body weight support on lower limb joints' kinematics during treadmill walking at different gait speeds: Reference data on healthy adults to define trajectories for robot assistance.

Several robotic devices have been developed for the rehabilitation of treadmill walking in patients with movement disorders due to injuries or diseases of the central nervous system. These robots induce coordinated multi-joint movements aimed at reproducing the physiological walking or stepping patterns. Control strategies developed for robotic locomotor training need a set of predefined lower limb joint angular trajectories as reference input for the control algorithm. Such trajectories are typically taken from normative database of overground unassisted walking. However, it has been demonstrated that gait speed and the amount of body weight support significantly influence joint trajectories during walking. Moreover, both the speed and the level of body weight support must be individually adjusted according to the rehabilitation phase and the residual locomotor abilities of the patient. In this work, 10 healthy participants (age range: 23-48 years) were asked to walk in movement analysis laboratory on a treadmill at five different speeds and four different levels of body weight support; besides, a trial with full body weight support, that is, with the subject suspended on air, was performed at two different cadences. The results confirm that lower limb kinematics during walking is affected by gait speed and by the amount of body weight support, and that on-air stepping is radically different from treadmill walking. Importantly, the results provide normative data in a numerical form to be used as reference trajectories for controlling robot-assisted body weight support walking training. An electronic addendum is provided to easily access to such reference data for different combinations of gait speeds and body weight support levels.

Blood pressure and leg deoxygenation are exaggerated during treadmill walking in patients with peripheral artery disease.

The purpose of this study was to investigate blood pressure (BP) and leg skeletal muscle oxygen saturation (Smo2) during treadmill walking in patients with peripheral artery disease (PAD) and healthy subjects. Eight PAD patients (66 ± 8 yr, 1 woman) and eight healthy subjects (65 ± 7 yr, 1 woman) walked on a treadmill at 2 mph (0.89 m/s). The incline increased by 2% every 2 min, from 0 to 15% or until maximal discomfort. BP was measured every 2 min with an auscultatory cuff. Heart rate (HR) was recorded continuously with an ECG. Smo2 in the gastrocnemius muscle was measured on each leg using near-infrared spectroscopy. The change in systolic BP from seated to peak walking time (PWT) was greater in PAD (healthy: 23 ± 9 vs. PAD: 44 ± 19 mmHg, P = 0.007). HR was greater in PAD patients compared with controls at PWT (P = 0.011). The reduction in Smo2 (PWT - seated) was greater in PAD (healthy: 15 ± 12 vs. PAD: 49 ± 5%, P < 0.001) in the most affected leg and in the least affected leg (healthy: 12 ± 11 vs. PAD: 32 ± 18%, P = 0.003). PAD patients have an exaggerated decline in leg Smo2 during walking compared with healthy subjects, which may elicit the exaggerated rise in BP and HR during walking in PAD.NEW & NOTEWORTHY This is the first study to simultaneously measure skeletal muscle oxygen saturation and blood pressure (BP) during treadmill exercise in patients with peripheral arterial disease. We found that BP and leg deoxygenation responses to slow-paced, graded treadmill walking are greater in patients with peripheral arterial disease compared with healthy subjects. These data may help explain the high cardiovascular risk in patients with peripheral arterial disease.

Immediate effects of perturbation treadmill training on gait and postural control in patients with Parkinson’s disease

The study investigates immediate adaptations of gait and balance to a single session of perturbed treadmill walking in patients with Parkinson’s disease. 39 Parkinson’s patients in stage 1–3.5 of the Hoehn and Yahr Scale were randomized into one of two groups, stratified by disease severity: The experimental group (n=19) walked on a treadmill prototype which constantly applied perturbation by small three-dimensional tilting movements of the walking surface. The control group (n=20) trained on the identical treadmill without perturbations. Patients walked on the treadmill for 20min. Primary outcome measure was overground walking speed. Secondary outcomes were postural sway during quiet standing and spatiotemporal gait parameters during treadmill walking. Outcomes were measured repeatedly throughout the training session and after 10min retention. The experimental group significantly increased overground walking speed after intervention compared to the control group (p=0.014; ES=+0.41). Gait variability during treadmill walking significantly decreased after walking with perturbation. Sway area increased with treadmill walking only in the control group (p=0.009; ES=+0.49). No other postural sway measures changed over time. Subgroup analyses revealed that in the experimental group patients with more pronounced motor impairment demonstrated larger increases in overground walking speed (p=0.016; ES=+0.40) and stance phase symmetry (p=0.011; ES=−0.42). In conclusion, a single session of perturbation treadmill training led to gait improvements, which were more pronounced compared to unperturbed treadmill walking. Effects on static postural sway were less pronounced.

