Peak Walking Research Articles

The long-lasting impact of high-intensity training via collaborative care in patients with schizophrenia: A 5-year follow-up study.

Forty-eight outpatients (28 men/20 women: 35±11 (mean±SD) years) with schizophrenia (ICD-10: F20-29) were randomised to: 1) collaborative care group (TG), performing aerobic interval (AIT; 4×4-min treadmill walking/running at ∼90% peak heart rate) and leg press maximal strength training (MST; 4×4 repetitions at ∼90% maximal strength [1RM]) 2d·wk.-1 for 1-year, supported by transportation and training supervision; or 2) control group (CG). Peak oxygen uptake (V̇O2peak) and walking work efficiency were measured directly along with scaled 1RM/power, anthropometry, blood pressure, and blood samples at inclusion, 1-year, and 5-years post-intervention. The TG increased V̇O2peak (11%, p<.01), scaled 1RM (40%, p<.001), and power (26%, p<.001) compared to CG after 1-year. At follow-up, no intergroup differences in these factors were observed (all p>.05). Both groups improved walking work efficiency (TG: 11%; CG: 18%; both p<.05) after 1-year (no intergroup difference, p>.05), but not at follow-up (both p>.05). At follow-up, HDL (high-density lipoprotein)-cholesterol (-15%, p<.01) and glucose (26%, p<.01) decreased/increased(respectively) more in the TG than CG. No other intergroup differences were observed in anthropometry or blood samples. 1-year adherence-supported high-intensity training improves V̇O2peak, 1RM, and power in outpatients with schizophrenia. However, the improvements in these factors key to longevity are not maintained after 5years. These findings highlight the importance of long-lasting cost-efficient adherence support, ultimately affecting the population's prognosis.

Heel Raises and Calf Stretches Exercises Versus Medication Only in Ischemic Intermittent Claudication: A Randomized Controlled Trial.

Intermittent claudication is a primary symptom of peripheral artery disease (PAD). a chronic progressive disease caused primarily by atherosclerosis. It is usually characterized by leg pain, aches, cramps, or fatigue when walking, which improves with rest. Physical therapy, including a supervised exercise program, is often recommended as the first treatment for sprains. This study aims to evaluate the short-term effects of incorporating heel raise and calf stretch exercises with standard medical therapy compared to medical therapy alone in managing intermittent claudication. From May 2022 to November 2023, 160 patients with Stage II Fontaine PAD were randomly assigned to two equal groups. Group A (80 patients) received heel raise and calf stretch exercises in addition to medical treatment, while Group B (80 patients) received only medical treatment. Both groups underwent treadmill walking tests before and after three months to measure absolute walking distance (ACD), peak walking time (PWT), and Walking Impairment Questionnaire (WIQ) scores, including distance, speed, and symptom severity. At baseline, there were no significant differences between the groups in terms of ACD, peak walking time, ankle-brachial index, distance, speed, and symptoms. At follow-up, Group A showed significantly greater improvements in ACD (312.00 ± 45.43 m), peak walking time (8.54 ± 1.55 min), distance (29.46 ± 4.63 km), speed (20.01 ± 3.13 kph), and WIQ symptoms (22.10 ± 1.02) compared to Group B, which had ACD (276.55 ± 29.07 m), peak walking time (6.72 ± 1.70 min), distance (23.68 ± 3.89 km), speed (15.71 ± 2.71 kph), and WIQ symptoms (20.80 ± 1.47) (P < .001). The ankle-brachial index remained similar between the groups (P > .05). We concluded that integrating standard physical therapy exercises, such as calf raises and leg stretches, with medical therapy significantly enhances walking function in patients with ischemic intermittent claudication.

Relationship between activity and sleep, as measured through a wearable accelerometer, and appropriate cardioverter defibrillator interventions: a prospective SafeHeart substudy.

