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Goal: This study introduces a novel approach to examine the temporal-spatial information derived from High-Density surface Electromyography (HD-sEMG). By integrating and adapting postural control parameters into a framework for the analysis of myoelectrical activity, new metrics to evaluate muscle fatigue progression were proposed, investigating their ability to predict endurance time. Methods: Nine subjects performed a fatiguing isometric contraction of the lumbar erector spinae. Topographical amplitude maps were generated from two HD-sEMG grids. Once identified the coordinates of the muscle activity, novel metrics for quantifying the muscle spatial distribution over time were calculated. Results: Spatial metrics showed significant differences from beginning to end of the contraction, highlighting their ability of characterizing the neuromuscular adaptations in presence of fatigue. Additionally, linear regression models revealed strong correlations between these spatial metrics and endurance time. Conclusions: These innovative metrics can characterize the spatial distribution of muscle activity and predict the time of task failure.
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Background: Aerobic capacity has shown to predict physical and mental health-related quality of life in bipolar disorder (BD). However, the correlation between exercise respiratory capacity and mitochondrial function remains understudied. We aimed to assess longitudinally intra-individual differences in these factors during mood episodes and remission in BD. Methods: This study included eight BD patients admitted to an acute psychiatric unit. Incremental cardiopulmonary exercise test (CPET) was conducted during acute episodes (T0), followed by constant work rate cycle ergometry (CWRCE) to evaluate endurance time, oxygen uptake at peak exercise (VO2peak) and at the anaerobic threshold. The second test was repeated during remission (T1). Mitochondrial respiration rates were assessed at T0 and T1 in peripheral blood mononuclear cells. Results: Endurance time, VO2peak, and anaerobic threshold oxygen consumption showed no significant variations between T0 and T1. Basal oxygen consumption at T1 tended to inversely correlate with maximal mitochondrial respiratory capacity (r=-0.690, p=0.058), and VO2peak during exercise at T1 inversely correlated with basal and minimum mitochondrial respiration (r=-0.810, p=0.015; r=-0.786, p=0.021, respectively). Conclusions: Our preliminary data showed that lower basal oxygen consumption may be linked to greater mitochondrial respiratory capacity, and maximum oxygen uptake during the exercise task was associated with lower basal mitochondrial respiration, suggesting that lower oxygen requirements could be associated with greater mitochondrial capacity. These findings should be replicated in larger samples stratified for manic and depressive states.
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BACKGROUND AND OBJECTIVE: Interstitial lung disease (ILD) is characterized by dyspnoea on exertion and exercise-induced hypoxaemia. High-flow nasal cannula (HFNC) therapy reduces the respiratory workload through higher gas flow and oxygen supplementation, which may affect exercise tolerance. This study aimed to examine the effects of oxygen and gas flow rates through HFNC therapy on exercise tolerance in ILD patients. METHODS: We conducted three-treatment crossover study. All ILD patients performed the exercises on room air (ROOM AIR setting: flow, 0 L/min; fraction of inspired oxygen [FiO2], 0.21), HFNC (FLOW setting: flow 40 L/min, FiO2 0.21), and HFNC with oxygen supplementation (FLOW + OXYGEN setting: flow 40 L/min, FiO2 0.6). The primary endpoint was the endurance time, measured using constant-load cycle ergometry exercise testing at a peak work rate of 80%. RESULTS: Twenty-five participants (10 men, 71.2 ± 6.7 years) were enrolled. The increase in exercise duration between the ROOM AIR and FLOW was 46.3 s (95% CI, -6.1 to 98.7; p = 0.083), and the FLOW and FLOW + OXYGEN was 91.5 s (39.1-143.9; p < 0.001). The percutaneous oxygen saturation (SpO2) at rest was significantly higher with the FLOW + OXYGEN setting than with the ROOM AIR and FLOW settings, and the difference persisted during exercise. At equivalent time points during exercise, the SpO2 with the FLOW setting was significantly higher than that with the ROOM AIR setting. CONCLUSION: Oxygen supplementation in HFNC therapy improved exercise tolerance and SpO2. We found that gas flow alone did not improve exercise tolerance, but improved SpO2 during exercise.
