Should We Use the Functional Electrical Stimulation-Cycling Exercise in Clinical Practice? Physiological and Clinical Effects Systematic Review With Meta-analysis.

OBJECTIVE: To examine the evidence regarding functional electrical stimulation cycling's (FES-cycling's) physiological and clinical effects. DATA SOURCES: The study was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses protocol. PubMed, Embase, Cochrane Review, CINAHL, Scopus, Sport Discus, and Web of Science databases were used. STUDY SELECTION: Randomized controlled trials involving FES-cycling were included. Studies that did not involve FES-cycling in the intervention group or without the control group were excluded. Two reviewers screened titles and abstracts and then conducted a blinded full-text evaluation. A third reviewer resolved the discrepancies. DATA EXTRACTION: Meta-analysis was performed using inverse variance for continuous data, with effects measured using the mean difference and random effects analysis models. A 95% confidence interval was adopted. The significance level was set at P<.05, and trends were declared at P=.05 to ≤.10. The I2 method was used for heterogeneity analysis. The minimal clinically important difference was calculated. Methodological quality was assessed using the risk of bias tool for randomized trials. The Grading of Recommendations Assessment, Development, and Evaluation method was used for the quality of the evidence analysis. DATA SYNTHESIS: A total of 52 studies were included. Metabolic, cardiocirculatory, ventilatory, and peripheral muscle oxygen extraction variables presented statistical (P<.05) and clinically important differences favoring FES-cycling, with moderate-to-high certainty of evidence. It also presented statistical (P<.05) and clinically important improvements in cardiorespiratory fitness, leg and total body lean mass, power, physical fitness in intensive care (moderate-to-high certainty of evidence), and torque (low certainty of evidence). It presented a trend (P=.05 to ≤.10) of improvement in muscle volume, spasticity, and mobility (low-to-moderate certainty of evidence). It showed no difference (P>.10) in 6-minute walking distance, muscle cross-sectional area, bone density, and length of intensive care unit stay (low-to-moderate certainty of evidence). CONCLUSIONS: FES-cycling exercise is a more intense stimulus modality than other comparative therapeutic modalities and presented clinically important improvement in several clinical outcomes.

Functional electrical stimulation cycling-based muscular evaluation method in mechanically ventilated patients.

BACKGROUND: Intensive care acquired muscle weakness is a common feature in critically ill patients. Beyond the therapeutic uses, FES-cycling could represent a promising nonvolitional evaluation method for detecting acquired muscle weakness. OBJECTIVES: To assess whether FES-cycling is able to identify muscle dysfunctions, and to evaluate the survival rate in patients with detected muscle dysfunction. METHODS: A prospective observational study was carried out, with 29 critically ill patients and 20 healthy subjects. Maximum torque and power achieved were recorded, in addition to the stimulation cost, and patients were followed up for six months. RESULTS: Torque (2.64 [1.53 to 4.81] vs 6.03 [4.56 to 6.73] Nm) and power (3.31 [2.33 to 6.37] vs 6.35 [5.22 to 10.70] watts) were lower and stimulation cost (22 915 [5069 to 37 750] vs 3411 [2080 to 4024] µC/W) was higher in patients compared to healthy people (p < 0.05). Surviving patients showed a nonsignificant difference in power and torque in relation to nonsurvivors (p > 0.05), but they had a lower stimulation cost (4462 [3598 to 11 788] vs 23 538 [10 164 to 39 836] µC/W) (p < 0.05). In total, 34% of all patients survived during the six months of follow-up. Furthermore, 62% of patients with a stimulation cost below 15 371 µC/W and 7% of patients with a stimulation cost above 15 371 µC/W survived. CONCLUSIONS: FES-cycling has good sensitivity and specificity for detecting muscle disorders. Critical patients have low torque and power and a high stimulation cost. Stimulation cost is related to survival. A low stimulation cost was related to a 3 times greater chance of survival.

Safety and feasibility of a functional electrical stimulation cycling-based muscular dysfunction diagnostic method in mechanically ventilated patients.

