Standardized Walk Test Research Articles

Differential scanning calorimetric evaluation of the human plasma in patients using cilostazol for the treatment of intermittent claudication (a preliminary study)

This preliminary study employs differential scanning calorimetry (DSC) to assess alterations in human plasma composition in patients treated with cilostazol for intermittent claudication. Cilostazol, an antiplatelet and vasodilator agent, is commonly prescribed to moderate symptom associated with PAD caused by reduced peripheral blood flow. Patients selected according to study protocol were treated with cilostazol for a duration of three months. At the visits, subjects exercised by a standard walking test controlled by physiotherapist. The blood samples were taken on day 0 (control), day 15, 1, 2 and 3 months. Through DSC analysis, we investigate potential thermodynamic changes in plasma composition induced by cilostazol treatment. As a result of the treatment, the pain-free walking distance improved significantly in the first 3 months. The thermal unfolding of the human plasma showed a correlation with the walking improvement. Our findings provide insights into the systemic effects of cilostazol and its impact on plasma constituents in the context of PAD and intermittent claudication management.

Detection of freezing of gait in Parkinson's disease from foot-pressure sensing insoles using a temporal convolutional neural network.

Freezing of gait (FoG) is a common and debilitating symptom of Parkinson's disease (PD) that can lead to falls and reduced quality of life. Wearable sensors have been used to detect FoG, but current methods have limitations in accuracy and practicality. In this paper, we aimed to develop a deep learning model using pressure sensor data from wearable insoles to accurately detect FoG in PD patients. We recruited 14 PD patients and collected data from multiple trials of a standardized walking test using the Pedar insole system. We proposed temporal convolutional neural network (TCNN) and applied rigorous data filtering and selective participant inclusion criteria to ensure the integrity of the dataset. We mapped the sensor data to a structured matrix and normalized it for input into our TCNN. We used a train-test split to evaluate the performance of the model. We found that TCNN model achieved the highest accuracy, precision, sensitivity, specificity, and F1 score for FoG detection compared to other models. The TCNN model also showed good performance in detecting FoG episodes, even in various types of sensor noise situations. We demonstrated the potential of using wearable pressure sensors and machine learning models for FoG detection in PD patients. The TCNN model showed promising results and could be used in future studies to develop a real-time FoG detection system to improve PD patients' safety and quality of life. Additionally, our noise impact analysis identifies critical sensor locations, suggesting potential for reducing sensor numbers.

Ecological Validation of Machine Learning Models for Spatiotemporal Gait Analysis in Free-Living Environments Using Instrumented Insoles

Continuous gait monitoring may aid the early diagnosis of neurological and musculoskeletal conditions and help validate the effectiveness of new treatments. However, consumer-grade activity trackers can only capture summary gait metrics, whereas most of the research-grade devices capable of estimating fine-grained gait parameters are too cumbersome for extended-time use in real-life environments. Instrumented footwear may offer a promising alternative tool owing to their good accuracy and relatively small form factor, but their ability to detect stride-by-stride spatial gait parameters in free-living conditions has not been well explored to date. This work describes machine learning (ML) inference models for an insole system capable of accurately estimating stride time (ST), length (SL), and velocity (SV) in real-life environments. Functional validity was assessed through unstructured tests including straight-line walking, curve walking, and turns. Ecological validity was examined in free-living conditions. The ML models demonstrated better accuracy than conventional data processing methods (mean absolute errors in unstructured conditions were 3.55% for SL and 3.59% for SV). Real-life gait parameters estimated with the ML models showed stronger associations with a standardized walking test compared with the same parameters obtained with conventional methods. These results indicate proof-of-concept feasibility of using instrumented insoles and ML inference models for free-living spatiotemporal gait analysis.