Physical activity has shown association with ventricular arrhythmia, however, the role of specific behavioral patterns over a 24 h cycle remains unknown. Therefore, we aimed to explore associations between physical behavior and appropriate implantable cardioverter defibrillator (ICD) therapy. We included patients with an ICD at two European sites, who wore wrist-based accelerometers capturing 24 h movement and sleep behaviours for 28 days. Behavioural measures included activity volume, duration and intensity, sleep duration, and efficiency. Participants were followed for 12 months for the outcome of appropriate ICD therapy. Cox proportional hazard models with restricted cubic splines were used for the analysis. Lastly, the predictive capacity was tested. A total of 253 ICD patients were included (mean age 63.5 (±10.2), 48 (19.0%) female). During follow-up, 40 participants (15.8%) received appropriate ICD therapy; 32 anti-tachycardia pacing (ATP) only (12.6%), 5 shock only (2.0%), and 3 combined ATP and shock (1.2%). In the adjusted model, high inactive duration (HR 1.40 (95% 1.10-1.78)), peak walking cadence (HR 1.07 (95% 1.03-1.12)), and total sleep duration (HR 1.50 (1.02-2.22)) were associated with the outcome. The dose-response relationship was U-shaped for inactive duration with a cut-off at 16 h, and linear for peak cadence and sleep. The prediction model reached an area under the receiver operating characteristic curve of 0.70 ± 0.03, with highest accuracy in the first months. Wearable-derived 24 h movement and sleep behaviours collected over 28 days were associated with later appropriate ICD therapy risk. Testing of the predictive value of digital biomarkers for enhanced risk stratification of ventricular arrhythmia warrants larger prospective studies. National Trial Registration (NL9218, http://onderzoekmetmensen.nl/).

Semi-automated finite element analyses of surgically treated acetabular fractures to investigate the biomechanical behaviour of patient-specific compared to conventional implants

BackgroundIn acetabular fracture surgery, understanding the biomechanical behaviour of fractures and implants is beneficial for clinical decision-making about implant selection and postoperative (early) weightbearing protocols. This study outlines a novel approach for creating finite element models (FEA) from actual clinical cases. Our objectives were to (1) create a detailed semi-automatic three-dimensional FEA of a patient with a transverse posterior wall acetabular fracture and (2) biomechanically compare patient-specific implants with manually bent off-the-shelf implants.MethodsA computational study was performed in which we developed three finite element models. The models were derived from clinical imaging data of a 20-year-old male with a transverse posterior wall acetabular fracture treated with a patient-specific implant. This implant was designed to fit the patient's anatomy and fracture configuration, allowing for optimal placement and predetermined screw trajectories. The three FEA models included an intact hemipelvis for baseline comparison, one with a fracture fixated with a patient-specific implant, and another with a conventional implant. Two loading conditions were investigated: standing up and peak walking forces. Von Mises stress and displacement patterns in bone, implants and screws were analysed to assess the biomechanical behaviour of fracture fixation with either a patient-specific versus a conventional implant.ResultsThe finite element models demonstrated that for a transverse posterior wall type fracture, a patient-specific implant resulted in lower peak stresses in the bone (30 MPa and 56 MPa) in standing-up and peak walking scenario, respectively, compared to the conventional implant model (46 MPa and 90 MPa). The results suggested that patient-specific implant could safely withstand standing-up and walking after surgery, with maximum von Mises stresses in the implant of 156 MPa and 371 MPa, respectively. The results from the conventional implant indicate a likelihood of implant failure, with von Mises stresses in the implant (499 MPa and 1000 MPa) exceeding the yield stress of stainless steel.ConclusionThis study presents a workflow for conducting finite element analysis of real clinical cases in acetabular fracture surgery. This concept of personalized biomechanical fracture and implant assessment can eventually be applied in clinical settings to guide implant selection, compare conventional implants with innovative patient-specific ones, optimizing implant designs (including shape, size, materials, screw positions), and determine whether immediate full weight-bearing can be safely permitted.

Effects of short-term dietary nitrate supplementation on exercise and coronary blood flow responses in patients with peripheral artery disease.

