The effects of inspiratory muscle fatigue on subsequent high-intensity exercise performance and muscle tissue oxygenation / 体力科学

It has been suggested that inspiratory muscles fatigue impairing blood flow to the active limb muscle via respiratory muscle metaboreflex. The purpose of this study was to investigate the effects of inspiratory muscle fatigue on exercise performance and muscle tissue oxygenation in high-intensity exercise takes about 3.5~5min. Eleven healthy males subjects performed two conditions of constant-load exercise to exhaustion (TTE) on a cycle ergometer at 100% of maximal oxygen uptake. The two conditions—inspiratory muscle fatiguing (IMF) and non-fatiguing (PLA) —which had different intensity inspiratory resistance breathing (IRB) were performed before exercise. Muscle tissue oxygenations were measured by deoxyhemogrobin (HHb), oxygen saturation index (StO2) from right vastus lateralis during TTE. All data were analyzed from nine subjects whose inspiratory muscle were fatigued by IRB in IMF. Results: TTE was significantly shorter in IMF compare to PLA (244±31s vs. 268±38s, p<0.05). HHb was significantly higher and StO2 was significantly lower in IMF than in PLA (p<0.05). Conclusion: High-intensity exercise completed in 3.5~5 minutes, it was suggested that inspiratory muscle fatigue reduced the oxygen deriver to active limb muscle, resulting in decrease exercise performance. Improving function of inspiratory muscles, such as in inspiratory muscle training, may improve oxygenation of the active limb muscle and enhance exercise performance.

Predictive equations for ventilatory muscle strength in the Brazilian population: a systematic review / Equações preditivas da força muscular ventilatória na população brasileira: uma revisão sistemática / Ecuaciones predictivas de la fuerza muscular respiratoria en la población brasileña: una revisión sistemática

ABSTRACT Maximal inspiratory and expiratory pressures (MIP and MEP) assess the strength index of the respiratory muscles. These measures are relevant to assess respiratory muscle strength and for clinical monitoring. This study evaluates papers that suggest predictive equations of MIP and MEP for the Brazilian population. We included studies that established prediction equations for MIP and MEP for the healthy Brazilian population, aged from 4 to 90 years old, both men and women and that had the maximum respiratory pressures measured in a sitting position. A search was carried out in March 2020 on MEDLINE, LILACS, Cochrane, SciELO, CINAHL, Web of Science, and SCOPUS databases, without date or language filters. The descriptors used were "muscle strength," "equations," "predictive respiratory muscles" and their respective synonyms. Out of the 3,920 studies found in databases, 963 were duplicates, 2,779 were excluded, 178 had their full texts analyzed, and only 9 met the inclusion criteria. The predictive equations of ventilatory muscle strength analyzed in this review used age, weight, and stature as variables. However, the studies showed methodological weaknesses, such as lack of cross-validation of the equation, exclusion of outliers, and lack of familiarization of MIP and MEP.

RESUMO As pressões respiratórias máximas (PImáx e PEmáx) avaliam o índice de força dos músculos respiratórios. Essas medidas são relevantes para a avaliação da força muscular respiratória e para o monitoramento clínico. O objetivo deste estudo foi avaliar os artigos que sugerem equações preditivas de PImáx e PEmáx para a população brasileira. Foram incluídos estudos que estabeleceram equações de predição para PImáx e PEmáx da população brasileira saudável, com idades entre 4 e 90 anos e de ambos os sexos, que mediam as pressões respiratórias máximas na posição sentada. Uma pesquisa foi realizada, em março de 2020, nas bases de dados MEDLINE, LILACS, Cochrane, SciELO, CINAHL, Web of Science e SCOPUS, sem filtros de tempo ou idioma. Os descritores utilizados foram "força muscular", "equações" e "músculos respiratórios preditivos", com seus respectivos sinônimos. Dos 3.920 estudos encontrados nas bases de dados, 963 eram duplicados e 2.779 foram excluídos, 178 tiveram seus textos analisados integralmente e apenas 9 atendiam aos critérios de inclusão. As variáveis utilizadas nas equações preditivas de força muscular ventilatória analisadas nesta revisão foram: idade, peso e estatura. No entanto, os estudos mostraram fragilidades metodológicas, como falta de validação cruzada da equação, exclusão de outliers e familiarização do PImáx e PEmáx.

