Evolución de las ecuaciones del Shuttle Run Test 20m para la obtención del VO2máx: Revisión documental / Evolution of the equations of the Shuttle Run Test 20m to obtain VO2max: Documentary review

Para la evaluación del fitness cardiorrespiratorio existen pruebas directas en laboratorio que proporcionan información objetiva respecto a esta cualidad. No obstante, cuando no se cuenta con los recursos se recurre al uso de pruebas de campo como el Shuttle Run Test 20 metros (SRT-20m), el cual busca establecer el VO2max para cada sujeto, relacionando los valores obtenidos con aspectos como la composición corporal, edad y contexto poblacional, siendo una de las pruebas más confiables y con concordancia clínica existente. El propósito fue reconocer los cambios o variaciones presentes en los modelos matemáticos o lineales empleados en esta prueba con diferentes grupos poblacionales. Se realizó una revisión de la literatura bajo el marco básico para revisiones integradoras con algunas precisiones dadas por la guía PRISMA, identificando en su mayoría estudios de corte transversal los cuales evidencian los cambios realizados al planteamiento de la fórmula matemática donde las variables que inciden en el valor resultante para la resistencia aeróbica son: velocidad final, etapa de la prueba, edad y aspectos antropométricos del sujeto. Por lo anterior, se concluye que, para efectos prácticos, la estimación del VO2máx debe considerar factores intrínsecos del sujeto y aquellos relacionados con la ejecución de la prueba (AU)

For the evaluation of cardiorespiratory fitness, there are direct laboratory tests that provide objective information regarding this quality. However, when the resources are not available, the use of field tests such as the Shuttle Run Test 20 meters (SRT-20m) is used, which seeks to establish the VO2max for each subject, relating the values obtained with aspects such as body composition, age, and population context, being one of the most reliable tests with existing clinical agreement. The purpose was to recognize the changes or variations present in the mathematical or linear models used in this test with different population groups. A review of the literature was carried out under the basic framework for integrative reviews with some clarifications given by the PRISMA guide, identifying mostly cross-sectional studies which show the changes made to the approach of the mathematical formula where the variables that affect the resulting value for aerobic endurance are final speed, stage of the test, age, and anthropometric aspects of the subject. Therefore, it is concluded that, for practical purposes, the estimation of VO2max should consider intrinsic factors of the subject and those related to the execution of the test (AU)

Relação entre variáveis antropométricas e de aptidão física em crianças e adolescentes estratificados por sexo / Relationship between anthropometric and physical fitness variables in children and adolescents stratified by sex / Relación entre variables antropométricas y de aptitud física en niños y adolescentes estratificados por sexo

A aptidão física (ApF) pode estar associada à saúde, ao desempenho esportivo e refere-se a capacidade de apresentar um determinado desempenho motor quando submetido a situações que envolvam esforços físicos. O objetivo deste estudo foi relacionar as variáveis antropométricas e de aptidão física em crianças e adolescentes da cidade de Pelotas/RS, estratificados por sexo. Foram avaliados 1720 escolares da rede municipal de Pelotas/RS, sendo 896 crianças (idade = 9,91 ± 1,21 anos) e 824 adolescentes (idade = 13,11 ± 1,04 anos), através de uma bateria de avaliações das medidas antropométricas (estatura [EST], massa corporal [MC], envergadura [ENV], índice de massa corporal [IMC]) e de testes físicos (flexibilidade [FLEX], potência de membros superiores [PMS], potência de membros inferiores [PMI], velocidade com troca de direção [VTD], velocidade linear [VL], resistência muscular localizada [RML] e capacidade cardiorrespiratória [CC]). O estudo de caráter de diagnóstico com cunho observacional utilizou o teste de correlação através do r de Pearson e classificou-as como muito fraca (0-0,19), fraca (0,2-0,39), moderada (0,4-0,69), forte (0,7-0,89) e muito forte (0,9-1). Destacou-se que no sexo feminino houve correlação moderada com IMC e PMS, as variáveis antropométricas EST, ENV e MC apresentaram pelo menos uma correlação com as variáveis de ApF, enquanto que estas variáveis demonstraram correlações moderadas entre PMS, VL e VTD. Já no sexo masculino foi observada correlação moderada entre IMC e CC, além de correlações fracas e moderadas entre EST, ENV e MC com pelo menos uma das variáveis de ApF, enquanto as variáveis de ApF demonstraram correlações moderadas entre PMI, VL e VTD. Portanto, ressalta-se a importância do diagnóstico destas variáveis para controle dos fatores de risco à saúde bem como para identificar potenciais relacionados ao desempenho esportivo.