Inertial Sensor Algorithm to Estimate Walk Distance

The “total distance walked” obtained during a standardized walking test is an integral component of physical fitness and health status tracking in a range of consumer and clinical applications. Wearable inertial sensors offer the advantages of providing accurate, objective, and reliable measures of gait while streamlining walk test administration. The aim of this study was to develop an inertial sensor-based algorithm to estimate the total distance walked using older subjects with impaired fasting glucose (Study I), and to test the generalizability of the proposed algorithm in patients with Multiple Sclerosis (Study II). All subjects wore two inertial sensors (Opals by Clario-APDM Wearable Technologies) on their feet. The walking distance algorithm was developed based on 108 older adults in Study I performing a 400 m walk test along a 20 m straight walkway. The validity of the algorithm was tested using a 6-minute walk test (6MWT) in two sub-studies of Study II with different lengths of a walkway, 15 m (Study II-A, n = 24) and 20 m (Study II-B, n = 22), respectively. The start and turn around points were marked with lines on the floor while smaller horizontal lines placed every 1 m served to calculate the manual distance walked (ground truth). The proposed algorithm calculates the forward distance traveled during each step as the change in the horizontal position from each foot-flat period to the subsequent foot-flat period. The total distance walked is then computed as the sum of walk distances for each stride, including turns. The proposed algorithm achieved an average absolute error rate of 1.92% with respect to a fixed 400 m distance for Study I. The same algorithm achieved an absolute error rate of 4.17% and 3.21% with respect to an averaged manual distance for 6MWT in Study II-A and Study II-B, respectively. These results demonstrate the potential of an inertial sensor-based algorithm to estimate a total distance walked with good accuracy with respect to the manual, clinical standard. Further work is needed to test the generalizability of the proposed algorithm with different administrators and populations, as well as larger diverse cohorts.

Reference Walking Speeds for Healthy Young Adults in Qatar: Moderating Effect of Obesity and Physical Activity

Walking speed (WS) is considered an important indicator for overall health. Despite this, there is a paucity of data relating to WS values in the Arab region. The present study aims to establish preferred (PWS) and maximal walking speeds (MWS) in young adults in Qatar and examine how gender, body mass index, and physical activity (PA) components influence WS. One hundred ninety-six healthy participants (age: 22 ± 2 years; 60% females) performed a standardized walking test on a flat 10-m pathway, completed the short form of the International PA Questionnaire, and had their height and weight measured. PWS and MWS were normalized for height (rPWS and rMWS). Results. Females demonstrated slower PWS, MWS, and rMWS compared to males. Moreover, MWS and rMWS were lower in obese participants compared to underweight, normal weight and overweight individuals. There was a significant positive relationship only between vigorous PA and rPWS and rMWS. This is the first study to establish reference WS values for healthy young adults in Qatar. Overall, we demonstrated that WS was lower compared to similar adults worldwide. The established healthy walking values can serve as reference for clinical evaluations within Qatar. Future PA guidelines and public health interventions should focus on WS values.

Compromised intestinal integrity in older adults during daily activities: a pilot study

BackgroundMalnutrition is a common and significant problem in older adults. Insight into factors underlying malnutrition is needed to develop strategies that can improve the nutritional status. Compromised intestinal integrity caused by gut wall hypoperfusion due to atherosclerosis of the mesenteric arteries in the aging gastrointestinal tract may adversely affect nutrient uptake. The presence of compromised intestinal integrity in older adults is not known. The aim of this study is to provide a proof-of-concept that intestinal integrity is compromised in older adults during daily activities.MethodsAdults aged ≥75 years living independently without previous gastrointestinal disease or abdominal surgery were asked to complete a standardized walking test and to consume a standardized meal directly afterwards to challenge the mesenteric blood flow. Intestinal fatty acid-binding protein (I-FABP) was measured as a plasma marker of intestinal integrity, in blood samples collected before (baseline) and after the walking test, directly after the meal, and every 15 min thereafter to 75 min postprandially.ResultsThirty-four participants (median age 81 years; 56% female) were included. Of the participants, 18% were malnourished (PG-SGA score ≥ 4), and 32% were at risk of malnutrition (PG-SGA score, 2 or 3). An I-FABP increase of ≥50% from baseline was considered a meaningful loss of intestinal integrity and was observed in 12 participants (35%; 8 females; median age 80 years). No significant differences were observed in either baseline characteristics, walking test scores, or calorie/macronutrient intake between the groups with and without a ≥ 50% I-FABP peak.ConclusionThis study is first to indicate that intestinal integrity is compromised during daily activities in a considerable part of older adults living independently.