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Cánula , Estudios Cruzados , Tolerancia al Ejercicio , Enfermedades Pulmonares Intersticiales , Terapia por Inhalación de Oxígeno , Humanos , Masculino , Enfermedades Pulmonares Intersticiales/terapia , Enfermedades Pulmonares Intersticiales/fisiopatología , Terapia por Inhalación de Oxígeno/métodos , Tolerancia al Ejercicio/fisiología , Femenino , Anciano , Prueba de Esfuerzo , Persona de Mediana Edad , Resultado del Tratamiento , Oxígeno/administración & dosificación , Oxígeno/sangreRESUMEN
OBJECTIVE: To explore characteristics of tongue pressure changes in nasopharyngeal carcinoma (NPC) patients with dysphagia after radiotherapy using a novel system with multisite flexible sensors. DESIGN: Prospective observational study. SETTING: Inpatient rehabilitation centers and community dwellings. PARTICIPANTS: Nineteen patients with dysphagia after radiotherapy for NPC and 19 healthy participants were recruited for this study (N=38). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: A new 9-site (3 × 3) flexible tongue pressure sensor was used to measure tongue-to-palate pressure across different parts of the tongue. The oral tongue was divided into 3 parts: anterior tongue region (TAR), central tongue region (TCR), and posterior tongue region (TPR); 3 sensors were placed on each part. The mean tongue pressure and endurance time at the 3 sites in the TAR, TCR, and TPR were analyzed. The ratios of the mean TAR, TCR, and TPR values were calculated. RESULTS: Pressures of TAR, TCR, and TPR in NPC patients with dysphagia were significantly lower than those in healthy participants (P<.05). The pressure in TPR decreased most significantly, followed by that in TCR. The endurance times of TAR and TCR were longer than those of healthy participants (P<.05). The endurance time of TPR was not significantly different between the patients and healthy participants (P>.05). Ratios of pressure between TAR and TCR and TAR and TPR in patients were lower than that in healthy participants (P<.05). There was no significant difference in the TCR to TPR pressure ratio between patients and healthy participants (P>.05). CONCLUSIONS: Tongue pressure significantly decreased in NPC patients with dysphagia, and the drop in pressure was most pronounced in the TPR area. The results of our study indicate that we should pay attention to the pressure training of the TPR during treatments. The endurance time of the TAR and TCR increased significantly, which may be due to bolus transport compensation. Therefore, clinical rehabilitation strategies should aim to increase the endurance time training in NPC patients after radiotherapy to help increase the effectiveness of the swallowing process in patients.
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Trastornos de Deglución , Neoplasias Nasofaríngeas , Humanos , Trastornos de Deglución/etiología , Carcinoma Nasofaríngeo/radioterapia , Presión , Lengua , Neoplasias Nasofaríngeas/radioterapia , Receptores de Antígenos de Linfocitos TRESUMEN
In seismic performance evaluations, the force-deformation response of a structure is typically assessed using a deterministic analytical model, and inherent uncertainty is often neglected. For reinforced concrete structures, a source of uncertainty is variability in the mechanical properties of reinforcing steel and concrete (that is, material uncertainty). This paper presents an analytical investigation to quantify the impact of the statistical variability in mechanical properties of ASTM A706 Grade 60, 80, and 100 reinforcing steel and normalweight concrete on the seismic response of reinforced concrete bridge columns. The effects on the drift response, expressed by the coefficient of variation (COV), range between COV values of 0.1 for low-to-moderate ductility demands (that is, drift ratio < 5%), and 0.3 for larger ductility demands. The COV of the force demand is lower, ranging between 0.05 and 0.1. Overall, the study shows that material uncertainty can be incorporated in seismic performance assessments through a few additional analyses.