Physical fitness (PhF) can be associated with health, sports performance and refers to the ability to present a certain motor performance when submitted to situations involving physical efforts. The aim of this study was to relate anthropometric and physical fitness variables in children and adolescents from the city of Pelotas/RS, stratified by sex. A total of 1720 schoolchildren from the municipal schools of Pelotas/RS were evaluated, 896 children (age = 9.91 ± 1.21 years) and 824 adolescents (age = 13.11 ± 1.04 years), through a battery of the anthropometric measurements (height [HT], body mass [BM], wingspan [WP], body mass index [BMI]) and physical tests (flexibility [FLEX], upper limb power [ULP], lower limb power [LLP], change of direction speed [CODS], linear speed [LS], localized muscular endurance [LME] and cardiorespiratory capacity [CC]). The study of a diagnostic character with an observational nature used the correlation test through Pearson's r and classified them as very small (0-0.19), small (0.2- 0.39), moderate (0.4- 0.69), large (0.7-0.89) and very large (0.9-1). It was highlighted that in females there was moderate correlation with BMI and ULP, the anthropometric variables HT, WP and BM showed at least one correlation with the PhF variables, while these variables showed moderate correlations between ULP, LS and CODS. In males, a moderate correlation was observed between BMI and CC, in addition to small and moderate correlations between HT, WP and BM with at least one of the PhF variables, while the PhF variables showed moderate correlations between LLP, LS and CODS. Therefore, it emphasizes the importance of diagnosing these variables to control health risk factors as well as to identify potentials related to sports performance.

La aptitud física (AF) puede estar asociada a la salud, al rendimiento deportivo y se refiere a la capacidad de presentar un determinado desempeño motor cuando sometido a situaciones que impliquen esfuerzos físicos. El objetivo de este estudio fue relacionar variables antropométricas y de aptitud física en niños y adolescentes de la ciudad de Pelotas/RS, estratificados por sexo. Fueron evaluados 1720 escolares de las escuelas municipales de Pelotas/RS, 896 niños (edad = 9,91 ± 1,21 años) y 824 adolescentes (edad = 13,11 ± 1. 04 años), a través de una batería de medidas antropométricas (altura [HT], masa corporal [BM], envergadura [WP], índice de masa corporal [IMC]) y pruebas físicas (flexibilidad [FLEX], potencia de miembros superiores [ULP], potencia de miembros inferiores [LLP], velocidad de cambio de dirección [CODS], velocidad lineal [LS], resistencia muscular localizada [LME] y capacidad cardiorrespiratoria [CC]). El estudio, de carácter diagnóstico y observacional, utilizó la prueba de correlación mediante la r de Pearson y las clasificó en muy pequeñas (0-0,19), pequeñas (0,2-0,39), moderadas (0,4- 0,69), grandes (0,7-0,89) y muy grandes (0,9-1). Se destacó que en las hembras hubo una correlación moderada con el IMC y el ULP, las variables antropométricas HT, WP y BM mostraron al menos una correlación con las variables PhF, mientras que estas variables mostraron correlaciones moderadas entre ULP, LS y CODS. En los varones, se observó una correlación moderada entre IMC y CC, además de correlaciones pequeñas y moderadas entre HT, WP y BM con al menos una de las variables PhF, mientras que las variables PhF mostraron correlaciones moderadas entre LLP, LS y CODS. Por lo tanto, se destaca la importancia del diagnóstico de estas variables para controlar los factores de riesgo para la salud, así como para identificar potenciales relacionados con el rendimiento deportivo.

Aerobic Capacity of Preterm Children with Very Low Birth Weight at School Age and its Associated Factors / Capacidad aeróbica de niños prematuros de muy bajo peso al nacer y edad escolar y sus factores asociados

INTRODUCTION: Respiratory morbidities of preterm infants can cause significant ventilatory impairment thus compromising the aerobic capacity in childhood and adolescence. Therefore, the present study was conducted to evaluate the aerobic capacity in school age preterm children with VLBW and its associated factors. METHODS: A cross-sectional study was conducted among preterm born with VLBW and term children, both aged 6-9 years. An individualized symptom-limited treadmill testing protocol performed aerobic capacity. Measured variables: oxygen pulse (PuO2), percentage of maximum heart rate for age (%HR max), tidal volume/inspiratory capacity ratio (TV/IC), oxygen consumption (VO2) peak, and the ratio of the anaerobic threshold of gas exchange to the predicted percentage of maximum VO2 (VO2@LA/%VO2 max.pred.) were compared between groups. Univariate and multiple linear regression analyses were used to determine the factors associated with aerobic capacity. RESULTS: Thirty-four preterm and 32 term children were included. Similar VO2 peak and the other variables were observed. The development of bronchopulmonary dysplasia (BPD) and being obese/overweight was positively associated with %HR max. The Z-score for height/age and birth weight < 1000 g was positively associated with PuO2 and peak VO2, and negatively associated with overweight/obesity and female sex. CONCLUSIONS: Aerobic capacity was similar in both groups. Sex, development of BPD, birth weight < 1000 g and factors related to body growth, such as Z-score for height/age and overweight/obesity, were associated with aerobic capacity in preterm children with VLBW