Assessment of Walking Ability in Patients with Intermittent Claudication Using a Smartphone Accelerometer

<strong>Objectives:</strong> It is challenging to accurately monitor the progress of intermittent claudication patients during or after treatment. Furthermore, diagnostic tools for intermittent claudication are not always adequate to determine whether other diseases are the primary cause of any walking complaints. This makes it difficult to determine the optimal treatment for the patient and impairs proper follow-up. The objective was to investigate the feasibility of measuring disease specific changes in the gait pattern of intermittent claudication patients by using a smartphone accelerometer. <strong>Methods:</strong> This study is a clinical Proof-of-concept study. Included were 12 subjects. Seven of the subjects were healthy controls, the other five intermittent claudication patients. Raw accelerometer data was collected during a standardized walking test with an Iphone. Processed data was analyzed using the GaitPy package in Python, resulting in 20 different gait parameters per gait cycle. The data were divided, resulting in three groups: The control group, the patient group without symptoms and the patient group with active symptoms. Mann-Whitney U tests and Wilcoxon ranks test were used to examine the outcomes. <strong>Results:</strong> Five of the 20 parameters are significantly different between patients before symptoms and patients with active symptoms. All parameters except cadence and stride duration differ between our control group and the patients while experiencing symptoms. Nine of 20 parameters where significantly different between the control group and the patient group without symptoms. <strong>Conclusions:</strong> This study demonstrated the potential clinical applicability of measuring changes in intermittent claudication gait characteristics with a smartphone.

Exercise capacity in patients implanted with left ventricular assist devices for end-stage heart failure treatment

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Left ventricular assist device (LVAD) is an expanding therapy in end-stage heart failure today. Although LVAD therapy bears the potential to normalize cardiac output, a majority of patients show a severely impaired physical condition at the time of LVAD implantation. To date, no validated standardized training protocol is available, and established practices to effectively improve LVAD patients’ exercise tolerance is lacking. This study sought to investigate exercise capacity quantified by cardiopulmonary exercise testing (CPX) and a standardized six-minute walk test (6MWT) in patients after LVAD implantation. Methods We enrolled 30 end-stage heart failure patients who had received an LVAD implantation 20.7 ± 7.6 days prior to examination, mean age 54.9 ± 7.8 years, 26 males (87 %). Exercise tolerance was assessed using cardiopulmonary exercise testing (CPX) for maximal and submaximal exercise capacity, followed by a standardized (6MWT). Results Patients showed peak oxygen uptake values of 8.3 ± 2.4 ml/min/kg at a mean workload of 46.7 ± 11.3 watts and a mean anaerobic threshold of 6.7 ± 1.7 ml/min/kg at a workload of 32.6 ± 6.9 watts. Mean standardized 6-minute walking distance was at 183.8 ± 71.4 meters. There were no adverse events during exercise testing. Conclusions Cardiopulmonary exercise testing (CPX) and standardized 6MWT show severely impaired cardiopulmonary exercise capacity in patients after LVAD implantation, warranting further studies for dedicated training protocols, specifically focusing on LVAD patients to improve exercise tolerance at an acceptable safety profile.

Portable NIV for patients with moderate to severe COPD: two randomized crossover trials

BackgroundLong-term non-invasive ventilation (NIV) is as an established treatment option for chronic hypercapnic COPD patients. Beneficial effects have also been shown during exercise, but this is restricted to rehabilitation programs. New portable NIV (pNIV) devices may now enable NIV application during walking at home.Study design and methodsIn two randomized crossover trials, the impact of pNIV on dyspnea and endurance capacity was investigated in patients with moderate to severe COPD. Participants performed a standardized 6-min walking test, with and without pNIV, using a pre-set inspiratory/expiratory positive airway pressure of 18/8 cmH2O. The first study was performed in NIV-naïve patients (Study I), while the second study was performed in those already established on long-term NIV (Study II).Results38 patients (66.9 ± 7.4 years, mean FEV1: 30.3 ± 8%pred) and 23 patients (67.6 ± 8.7 years, mean FEV1: 29.8 ± 10.4%pred) participated in Study I and II, respectively. In Study I, the mean difference in the Borg Dyspnea Scale (BDS, primary outcome) score following walking was 3.2 (IQR 2–4) without pNIV, compared to 2.6 (IQR 1–4) with pNIV (ΔBDS 0.65, P = 0.04), while walking distance increased from 311.8 m (95%CI 276.9–346.6 m) to 326.3 m (95%CI 291.5–361.2 m) (P = 0.044) when pNIV was used. Accordingly, in Study II, the mean difference in BDS was 4.4 (IQR 3–6) without pNIV, compared to 4.5 (IQR 3–6) with pNIV (ΔBDS 0.09, P = 0.54), while walking distance decreased from 291.5 m (95%CI 246.1–336.9 m) to 258.4 m (95%CI 213–303.8 m) (P ≤ 0.001).InterpretationThe use of a pNIV device during walking can improve dyspnea and walking distance in patients with moderate to severe COPD. Patients who do not already receive long-term NIV therapy are more likely to benefit compared to those undergoing long-term NIV. Careful patient selection is mandatory.Clinical Trial Register: DRKS00013203; DRKS00012913 registered October 20th 2017 and October 16th 2017; https://www.drks.de/drks_web/

Ratings of Perceived Exertion During Walking: Predicting Major Mobility Disability and Effect of Structured Physical Activity in Mobility-Limited Older Adults.