RESUMEN Las presiones inspiratoria y espiratoria máximas (PImáx y PEmáx) evalúan el índice de fuerza muscular respiratoria. Estas medidas son importantes en la evaluación de la fuerza muscular respiratoria y el seguimiento clínico. El objetivo de este estudio fue evaluar los artículos proponen ecuaciones predictivas para PImáx y PEmáx a la población brasileña. Se incluyeron estudios que establecieron ecuaciones predictivas para PImáx y PEmáx a la población brasileña sana de ambos sexos, de entre 4 y 90 años de edad, y que miden las presiones respiratorias máximas en posición sentada. Se realizó, en marzo de 2020, una búsqueda en las bases de datos MEDLINE, LILACS, Cochrane, SciELO, CINAHL, Web of Science y SCOPUS, sin año de publicación específico ni idioma. Los descriptores utilizados fueron "fuerza muscular", "ecuaciones" y "músculos respiratorios predictivos" y sus respectivos sinónimos. De los 3.920 estudios encontrados, 963 eran duplicados y se excluyeron 2.779, así se analizaron 178 textos en su totalidad y solo 9 cumplieron con los criterios de inclusión. Las variables edad, peso y talla fueron las que habían sido utilizadas en las ecuaciones predictivas de fuerza muscular respiratoria analizadas por esta revisión. Sin embargo, los estudios apuntaron limitaciones metodológicas, como falta de validación cruzada de la ecuación, exclusión de outliers y familiaridad de la PImáx y PEmáx.

Efecto del entrenamiento de la musculatura inspiratoria con válvula umbral sobre la capacidad funcional en mujeres físicamente activas mayores de 60 años / Effect of inspiratory muscle training with threshold valve on functional capacity of physically active women who are older than 60 years of age

Resumen Introducción: Los cambios fisiológicos asociados al envejecimiento generan una serie de modificaciones funcionales, destacando una disminución en la capacidad respiratoria. En este sentido, una estrategia alternativa para mejorar tal condición podría ser el entrenamiento de la musculatura inspiratoria (EMI). Objetivo: Analizar el efecto del EMI con válvula umbral, sobre la capacidad funcional en mujeres físicamente activas mayores de 60 años. Materiales y métodos: Se realizó un EMI con válvula umbral durante 4 semanas, sobre un grupo experimental (GE; n:10), contrastado con un grupo control (GC; n:5). Se valoraron las siguientes variables hemodinámicas y antropométricas: peso, talla, índice de masa corporal (IMC), lactato, doble producto y capacidad funcional, analizando los cambios pre y post entrenamiento. Resultados: en el grupo GE disminuye post intervención la concentración de lactato y la escala de percepción del esfuerzo; 3,16±0,51 a 2,5±0,39 y 5,56 ± 1,81 a 4±2, respectivamente. En el mismo grupo se incrementan los valores de presión inspiratoria máxima (Pimáx) post intervención; 42,11±14,57 a 60,44±14,47. El GC no presentó cambios en sus valores. Conclusión: No se evidencian cambios favorables en los metros recorridos post intervención, sin embargo, el EMI mostró una disminución sobre la concentración de lactato post ejercicio, lo que podría identificar un retraso en la aparición de la fatiga.