Imbalances Of Trunk Muscle Activation During Treadmill Walking In Patients With Multiple Sclerosis

One of the early signs of Multiple Sclerosis (MS) is weakness on one side of the body, which may contribute to walking impairments experienced by more than 75% of patients with MS. Poor balance, muscle weakness, and less fatigue resistance also contribute to reduced walking capacity and physical activity levels within this population. Trunk control is a key component of balance to ensure safe and efficient walking. PURPOSE:To investigate the activity of trunk muscle groups (flexors, extensors, lateral flexors) during walking in patients with MS. METHODS:Eight patients (4 men) with relapsing-remitting MS (aged 44.9 ± 8.6 years) and eight (4 men) healthy controls (aged 37.9 ± 8.4 years) walked on a treadmill for 15 min at a self-selected speed, during which [18F]-Fluorodeoxyglucose ([18F]-FDG), a glucose analog, was injected. Immediately after walking, Positron Emission Tomography / Computed Tomography imaging was performed. Muscle activity was quantified by Standardized Uptake Value (SUV), with higher uptake signifying greater activity. RESULTS:Between the MS and control groups, no differences in total (P = 0.65) or individual (P > 0.2) trunk muscle activity were found. Healthy controls showed no differences between sides of the trunk muscle groups (P > 0.21). However, side-to-side differences were identified in the MS group: lateral flexor muscle group (SUV: 0.82 SD 0.20, 0.68 SD 0.14, P < 0.01), external (SUV: 0.76 SD 0.19, 0.62 SD 0.11, P = 0.04) and internal (SUV: 0.86 SD 0.20, 0.68 SD 0.11, P = 0.02) obliques, as well as the rectus abdominis (SUV: 0.79 SD 0.26, 0.70 SD 0.17, P = 0.04). CONCLUSIONS:This data indicates that patients with MS have imbalanced activation of the trunk muscles during walking, with the less-affected side being activated more. This activation pattern suggests a compensatory mechanism used by patients with MS in order to maintain balance and postural control, which may contribute to the increased energy cost of walking reported in patients with MS. Based on these findings, trunk muscle activity should be evaluated during physical rehabilitation to identify and target factors contributing to impaired walking ability in patients with MS. Funded by MS Society (PP 1907), NIH/NCATS Colorado CTSI # UL1 TR000154

Pilot investigation of the oxygen demands and metabolic cost of incremental shuttle walking and treadmill walking in patients with cardiovascular disease

ObjectiveTo determine if the metabolic cost of the incremental shuttle-walking test protocol is the same as treadmill walking or predicted values of walking-speed equations.SettingPrimary care (community-based cardiac rehabilitation).ParticipantsEight Caucasian cardiac...

The continuum of physiological impairment during treadmill walking in patients with mild-to-moderate COPD: patient characterization phase of a randomized clinical trial.

BackgroundTo have a better understanding of the mechanisms of exercise limitation in mild-to-moderate chronic obstructive pulmonary disease (COPD), we compared detailed respiratory physiology in patients with COPD and healthy age- and sex-matched controls.MethodsData were collected during the pre-treatment, patient characterization phase of a multicenter, randomized, double-blind, crossover study. Patients with COPD met Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 or 2 spirometric criteria, were symptomatic, and had evidence of gas trapping during exercise. All participants completed pulmonary function and symptom-limited incremental treadmill exercise tests.ResultsChronic activity-related dyspnea measured by Baseline Dyspnea Index was similarly increased in patients with GOLD 1 (n = 41) and 2 (n = 63) COPD compared with controls (n = 104). Plethysmographic lung volumes were increased and lung diffusing capacity was decreased in both GOLD groups. Peak oxygen uptake and work rate were reduced in both GOLD groups compared with controls (p<0.001). Submaximal ventilation, dyspnea, and leg discomfort ratings were higher for a given work rate in both GOLD groups compared with controls. Resting inspiratory capacity, peak ventilation, and tidal volume were reduced in patients with GOLD 2 COPD compared with patients with GOLD 1 COPD and controls (p<0.001).ConclusionsLower exercise tolerance in patients with GOLD 1 and 2 COPD compared with controls was explained by greater mechanical abnormalities, greater ventilatory requirements, and increased subjective discomfort. Lower resting inspiratory capacity in patients with GOLD 2 COPD was associated with greater mechanical constraints and lower peak ventilation compared with patients with GOLD 1 COPD and controls.Trial RegistrationClinicalTrials.gov: NCT01072396