This study evaluated the association between ratings of perceived exertion (RPE) of walking and major mobility disability (MMD), as well as their transitions in response to a physical activity (PA) compared to a health education (HE) program. Older adults (n = 1633) who were at risk for mobility impairment were randomized to structured PA or HE programs. During a 400 m walk, participants rated exertion as "light" or "hard." An MMD event was defined as the inability to walk 400 m. MMD events and RPE values were assessed every 6 months for an average of 2.6 years. Participants rating their exertion as "hard" had a nearly threefold higher risk of MMD compared with those rating their exertion as "light" (HR: 2.61, 95% CI: 2.19-3.11). The association was held after adjusting for disease conditions, depression, cognitive function, and walking speed (HR: 2.24, 95% CI: 1.87-2.69). The PA group was 25% more likely to transition from "light" to "hard" RPE than the HE group (HR: 1.25, 95% CI: 1.05-1.49). Additionally, the PA group was 27% (HR: 0.73, 95% CI: 0.55 - 0.97) less likely to transition from a "hard" RPE to inability to walk 400 m and was more likely to recover their ability to walk 400 m by transitioning to a "hard" RPE (HR: 2.10, 95% CI: 1.39-3.17) than the HE group. Older adults rating "hard" effort during a standardized walk test were at increased risk of subsequent MMD. A structured PA program enabled walking recovery, but was more likely to increase transition from "light" to "hard" effort, which may reflect the greater capacity to perform the test.

Cardiac Function Monitoring for Patients Undergoing Cancer Treatments Using Wearable Seismocardiography: A Proof-of-Concept Study.

Advances in cancer therapeutics have dramatically improved the survival rate and quality of life in patients affected by various cancers, but have been accompanied by treatment-related cardiotoxicity, e.g. left ventricular (LV) dysfunction and/or overt heart failure (HF). Cardiologists thus need to assess cancer treatment-related cardiotoxic risks and have close followups for cancer survivors and patients undergoing cancer treatments using serial echocardiography exams and cardiovascular biomarkers testing. Unfortunately, the cost-prohibitive nature of echocardiography has made these routine follow-ups difficult and not accessible to the growing number of cancer survivors and patients undergoing cancer treatments. There is thus a need to develop a wearable system that can yield similar information at a minimal cost and can be used for remote monitoring of these patients. In this proof-of-concept study, we have investigated the use of wearable seismocardiography (SCG) to monitor LV function non-invasively for patients undergoing cancer treatment. A total of 12 subjects (six with normal LV relaxation, five with impaired relaxation and one with pseudo-normal relaxation) underwent routine echocardiography followed by a standard six-minute walk test. Wearable SCG and electrocardiogram signals were collected during the six-minute walk test and, later, the signal features were compared between subjects with normal and impaired LV relaxation. Pre-ejection period (PEP) from SCG decreased significantly (p < 0.05) during exercise for the subjects with impaired relaxation compared to the subjects with normal relaxation, and changes in PEP/LV ejection time (LVET) were also significantly different between these two groups (p < 0.05). These results suggest that wearable SCG may enable monitoring of patients undergoing cancer treatments by assessing cardiotoxicity.

Complementing Clinical Gait Assessments of Spinal Cord Injured Individuals using Wearable Movement Sensors.

Today's standard clinical practice to assess the walking ability of patients with neurological disorders during rehabilitation is based on simple gait tests such as the six-minute walking test (6MWT). Since the outcome of these tests is the average walking speed only, the aim of this work was to show that the application of movement sensors during a standardized walking test for the population of spinal cord injured (SCI) patients provides additional information on gait quality not directly described by the average speed. Hence, gait features that are related to quantitative and qualitative aspects of gait were extracted from the ankle sensor recordings of 29 SCI subjects and 19 healthy controls performing the 6MWT. The subjects were clustered into groups based on these gait features, and six gait features were selected to demonstrate the key differences between the clusters. The correlation of these features to the outcome of the 6MWT is discussed with their implications on gait quality.