BACKGROUND: A nonvolitional diagnostic method based on FES-Cycling technology has recently been demonstrated for mechanically ventilated patients. This method presents good sensitivity and specificity for detecting muscle dysfunction and survival prognosis, even in unconscious patients. As the clinical relevance of this method has already been reported, we aimed to evaluate its safety and feasibility. METHODS: An observational prospective study was carried out with 20 critically ill, mechanically ventilated patients. The FES-cycling equipment was set in a specific diagnostic mode. For safety determination, hemodynamic parameters and peripheral oxygen saturation were measured before and immediately after the diagnostic protocol, as well as venous oxygen saturation and blood lactate. The creatine phosphokinase level (CPK) was measured before and 24, 48, and 72 h after the test. The time taken to carry out the entire diagnostic protocol and the number of patients with visible muscle contraction (capacity of perceptive muscular recruitment) were recorded to assess feasibility. RESULTS: Heart rate [91 ± 23 vs. 94 ± 23 bpm (p = 0.0837)], systolic [122 ± 19 vs. 124 ± 19 mm Hg (p = 0.4261)] and diastolic blood pressure [68 ± 13 vs. 70 ± 15 mm Hg (p = 0.3462)], and peripheral [98 (96-99) vs. 98 (95-99) % (p = 0.6353)] and venous oxygen saturation [71 ± 14 vs. 69 ± 14% (p = 0.1317)] did not change after the diagnostic protocol. Moreover, blood lactate [1.48 ± 0.65 vs. 1.53 ± 0.71 mmol/L (p = 0.2320)] did not change. CPK did not change up to 72 h after the test [99 (59-422) vs. 125 (66-674) (p = 0.2799) vs. 161 (66-352) (p > 0.999) vs. 100 (33-409) (p = 0.5901)]. The time taken to perform the diagnostic assessment was 11.3 ± 1.1 min. In addition, 75% of the patients presented very visible muscle contractions, and 25% of them presented barely visible muscle contractions. CONCLUSIONS: The FES cycling-based muscular dysfunction diagnostic method is safe and feasible. Hemodynamic parameters, peripheral oxygen saturation, venous oxygen saturation, and blood lactate did not change after the diagnostic protocol. The muscle damage marker (CPK) did not increase up to 72 h after the diagnostic protocol.

Correction to: Obstructive sleep apnea does not impair cardiorespiratory responses to progressive exercise performed until exhaustion in hypertensive elderly.

The original version of this article was published online containing two items that require correction, namely the abstract (Results section) and Table 3.

Obstructive sleep apnea does not impair cardiorespiratory responses to progressive exercise performed until exhaustion in hypertensive elderly.

BACKGROUND: Elderly people have a high prevalence to systemic arterial hypertension (SAH) and obstructive sleep apnea (OSA). Both comorbidities are closely associated and inflict damage on cardiorespiratory capacity. METHODS: In order to assess cardiorespiratory responses to the cardiopulmonary exercise test (CPET) among hypertensive elderly with OSA, we enrolled 28 subjects into two different groups: without OSA (No-OSA: apnea/hypopnea index (AHI) < 5 events/h; n = 15) and with OSA (OSA: AHI ≥ 15 events/h; n = 13). All subjects underwent CPET and polysomnographic assessments. After normality and homogeneity evaluations, independent t test and Pearson's correlation were performed. The significance level employed was p ≤ 0.05. RESULTS: Hypertensive elderly with OSA presented lower heart rate recovery (HRR) in the second minute (HRR2) in relation to the No-OSA group. A negative correlation between AHI and ventilation (VE) (r = -0.63, p = 0.02) was found in polysomnography and CPET data comparisons, and oxygen saturation (O2S) levels significantly correlated with VE/VCO2slope (r = 0.66, p = 0.01); in addition, OSA group presented a positive correlation between oxygen consumption and O2S (r = 0.60, p = 0.02), unlike the no-OSA group. CONCLUSIONS: OSA does not affect the CPET variables in hypertensive elderly, but it attenuates the HRR2. The association between O2S during sleep with ventilatory responses probably occurs due to the adaptations in the oxygen transport system unleashed via mechanical respiratory feedback; thus, it has been identified that OSA compromises the oxygen supply in hypertensive elderly.

Impaired Neuromuscular Efficiency and Symptom-Limited Aerobic Exercise Capacity 4 Weeks After Recovery From COVID-19 Appear to Be Associated With Disease Severity at Onset.