Peripheral arterial disease (PAD) is a prevalent vascular disorder characterized by atherosclerotic occlusion of peripheral arteries, resulting in reduced blood flow to the lower extremities and poor walking ability. Older patients with PAD are also at a markedly increased risk of cardiovascular events, including myocardial infarction. Recent evidence indicates that inorganic nitrate supplementation, which is abundant in certain vegetables, augments nitric oxide (NO) bioavailability and may have beneficial effects on walking, blood pressure, and vascular function in patients with PAD. We sought to determine if short-term nitrate supplementation (via beetroot juice) improves peak treadmill time and coronary hyperemic responses to plantar flexion exercise relative to placebo (nitrate-depleted juice) in older patients with PAD. The primary endpoints were peak treadmill time and the peak coronary hyperemic response to plantar flexion exercise. Eleven PAD patients (52-80 yr.; 9 men/2 women; Fontaine stage II) were randomized (double-blind) to either nitrate-rich (Beet-IT, 0.3 g inorganic nitrate twice/day; BRnitrate) or nitrate-depleted (Beet-IT, 0.04 g inorganic nitrate twice/day, BRplacebo) beetroot juice for 4 to 6 days, followed by a washout of 7 to 14 days before crossing over to the other treatment. Patients completed graded plantar flexion exercise with their most symptomatic leg to fatigue, followed by isometric handgrip until volitional fatigue at 40% of maximum on day 4 of supplementation, and a treadmill test to peak exertion 1-2 days later while continuing supplementation. Hemodynamics and exercise tolerance, and coronary blood flow velocity (CBV) responses were measured. Although peak walking time and claudication onset time during treadmill exercise did not differ significantly between BRplacebo and BRnitrate, the diastolic blood pressure response at the peak treadmill walking stage was significantly lower in the BRnitrate condition. Increases in CBV from baseline to peak plantar flexion exercise after BRplacebo and BRnitrate showed a trend for a greater increase in CBV at the peak workload of plantar flexion with BRnitrate (p = 0.06; Cohen's d = 0.56). Overall, these preliminary findings suggest that inorganic nitrate supplementation in PAD patients is safe, well-tolerated, and may improve the coronary hyperemic and blood pressure responses when their calf muscles are most predisposed to ischemia.Clinical trial registration:https://clinicaltrials.gov/, identifier NCT02553733.

Impact of Multidisciplinary Prehabilitation Interventions on Postoperative Hospital Length of Stay and Functional Capacity in Patients Undergoing Resection of Colorectal Cancer: A Systematic Review and Meta-analysis.

Although surgery is commonly regarded as the primary curative treatment for colorectal cancer, it could potentially be associated with postoperative morbidity and mortality. To determine the pooled effect of exercise and multidisciplinary prehabilitation interventions on postoperative hospital length of stay and functional capacity in patients undergoing resection of colorectal cancer. A systematic search was conducted in MEDLINE (via PubMed) and Web of Science databases from inception to November 2022. The original systematic search retrieved 2005 studies. After the removal of duplicates and screening by title and abstract, 77 eligible full-text documents were evaluated for final inclusion in the meta-analysis. A total of 12 randomized controlled trials, 5 nonrandomized controlled trials, and 3 uncontrolled before-and-after studies were selected. Postoperative hospital length of stay (in days) and functional capacity (assessed with the peak of oxygen consumption [VO2 peak] and 6-minute walking test) were the outcome measures. The meta-analysis was conducted on 20 studies (3805 participants). Randomized controlled trials and nonrandomized controlled trials showed significant reductions in postoperative hospital length of stay (d = -0.10, nearly 2 days) and significant incremental improvements in VO2 peak (d = 0.27) and 6-minute walking test (d = 0.31). Regarding the before-and-after studies, the pooled effect of multidisciplinary prehabilitation interventions was positively significant for VO2 peak (d = 0.29) and 6-minute walking test (d = 0.29). There was no risk of publication bias (Egger test: p > 0.05), with a score of 0.71 (0-1) on average. There was a high between-studies heterogeneity, and several outcomes did not have the required number of studies for a desirable statistical power. These findings suggest that multidisciplinary prehabilitation interventions might be effective at decreasing postoperative hospital length of stay (nearly 2 days) and improving functional capacity. PROSPERO registration number CRD42022373982.

Walking energetics and white matter hyperintensities: findings from the Baltimore Longitudinal Study of Aging (BLSA)