Using force data to self-pace an instrumented treadmill and measure self-selected walking speed

BackgroundSelf-selected speed is an important functional index of walking. A self-pacing controller that reliably matches walking speed without additional hardware can be useful for measuring self-selected speed in a treadmill-based laboratory.MethodsWe adapted a previously proposed self-pacing controller for force-instrumented treadmills and validated its use for measuring self-selected speeds. We first evaluated the controller’s estimation of subject speed and position from the force-plates by comparing it to those from motion capture data. We then compared five tests of self-selected speed. Ten healthy adults completed a standard 10-meter walk test, a 150-meter walk test, a commonly used manual treadmill speed selection test, a two-minute self-paced treadmill test, and a 150-meter self-paced treadmill test. In each case, subjects were instructed to walk at or select their comfortable speed. We also assessed the time taken for a trial and a survey on comfort and ease of choosing a speed in all the tests.ResultsThe self-pacing algorithm estimated subject speed and position accurately, with root mean square differences compared to motion capture of 0.023 m s −1 and 0.014 m, respectively. Self-selected speeds from both self-paced treadmill tests correlated well with those from the 10-meter walk test (R>0.93,p<1×10−13). Subjects walked slower on average in the self-paced treadmill tests (1.23±0.27 ms−1) than in the 10-meter walk test (1.32±0.18 ms−1) but the speed differences within subjects were consistent. These correlations and walking speeds are comparable to those from the manual treadmill speed selection test (R=0.89,p=3×10−11;1.18±0.24 ms−1). Comfort and ease of speed selection were similar in the self-paced tests and the manual speed selection test, but the self-paced tests required only about a third of the time to complete. Our results demonstrate that these self-paced treadmill tests can be a strong alternative to the commonly used manual treadmill speed selection test.ConclusionsThe self-paced force-instrumented treadmill well adapts to subject walking speed and reliably measures self-selected walking speeds. We provide the self-pacing software to facilitate use by gait researchers and clinicians.

RATINGS OF PERCEIVED EXERTION: PREDICTING MOBILITY DISABILITY AND RESPONSE TO PHYSICAL ACTIVITY IN OLDER ADULTS

Ratings of perceived exertion (RPE) during exercise are linked to several physiological indices and are often elevated in older adults. This study evaluated the association between RPE of walking and incident major mobility disability (MMD) as well as response to a physical activity (PA) program. Older adults (n=1633) at-risk for mobility impairment were randomized to a structured PA or health education (HE) program. During a 400m walk, participants rated exertion as “none”, “light”, “somewhat hard” or “hard”. An MMD event was defined as the inability to complete the 400m walk. Transitions between RPE states and an MMD event—when RPE was not collected— were assessed over the follow-up (every 6 months for an average of 2.6 years). Participants rating their exertion as “hard” at baseline 400m walk had nearly 3-fold higher risk of MMD compared with those rating as “light” (HR: 2.61, 95%CI: 2.19-3.11). During follow-up, the PA group was 25% more likely to transition from “light” to “hard” RPE (1.25, 1.05-1.49), but was 27% (0.73, 0.55 – 0.97) less likely to transition from a “hard” RPE to MMD than the HE group. Additionally, the PA group was more likely to transition from an MMD event to a “hard” RPE (2.09, 1.38-3.17) than the HE group (i.e. recovery). Older adults rating “hard” effort during a standardized walk test were at increased risk of MMD. A structured PA program increased transition from light to hard effort, which may reflect greater capacity to perform the test and increased recovery from an MMD event.

P6320Unilateral phrenic nerve stimulation improves functional capabilities in heart failure patients