INTRODUCCIÓN: Las enfermedades respiratorias de los niños prematuros pueden causar importantes impedimentos ventilatorios que comprometen la capacidad aeróbica en la infancia y en la adolescencia. El presente estudio se llevó a cabo para evaluar la capacidad aeróbica de niños prematuros en edad escolar de muy bajo peso al nacer (BPN) y los factores asociados. MÉTODOS: Se llevó a cabo un estudio transversal con niños prematuros de muy BPN y con niños a término, ambos grupos con edades comprendidas entre los 6 y 9 años. Las siguientes variables se compararon entre los 2 grupos: el pulso de oxígeno (PuO2), el porcentaje de frecuencia cardíaca máxima (%FC máx.), la relación entre el volumen corriente y la capacidad inspiratoria (TV/IC), el consumo pico de oxígeno (VO2) y la relación entre el umbral anaeróbico de intercambio de gas y el porcentaje estimado de VO2 máximo (VO2@LA/%VO2 máx. pred.). Se llevaron a cabo análisis de regresión lineal univariante y multivariante para determinar los factores asociados con la capacidad aeróbica. RESULTADOS: Se incluyeron 34 niños prematuros y 32 niños a término. Se registraron valores similares de VO2 pico y de otras variables. El desarrollo de displasia broncopulmonar (BPD) y de obesidad/sobrepeso mostró una asociación positiva con el %FC máx. El Z-score para la altura/edad y el peso al nacer < 1.000 g se asoció positivamente con la SaO2 y el VO2 y negativamente con el sobrepeso/obesidad y el sexo femenino. CONCLUSIONES: La capacidad aeróbica fue similar entre los 2 grupos. El sexo, el desarrollo de BPD, peso al nacer < 1.000 g y factores relacionados con el crecimiento corporal, tales como el Z-score para la altura/edad y para el sobrepeso/obesidad se asociaron con la capacidad aeróbica en niños prematuros de muy BPN

Effects of high- and moderate-intensity exercise on central hemodynamic and oxygen uptake recovery kinetics in CHF-COPD overlap.

The oxygen uptake (V˙O2) kinetics during onset of and recovery from exercise have been shown to provide valuable parameters regarding functional capacity of both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) patients. To investigate the influence of comorbidity of COPD in patients with CHF with reduced ejection fraction on recovery from submaximal exercise, 9 CHF-COPD male patients and 10 age-, gender-, and left ventricle ejection fraction (LVEF)-matched CHF patients underwent constant-load exercise tests (CLET) at moderate and high loads. The V˙O2, heart rate (HR), and cardiac output (CO) recovery kinetics were determined for the monoexponential relationship between these variables and time. Within-group analysis showed that the recovery time constant of HR (P<0.05, d=1.19 for CHF and 0.85 for CHF-COPD) and CO (P<0.05, d=1.68 for CHF and 0.69 for CHF-COPD) and the mean response time (MRT) of CO (P<0.05, d=1.84 for CHF and 0.73 for CHF-COPD) were slower when moderate and high loads were compared. CHF-COPD patients showed smaller amplitude of CO recovery kinetics (P<0.05) for both moderate (d=2.15) and high (d=1.07) CLET. Although the recovery time constant and MRT means were greater in CHF-COPD, CHF and CHF-COPD groups were not differently affected by load (P>0.05 in group vs load analysis). The ventilatory efficiency was related to MRT of V˙O2 during high CLET (r=0.71). Our results suggested that the combination of CHF and COPD may further impair the recovery kinetics compared to CHF alone.

Cardiorespiratory fitness and the relationship between body fat and resting testosterone in men.

Objective: To examine the effect of cardiovascular fitness, i.e. VO2max, on the relationship between weight status and resting testosterone level (RTL) in males.Materials and methods: A subset of male participants from the 2003-2004 National Health and Nutrition Examination Survey were analyzed by weight status, i.e. normal, overweight, obese, and all participants. Bivariate correlation coefficients were computed for RTL, percent body fat (BF%), and VO2max. Partial correlation coefficients were computed between RTL and BF% controlling for VO2max and between RTL and VO2max controlling for BF%.Results: Bivariate correlations between RTL and BF%, and RTL and VO2max were significant in all groups. The partial correlation coefficients between RTL and BF% controlling for VO2max were significant in the normal and all participants group. When RTL and VO2max were analyzed controlling for BF% only the all participants group remained significant.Conclusion: Cardiovascular fitness or weight status may independently influence RTL in males.