Correlation of Patient-reported Symptom Outcomes and Treadmill Test Outcomes after Treatment for Aortoiliac Claudication

PurposeTo examine the relationship between objective treadmill test outcomes and subjective symptom outcomes among patients with claudication treated with stent revascularization (ST) compared with supervised exercise (SE). Materials and MethodsFive scales of the Peripheral Artery Questionnaire and Walking Impairment Questionnaire were correlated with peak walking time and treadmill claudication onset time. ResultsThe correlation between change in disease-specific quality of life (QOL) and change in peak walking time differed according to treatment group, with statistically significant correlations for all five scales for the ST group and weaker trends for the SE group, only one of which was statistically significant. In contrast, improvements in disease-specific QOL correlated well with increases in claudication onset time, with no significant interaction with treatment group for any of the five scales. ConclusionsDisease-specific QOL results at 6 months in the Claudication: Exercise Vs. Endoluminal Revascularization (CLEVER) study show that improved maximal treadmill walking in patients with claudication treated with SE correlated poorly with self-reported symptom relief. Conversely, patients treated with ST showed good correlation between improved maximal treadmill walking and self-reported symptom improvement. The correlation between claudication onset time and self-reported symptom relief was good across treatment groups. This finding indicates that traditional objective treadmill test outcomes may not correlate well with symptom relief in patients with claudication. Future studies should investigate these data and improve understanding of patient relevance of traditional objective treadmill-based treatment outcomes.

Exercise-Ankle Brachial Pressure Index with One-Minute Treadmill Walking in Patients on Maintenance Hemodialysis

The ankle-brachial pressure index (ABI) is widely used as a standard screening method for arterial occlusive lesion above the knee. However, the sensitivity of ABI is low in hemodialysis (HD) patients. Exercise stress (Ex-ABI) may reduce the false negative results. After measuring resting ABI and toe-brachial pressure index (TBI), ankle pressure and ABI immediately after walking (Post-AP, Post-ABI) were measured using one-minute treadmill walking in 52 lower limbs of 26 HD patients. The definition of peripheral arterial occlusive disease (PAD) required an ABI value of less than 0.90, TBI value of less than 0.60, and decrease of more than 15% of the Post-ABI value and 20 mmHg of Post-AP in Ex-ABI. Computed tomographic angiography (CTA) was performed in 32 lower limbs of 16 HD patients. PAD is defined as presence of stenosis of more than 75% in the case of lesions from an iliac artery to knee on CTA. The accuracy of Ex-ABI (Sensitivity, 85.7%; Specificity, 77.7%) was higher than those of ABI (Sensitivity, 42.9%; Specificity, 83.3%) or TBI (Sensitivity, 78.6%; Specificity, 61.1%). Ex-ABI with one-minute treadmill walking is the most useful tool for the screening of arterial occlusive lesions above the knee in maintenance HD patients.