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BACKGROUND AND OBJECTIVE: Exercise capacity in idiopathic pulmonary fibrosis (IPF) is limited by exercise-induced hypoxaemia. This study aimed to examine the effect of high-flow nasal cannula oxygen therapy (HFNC) on exercise tolerance in patients with IPF. METHODS: We conducted a single-centre, open-label, randomized crossover trial to compare HFNC and Venturi mask (VM) therapy in terms of exercise tolerance. Patients underwent constant-load symptom-limited exercise testing at 80% peak work rate with HFNC or a VM in a randomized order. The settings were 60 L/min and a 50% fraction of inspired oxygen (FiO2 ) for HFNC and 12 L/min and 50% FiO2 for VM. The primary outcome was endurance time, and the secondary outcomes were heart rate (HR), percutaneous oxygen saturation (SpO2 ), dyspnoea and leg fatigue, as determined by the modified Borg Scale at the isotime and endpoint, and the level of comfort while using the devices. RESULTS: Twenty-four participants (75.0% men; age, median [interquartile range]: 77.5 [68.8-83.0] years) were enrolled. Compared with VM, HFNC significantly improved the endurance time (647.5 s [454.0-1014.8] vs. 577.5 s [338.0-861.5]), minimum SpO2 (96.0% [95.0-98.0] vs. 94.0% [92.8-96.0]) and leg fatigue at the isotime (3.0 [1.6-4.0] vs. 5.0 [3.0-6.3]) and endpoint (4.0 [2.8-5.0] vs. 5.0 [3.8-6.3]). Differences in maximum HR, dyspnoea at the isotime and endpoint and comfort were non-significant between HFNC and VM therapy. CONCLUSION: HFNC increased exercise tolerance in patients with stable IPF experiencing exercise-induced hypoxaemia.
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Fibrosis Pulmonar Idiopática , Insuficiencia Respiratoria , Anciano , Cánula , Estudios Cruzados , Tolerancia al Ejercicio/fisiología , Femenino , Humanos , Fibrosis Pulmonar Idiopática/terapia , Masculino , Oxígeno , Terapia por Inhalación de Oxígeno , Insuficiencia Respiratoria/terapiaRESUMEN
BACKGROUND: Two new protocols have been developed for bicycle exercise testing in chronic obstructive pulmonary disease (COPD) with an individualized cardiopulmonary exercise test (ICPET) and subsequent customized endurance test (CET), which generate less interindividual spread in endurance time compared with the standard endurance test. Main objectives of this study were to improve the prediction algorithm for WMAX for the ICPET and validate the CET by examining treatment effects on exercise performance of indacaterol/glycopyrronium (IND/GLY) compared with placebo. METHODS: COPD patients, with forced expiratory volume in 1 s (FEV1) 40-80% predicted, were recruited. Pooled baseline data from two previous studies (n = 38) were used for the development of an improved WMAX prediction algorithm. Additional COPD patients (n = 14) were recruited and performed the ICPET, using the new prediction formula at visit 1. Prior to the CET at visits 2 and 3, they were randomized to a single dose of IND/GLY (110/50 µg) or placebo. RESULTS: The improved multiple regression algorithm for WMAX includes diffusing capacity for carbon monoxide (DLCO), FEV1, sex, age and height and correlated to measured WMAX (R2 = 0.89 and slope = 0.89). Treatment with IND/GLY showed improvement in endurance time versus placebo, mean 113 s [95% confidence interval (CI): 6-220], p = 0.037, with more prominent effect in patients with FEV1 < 70% predicted. CONCLUSION: The two new protocols for ICPET (including the new improved algorithm) and CET were retested with consistent results. In addition, the CET showed a significant and clinically relevant prolongation of endurance time for IND/GLY versus placebo in a small number of patients.