AbstractBackgroundWhite matter hyperintensities (WMH) increase with advancing age and may contribute to the development of Alzheimer’s Disease. Energy utilization, as defined by walking efficiency, worsens with advancing age and is a prognostic marker of physical and cognitive function in older adults. While both WMH and energy utilization have been associated with cognition and Alzheimer’s‐related pathology, the links between WMH and walking energy utilization are unexplored. The purpose of this study was to examine the cross‐sectional association between walking energy utilization and WMH in cognitively normal middle‐to‐late aged men and women.MethodThe study included 708 BLSA participants who completed standardized slow‐ and peak‐pace walking assessments with indirect calorimetry (VO2 ml/kg/min) and underwent brain magnetic resonance imaging. Energy utilization was defined as the ratio of slow‐to‐peak walking energy capacity (the cost‐ratio), which describes the percentage of peak walking capacity required for the standardized slow walking task; a higher percentage indicates worse energy utilization. T2‐weighted scans and FLAIR images based on a validated support vector machine classifier approach were used to quantify total WMH volumes, which were log‐transformed to normalize the distribution. Sample characteristics were summarized using means and standard deviations. Linear regression was used to examine the association between WMH and the cost‐ratio adjusted for total white matter volume, age, sex, race, lean mass, fat mass, education, height, and comorbid conditions.ResultIn this sample of cognitively normal adults (56% women, mean age 66.7±15.3 years) the average cost‐ratio was 71.6±12.2% (range 34.3‐98.7) and mean log10(WHH) was 3.01±0.80 (range 0.08‐4.68). After covariate adjustment, a higher cost‐ratio was associated with greater total WMH (B = 0.008; SE = 0.002; p&lt;.001; Table 1). Aside from age and total white matter volume, which track closely with WMH, the cost‐ratio was most strongly associated with WMH in our model (Table 1).ConclusionIn a large sample of community‐dwelling middle‐to‐late aged adults, walking energy utilization was associated with WMH volumes, suggesting that a combination of higher energy cost of walking and lower peak walking energy capacity is associated with adverse brain health in mid‐to‐late life. Longitudinal research is needed to elucidate the directionality and temporality of the observed association.

Physiological responses during walking in men and women with intermittent claudication.

Miyasato et al. show that peak oxygen consumption, walking economy, anaerobic threshold, and cardiovascular responses (heart rate, blood pressure, and rate pressure product) during walking were similar between men and women with peripheral artery disease and intermittent claudication. There were no differences in the physiological responses to walking between men and women with intermittent claudication. Sex per se is not a factor that demands changes in walking prescription for patients with intermittent claudication. Peak oxygen consumption (VO2peak), anaerobic threshold, walking economy, and cardiovascular responses during walking are used to guide and monitor walking training in patients with peripheral artery disease and intermittent claudication. Women with peripheral artery disease and intermittent claudication present greater impairments than men, and evaluating training markers according to sex for decisions regarding walking prescription in this population is important. This study aimed to compare VO2peak, walking economy, anaerobic threshold, and cardiovascular responses during walking in men and women with peripheral artery disease and intermittent claudication. Forty patients (20 men and 20 women with similar baseline characteristics) underwent a cardiopulmonary treadmill test (3.2km/h and 2% increase in slope every 2 minutes until maximal leg pain). The VO2 and rate-pressure product were assessed. Data from men and women were compared using t-tests. There were no significant differences between men and women (VO2peak: 15.0±4.8 versus 13.9±2.9mL∙kg-1∙min-1, p=0.38; walking economy: 9.6±2.7 versus 8.4±1.6mL∙kg-1∙min-1, p=0.09; anaerobic threshold: 10.5±3.2 versus 10.5±2.2mL∙kg-1∙min-1, p=0.98; rate pressure product at 1st stage: 13,465± 2,910 versus 14,445±4,379bpm∙mmHg, p=0.41; and rate pressure product at anaerobic threshold:13,673±3,100 versus 16,390±5,870bpm∙mmHg, p=0.08 and rate pressure product at peak exercise: 21,253±6,141 versus 21,923±7,414bpm∙mmHg, p=0.76, respectively). Men and women with peripheral artery disease and similar baseline characteristics presented similar responses to walking, suggesting that decisions regarding walking prescription and monitoring can be made regardless of sex in this specific population.

Empagliflozin effects on iron metabolism as a possible mechanism for improved clinical outcomes in non-diabetic patients with systolic heart failure

Sodium-glucose co-transporter-2 (SGLT2) inhibitors improve clinical outcomes in patients with heart failure (HF), but mechanisms of action are incompletely understood. In the EMPA-TROPISM trial, empagliflozin reversed cardiac remodeling and increased physical capacity in stable non-diabetic patients with systolic HF. Here we explore, post hoc, whether treatment effects in this cohort, comprising patients who had a high prevalence of iron deficiency, were related to iron metabolism. Myocardial iron content estimated by cardiac magnetic resonance T2* quantification increased after initiation of empagliflozin but not placebo (treatment effect: P = 0.01). T2* changes significantly correlated with changes in left ventricular volumes, mass and ejection fraction, peak oxygen consumption and 6-minute walking distance; concomitant changes in red blood cell indices were consistent with augmented hematopoiesis. Exploratory causal mediation analysis findings indicated that changes in myocardial iron content after treatment with empagliflozin may be an important mechanism to explain its beneficial clinical effects in patients with HF.ClinicalTrials.gov: NCT03485222.