Effects of high- and moderate-intensity exercise on central hemodynamic and oxygen uptake recovery kinetics in CHF-COPD overlap

The oxygen uptake (V˙O2) kinetics during onset of and recovery from exercise have been shown to provide valuable parameters regarding functional capacity of both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) patients. To investigate the influence of comorbidity of COPD in patients with CHF with reduced ejection fraction on recovery from submaximal exercise, 9 CHF-COPD male patients and 10 age-, gender-, and left ventricle ejection fraction (LVEF)-matched CHF patients underwent constant-load exercise tests (CLET) at moderate and high loads. The V˙O2, heart rate (HR), and cardiac output (CO) recovery kinetics were determined for the monoexponential relationship between these variables and time. Within-group analysis showed that the recovery time constant of HR (P<0.05, d=1.19 for CHF and 0.85 for CHF-COPD) and CO (P<0.05, d=1.68 for CHF and 0.69 for CHF-COPD) and the mean response time (MRT) of CO (P<0.05, d=1.84 for CHF and 0.73 for CHF-COPD) were slower when moderate and high loads were compared. CHF-COPD patients showed smaller amplitude of CO recovery kinetics (P<0.05) for both moderate (d=2.15) and high (d=1.07) CLET. Although the recovery time constant and MRT means were greater in CHF-COPD, CHF and CHF-COPD groups were not differently affected by load (P>0.05 in group vs load analysis). The ventilatory efficiency was related to MRT of V˙O2 during high CLET (r=0.71). Our results suggested that the combination of CHF and COPD may further impair the recovery kinetics compared to CHF alone.

Impacto de la gastrectomía vertical sobre la cinética de consumo de oxígeno en mujeres post cirugía bariátrica / Impact of sleeve gastrectomy on the kinetics of oxygen consumption in women after bariatric surgery

Introducción: La obesidad es considerada uno de los principales problemas de salud de la sociedad moderna, existiendo variados tratamientos para revertirla, siendo la cirugía bariátrica (CB) el método más efectivo en los casos de obesidad severa. La capacidad cardiorrespiratoria (CCR) es un componente de la condición física valorada a través del consumo máximo de oxígeno (VO2max); la cinética del VO2 es un aspecto poco estudiado de la CCR; se ha descrito que esta variable permite estimar la CCR sin elevados esfuerzos físicos en comparación con otras formas de evaluación; a pesar de lo anterior, no existe información respecto del impacto que tiene la gastrectomía vertical (GV) sobre la CCR evaluada a través de esta variable. Objetivo: Determinar el impacto de la GV en la cinética del VO2 de mujeres con obesidad. Material y método: Estudio de tipo cuasi experimental, participaron 15 mujeres con edad de 32,9±10,3 años y un IMC inicial de 35,2 ± 3,9 kg/m2. La muestra es de tipo no probabilística a través de grupo de voluntarios evaluados en tres momentos: previo a la cirugía (pre), 30 y 90 días post gastrectomía vertical (30post y 90post respectivamente). Se evaluó peso corporal, índice de masa corporal (IMC), circunferencia cintura (CC), VO2peak y cinética del VO2. Resultados: Post cirugía las variables peso corporal, CC e IMC reportan disminución significativa (p < 0,001) respecto del momento pre-cirugía. El VO2peak relativo (ml/kg/min) aumentó entre 30post y 90post (p < 0,001); el VO2peak absoluto (L/min) disminuyó entre los momentos pre con 30post y pre con 90post (p < 0,05); la cinética del VO2 presentó un incremento del tiempo a los 30post (p < 0,05). Conclusión: La cinética del VO2 se ve incrementada en mujeres obesas intervenidas con GV a los 30 días post cirugía, lo que evidencia un deterioro de la capacidad cardiorrespiratoria

Introduction: Obesity is considered one of the main health problems of modern society, there are several treatments to reverse it, being bariatric surgery (BS) the most effective method in cases of severe obesity. Cardiorespiratory fitness (CRF) is an aspect of physical condition assessed through maximum oxygen consumption (VO2max); the kinetics of VO2 is a less studied aspect of CRF; it has been described that this variable allows estimation of the CRF without high physical efforts in comparison with other forms of evaluation; In spite of the above, there is no information regarding the impact that sleeve gastrectomy (SG) has on the CRF evaluated through this variable.Objective: To determine the impact of SG on the VO2 kinetics of women with obesity. Material and method: Quasi-experimental study, 15 women with an age of 32,9 ± 10,3 years and an initial BMI of 35,2 ± 3,9 kg/m2 participated. The sample is non-probabilistic through a group of volunteers evaluated at three times: before surgery (pre), 30 and 90 days post vertical gastrectomy (30post and 90post respectively). Body weight, body mass index (BMI), waist circumference (WC), VO2peak and VO2 kinetics were evaluated. Results: After surgery, the variables body weight, CC and BMI reported a significant decrease (p < 0,001) compared to the pre-surgery moment. The relative VO2peak (ml/kg/min) increases between 30post and 90post (p < 0,001); the absolute VO2peak (L/min) decreased between the pre moments with 30post and pre with 90post (p < 0,05); the kinetics of VO2 showed an increase intime at 30post (p < 0,05). Conclusion: The VO2 kinetics is increased in obese women undergoing SG at 30post surgery, which shows a deterioration of this capacity

A Comparison of Maximal Voluntary Ventilation and Forced Vital Capacity in Adolescent Idiopathic Scoliosis Patients.