OBJECTIVE: The objectives of this study were to evaluate neuromuscular recruitment and efficiency in participants who recovered from COVID-19 and assess the association between neuromuscular efficiency and symptom-limited aerobic exercise capacity. METHODS: Participants who recovered from mild (n = 31) and severe (n = 17) COVID-19 were evaluated and compared with a reference group (n = 15). Participants underwent symptom-limited ergometer exercise testing with simultaneous electromyography evaluation after a 4-week recovery period. Activation of muscle fiber types IIa and IIb and neuromuscular efficiency (watts/percentage of root-mean-square obtained at the maximum effort) were determined from electromyography of the right vastus lateralis. RESULTS: Participants who had recovered from severe COVID-19 had lower power output and higher neuromuscular activity than the reference group and those who had recovered from mild COVID-19. Type IIa and IIb fibers were activated at a lower power output in participants who had recovered from severe COVID-19 than in the reference group and those who had recovered from mild COVID-19, with large effect sizes (0.40 for type IIa and 0.48 for type IIb). Neuromuscular efficiency was lower in participants who had recovered from severe COVID-19 than in the reference group and those who had recovered from mild COVID-19, with a large effect size (0.45). Neuromuscular efficiency showed a correlation with symptom-limited aerobic exercise capacity (r = 0.83). No differences were observed between participants who had recovered from mild COVID-19 and the reference group for any variables. CONCLUSION: This physiological observational study supports the notion that more severe COVID-19 symptoms at disease onset appear to correspondingly impair neuromuscular efficiency in survivors over a short time frame of 4 weeks after recovery, potentially contributing to reduced cardiorespiratory capacity. Further studies are needed to replicate and extend these findings with respect to their clinical implications for assessment/evaluation and interventions. IMPACT: After 4 weeks of recovery, neuromuscular impairment is particularly evident in severe cases; this problem may contribute to reduced cardiopulmonary exercise capacity.

Metabolic, ventilatory and cardiovascular responses to FES-cycling: A comparison to NMES and passive cycling.

BACKGROUND: Cyclergometry with functional electrical stimulation (FES-cycling) is a feasible method for rehabilitation. The concept is to promote exercise induced by depolarization of the motoneuron and muscular contraction. OBJECTIVE: To measure acute physiological responses to FES-cycling. METHODS: Retrospective study of data from ten healthy volunteers who performed FES-cycling, passive cycling and neuromuscular electrical stimulation (NMES) alone. Metabolic, ventilatory and cardiovascular parameters were analyzed. RESULTS: Oxygen uptake enhanced 97 ± 15% during FES-cycling, with medium effect size compared to NMES and large effect size compared to passive cycling. Energy expenditure enhanced 102 ± 15% during FES-cycling, with medium effect size compared to NMES and large effect size compared to passive cycling. Minute ventilation enhanced 115 ± 26% during FES-cycling, with small effect size compared to NMES and medium effect size compared to passive cycling. Cardiac output enhanced 21 ± 4% during FES-cycling, with medium effect size compared to NMES and passive cycling. Arterial - mixed venous oxygen content difference enhanced 60 ± 8% during FES-cycling, with a medium effect size compared to NMES and large effect size compared to passive cycling. CONCLUSIONS: FES-cycling enhances metabolic, ventilatory and cardiovascular demands and the physiological responses are higher than NMES and passive cycling.

Neuromuscular efficiency is impaired during exercise in COPD patients.

AIM: to analyze respiratory and peripheral neuromuscular efficiency during exercise in COPD. METHODS: COPD patients (VEF1 = 39.25 ± 13.1 %) were paired with healthy subjects. It was performed cardiopulmonary exercise test with simultaneously electromyography (EMG). Respiratory neuromuscular efficiency was determined by relationship between tidal volume and diaphragm EMG. Peripheral neuromuscular efficiency was determined by relationship between power output and vastus lateralis EMG. RESULTS: Healthy subjects presented higher respiratory neuromuscular efficiency at moderate, heavy and maximum exercise intensities compared to COPD (p < 0.05). Healthy subjects presented higher peripheral neuromuscular efficiency at light, moderate, heavy and maximum exercise intensities compared to COPD (p < 0.001). Dynamic hyperinflation presented correlation with respiratory and peripheral neuromuscular efficiency (r = -0.73 and r = -0.76, p < 0.001). CONCLUSION: COPD patients have lower respiratory neuromuscular efficiency at moderate exercise intensity and lower peripheral neuromuscular efficiency at light exercise intensity. Dynamic hyperinflation affects respiratory and peripheral neuromuscular efficiency.