Wearable sensor and machine learning estimate tendon load and walking speed during immobilizing boot ambulation

The purpose of this study is to develop a wearable paradigm to accurately monitor Achilles tendon loading and walking speed using wearable sensors that reduce subject burden. Ten healthy adults walked in an immobilizing boot under various heel wedge conditions (30°, 5°, 0°) and walking speeds. Three-dimensional motion capture, ground reaction force, and 6-axis inertial measurement unit (IMU) signals were collected. We used a Least Absolute Shrinkage and Selection Operator (LASSO) regression to predict peak Achilles tendon load and walking speed. The effects of altering sensor parameters were also explored. Walking speed models (mean absolute percentage error (MAPE): 8.81 ± 4.29%) outperformed tendon load models (MAPE: 34.93 ± 26.3%). Models trained with subject-specific data performed better than models trained without subject-specific data. Removing the gyroscope, decreasing the sampling frequency, and using combinations of sensors did not change the usability of the models, having inconsequential effects on model performance. We developed a simple monitoring paradigm that uses LASSO regression and wearable sensors to accurately predict (MAPE ≤ 12.6%) Achilles tendon loading and walking speed while ambulating in an immobilizing boot. This paradigm provides a clinically implementable strategy to longitudinally monitor patient loading and activity while recovering from Achilles tendon injuries.

Wi-CL: Low-Cost WiFi-Based Detection System for Nonmotorized Traffic Travel Mode Classification

Traffic travel mode identification and classification are crucial for the development of intelligent transportation systems (ITSs). At present, scholars have investigated the classification of motorized and nonmotorized traffic travel in various road environments; however, the classification of walking and bicycle modes in nonmotorized travel has been largely ignored. Therefore, in this paper, we investigate nonmotorized traffic travel and propose a new low-cost nonmotorized traffic travel mode classification system, known as the Wi-Fi classification (Wi-CL) system that uses Wi-Fi signal detectors and the refined characteristics of nonmotorized travel modes. The Wi-CL system includes four modules: data acquisition module, data processing module, feature extraction module, and mode classification module. In the data acquisition module, the proposed system detects the Wi-Fi signals of traffic participants in road environments. In addition, we propose a received signal strength indicator (RSSI) filtering algorithm for hybrid traffic networks that effectively addresses surrounding obstacles and environmental noise. In the feature extraction module, we extract relevant traffic features to construct a mode classification model. Finally, a recurrent neural network (RNN) framework based on the long short-term memory (LSTM) algorithm is successfully implemented in the mode classification module for traffic travel mode identification. To validate the effectiveness of the Wi-CL system, extensive experiments were conducted using field data collected by Wi-Fi detectors installed at the South China University of Technology (SCUT). The experimental results show that the proposed RSSI filtering algorithm achieves excellent signal filtering results in real road traffic environments. In addition, the constructed travel speed estimation algorithm outperforms other baseline models in four different scenarios (flat-peak walking, midday peak walking, flat-peak cycling, and midday peak cycling), achieving an overall classification accuracy of 97.92%. In summary, our Wi-CL system is a feasible approach for nonmotorized traffic travel mode classification.

Effects of home-based high interval inspiratory muscle training on inspiratory muscle strength and exercise capacity in individuals with chronic heart failure