Evaluation of muscle fatigue during treadmill walking in patients with type 2 diabetes and peripheral vasculopathy

Evaluation of muscle fatigue during treadmill walking in patients with type 2 diabetes and peripheral vasculopathy

Estimation of the functional role of arterial pathways to the buttock circulation during treadmill walking in patients with claudication

The aim of the study was to estimate the functional contribution of the arterial inflow pathways to the pelvic circulation during walking in patients with stage 2 lower extremity arterial disease. Transcutaneous oxygen pressure (Ptc(O(2))) changes during exercise can be used to estimate the severity of regional blood flow impairment while walking. Seventy patients with stable lower limb claudication were studied using a multivariate linear regression model. The relationship between exercise-induced buttock Ptc(O(2)) changes, the ipsilateral calf Ptc(O(2)) changes, and the arterial diameters of the pelvic arteriographic pathways were analyzed. The ipsilateral hypogastric and lumbar pathway, as well as the ipsilateral calf Ptc(O(2)) changes, were the only variables significantly related to buttock Ptc(O(2)) changes (r = 0.47; P < 0.001). Their normalized respective contribution to the regressive model was 39%, 19%, and 18%. None of the contralateral hypogastric, mesenteric, and sacral pathways or pathways stemming from the external iliac artery showed significant correlation to buttock Ptc(O(2)) changes. The ipsilateral hypogastric and ipsilateral lumbar pathways are the major pathways responsible for the functional buttock blood flow supply during walking. The role of contralateral hypogastric, inferior mesenteric, and median sacral pathways and arteries distal to the internal iliac trunk is negligible in the normal or compensatory blood flow supply. Distal Ptc(O(2)) decrease at exercise aggravates proximal Ptc(O(2)) decrease, possibly through the occurrence of a "steal phenomenon" of distal over proximal circulation during walking.

High Failure Rates When Avoiding Obstacles During Treadmill Walking in Patients With a Transtibial Amputation

Hofstad CJ, van der Linde H, Nienhuis B, Weerdesteyn V, Duysens J, Geurts AC. High failure rates when avoiding obstacles during treadmill walking in patients with a transtibial amputation. Objective To investigate if and to what extent patients with a transtibial amputation are less successful in avoiding unexpected obstacles while walking than healthy adults. Design Experimental 2-group design. Setting Dutch rehabilitation center. Participants Eleven patients with a transtibial amputation and 14 healthy controls. Interventions Not applicable. Main Outcome Measures Subjects walked on a treadmill at .56m/s. In 2 series of 12 trials each, an obstacle was dropped in front of the prosthetic or the nonprosthetic leg of the amputation group and the left leg of the control group at different phases during the step cycle. It was noted which avoidance strategy was used (a long step strategy [LSS] or a short step strategy [SSS]) and whether the obstacle was avoided successfully or not. These data were expressed as a percentage of the total number of trials completed by each subject. Results With either leg, the amputation group made significantly more errors than the control subjects (prosthetic leg, 24%±17%; nonprosthetic leg, 21%±17% vs 2%±2% for the control group). Highest failure rates were in the amputation group when time pressure was high, requiring an SSS, especially on the prosthetic side. An LSS under time pressure, however, nearly always resulted in failure for both the prosthetic and nonprosthetic legs. Subjects with the longest time since amputation were most successful in avoiding unexpected obstacles. Conclusions Under time pressure, patients with a lower-leg prosthesis perform best when they use their nonprosthetic leg as the lead limb in an SSS. The fact that some subjects with the longest time since amputation made no errors suggests that over many years it is possible to relearn the appropriate avoidance reactions sufficiently fast.

Gait recovery is not associated with changes in the temporal patterning of muscle activity during treadmill walking in patients with post-stroke hemiparesis