EMG breakpoints for detecting anaerobic threshold and respiratory compensation point in recovered COVID-19 patients.

INTRODUCTION: A huge number of COVID-19 patients should be referred to rehabilitation programmes. Individualizing the exercise intensity by metabolic response provide good physiological results. The aim of this study was to investigate the validity of EMG as a non-invasive determinant of the anaerobic threshold and respiratory compensation point, for more precise exercise intensity prescription. METHODS: An observational cross-sectional study with 66 recovered COVID-19 patients was carried out. The patients underwent a cardiopulmonary exercise test with simultaneous assessment of muscle electromyography in vastus lateralis. EMG breakpoints were analyzed during the ramp-up protocol. The first and second EMG breakpoints were used for anaerobic threshold and respiratory compensation point determination. RESULTS: EMG and gas exchange analysis presented strong correlation in anaerobic threshold (r = 0.97, p < 0.0001) and respiratory compensation point detection (r = 0.99, p < 0.0001) detection. Bland-Altman analysis demonstrated a bias = -4.7 W (SD = 6.2 W, limits of agreement = -16.9 to 7.6) for anaerobic threshold detection in EMG compared to gas exchange analysis. In respiratory compensation point detection, Bland-Altman analysis demonstrated a bias = -2.1 W (SD = 4.5 W, limits of agreement = -10.9 to 6.6) in EMG compared to gas exchange analysis. EMG demonstrated a small effect size compared to gas exchange analysis in oxygen uptake and power output at anaerobic threshold and respiratory compensation point detection. CONCLUSIONS: EMG analysis detects anaerobic threshold and respiratory compensation point without clinical significant difference than gas exchange analysis (gold standard method) in recovered COVID-19 patients.

Dynamic Hyperinflation Impairs Cardiac Performance During Exercise in COPD.

PURPOSE: To investigate the correlation between a plateau in minute ventilation (Equation is included in full-text article.)E during cardiopulmonary exercise tests (CPETs) and its impact on cardiac performance. METHODS: This retrospective study analyzed 2575 CPETs of patients with chronic obstructive pulmonary disease. The study randomly selected 10 patients with a plateau in the (Equation is included in full-text article.)E curve, suggesting dynamic hyperinflation, 10 patients with normal pattern for the (Equation is included in full-text article.)E curve, and 10 healthy persons. Classic CPET variables, the new ventilation hyperinflation index, and the dynamic cardiac constraint index were analyzed. RESULTS: The patients with dynamic hyperinflation presented with lower ventilation at 100% work rate (P < .0001), without significant differences in (Equation is included in full-text article.)E at 50% and 100% work rate. Patients with dynamic hyperinflation also presented with a lower oxygen pulse (O2 pulse) at 100% (P < .0001), without significant difference in O2 pulse at 50% and 100% work rate. The subjects with dynamic hyperinflation had a higher ventilation hyperinflation index (P < .0001) and dynamic cardiac constraints index (P < .0001). The ventilation hyperinflation index correlated with the dynamic cardiac constraints index (r = 0.81, P < .0001); oxygen pulse variation (r =-0.63, P < .001); (Equation is included in full-text article.)E/(Equation is included in full-text article.)CO2 slope (r =-0.57, P < .01); work rate (r =-0.86, P < .0001); (Equation is included in full-text article.)O2 (r =-0.80, P < .0001), and (Equation is included in full-text article.)E (r =-0.83, P < .0001). CONCLUSION: There is a correlation between a plateau in the (Equation is included in full-text article.)E during CPET, suggesting hyperinflation, and it has an impact on cardiac performance.

Assessment of Maximum Dynamic Inspiratory Pressure.