STUDY DESIGN: Prospective, single center. OBJECTIVE: To compare maximal voluntary ventilation (MVV) and forced vital capacity (FVC) testing in the outpatient scoliosis clinic to determine their relative feasibility and sensitivity in assessing pulmonary function in the AIS population. SUMMARY OF BACKGROUND DATA: Evidence of compromised pulmonary function in patients with severe AIS is well established. The American Thoracic Society (ATS) has established criteria for the reliability and accuracy of pulmonary function tests (PFTs), including MVV and FVC. METHODS: A total of 91 AIS patients with thoracic curves of 20° or greater were enrolled in the orthopedic clinic. Patients performed PFTs using the CareFusion MicroLoop Spirometer. MVV and FVC values were collected. Results were considered reliable or "passing" when ATS spirometer guidelines were met. RESULTS: Eighty-seven of the 91 patients (96%) met ATS criteria for the MVV test and 43 of the 91 patients (47%) met criteria for the FVC test. Both MVV (r = -0.41, p < .01) and FVC (r = -0.37, p = .01) were significantly correlated with thoracic Cobb angle. The percentile predicted (%predicted) MVV (r = -0.24, p = .03) and %predicted FVC (r = -0.32, p = .04) were also significantly correlated with thoracic Cobb angle. Of those who passed both tests (42/91 patients), 26% had abnormal MVV results with normal FVC results, and 5% had abnormal FVC results with normal MVV results. CONCLUSION: MVV and FVC correlated closely with Cobb angle. Twice as many AIS patients could perform an MVV test compared with an FVC test. MVV seems to be a more practical and sensitive PFT than FVC for assessing the pulmonary function of AIS patients in the orthopedic clinic setting. LEVEL OF EVIDENCE: Level II.

Aerobic fitness predicts the air consumption time in the self-contained breathing apparatus during physical task of firefighters / La capacidad aeróbica predice el tiempo de consumo de aire de un equipo de respiración autónoma durante tareas físicas de bomberos / Aptidão aeróbia prediz o tempo de consume de ar no equipamento autônomo de proteção respiratória durante tarefa física de bombeiros

Objective: The aerobic fitness on predicting firefighters' air consumption time from self-contained breathing apparatus (T_SCBA) during physical task was investigated. Methods: Twenty firefighters were divided in two groups: G1 (n=10; 28.0±3.1 years) for the generation of a predictive equation of T_SCBA and G2 (n=10; 25.4±2.3 years) for the validation of the predictive equation. The groups completed two performance tests in separate days: 1) maximal 1600m running in order to determine mean velocity (1600mV) and maximal heart rate; 2) submaximal running/walking at intensity between 88-92% of the maximal heart rate. In second test, the firefighters were equipped with protective clothing (boots, gloves, cape, helmet and balaclava) and the self-contained breathing apparatus. The T_SBCA (corresponding to 1020 liters of pressurized air), blood lactate, heart rate and rate of perceived exertion were measured. Results: The linear regression of G1 (T_SCBA vs. 1600mV) resulted in the following predictive equation: T_SCBA= 0.0442*1600mV (m.min-1) + 4.5029 (r= 0.85; SEE= 0.73; p<0.001). When analyzing in G2, the measured and predicted T_SCBA using the equation generated in G1, no significant differences were found (T_SCBA measured= 15.5±2.5 min vs. T_SCBA predicted= 14.7±0.4 min; p=0.21). High correlation (r=0.95; SEE= 0.79; p<0.001) and agreement of the difference of the means (0.9 min [-3.1/+4.8]) were also found. Conclusion: Aerobic fitness presented high correlation with T_SCBA. In addition, the proposed predictive equation was considered valid to estimate T_SCBA during physical task of firefighters, which can have practical application in the labor activity of this population