Abstract Introduction: Physiological changes associated with aging generate a series of functional modifications, mainly a decrease in respiratory capacity. In this regard, an alternative strategy to improve such a condition could be inspiratory muscle training (IMT). Objective: To analyze the effect of IMT with threshold valve on the functional capacity of physically active women who are older than 60 years of age. Materials and methods: IMT with threshold valve was carried out over a period of 4 weeks, comparing data from the experimental group (GE; n:10) to the control group (GC; n:5). The following hemodynamic and anthropometric variables were assessed: weight, height, body mass index (BMI), lactate, double product (DP) and functional capacity. Pre and post training changes were evaluated. Results: The GE group showed a decrease in both post-intervention lactate concentration (from 3.16±0.51 to 2.5±0.39) and effort perception scale (from 5.56 ± 1.81 to 4±2). On the other hand, this group experienced a post-intervention increase in maximal inspiratory pressure (MIP) from 42.11±14.57 to 60.44±14.47. The GC group did not present changes in its values. Conclusion: Although no evidence was found regarding favorable changes in the walked distance post-intervention, IMT induced a reduction in post-exercise lactate concentration, which could indicate a delay of onset of fatigue.

Assessment Of Respiratory Muscle Strength Using Maximal Inspiratory Pressure And Maximal Expiratory Pressure In Patients With Chronic Obstructive Pulmonary Disease: A Study On Indian Population

Chronic Obstructive Pulmonary Disease (COPD) is a common disease seen in Indian population. It is most commonly seen in the lower strata where beedi and cigarette smoking is most prevalent and starts at an early age. Smoke arising from cooking stoves during cooking is the cause of COPD in females. Though the number of males suffering from COPD is much larger than females, we observed a proportionate number of females in all age group suffering from this disease. It is the leading cause of mortality and should be studied in detail so as to avoid complications in such patients. We have studied the strength of respiratory muscles in such patients using newer techniques like Maximal Inspiratory Pressure (MIP) and 7 8 Maximal Expiratory Pressure (MEP). Terzano et al. (2008) and Khalil et al.(2014) have carried out similar studies in COPD patients. We have checked correlation between anthropometric measurements and strength of respiratory muscles, correlation between airway resistance and muscle strength and also compared the sensitivity and specificity of this technique using ROC (receiver operating Curve) as compared to the age old spirometry. These techniques may help in monitoring the status of COPD patients and assessing muscle weakness.

Efectos agudos del ciclismo indoor en la presión inspiratoria máxima (PIMax) y la presión espiratoria máxima (PEMax) de adultos activos / Acute effects of indoor cycling on maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in active adults

Objetivo: verificar el efecto agudo del ciclismo indoor en el PIM y la PEM. Método: estudio experimental con muestra de 10 sujetos, de sexo masculino, de 20 a 30 años, practicantes de entrenamiento de ciclismo indoor durante al menos ocho semanas, con una frecuencia semanal de dos a tres veces. Las variables PIM y PEM se midieron antes y después del entrenamiento de ciclismo indoor con duración de 40 minutos, a través del método continuo. Resultados: Ambas variables mostraron una reducción significativa en comparación con los valores pre y post entrenamiento. PIM (pre: -117.5 ± 19.61; post: -110 ± 21.08) con p = 0.02, mientras que PEM (pre: 50 ± 00; post: 142.5 ± 4.8) con p = 0.01. Conclusiones: la intervención se realiza de forma continua y gradualmente creciente cuya sobrecarga puede generar adaptaciones crónicas tales como aumento de la PIM y PEM. Sin embargo, es necesario más estudios en la misma línea para verificar las relaciones y correlaciones.

Objective: To verify the acute effects of Indoor Cycling on the MIP and MEP. Method: An experimental study sample of ten male subjects, ranging in age from 20 to 30 years old, and who have practiced indoor cycling training for at least eight weeks, two to three times a week. The MIP and MEP variables were measured before and after the indoor cycling workout, lasting 40 minutes and using the continuous method. Results: Both variables showed a significant reduction when compared to pre and post training values. MIP (pre: -117.5 ± 19.61; post: -110 ± 21.08; p = 0.02) while the MEP (pre: 50 ± 00; post: 142.5 ± 4.8; p = 0.01). Conclusion: A continuous intervention with a gradual overload increase which can generate chronic adaptations such as increased MIP and MEP. However, it is necessary to carry out further studies within the same line to verify the correlation.