Study objective: Heart failure (HF) is a global disease that affects people worldwide. Individuals with HF have symptoms such as dyspnea, fatigue, and exercise intolerance. Inspiratory muscle strength plays an important role in individuals with chronic heart failure (CHF). Recent studies have shown that a long duration (15-30 mins/session) of low-intensity inspiratory muscle training (LI-IMT) improves inspiratory muscle function, exercise capacity, and quality of life in individuals with CHF. However, the long duration of training decreases the compliance of patients. Recently, a short duration (5 mins/session) of high-intensity interval IMT(HI-IMT) was found to improve inspiratory strength and exercise endurance in healthy individuals and individuals with obstructive sleep apnea. To date, the effectiveness of HI-IMT in individuals with HF is unknown. The aim of the study was to examine the effects of HI-IMT in individuals with CHF. The hypothesis of the study was HI-IMT improves inspiratory muscle strength, exercise capacity, and quality of life in individuals with CHF. Methods: This is a randomized control trial. Thirty-six individuals with HF (68% male) were randomly allocated to the HI-IMT group and the control group. Both groups of participants received home-based IMT 6 days/week for 12 weeks. Every session consisted of 30 breaths (5 breaths/set, 6 sets). The intensity of HI-IMT and the control group was 60% and 0% of maximal inspiratory pressure (MIP max ), respectively. Exercise capacity (VO 2 peak and 6-minute walking distance, 6MWD), MIP max , and quality of life (Minnesota living with heart failure questionnaire, MLHFQ) were examined before and after training. Analysis of covariance and paired T-tests were used to examine the training effects. P&lt;0.05 was considered different. Results: Thirty-six individuals with CHF were included in the study. The average age and the left ventricular ejection fraction were 64.7±11.9 years old and 44.5±12.3%, respectively. The improvements of MIP max , 6MWD, VO 2 peak , and MLHFQ were greater in the HI-IMT group than in the control group (p&lt;0.05). The HI-IMT group, but not the control group, showed significant improvements in oxygen uptake efficiency slope after the intervention (p&lt;0.05). Conclusion: 12 weeks of HI-IMT was an effective intervention to improve inspiratory muscle strength, exercise capacity, and quality of life in individuals with CHF. This study was supported by Yen Tjing Ling Medical Foundation, Taiwan. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Peak performance and cardiometabolic responses of modern US army soldiers during heavy, fatiguing vest-borne load carriage

IntroductionPhysiological limits imposed by vest-borne loads must be defined for optimal performance monitoring of the modern dismounted warfighter. PurposeTo evaluate how weighted vests affect locomotion economy and relative cardiometabolic strain during military load carriage while identifying key physiological predictors of exhaustion limits. MethodsFifteen US Army soldiers (4 women, 11 men; age, 26 ± 8 years; height, 173 ± 10 cm; body mass (BM), 79 ± 16 kg) performed four incremental walking tests with different vest loads (0, 22, 44, or 66% BM). We examined the effects of vest-borne loading on peak walking speed, the physiological costs of transport, and relative work intensity. We then sought to determine which of the cardiometabolic indicators (oxygen uptake, heart rate, respiration rate) was most predictive of task failure. ResultsPeak walking speed significantly decreased with successively heavier vest loads (p < 0.01). Physiological costs per kilometer walked were significantly higher with added vest loads for each measure (p < 0.05). Relative oxygen uptake and heart rate were significantly higher during the loaded trials than the 0% BM trial (p < 0.01) yet not different from one another (p > 0.07). Conversely, respiration rate was significantly higher with the heavier load in every comparison (p < 0.01). Probability modeling revealed heart rate as the best predictor of task failure (marginal R2, 0.587, conditional R2, 0.791). ConclusionHeavy vest-borne loads cause exceptional losses in performance capabilities and increased physiological strain during walking. Heart rate provides a useful non-invasive indicator of relative intensity and task failure during military load carriage.

Magnetic Resonance Imaging-Derived Microvascular Perfusion Modeling to Assess Peripheral Artery Disease.

Background Computational fluid dynamics has shown good agreement with contrast-enhanced magnetic resonance imaging measurements in cardiovascular disease applications. We have developed a biomechanical model of microvascular perfusion using contrast-enhanced magnetic resonance imaging signal intensities derived from skeletal calf muscles to study peripheral artery disease (PAD). Methods and Results The computational microvascular model was used to study skeletal calf muscle perfusion in 56 individuals (36 patients with PAD, 20 matched controls). The recruited participants underwent contrast-enhanced magnetic resonance imaging and ankle-brachial index testing at rest and after 6-minute treadmill walking. We have determined associations of microvascular model parameters including the transfer rate constant, a measure of vascular leakiness; the interstitial permeability to fluid flow which reflects the permeability of the microvasculature; porosity, a measure of the fraction of the extracellular space; the outflow filtration coefficient; and the microvascular pressure with known markers of patients with PAD. Transfer rate constant, interstitial permeability to fluid flow, and microvascular pressure were higher, whereas porosity and outflow filtration coefficient were lower in patients with PAD than those in matched controls (all P values ≤0.014). In pooled analyses of all participants, the model parameters (transfer rate constant, interstitial permeability to fluid flow, porosity, outflow filtration coefficient, microvascular pressure) were significantly associated with the resting and exercise ankle-brachial indexes, claudication onset time, and peak walking time (all P values ≤0.013). Among patients with PAD, interstitial permeability to fluid flow, and microvascular pressure were higher, while porosity and outflow filtration coefficient were lower in treadmill noncompleters compared with treadmill completers (all P values ≤0.001). Conclusions Computational microvascular model parameters differed significantly between patients with PAD and matched controls. Thus, computational microvascular modeling could be of interest in studying lower extremity ischemia.