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Broncodilatadores , Enfermedad Pulmonar Obstructiva Crónica , Agonistas de Receptores Adrenérgicos beta 2 , Algoritmos , Combinación de Medicamentos , Prueba de Esfuerzo , Volumen Espiratorio Forzado , Glicopirrolato , Humanos , Indanos/uso terapéutico , Pulmón , Antagonistas Muscarínicos , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Enfermedad Pulmonar Obstructiva Crónica/tratamiento farmacológico , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
BACKGROUND AND OBJECTIVES: Patients with interstitial lung disease (ILD) experience early symptoms of dyspnoea and leg fatigue during exercise together with severe and rapid oxygen desaturation. Heated and humidified nasal high flow oxygen (NHF) has been proven to enhance exercise endurance and physiological parameters in COPD patients. This study aims to evaluate the effect of NHF on exercise tolerance in ILD patients. METHODS: Twenty-five patients (10 female) with severe ILD performed three constant-load (70% maximal workload) cycling tests to exhaustion under different breathing conditions: room air, oxygen supplementation (4 L min-1 O2) and NHF (inspiratory O2 fraction 0.5, 30-50 L min-1, heated 34 °C and humidified). RESULTS: Endurance time was significantly longer with NHF (618 ± 297 s) compared to O2 (369 ± 217 s, p < 0.001) and room air (171 ± 76 s, p < 0.001). Kinetics of oxygen desaturation, chronotropic response, dyspnoea and leg fatigue sensations were delayed with NHF. At exhaustion with NHF, compared to the two other conditions, oxygen desaturation was less severe while heart rate, dyspnoea and leg fatigue were similar. CONCLUSION: NHF significantly improved endurance time, physiological parameters and sensations during exercise in severe ILD patients. NHF may be useful to improve functional capacities and facilitate pulmonary rehabilitation in ILD.
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Tolerancia al Ejercicio/fisiología , Calor , Humedad , Enfermedades Pulmonares Intersticiales/fisiopatología , Enfermedades Pulmonares Intersticiales/rehabilitación , Terapia por Inhalación de Oxígeno/métodos , Oxígeno/administración & dosificación , Anciano , Disnea/etiología , Disnea/terapia , Fatiga/etiología , Fatiga/terapia , Femenino , Humanos , Pierna , Enfermedades Pulmonares Intersticiales/complicaciones , Masculino , Gravedad del Paciente , Proyectos Piloto , Resultado del TratamientoRESUMEN
Purpose: For exercise testing of COPD patients, a standard endurance test (ET) with constant workload is recommended. The test suffers from large inter-individual variability and need for large sample sizes in order to evaluate treatment effects. Methods: A new protocol for ET in COPD was designed. In contrast to the standard ET, the new ET involved an increasing workload in order to reduce the standard deviation of endurance time. Two new ETs were compared with the standard ET. In Study A, the new ET started at 75% of the patient's maximum workload (WMAX) and increased stepwise with 3%/2 min until exhaustion. Study B started at 70% of WMAX and increased linearly with 1%/min. Results: In Study A, that included 15 patients, the standard deviation and range for endurance time and work capacity were narrower for the new versus the standard ET. However, the higher mean workload at end and the low mean work capacity relative to the standard ET indicated that the stepwise increase was too aggressive. In Study B, that included 18 patients, with a modified protocol, the averages for endurance time, workload at end and work capacity were similar for new and standard ET, while the standard deviations and ranges for endurance time and work capacity were kept more narrow in the new ET. The variances for endurance time were not equal between the standard ET and the two new ETs (p<0.05 for both according to Levene's test). Conclusion: The new ET reduced the number of patients with extreme endurance times (short and long) compared to the standard test. The new test showed a significant lower variance for endurance time, which potentially can lead to fewer patients needed in comparative studies. The overall best results were observed with a low linear increase during endurance.
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Prueba de Esfuerzo , Enfermedad Pulmonar Obstructiva Crónica , Tolerancia al Ejercicio , Humanos , Estado Nutricional , Resistencia Física , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Carga de TrabajoRESUMEN
Background: Dynamic lung hyperinflation (DLH) has been evaluated based on decreased inspiratory capacity (IC) during exercise load. However, this is not routinely done in clinical practice. We have developed a convenient method of metronome-paced incremental hyperventilation (MPIH) and reported its usefulness. In the present study, we compared these two methods for evaluating DLH and examined whether our MPIH method can be used to predict DLH during exercise. Methods: DLH was measured by MPIH and constant load exercise (CLE) in 35 patients with stable COPD. DLH was defined as the most decreased IC (IClowest) and the most decreases in IC from IC at rest (-IClowest), and we compared between these two methods. Results: The IClowest in CLE and the -IClowest in MPIH were significantly lower in emphysema-dominant COPD than in emphysema-nondominant COPD. Both IClowest and -IClowest showed significant correlations between the two methods (r = 0.67, p < 0.01 and r = 0.44, p < 0.01, respectively). The endurance time of CLE was significantly correlated with IClowest following MPIH (r = 0.62, p < 0.01) but not with that obtained by the CLE method. Furthermore, the IClowest of MPIH was more significantly correlated with endurance time in emphysema-dominant COPD. Weak but significant correlations between the -IClowest obtained by each method and maximum modified Borg scale were observed (MPIH: r = 0.38, p = 0.02; CLE: r = 0.37, p = 0.03). Conclusion: The MPIH method may be a convenient method to predict exercise tolerance and dyspnea as a clinically useful synergic screening surrogate for DLH during exercise.