Pressão inspiratória máxima e sua relação com sintomas e fatoresassociados a doença de refluxo gastroesofágico

A doença do refluxo gastroesofágico é o retorno do conteúdo gástrico através do esfíncter esofágico inferior independentemente da sua etiologia, manifestando-se por sintomas (típicos ou atípicos) ou dano tecidual. O diafragma é o principal músculo respiratório e a sua parte crural um dos componentes fundamentais da barreira antirefluxo. As contrações deste são relacionadas às mudanças na pressão da junção esofagogástrica que normalmente são relacionadas com a respiração. Estudos apontamevidências de déficit diafragmático na doença de refluxo gastroesofágico que pode ser melhorado com treinamento diafragmático. A pressão inspiratória máxima é um método simples de avaliar a força inspiratória determinada pelo diafragma. A partir deste contexto, surgiu a hipótese de que os sintomas da doença de refluxo gastro esofágico podem se associar à pressão inspiratória máxima...

The gastroesophageal reflux disease is the return of gastric contents through the lower esophageal sphincter regardless of etiology, manifesting itself by symptoms (typical or atypical) or tissue damage. The diaphragm is the main respiratory muscle and its crural part one of the fundamental components of the antireflux barrier. Contractions of this are related to changes in pressure of the gastroesophageal junction that are usually related to breathing. Studies show evidence of diaphragmatic weaknessin gastroesophageal reflux disease that can be improved with diaphragmatic training. The maximalinspiratory pressure is a simple method to evaluate the inspiratory force determined by diaphragm. From this context, the hypothesis that the symptoms of gastroesophageal reflux disease may be associated with the maximal inspiratory pressure...

Reference Range of Respiratory Muscle Strength and Its Clinical Application in Amyotrophic Lateral Sclerosis: A Single-Center Study

BACKGROUND AND PURPOSE: Evaluating respiratory function is important in neuromuscular diseases. This study explored the reference ranges of the maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP) in healthy adults, and applied them to amyotrophic lateral sclerosis (ALS) patients. METHODS: MIP, MEP, and SNIP were measured in 67 healthy volunteers aged from 21 to 82 years. Reference ranges were evaluated by multivariate regression analysis using the generalized additive modeling of location, scale, and shape method. Thirty-six ALS patients were reviewed retrospectively, and abnormal values of MIP, MEP, and SNIP were determined according to the reference ranges. RESULTS: MIP, MEP, and SNIP were abnormal in 57.1%, 51.4%, and 25.7% of the ALS patients, respectively. MIP and SNIP were significantly correlated with the degree of restrictive pattern and respiratory symptoms. The ALS Functional Rating Scale-Revised score was correlated with SNIP. CONCLUSIONS: This study has provided the reference range of respiratory muscle strength in healthy adults. This range is suitable for evaluating respiratory function in ALS patients.

Pattern of Respiratory Deterioration in Sporadic Amyotrophic Lateral Sclerosis According to Onset Lesion by Using Respiratory Function Tests