BACKGROUND: Inspiratory muscle strength has been considered an important marker of ventilatory capacity and a predictor of global performance. A new tool has become available for dynamically evaluating the maximum inspiratory pressure (the S-Index). However, the proper assessment of this parameter needs to be determined. Thus, the aim of the present study was to investigate the number of inspiratory maneuvers necessary to reach a maximum and reliable S-Index and the influence of inspiratory muscle warm-up on this assessment. METHOD: We performed a retrospective study from the database of 432 healthy subjects who underwent S-Index tests and inspiratory muscle warm-up or sham. The effect of repeated maneuvers on the S-Index and the impact of inspiratory muscle warm-up were analyzed by using the intraclass correlation coefficient and unpaired t test. RESULTS: We analyzed 81 subjects, (55% men), mean ± SD age 38.1 ± 9.6 y, 43 subjects in the inspiratory muscle warm-up group. Maximum and reliable S-Indexes were reached at the eighth maneuver in both groups preceding inspiratory muscle warm-up or sham, 102 cm H2O (95% CI 95-109 cm H2O); intraclass correlation coefficient 0.96; P < .001. Only the inspiratory muscle warm-up group presented a significant increase in the S-Index after warm-up, 13.5 cm H2O (95% CI 10-17), P < .001. CONCLUSIONS: Eight maneuvers were necessary to reach maximum and reliable values of the S-Index preceding inspiratory muscle warm-up or sham. Moreover, inspiratory muscle warm-up preceding S-Index assessment improved inspiratory muscle performance.

Alterações fisiológicas da caminhada e tempo de internamento no pós-operatório de cirurgia cardíaca / Physiological changes from walking and time of stay after heart surgery

Fundamentos: Nas últimas décadas a fisioterapia vem se destacando no manejo de pacientes submetidos à cirurgiacardíaca, e a deambulação é um tipo de exercício bem tolerado pelos pacientes.Objetivos: Avaliar as alterações fisiológicas da caminhada e verificar a correlação com o tempo de internamentohospitalar no pós de cirurgia cardíaca (CC).Métodos: Realizado ensaio clínico transversal, quantitativo e observacional. Foram selecionados 30 pacientes.Avaliadas as variáveis hemodinâmicas: frequência cardíaca (FC), pressão arterial sistólica (PAS) e diastólica (PAD)e duplo-produto (DP); e respiratórias: frequência respiratória (FR) e saturação periférica de oxigênio (SpO2), umminuto antes de andar e imediatamente após o término da caminhada.Resultados: Constatou-se elevação na: PAS 112,0±11,9 mmHg para 118,2±19,1 mmHg (p=0,06); FC final 94,1±17,6 bpmpara 81,7±14,6 bpm (p=0,00); DP 9166,0±2041,6 para 11230,7±3441,3 (p=0,00); e PAD 74,0±18,7 mmHg para77,3±11,7 mmHg (p=0,27). Já a FR 19,4±4,4 ipm para 24,0±4,4 ipm (p=0,00); e a SpO2 95,3±2,4% para 94,9±3,2%(p=0,53). Observou-se também correlação significativa entre a variação da FC, do DP e da PAS pós-exercício.Conclusões: A caminhada gerou efeitos hemodinâmicos sobre a FC e o DP e alteração da FR. A FC, o DP e a PASpós apresentaram relação direta com o tempo de permanência hospitalar.

Background: In the past decades, physical therapy has been outstanding in the management of patients undergoing heart surgeryand walking is a type of exercise well tolerated by patients.Objectives: To evaluate the physiological changes from walking and the correlation with hospital stay after heart surgery (HS).Methods: Cross-sectional quantitative observational clinical trial has been conducted. Thirty 30 patients were selected. The followinghemodynamic variables have been evaluated: heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) anddouble product (DP); as well as the following respiratory variables: respiratory rate (RR), peripheral oxygen saturation (PO2S), oneminute before walking and immediately after the end of the walk.Results: The following rates were increased: SBP 112.0±11.9 mmHg to 118.2±19.1 mmHg (p=0.06); end HR 94.1±17.6 bpm to81.7±14.6 bpm (p=0.00); DP 9166.0±2041.6 to 11230.7±3441.3 (p=0.00); and DBP 74.0±18.7 mmHg to 77.3±11.7 mmHg (p=0.27).RR increased from 19.4±4.4 ipm to 24.0±4.4 ipm (p=0.00); and PO2S 95.3±2.4% to 94.9±3.2% (p=0.53). There was also a significantcorrelation between the variation of HR, DP and SBP after exercise.Conclusions: Walking generated hemodynamic effects over HR, DP, and changes in RR. HR, DP and SBP after heart surgery hada direct relationship with the length of hospital stay.