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Tolerancia al Ejercicio , Enfermedad Pulmonar Obstructiva Crónica , Disnea/diagnóstico , Disnea/etiología , Prueba de Esfuerzo , Volumen Espiratorio Forzado , Humanos , Hiperventilación/diagnóstico , Capacidad Inspiratoria , Pulmón , Enfermedad Pulmonar Obstructiva Crónica/diagnósticoRESUMEN
Although the rotator cuff muscles are susceptible to fatigue, shoulder fatigue studies reporting torque decline during intermittent tasks are relatively uncommon in the literature. A previous modification to the three-compartment controller (3CC) fatigue model incorporated a rest recovery multiplier (3CC-r model) to represent augmented blood flow to muscle during rest intervals (Looft et al., 2018). A rest recovery value of r = 15 was optimal for ankle, knee, and elbow joint regions, whereas r = 30 was better for hand/grip muscles. However, shoulder torque decline data was unavailable in the literature for comparison. Thus, the purpose of this study was to collect fatigue data for two different intermittent, isometric shoulder flexion fatiguing tasks and assess the 3CC-r model with r = 15 or 30 compared to the original 3CC model. Twenty healthy participants (9 M) completed two fatigue tasks: 50% maximum voluntary contraction (MVC) with 50% duty cycle (DC) and 70% MVC with 70% DC. MVCs were assessed at discrete time points (1, 3, 5, 10, and 15 min) until endurance time (MET). Mean observed percent torque decline (%TD) for the two tasks were compared to three model estimates: 3CC-r (using r = 15 and r = 30) and 3CC. Using these data, we confirmed that the addition of a rest multiplier (r = 15 somewhat better than r = 30) substantially improved predictions of shoulder fatigue using a previously validated analytical fatigue model (3CC). The relatively large reduction in model errors over the original model suggests the importance of representing augmented recovery during rest periods.
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Fatiga Muscular , Hombro , Electromiografía , Fatiga , Humanos , Contracción Isométrica , Músculo Esquelético , Rango del Movimiento Articular , TorqueRESUMEN
BACKGROUND AND OBJECTIVE: The efficacy of supplemental oxygen during exercise remains unclear for patients with IPF, as there have been conflicting results from recent prospective studies with small sample sizes. METHODS: This prospective, single-blind, randomized, crossover trial evaluated the efficacy of supplemental oxygen compared with placebo air during exercise in consecutive patients with IPF without resting hypoxaemia at initial evaluation. Patients with <90% SpO2 in a 6MWT using room air were randomly assigned to a CWRET at 80% of peak work rate with oxygen or placebo air gas via nasal cannula at 4 L/min. The primary endpoint was the effect of supplemental oxygen on endurance time. RESULTS: We recruited 72 consecutive patients (median age: 66.5 years, % FVC: 84.6%, % DLCO : 61.4%). Supplemental oxygen significantly increased the endurance time (340-424 s; P < 0.001) and minimum SpO2 (88.0-94.0%; P < 0.001) compared with placebo air. Furthermore, supplemental oxygen significantly improved dyspnoea and leg fatigue. In a multivariate linear regression analysis, the endurance time on air was an independent explanatory variable of the improvement rate of endurance time (P = 0.02). CONCLUSION: In mild-moderate IPF with exercise-induced hypoxaemia even without resting hypoxaemia, supplemental oxygen during exercise improved the endurance time, desaturation and subjective symptoms. Patients with shorter endurance times with placebo air showed better improvement with supplemental oxygen.