Estimating ground reaction force with novel carbon nanotube-based textile insole pressure sensors.

This study presents a new wearable insole pressure sensor (IPS), composed of fabric coated in a carbon nanotube-based composite thin film, and validates its use for quantifying ground reaction forces (GRFs) during human walking. Healthy young adults (n = 7) walked on a treadmill at three different speeds while data were recorded simultaneously from the IPS and a force plate (FP). The IPS was compared against the FP by evaluating differences between the two instruments under two different assessments: (1) comparing the two peak forces at weight acceptance and push-off (2PK) and (2) comparing the absolute maximum (MAX) of each gait cycle. Agreement between the two systems was evaluated using the Bland-Altman method. For the 2PK assessment, the group mean of differences (MoD) was -1.3 ± 4.3% body weight (BW) and the distance between the MoD and the limits of agreement (2S) was 25.4 ± 11.1% BW. For the MAX assessment, the average MoD across subjects was 1.9 ± 3.0% BW, and 2S was 15.8 ± 9.3% BW. The results of this study show that this sensor technology can be used to obtain accurate measurements of peak walking forces with a basic calibration and consequently open new opportunities to monitor GRF outside of the laboratory.

Relation of non-exercise walking activity with exercise performance in patients with peripheral artery disease: NEW activity for PAD

IntroductionCommunity-based structured exercise training (CB-SET) programs are beneficial for patients with peripheral artery disease (PAD). However, the impact of lower levels of walking activity accumulated separately from formal exercise is unclear. The aim of this study was to determine the relation of non-exercise walking (NEW) activity with exercise performance in PAD. MethodsThis was a post hoc analysis from twenty patients with PAD enrolled in a 12 week CB-SET program using diaries and accelerometry. Formal exercise (3 sessions·week−1) was detected using patient-reported diary entries that corresponded with accelerometer step data. NEW activity was characterized as steps completed over five days each week, excluding steps achieved during formal exercise sessions. The primary exercise performance outcome was peak walking time (PWT) assessed on a graded treadmill. Secondary performance outcomes included claudication onset time (COT) from the graded treadmill and peak walking distance (PWD) achieved during the six-minute walk test (6MWT). Partial Pearson correlations evaluated the relation of NEW activity (step·week−1) with exercise performance outcomes using exercise session intensity (step·week−1) and duration (min·week−1) as covariates. ResultsNEW activity demonstrated a moderate, positive correlation with change in PWT (r=0.50, p=0.04). Other exercise performance outcomes were not significantly related to NEW activity (COT: r=0.14; 6MWT PWD: r=0.27). ConclusionsA positive association was demonstrated between NEW activity and PWT following 12 weeks of CB-SET. Interventions to increase physical activity levels outside of formal exercise sessions may be beneficial for patients with PAD.

Clinical Pediatric Exercise Laboratories, Reactive Balance, Sleep, and Muscle Stimulation Considerations

Clinical Pediatric Exercise Laboratories, Reactive Balance, Sleep, and Muscle Stimulation Considerations

Does Exercise Training Improve Physical Fitness and Health in Adult Liver Transplant Recipients? A Systematic Review and Meta-analysis.