Most amyotrophic lateral sclerosis (ALS) patients show focal onset of upper and lower motor neuron signs and spread of symptoms to other regions or the other side clinically. Progression patterns of sporadic ALS are unclear. The aim of this study was to evaluate the pattern of respiratory deterioration in sporadic ALS according to the onset site by using respiratory function tests. Study participants included 63 (42 cervical-onset [C-ALS] and 21 lumbosacral-onset [L-ALS]) ALS patients and 31 healthy controls. We compared respiratory function test parameters among the 3 groups. Age was 57.4+/-9.6 (mean+/-SD), 60.8+/-9, and 60.5+/-7 years, and there were 28, 15, and 20 male participants, in the C-ALS, L-ALS, and control groups, respectively. Disease duration did not differ between C-ALS and L-ALS patients. Sniff nasal inspiratory pressure (SNIP) was significantly low in C-ALS patients compared with controls. Maximal expiratory pressure (MEP) and forced vital capacity percent predicted (FVC% predicted) were significantly low in C-ALS and L-ALS patients compared with controls. Maximal inspiratory pressure to maximal expiratory pressure (MIP:MEP) ratio did not differ among the 3 groups. Eighteen C-ALS and 5 L-ALS patients were followed up. DeltaMIP, DeltaMEP, DeltaSNIP, DeltaPEF, and DeltaFVC% predicted were higher in C-ALS than L-ALS patients without statistical significance. Fourteen C-ALS (77.8%) and 3 L-ALS (60%) patients showed a constant MIP:MEP ratio above or below 1 from the first to the last evaluation. Our results suggest that vulnerability of motor neurons in sporadic ALS might follow a topographic gradient.

Força muscular respiratória é marcantemente reduzida em mulheres obesas mórbidas / Respiratory muscle strength is markedly reduced in morbid obese women

Comparar a força muscular respiratória (FMR)entre obesas mórbidas com mulheres eutróficas da mesmafaixa etária. Método: Foram avaliadas doze mulheres obesasmórbidas (média de idade de 26 ± 5 anos e IMC – índice demassa corpórea de 47 ± 6 kg/m2) e doze mulheres eutróficas(27 ± 4 anos e IMC de 24 ± 2 kg/m2). Em ambos os grupos,foram realizadas as medidas antropométricas e testada a FMRcom um manovacuômetro (Gerar MVD300) sendo obtidas aspressões inspiratória máxima (PImax) e expiratória máxima(PEmax). As voluntárias foram previamente instruídas quantoà realização correta das manobras, permanecendo sentadas eusando um clipe nasal. A PImax foi obtida a partir do volumeresidual e a PEmax a partir da capacidade pulmonar total. O testet de Student não pareado foi utilizado para comparar os valorespressóricos entre os grupos, e o teste t de Student pareado paracomparar os valores obtidos com os previstos, sendo o nívelde significância de 5%, para ambos os testes. Resultados: Foiverificada redução significativa tanto dos valores da PImax (74± 32 versus 102 ± 9 cmH20) como da PEmax (66 ± 28 versus107 ± 12cmH20) no grupo de mulheres obesas em relação aogrupo de mulheres eutróficas, respectivamente. Quando comparadocom os valores previstos, foi verificado que as mulheres obesasapresentaram menores valores para PImax (76% do predito) epara a PEmax (67% do predito), respectivamente. Conclusão: Aforça muscular respiratória parece estar prejudicada na presençade obesidade mórbida.

To compare respiratory muscle strength betweenmorbid obesity women with matched paired eutrophic women.Method: Twelve morbid obese women (26 ± 5 years and bodymass index – BMI = 47 ± 6 kg/m2) and twelve eutrophic women(27 ± 4 years and BMI = 24 ± 2 kg/m2) were evaluated. In bothgroups, the anthropometric measurements were taken andrespiratory muscle strength (RMS) was tested with a digitalmanovacuometer (Gerar MVD300) obtaining the maximal inspiratoryand expiratory pressures (PImax and PEmax; respectively). Allsubjects were previously instructed regarding the correct conductduring the maneuvers, maintaining sitting position and using anasal clip. PImax was inferred from residual volume and PEmaxwas obtained from total lung capacity. Unpaired Student t testwas used to compare inter-group pressure values, and pairedStudent t test was used to compare the real and predictedvalues, considering significant level 5%, for both tests. Results:It was verified significant reduction in both PImax and PEmaxfor morbid obese women when compared with control grouprespectively (PImax = 74 ± 32 versus 102 ± 9 cmH20 andPEmax = 66 ± 28 versus 107 ± 12 cmH20). When comparedthe reference with obtained values, lower values for PImax andPEmax (76% and 67% of predicted, respectively) in morbid obesewomen were observed. Conclusion: The respiratory musclestrength may be harmed in morbid obesity.