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Disnea , Tolerancia al Ejercicio/fisiología , Hipoxia , Fibrosis Pulmonar Idiopática , Terapia por Inhalación de Oxígeno/métodos , Anciano , Estudios Cruzados , Disnea/diagnóstico , Disnea/etiología , Disnea/terapia , Prueba de Esfuerzo/métodos , Femenino , Humanos , Hipoxia/etiología , Hipoxia/terapia , Fibrosis Pulmonar Idiopática/sangre , Fibrosis Pulmonar Idiopática/fisiopatología , Fibrosis Pulmonar Idiopática/terapia , Masculino , Esfuerzo Físico , Estudios Prospectivos , Método Simple Ciego , Resultado del TratamientoRESUMEN
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Swimming performance (aerobic and anaerobic) is often used to predict the ability of fish to adapt and survive. Fish raised in captivity are typically poor swimmers and have lower survival rates than wild conspecifics when released into the natural environment. We investigated the potential for exercise training to enhance the swimming performance of Schizothorax wangchiachii held in captivity. Juvenile fish (mean body mass 1.40 ± 0.13 g, mean body length 4.36 ± 0.24 cm) were trained under five different regimes [3 cm·s-1 control group (C), 10 cm·s-1 for 6 (L6) and 12 h (L12) per day and 20 cm·s-1 for 6 (H6) and 12 h (H12) per day] for 30 days and then detrained for 20 days (i.e. no training). Aerobic (i.e. critical swimming speed, Ucrit), anaerobic swimming performance (i.e. endurance time at 1.2 or 1.5 Ucrit), and morphological parameters were measured at the beginning (T0), after 30 days of exercise training (T30) and after 20 days of detraining (DT20). Aerobic exercise training significantly improved the Ucrit, endurance time at 1.2 and 1.5 Ucrit of juvenile S. wangchiachii (P < .05). After 20 days of detraining, both the aerobic and anaerobic swimming performance of the H6 and H12 groups declined and no longer differed from the control group indicating a failure to maintain improved swimming performance, whereas improved swimming performance was maintained in L6 and L12 groups. No significant difference in swimming performance was found between 6 and 12 hours training at 10 cm·s-1. Thus, exercise at close to 10 cm·s-1 for 6 h per day for 30 days or a longer time periods prior to release appears to be a suitable regime for swimming performance enhancement, potentially increasing survivability of released S. wangchiachii in wild.
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Aerobiosis , Anaerobiosis , Cyprinidae/fisiología , Explotaciones Pesqueras , Condicionamiento Físico Animal , Natación , Adaptación Fisiológica/fisiología , Animales , Consumo de OxígenoRESUMEN
Constant-force isometric muscle training is useful for increasing the maximal strength , rehabilitation and work-fatigue assessment. Earlier studies have shown that muscle fatigue characteristics can be used for evaluating muscle endurance limit. STUDY OBJECTIVE: To predict muscle endurance time during isometric task using frequency spectrum characteristics of surface electromyography signals along with analysis of frequency spectrum shape and scale during fatigue accumulation. METHOD: Thirteen subjects performed isometric lateral raise at 60% MVC of deltoid (lateral) till endurance limit. Time windowed sEMG frequency spectrum was modelled using 2-parameter distributions namely Gamma and Weibull for spectrum analysis and endurance prediction. RESULTS: Gamma distribution provided better spectrum fitting (P < 0.001) than Weibull distribution. Spectrum Distribution demonstrated no change in shape but shifted towards lower frequency with increase of magnitude at characteristic mode frequency. Support Vector Regression based algorithm was developed for endurance time estimation using features derived from fitted frequency spectrum. Time taken till endurance limit for acquired dataset 38.53 ± 17.33 s (Mean ± Standard Deviation) was predicted with error of 0.029 ± 4.19 s . R-square: 0.956, training and test sets RMSE was calculated as 3.96 and 4.29 s respectively. The application of the algorithm suggested that model required 70% of sEMG signal from maximum time of endurance for high prediction accuracy. CONCLUSION: Endurance Limit prediction algorithm was developed for quantification of endurance time for optimizing isometric training and rehabilitation. Our method could help personalize and change conventional training method of same weight and duration for all subjects with optimized training parameters, based upon individual sEMG activity.