Objective To establish whether functional recovery of gait in patients with post-stroke hemiparesis coincides with changes in the temporal patterning of lower extremity muscle activity and coactivity during treadmill walking. Methods Electromyographic (EMG) data from both legs, maximum walking speed, the amount of swing phase asymmetry and clinical measures were obtained from a group of post-acute patients with hemiparesis, as early as possible after admission in a rehabilitation centre (mean time post-stroke 35 days) and 1, 3, 6, and 10 weeks later, while all patients participated in a regular rehabilitation program. EMG data from the first assessment were compared to those obtained from a group of healthy controls to identify abnormalities in the temporal patterning of muscle activity. Within subject comparisons of patient data were made over time to investigate whether functional gait recovery was accompanied by changes in the temporal patterns muscle (co-)activity. Results EMG patterns during the first assessment showed a number of abnormalities on the paretic side, namely abnormally long durations of activity in biceps femoris (BF) during the single support (SS) phase and in gastrocnemius medialis (GM) during the first double support phase (DS1). Furthermore, in both legs a prolongation of the activity was seen in the rectus femoris (RF) during the SS phase. In addition, the duration of BF–RF coactivation was longer on the paretic side than it was in controls. Over time, the level of ambulatory independence, body mobility, and maximum walking speed increased significantly, indicating that substantial improvements in gait ability occurred. Despite these improvements, durations of muscle (co-) activity and the level of swing phase asymmetry did not change during rehabilitation. More specifically, timing abnormalities in muscle (co-)activity that were found during the first assessment did not change significantly, indicating that these aberrations were not an impediment for functional gait improvements. Conclusions Normalization of the temporal patterning of gait related muscle activity in the lower extremities is not a prerequisite for functional recovery of gait in patients with post-stroke hemiparesis. Apparently, physiological processes other than improved temporal muscular coordination must be important determinants of the restoration of ambulatory capacity after stroke. Significance Recovery of walking ability in post-stroke hemiparesis is not necessarily associated with, or dependent on, reorganization in the temporal control of gait related muscle activity. Normalization of the temporal coordination of muscle activity during gait may not be an important clinical goal during post-acute rehabilitation.

A comparison of cardiorespiratory responses to water and land treadmill walking in patients with rheumatoid arthritis

A comparison of cardiorespiratory responses to water and land treadmill walking in patients with rheumatoid arthritis

Inspiratory muscle relaxation rate slows during exhaustive treadmill walking in patients with chronic heart failure.

Exercise intolerance is a feature of chronic heart failure (CHF). We hypothesized that excessive loading of the respiratory muscle pump might contribute to exertional breathlessness. One marker of excessive muscle-loading is slowing of maximum relaxation rate (MRR) and, therefore, to test our hypothesis, we investigated the effect of exhaustive treadmill walking on inspiratory muscle MRR in patients with CHF. We studied eight stable patients with mild-moderate CHF walking on a treadmill until termination because of severe dyspnea. Inspiratory muscle MRR was determined from esophageal pressure (Pes) change during submaximal sniffs (Sn) before and immediately after exercise to a mean (SD) minute ventilation of 77 () L/min. For comparison, nine healthy subjects performed a similar protocol; exercise was terminated either by severe dyspnea or when minute ventilation reached 100 L/min. There were no significant differences in terms of heart rate, respiratory rate, tidal volume, or inspiratory duty cycle at cessation of exercise. The mean slowing of Sn Pes MRR in the first minute after termination of exercise in the CHF group was 22.4% and in the normal control group it was 2.8% (p < 0.01). Our data show that slowing of inspiratory muscle relaxation rate occurs in patients with CHF walking to severe breathlessness. We conclude that severe loading of the inspiratory muscles is a feature of exertional dyspnea in CHF.

Analysis of the metabolic and ventilatory response to self-paced 12-minute treadmill walking in patients with severe chronic obstructive pulmonary disease.

The 12-minute walking test is frequently used to measure exercise capacity in patients with severe chronic obstructive pulmonary disease. However, the physiological response to this test has been the subject of limited investigation. In this study, the metabolic and ventilatory consequences of a self-paced 12-minute treadmill walking test (WT) were measured in 17 patients with severe chronic obstructive pulmonary disease (FEV1: 40 +/- 9%) and evaluated using the physiological response to symptom-limited cycle ergometry (CE). During exercise testing, heart rate, transcutaneous oxygen saturation, and lactate concentration were measured, and oxygen consumption, carbon dioxide production, tidal volume, and breathing frequency were recorded breath by breath. After 4 minutes walking, the peak oxygen consumption (VO2) was already 99 +/- 11% of last-minute walking VO2. Walking speed was chosen within 2 minutes and remained stable throughout the test. The WT and CE showed similar (end-) test results for all measurements, except for a higher carbon dioxide production, venous lactate concentration, and respiratory quotient after CE. However, lactate concentration was also significantly increased after WT. Severe and prolonged desaturation was shown during walking in most patients. The physiological stress evoked during the WT is close to the stress developed at an incremental symptom-limited test and the relatively high metabolic and ventilatory stress is sustained from at least 4 to 12 minutes during the WT. This study has shown that anaerobic metabolism not only occurs during incremental cycle ergometry, but also during the WT.