Abstract Introduction Central sleep apnea is highly common in heart failure (HF) patients and often appears as Cheyne-Stokes-respiration (CSR). Presence of CSR in HF has been clearly shown to connote worse prognosis and HF patients with CSR experience increased mortality. Since widely used adaptive servoventilation is now contraindicated in HF with reduced ejection fraction alternative approaches for CSR treatment are needed. Unilateral phrenic nerve stimulation (PNS) is a novel technique to treat CSR and has recently been demonstrated to be safe and effective in HF patients, resulting in its market approval. While PNS has been shown to sufficiently treat CSR nothing is known in regard to functional characteristics in PNS treated HF patients. Therefore, this study investigated standardized six-minute walk test (6MWT) before and during PNS treatment in HF patients assessing functional impact of PNS on HF. Methods We prospectively enrolled 25 HF patients that have been implanted with novel PNS, mean age 67.05±11.22 years, 88% male, showing effective PNS CSR treatment. Adjacent to determine PNS effectiveness on CSR treatment standardized 6MWT was conducted before, at 6 months and at 12 months after PNS implantation. Results 25 (100%) patients had CSR, introduced PNS significantly suppressed respiratory events from 118.33±96.35 before to 34.65±51.41 after PNS therapy onset (p=0.001). Regarding functional improvements 6MWT improved from initial 369.5±163.56 meters before PNS implantation to 410±169.71 meters after 12 months. Hereby, total walking distance increased by 49.5% ± 100.8% (p=0.035). Conclusion PNS treatment is not only a novel technique to allow CSR treatment in HF, but for the first time, we provide comprehensible data illustrating functional improvements in HF in 6MWT, implying significant enhancements in daily physical capability of HF CSR patients treated with PN.

Evaluating the walking perimeter in patients with spinal stenosis. A comparison between clinical interview and standardized walk test at comfortable speed

Gait dysfunctions are common in patients with spinal stenosis. In fact, these patients may present intermittent radicular claudication, which result in a decreased walking perimeter. Thus in these patients, the walking perimeter reveals the impact of the disease on quality of life and accounts for the therapeutic decision, notably surgical. Usually, in clinical practice, walking perimeter is assessed by a medical interview. Some authors highlight the error of subjective verbal quantification. Therefore, the main objective was to quantify the difference between the walking perimeter determined using either a medical interview or a walk test at comfortable speed. The secondary objective was to correlate functional tests with walking perimeter. In this monocentric study, each patient was asked to verbally estimate his walking perimeter during a preoperative consultation. Walking perimeter was then evaluated using a walking test at comfortable speed in which the patient walked a maximal distance. Functional muscular tests (Sorensen and Shirado) were also performed. Twenty patients have been included (age: 68.9 ± 8.6 years, BMI: 28.7 ± 3.5 kg.m −2 ). During medical interview, patients reported a significantly lower average walking perimeter than during walk test (317 ± 178 m and 442 ± 99 m respectively; P < 0.05). Among functional tests (Shirado: 84.2 ± 51.0 s; Sorensen: 75.4 ± 39.1 s), only Shirado test was correlated with walking perimeter assessed by walk test (Shirado: r = 0.48; P = 0.03) whereas no correlation was found for walking perimeter assessed by medical interview. Our study confirms previous results showing that subjective walking perimeter estimation is not a valid outcome. Patients with spinal stenosis underestimated their actual walking perimeter during the preoperative consultation. Thus comfortable walk test should be used in clinical practice to quantify the walking perimeter in patients with spinal stenosis, and more broadly, because it seems correlated to functional capacities of patients. The underlying reasons explaining the difference observed need to be explored.

Social Participation Modifies the Effect of a Structured Physical Activity Program on Major Mobility Disability Among Older Adults: Results From the LIFE Study.

To investigate whether baseline social participation modifies the effect of a long-term structured physical activity (PA) program on major mobility disability (MMD). 1,635 sedentary adults (70-89 years) with physical limitations were randomized to either a structured PA or health education (HE) intervention. Social participation was defined categorically at baseline. High social participation was defined as attending organized group functions at least once per week and visiting with noncohabitating friends and family ≥7 hr per week. Anything less was considered limited social participation. Participants performed a standardized walking test at baseline and every 6 months for up to 42 months. MMD was defined as the loss in the ability to walk 400 m. There was a significant intervention by social participation interaction (p = .003). Among individuals with high levels of social participation, those randomized to PA had significantly lower incidence of MMD (hazard ratio [HR], 0.43 [95% confidence interval (CI), 0.27-0.68]; p < .01) than those randomized to HE. Individuals with limited social participation showed no mobility benefit of the PA intervention when compared with their HE counterparts (HR, 0.92 [95% CI, 0.77-1.11]; p = .40). Our findings suggest that baseline social participation is an important factor for the success of a PA intervention aimed at delaying mobility disability.