The impaired physical fitness of end-stage liver disease patients often persists after liver transplantation (LT) and compromises posttransplant recovery. This systematic review and meta-analysis evaluated evidence supporting the potential of exercise training to improve physical fitness and health-related quality of life (HRQOL) after LT. Bibliographic searches identified all randomized controlled trials (RCTs) comparing aerobic and strength training versus usual care after LT. Risk of bias was assessed, and study outcomes measuring physical fitness and HRQOL were extracted. Meta-analysis was performed if at least 3 studies reported on an outcome. Eight RCTs (n = 334) were identified. Methodological study quality varied and was poorly reported. Meta-analyses showed a trend for favorable effects of exercise on cardiorespiratory fitness (peak oxygen uptake or 6-min walking distance; 6 studies, n = 275; standardized mean difference: 0.23, 95% confidence interval [CI], -0.01 to 0.48) and of strength training either or not combined with aerobic training on muscular fitness (dynamometry-assessed muscle strength or 30-s sit-to-stand test; 3 studies, n = 114; standardized mean difference: 0.34, 95% CI, -0.03 to 0.72). A favorable effect was found for exercise on the Short-Form Health Survey-36 HRQOL physical function subcomponent (3 studies, n = 194; mean difference: 9.1, 95% CI, 0.3-17.8). No exercise-related adverse events were observed. RCTs indicate that exercise training in LT recipients is safe, improves physical function aspects of HRQOL, and may benefit cardiorespiratory and muscular fitness. The strength of evidence is, however, limited by the low number of patients and study quality. More adequately powered, high-quality RCTs are warranted.

Outcomes following supervised exercise and home-based exercise for patients with intermittent claudication

Intermittent claudication (IC) is the most common symptom of peripheral arterial disease (PAD) which presents as a consequence of muscle ischaemia resulting from the atherosclerotic obstruction to arterial flow. High-quality evidence (Lane etal., 2017) shows that exercise programmes provide important benefits compared with usual care in improving pain-free and maximum walking distance in people with IC, but do not improve ankle-brachial pressure index (ABPI). Retrospective data were analysed to examine walking and ABPI outcomes for participants who completed a 12-week course of supervised or home-based exercise. All participants had a history of IC. 46 participants (mean age 69±11 years; 76% male; 29% current smokers) referred for exercise were assessed, completed a 12-week course of exercise (home-based or supervised) and subsequently attended for re-assessment. Claudication onset distance (COD) increased by 363% (mean improvement 344.7±265.1m; p<.001) and peak walking distance (PWD) by 324.4% in the supervised exercise group; COD increased by 30.6% (mean improvement 32.8±57.2m; p=0.026) and PWD by 31.5% in the home-based exercise group. Resting ABPI for the total cohort significantly improved from 0.82±0.25 at A1 to 0.88±0.25 at A2 (p=0.027). A 12-week course of supervised exercise results in significantly greater walking distance outcomes (COD and PWD) than unmonitored home-based exercise. In contrast with previous findings (Lane etal. 2017), this retrospective study demonstrated a significant improvement in resting ABPI with both supervised exercise as well as home-based exercise. A 12-week programme of exercise favourably influenced walking and ABPI outcomes for patients with IC. Both home-based exercise and supervised individualised exercise increased walking distances, but the magnitude of the improvement in walking outcomes was greater in individuals who attended supervised exercise therapy.

Impaired Modulation of Motor and Functional Performance in Patients after Total Knee Arthroplasty: A Prospective Observational Study.

Submaximal levels of effort are required for the performance of the most common daily tasks. Inaccuracy in modulating motor outputs during submaximal tasks has been reported as indicator of safety during daily activities in subjects with lower limb musculoskeletal disorders. The study is aimed at investigating performance modulation ability during motor and functional tasks in patients after total knee arthroplasty (TKA). Sixteen patients with end-stage osteoarthritis undergoing TKA and twenty age-matched healthy participants performed isokinetic knee extension, sit-to-stand, and walking tasks at three levels of self-estimated effort (100%, 50%, and 25%) the day before (T0) and 4 days after surgery (T1). Maximum performance in terms of peak torque (PT—knee extension), overshoot (OS—sit-to-stand), and walking speed was evaluated. Subsequently, relative error (RE) between target and observed performance was computed for the submaximal tasks (RE50% and RE25%). Our results showed a decline of maximum performance after surgery, which resulted lower in patients compared to healthy subjects. RE50% and RE25% for knee extension (involved limb) (p < 0.001) and RE25% for sit-to-stand (p < 0.001) increased from pre- to postsurgery. At T0, knee extension RE25% and walking RE50% and RE25% were higher in patients. At T1, RE50% and RE25% were higher in patients for knee extension (involved limb), sit-to-stand, and walking. In conclusion, the ability to modulate motor and functional performance decreased after TKA and resulted impaired when compared to healthy age-matched subjects. Based on relationship between ability to modulate motor outputs and risk of falling, the role of modulation ability as indicator of readiness for discharge and safe return to daily activities deserves further investigations in patients in early phase after TKA.