Objetivo: Investigar la capacidad aeróbica como factor de predicción del tiempo de consumo de aire de un equipo de respiración autónoma (T_ERA) durante la realización de tareas físicas de bomberos. Método: Veinte bomberos se dividieron en dos grupos: G1 (n=10; 28.0±3.1 años) para la generación de la ecuación predictiva de T_ERA y G2 (n=10; 25.4±2.3 años) para la validación de la ecuación predictiva. Los grupos completaron dos test en días separados: 1) 1600m de carrera máxima para determinar la velocidad media (1600mV) y la frecuencia cardiaca máxima; 2) carrera submáxima/caminata a una intensidad entre el 88-92% de la frecuencia cardiaca máxima. En el segundo test, los bomberos usaron su ropa de protección (botas, guantes, capa, casco y pasamontañas) y el equipo de respiración autónomo. Se midió: el T_ERA (correspondiente a 1020 litros de aire presurizado), el lactato en sangre, la frecuencia cardiaca y el índice de esfuerzo percibido. Resultados: La regresión lineal del G1 (T_ERA vs. 1600mV) resultó en la siguiente ecuación predictiva: T_ERA= 0.0442*1600mV (m.min-1) + 4.5029 (r= 0.85; EEE= 0.73; p<0.001). Cuando se analizó el G2, no se encontraron diferencias significativas entre el valor de T_ERA medido y el calculado usando la ecuación generada con el G1 (T_ERA medido= 15.5±2.5 min vs. T_ERA calculado= 14.7±0.4 min; p=0.21). Se encontró una alta correlación (r=0.95; EEE= 0.79; p<0.001) y concordancia con la diferencia de las medias (0.9 min [-3.1/+4.8]). Conclusión: La capacidad aeróbica presentó una alta correlación con el T_ERA. Además, la ecuación de predicción propuesta se consideró válida para estimar el T_ERA durante tareas físicas de bomberos, lo que tiene grandes aplicaciones prácticas en la labor de esta población

Objetivo: Investigar a aptidão aeróbia na predição do tempo de consumo de ar durante tarefa física de bombeiros a partir do equipamento de proteção respiratória (T_EPR). Método: Vinte bombeiros foram divididos em dois grupos: G1 (n=10; 28.0±3.1 anos) para geração da equação preditiva do T_EPR e G2 (n=10; 25.4±2.3 anos) para validação da equação preditiva. Os grupos realizaram dois testes de desempenho em dias distintos: 1) 1600m de corrida em máxima intensidade para determinar a velocidade média (Vm1600) e a frequência cardíaca máxima; 2) corrida/caminhada em intensidade submáxima entre 88-92% da frequência cardíaca máxima. No segundo teste, os bombeiros estavam equipados com roupa de proteção (botas, luvas, capa, capacete e balaclava) e equipamento de proteção respiratória. O T_EPR (correspondente a 1020 litros de ar pressurizado), lactate sanguíneo, frequência cardíaca e percepção subjetiva de esforço foram mensurados. Resultados: A regressão linear do G1 (T_EPR vs. Vm1600) resultou na seguinte equação de predição: T_EPR= 0.0442*Vm1600 (m.min-1) + 4.5029 (r= 0.85; EPM= 0.73; p<0.001). Quando analizado em G2, o T_EPR medido e predito a partir da equação gerada em G1, não foi encontrada diferença significante (T_EPR medido= 15.5±2.5 min vs. T_EPR predito= 14.7±0,4 min; p=0.21). Alta correlação (r=0.95; EPM= 0.79; p<0.001) e concordância na média das diferenças (0.9 min [-3.1/+4.8]) também foi encontrada. Conclusão: A aptidão aeróbia apresentou alta correlação com o T_EPR. Em adicional, a equação preditiva proposta foi considerada valida em estimar o T_EPR durante tarefa física de bombeiros, o que pode ter aplicação prática na atividade laboral dessa população

Clinical implication of maximal voluntary ventilation in myotonic muscular dystrophy.

Patients with myotonic muscular dystrophy type 1 (DM1) tend to exhibit earlier respiratory insufficiency than patients with other neuromuscular diseases at similar or higher forced vital capacity (FVC). This study aimed to analyze several pulmonary function parameters to determine which factor contributes the most to early hypercapnia in patients with DM1.We analyzed ventilation status monitoring, pulmonary function tests (including FVC, maximal voluntary ventilation [MVV], and maximal inspiratory and expiratory pressure), and polysomnography in subjects with DM1 who were admitted to a single university hospital. The correlation of each parameter with hypercapnia was determined. Subgroup analysis was also performed by dividing the subjects into 2 subgroups according to usage of mechanical ventilation.Final analysis included 50 patients with a mean age of 42.9 years (standard deviation = 11.1), 46.0% of whom were male. The hypercapnia was negatively correlated with MVV, FVC, forced expiratory volume in 1 second (FEV1), and their ratios to predicted values in subjects with myotonic muscular dystrophy type 1. At the same partial pressure of carbon dioxide, the ratio to the predicted value was lowest for MVV, then FEV1, followed by FVC. Moreover, the P values for differences in MVV and its ratio to the predicted value between ventilator users and nonusers were the lowest.When screening ventilation failure in patients with DM1, MVV should be considered alongside other routinely measured parameters.