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Electromiografía/métodos , Contracción Isométrica , Fatiga Muscular , Aprendizaje Automático Supervisado , Adulto , Femenino , Humanos , Masculino , Fuerza Muscular , Músculo Esquelético/fisiología , Resistencia FísicaRESUMEN
Manual material handling (MMH) tasks create a burden for workers which could result in musculoskeletal injuries. Assessments of the decrease of muscular strength and the maximum endurance time (MET) for MMH tasks are essential in studying the ergonomic risk of MMH tasks. A backpacking experiment was conducted for measuring the MET for MMH tasks. Human participants carried a load on their back and walked on a treadmill under various load, walking speed, and ramp angle conditions until they coud no longer do so. It was found that the participants were able to walk for approximately 15 min to two hours before they needed to have a pause. Their back and leg strengths declined moderately due to performing the tasks. These tasks resulted in an increase in heart rate and elevated perceived physical exertion. The rating of perceived exertion (RPE)/heart rate ratio in our backpacking tasks was 31% higher than that in the literature, implying the calibration of the RPE may be required for such tasks. A MET model incorporating the fMVC_back, body weight, walking speed, and ramp angle was established. This model may be used to determine the work/rest allowance for backpacking tasks under conditions similar to this study.
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Entrenamiento Aeróbico/métodos , Frecuencia Cardíaca/fisiología , Fuerza Muscular/fisiología , Resistencia Física/fisiología , Esfuerzo Físico/fisiología , Caminata/fisiología , Adulto , Prueba de Esfuerzo , Femenino , Humanos , MasculinoRESUMEN
This study aimed at experimentally validating a subject-specific maximum endurance time (MET) model. Thirty health participants (15 males and 15 females; Age: mean = 21.5 years, SD = 1.6 years) volunteered to conduct an isometric elbow flexion task until exhaustion. The endurance times of each participant were measured under relative exertion levels ranging from 30% MVC (Maximum Voluntary Contraction) to 70% MVC at 10% intervals. Assessment of the model showed that the intensity-endurance time relationship for each studied individual could be well fitted by the subject-specific MET model (R2 > 0.89). The fatigue rates identified from the model fitting were normally distributed (Mean = 0.96 min-1, SD = 0.29 min-1). In addition, the fatigue rates of the male group were significantly higher than the female group. The subject-specific MET model can be used to predict the MET for individual workers, and further support physical task design, based on the fatigability data of a targeted worker population. Practitioner Summary: Ergonomists have extensively used MET models in physical fatigue assessment and physical task design. A subject-specific MET model could be used to predict the MET at individual levels, and also to support work design for a target worker population, based on the fatigability data distribution obtained from sampled workers.
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Ergonomía/métodos , Contracción Isométrica/fisiología , Fatiga Muscular/fisiología , Resistencia Física/fisiología , Esfuerzo Físico/fisiología , Codo/fisiología , Electromiografía , Femenino , Voluntarios Sanos , Humanos , Masculino , Análisis y Desempeño de Tareas , Factores de Tiempo , Adulto JovenRESUMEN
BACKGROUND AND OBJECTIVE: The role of non-invasive ventilation (NIV) during exercise training (ET) in patients with chronic respiratory failure (CRF) is still unclear. The aim of this study was to test whether NIV during ET had an additional effect in increasing the 6-min walking distance (6MWD) and cycle endurance time compared with ET alone. METHODS: All patients underwent 20 sessions of cycle training over 3 weeks and were randomly assigned to ET with NIV or ET alone. Outcome measures were 6MWD (primary outcome), incremental and endurance cycle ergometer exercise time, respiratory muscle function, quality of life by the Maugeri Respiratory Failure questionnaire (MRF-28), dyspnoea (Medical Research Council scale) and leg fatigue at rest. RESULTS: Forty-two patients completed the study. Following training, no significant difference in 6MWD changes were found between groups. Improvement in endurance time was significantly greater in the NIV group compared with the non-NIV training group (754 ± 973 vs 51 ± 406 s, P = 0.0271); dyspnoea improved in both groups, while respiratory muscle function and leg fatigue improved only in the NIV ET group. MRF-28 improved only in the group training without NIV. CONCLUSION: In CRF patients on long-term NIV and long-term oxygen therapy (LTOT), the addition of NIV to ET sessions resulted in an improvement in endurance time, but not in 6MWD.