The function and respiratory muscle strength in Thai obese children.

Objective: This study was to compare the pulmonary function, respiratory muscle strength, and physical activity level between obese and non-obese children and to determine the correlation between pulmonary function, respiratory muscle strength and physical activity level in both child groups. Methods: Thai healthy children aged between 10-12 years participated in this study. They were classified into an obese group with body weight > +3 standard deviations and a non-obese group with body weight between+ 1.5 standard deviations of children who have the same height. Children in both groups were measured for pulmonary function, forced vital capacity (FVC), and forced expiratory volume in one second (FEV1), FEV1/FVC ratio, vital capacity (VC), inspiratory muscle strength (MIP), expiratory muscle strength (MEP), and physical activity level. Results: The results showed that FVC, FEV1 and VC of the obese group were statistically higher than the non-obese group (p<0.05). FEV1/FVC ratio of the obese group was statistically lower than the non-obese group (p<0.05). MIP and MEP were not significantly different between the groups (p>0.05). Physical activity levels were not significantly different between the groups (p>0.05). Moreover, the results demonstrated that physical activity level in the obese group had no correlation with FVC, FEV1, FEV1/FVC ratio and VC (r = 0.203, 0.170, -0.067 and 0.133 respectively; p > 0.05) and similarly the non-obese group showed no correlation with FVC, FEV1, FEV1/FVC ratio and VC (r = 0.225, 0.168, -0.207 and 0.168 respectively; p > 0.05). Additionally, the results demonstrated that physical activity level in the obese group had no correlation with MIP and MEP (r = 0.151 and 0.355 respectively; p > 0.05) and similarly the non-obese group showed no correlation with MIP and MEP (r = 0.202 and 0.006 respectively; p > 0.05). Conclusion: This study provides information about the pulmonary function and respiratory muscle strength in Thai obese children. FVC, FEV1 and VC of the obese group were higher than the non-obese group. In addition, FEV1/FVC ratio of the obese group was lower than the non-obese group. Although, all parameters including pulmonary function of both groups were in the normal range. However, obese children tend to observe airway obstruction higher than non-obese children. Moreover, respiratory muscle strength and physical activity level were not different between groups. Additionally, physical activity level had no correlation with pulmonary function and respiratory muscle strength in both groups.

Respiratory Muscle Strength and Cough Capacity in Patients with Duchenne Muscular Dystrophy

The function of inspiratory muscles is crucial for effective cough as well as expiratory muscles in patients with Duchenne muscular dystrophy (DMD). However, there is no report on the correlation between cough and inspiratory muscle strength. To investigate the relationships of voluntary cough capacity, assisted cough techniques, and inspiratory muscle strength as well as expiratory muscle strength in patients with DMD (n=32). The vital capacity (VC), maximum insufflation capacity (MIC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were measured. Unassisted peak cough flow (UPCF) and three different techniques of assisted PCF were evaluated. The mean value of MICs (1918 +/- 586 mL) was higher than that of VCs (1474 +/- 632 mL) (p < 0.001). All three assisted cough methods showed significantly higher value than unassisted method (212 +/- 52 L/min) (F = 66.13, p < 0.001). Combined assisted cough technique (both manual and volume assisted PCF; 286 +/- 41 L/min) significantly exceeded manual assisted PCF (MPCF; 246 +/- 49 L/ min) and volume assisted PCF (VPCF; 252 +/- 45 L/min) (F = 66.13, p < 0.001). MIP (34 +/- 13 cmH2O) correlated significantly with both UPCF and all three assisted PCFs as well as MEP (27 +/- 10 cmH2O) (p < 0.001). Both MEP and MIP, which are the markers of respiratory muscle weakness, should be taken into account in the study of cough effectiveness.