"Respiratory pattern" o donde hay patrón... ¿no manda marinero? / "Respiratory Pattern" or Where the Capitan Rules a Sailor has no Sway?

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Ventilatory Support via Mouthpiece to Facilitate Ambulation.

OBJECTIVE: The aim of the study was to evaluate the efficacy of noninvasive ventilatory assistance/support via mouthpiece to improve performance in 6-min walk tests for individuals with severe restrictive ventilatory disorders. DESIGN: Each subject performed the 6-min walk test breathing spontaneously and again while using mouthpiece noninvasive ventilatory assistance/support at full ventilatory support. Oxyhemoglobin saturation (O2 sat), heart rate, Borg scale, distance walked, and ambulation duration were recorded. RESULTS: Eighteen patients using nocturnal nasal noninvasive ventilatory assistance/support, median (interquartile range) age of 58.5 (20) yrs, were studied. Their median baseline forced vital capacity and PaCO2 were 940 (385) ml and 54.1 (6) mm Hg, respectively. All used noninvasive ventilatory assistance/support for at least overnight hours for 36 (111) mos. Because of the progression of ventilatory impairment and hypercapnia, daytime mouthpiece noninvasive ventilatory assistance/support was initiated. All the 6-min walk test parameters improved significantly by using noninvasive ventilatory assistance/support. Both initial and final values of O2 saturation significantly increased (92% [6] vs 96% [2], P < 0.001) and (80% [19] vs 85.50% [13], P = 0.001), respectively. The median distance walked increased by 43% with noninvasive ventilatory assistance/support (175 [218] m vs 250 [113] m, P = 0.017), and the total ambulation time also increased with noninvasive ventilatory assistance/support (5.45 [3] mins vs. 6 [0] mins, P = 0.008). CONCLUSIONS: The exercise tolerance of patients with severe ventilatory impairment can improve by using noninvasive ventilatory support.

The effects of the neck stabilization exercise on the muscle activity of trunk respiratory muscles and maximum voluntary ventilation of chronic stroke patients.

BACKGROUND: Unstable neck posture, muscle imbalance, and segmental instability can cause neck pain and decrease the respiratory function. OBJECTIVE: To examine effects of a neck stabilization exercise on respiratory muscle activity and maximal voluntary ventilation (MVV) in patients with a chronic stroke. METHODS: A total of 40 patients with a chronic stroke participated in this study. They were randomly divided into two groups (20 in each group). However, ten patients dropped out of the experiment (5 in each group). The experimental group (n= 15) performed a 15-minute neck stabilization exercise and a 15-minute breathing retraining exercise in addition to a rehabilitation exercise treatment. The control group (n= 15) completed a 30-minute breathing retraining exercise in addition to a rehabilitation exercise treatment. Exercises were conducted for 30 minutes a day, five times a week, for a total of six weeks. Activities of major respiratory muscles and MVV were measured before and after the experiment. RESULTS: Both the experimental group and the control group showed significant difference in activities of major respiratory muscles and MVV before and after the experiment (p< 0.05). The experimental group showed a significantly higher increase compared to the control group (p< 0.05). CONCLUSIONS: The application of a combination of a neck stabilization exercise and a breathing retraining exercise to patients with a chronic stroke can increase activity of respiratory muscles and MVV.

Respiratory muscle training positively affects vasomotor response in young healthy women.

Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympathetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic balance, a global factor regulating the vasomotor response. Endothelial function was determined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in %FMD/SR (+45%; p<0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance.

Reduced functional capacity in patients with Chagas disease: a systematic review with meta-analysis.

Reduced peak oxygen uptake (VO2peak) is a common clinical finding in progressive Chagas disease. However, the disease stage in which functional impairment is detectable remains uncertain. The present study compared functional capacity between healthy controls and patients with different clinical forms of Chagas disease. A systematic review and meta-analysis (PROSPERO database CRD42017058353) was conducted following a search of the MEDLINE, Web of Science, CINAHL, and LILACS databases from September to December 2017 for articles published in English, Spanish, or Portuguese, with no date restrictions. We included studies that compared the VO2peak between healthy and Chagas disease patients, stratified according to 3 clinical forms [no apparent cardiac disease, non-dilated Chagas heart disease (CHD), and dilated CHD]. Seven cross-sectional studies were included. Chagas disease patients without apparent cardiac disease (n=208) had VO2peak values [mean difference, -1.55ml/kg/min; 95% confidence interval (CI), -4.98ml/kg/min to 1.88ml/kg/min] similar to those of healthy controls (n=105; p=0.38, I2=52%). In non-dilated CHD (n=159), VO2peak was 8.71ml/kg/min lower (95% CI, -13.99 to -3.42ml/kg/min) than in healthy controls (n=59; p=0.001, I2=75%). VO2peak was also significantly lower (mean difference, -9.30ml/kg/min; 95% CI, -11.34 to -7.25ml/kg/min) in dilated CHD patients (n=131) than in healthy controls (n=53; p<0.001, I2=0%). Exercise capacity in Chagas disease patients without apparent cardiac disease is similar to that in healthy controls. Functional impairment in Chagas disease is detectable in the early stages of cardiac involvement, even in the absence of systolic dysfunction and signs of heart failure.