Asunto(s)
Terapia por Ejercicio , Tolerancia al Ejercicio/fisiología , Ventilación no Invasiva , Enfermedad Pulmonar Obstructiva Crónica/rehabilitación , Insuficiencia Respiratoria/fisiopatología , Insuficiencia Respiratoria/rehabilitación , Adulto , Anciano , Anciano de 80 o más Años , Disnea/etiología , Disnea/fisiopatología , Disnea/prevención & control , Femenino , Humanos , Hipercapnia/etiología , Hipercapnia/fisiopatología , Hipercapnia/terapia , Hipoxia/etiología , Hipoxia/fisiopatología , Hipoxia/terapia , Masculino , Persona de Mediana Edad , Evaluación de Resultado en la Atención de Salud , Terapia por Inhalación de Oxígeno , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Calidad de Vida , Insuficiencia Respiratoria/complicaciones , Músculos Respiratorios/fisiopatologíaRESUMEN
BACKGROUND: Recent evidences show that Pulmonary Rehabilitation (PR) is effective in patients with Interstitial Lung Disease (ILD). It is still unclear whether disease severity and/or etiology might impact on the reported benefits. We designed this prospective study 1) to confirm the efficacy of rehabilitation in a population of patients with ILDs and 2) to investigate whether baseline exercise capacity, disease severity or ILD etiology might affect outcomes. METHODS: Forty-one patients (IPF 63%, age 66.9 ± 11 ys) were enrolled in a standard PR course in two centers. Lung function, incremental and endurance cyclo-ergometry, Six Minutes Walking Distance (6MWD), chronic dyspnea (Medical Research Council scale-MRC) and quality of life (St. George Respiratory Questionnaire-SGRQ) were recorded before and at the end of PR to measure any pre-to-post change. Correlation coefficients between the baseline level of Diffuse Lung Capacity for Carbon monoxide (DLCO), Forced Vital Capacity (FVC), 6MWD, power developed during incremental endurance test, GAP index (in IPF patients only) and etiology (IPF or non-IPF) with the functional improvement at the 6MWDT (meters), at the incremental and endurance cyclo-ergometry (endurance time) and the HRQoL were assessed. RESULTS: Out of the 41 patients, 97% (n = 40) completed the PR course. Exercise performance (both at peak load and submaximal effort), symptoms (iso-time dyspnea and leg fatigue), SGRQ and MRC significantly improved after PR (p < .001). Patients with lower baseline 6MWD showed greater improvement in 6MWD (Spearman r score = - .359, p = .034) and symptoms relief at SGRQ (r = -.315, p = .025) regardless of underlying disease. CONCLUSION: Present study confirms that comprehensive rehabilitation is feasible and effective in patients with ILD of different severity and etiology. The baseline submaximal exercise capacity inversely correlates with both functional and symptom gains in this heterogeneous population.
Asunto(s)
Tolerancia al Ejercicio , Ejercicio Físico , Enfermedades Pulmonares Intersticiales/fisiopatología , Enfermedades Pulmonares Intersticiales/rehabilitación , Anciano , Disnea/etiología , Fatiga/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Calidad de Vida , Índice de Severidad de la Enfermedad , Encuestas y Cuestionarios , Capacidad Vital , Prueba de PasoRESUMEN
The existing computational models of frostbite injury are limited to one and two dimensional schemes. In this study, a coupled thermo-fluid model is applied to simulate a finger exposed to cold weather. The spatial variability of finger-tip temperature is compared to experimental ones to validate the model. A semi-realistic 3D model for tissue and blood vessels is used to analyze the transient heat transfer through the finger. The effect of heat conduction, metabolic heat generation, heat transport by blood perfusion, heat exchange between tissues and large vessels are considered in energy balance equations. The current model was then tested in different temperatures and air speeds to predict the danger of frostbite in humans for different gloves. Two prevalent gloves which are commonly used in cold climate are considered for investigation. The endurance time and the fraction of necrotic tissues are two main factors suggested for obtaining the response of digit tissues to different environmental conditions.