Impaired Carbon Monoxide Diffusing Capacity is the strongest lung function predictor of decline in 12 minute-walking distance in COPD; a 5-year follow-up study

Background: The purpose of this study was to evaluate the longitudinal relationship between functional exercise capacity, assessed through standardized 12-minute walk test (12MWT), and various lung function parameters obtained using spirometry, body plethysmography and diffusing capacity (DLco) measurements in patients with COPD. Methods: Spirometry, body plethysmography and DLco-measurements were performed at baseline in 84 subjects with moderate to very severe COPD and at follow-up visit (n = 34) after 5 years. Functional exercise capacity was determined using standardized 12MWT. Results: Patients were characterized at baseline by FEV1 of 1.2 ± 0.4 L (41 ± 13% predicted), RV of 3.4 ± 1.0 L (187 ± 58% predicted) and DLco of 3.8 ± 1.2 mmol/min/kPa (51 ± 16% predicted). A decrease of 12MWD was found between baseline and follow-up (928 ± 193 m vs. 789 ± 273 m, p < 0.001). DLco and 12MWD at baseline were the only independent predictors of 12MWD at follow-up in a multiple logistic regression model that also included all other lung function parameters, gender, age and BMI. Decline in 12MWD was mainly explained by deterioration in DLco. Furthermore, DLco value at baseline had the highest explanatory value for the loss in 12MWD after 5 years (R2 = 0.18, p = 0.009). Conclusions: In a 5-year longitudinal study, DLco-measurements at baseline were the most important predictors of declining exercise capacity in COPD patients. These results suggest that integration of DLco in the clinical workup provides a more comprehensive assessment in patients with COPD.

Improvement of Venous Pumping Function by Double Progressive Compression Stockings: Higher Pressure Over the Calf is More Important Than a Graduated Pressure Profile

Previous studies have shown that so-called progressive elastic compression stockings (PECS) with a negative pressure gradient have a more pronounced effect on venous pump function than conventional, graduated stockings. The aim of this study was to investigate the effect of higher graduated and non-graduated pressures on the venous calf pump in patients with venous disease. The ejection fraction (EF) of the calf pump was measured by plethysmography under a standardized walking test in 20 patients suffering from chronic venous disease (CEAP C2-C5) without compression, (a) with one and (b) two PECS on top of each other, and (c) with one additional conventional stocking covering only the gaiter area to achieve a graduated high pressure profile. Interface pressure was measured in the gaiter area and on the calf. A significant improvement of EF compared with baseline was found with all three compression modalities. The two superimposed PECS, providing median pressures of 33mmHg in the gaiter area and 46mmHg at calf level, increased EF significantly up into the normal range. Increasing the gaiter pressure to 56mmHg without changing the calf pressure did not result in further improvement. Two PECS applied on top of each other lead to a maximal improvement of the venous pump function, which cannot be further improved by increasing the pressure in the gaiter area thereby restoring a graduated pressure profile.

Gait disturbances as specific predictive markers of the first fall onset in elderly people: a two-year prospective observational study

Falls are common in the elderly, and potentially result in injury and disability. Thus, preventing falls as soon as possible in older adults is a public health priority, yet there is no specific marker that is predictive of the first fall onset. We hypothesized that gait features should be the most relevant variables for predicting the first fall. Clinical baseline characteristics (e.g., gender, cognitive function) were assessed in 259 home-dwelling people aged 66 to 75 that had never fallen. Likewise, global kinetic behavior of gait was recorded from 22 variables in 1036 walking tests with an accelerometric gait analysis system. Afterward, monthly telephone monitoring reported the date of the first fall over 24 months. A principal components analysis was used to assess the relationship between gait variables and fall status in four groups: non-fallers, fallers from 0 to 6 months, fallers from 6 to 12 months and fallers from 12 to 24 months. The association of significant principal components (PC) with an increased risk of first fall was then evaluated using the area under the Receiver Operator Characteristic Curve (ROC). No effect of clinical confounding variables was shown as a function of groups. An eigenvalue decomposition of the correlation matrix identified a large statistical PC1 (termed “Global kinetics of gait pattern”), which accounted for 36.7% of total variance. Principal component loadings also revealed a PC2 (12.6% of total variance), related to the “Global gait regularity.” Subsequent ANOVAs showed that only PC1 discriminated the fall status during the first 6 months, while PC2 discriminated the first fall onset between 6 and 12 months. After one year, any PC was associated with falls. These results were bolstered by the ROC analyses, showing good predictive models of the first fall during the first six months or from 6 to 12 months. Overall, these findings suggest that the performance of a standardized walking test at least once a year is essential for fall prevention.