Reduced functional capacity in patients with Chagas disease: a systematic review with meta-analysis

Abstract Reduced peak oxygen uptake (VO2peak) is a common clinical finding in progressive Chagas disease. However, the disease stage in which functional impairment is detectable remains uncertain. The present study compared functional capacity between healthy controls and patients with different clinical forms of Chagas disease. A systematic review and meta-analysis (PROSPERO database CRD42017058353) was conducted following a search of the MEDLINE, Web of Science, CINAHL, and LILACS databases from September to December 2017 for articles published in English, Spanish, or Portuguese, with no date restrictions. We included studies that compared the VO2peak between healthy and Chagas disease patients, stratified according to 3 clinical forms [no apparent cardiac disease, non-dilated Chagas heart disease (CHD), and dilated CHD]. Seven cross-sectional studies were included. Chagas disease patients without apparent cardiac disease (n=208) had VO2peak values [mean difference, -1.55ml/kg/min; 95% confidence interval (CI), -4.98ml/kg/min to 1.88ml/kg/min] similar to those of healthy controls (n=105; p=0.38, I2=52%). In non-dilated CHD (n=159), VO2peak was 8.71ml/kg/min lower (95% CI, -13.99 to -3.42ml/kg/min) than in healthy controls (n=59; p=0.001, I2=75%). VO2peak was also significantly lower (mean difference, -9.30ml/kg/min; 95% CI, -11.34 to -7.25ml/kg/min) in dilated CHD patients (n=131) than in healthy controls (n=53; p<0.001, I2=0%). Exercise capacity in Chagas disease patients without apparent cardiac disease is similar to that in healthy controls. Functional impairment in Chagas disease is detectable in the early stages of cardiac involvement, even in the absence of systolic dysfunction and signs of heart failure.

Short-Term Effects of Normocapnic Hyperpnea and Exercise Training in Patients With Chronic Obstructive Pulmonary Disease: A Pilot Study.

OBJECTIVE: The aim of the study was to evaluate the short-term physiologic effects of respiratory muscle training with normocapnic hyperpnea added to standard exercise training on respiratory muscle endurance/strength and exercise tolerance in patients with chronic obstructive pulmonary disease. DESIGN: The study used a randomized controlled trial. Patients referred for rehabilitation were randomly assigned to 20 sessions (twice daily 5 d/wk) of either normocapnic hyperpnea (group 1, n = 12) or sham maneuvers (group 2, n = 10) in addition to individualized cycle training and abdominal, upper, and lower limb muscle exercise. At baseline and end of study, patients underwent evaluation of respiratory muscle endurance, maximum voluntary ventilation, maximal inspiratory, and expiratory pressures, and 6-min walking distance. RESULTS: After training, a significant improvement was found only for group 1 in respiratory muscle endurance time (by 654 [481] secs versus 149 [216] secs for group 2, P = 0.0108) and maximal inspiratory (group 1: from 81.2 [21.9] cmH2O to 107.6 [23.0] cmH2O, P = 0.018 versus group 2: from 75.4 [13.8] cmH2O to 81.3 [18.9] cmH2O, P = 0.139). The difference between groups for 6-min walking distance, maximum voluntary ventilation, and expiratory pressures was not significant. CONCLUSIONS: Short-term normocapnic hyperpnea training added to standard exercise, compared with exercise training alone, improves respiratory muscle endurance and strength but not exercise tolerance in patients with chronic obstructive pulmonary disease.

Effect of altering breathing frequency on maximum voluntary ventilation in healthy adults.

BACKGROUND: Compared to other pulmonary function tests, there is a lack of standardization regarding how a maximum voluntary ventilation (MVV) maneuver is performed. Specifically, little is known about the variation in breathing frequency (fR) and its potential impact on the accuracy of test results. This study examines the effect of several preselected values for fR and one self-selected fR (fRself) on MVV. METHODS: Ten participants performed MVV maneuvers at various fR values, ranging from 50 to 130 breaths·min- 1 in 10 breaths·min- 1 intervals and at one fRself. Three identical trials with 2-min rest periods were conducted at each fR, and the sequence in which fR was tested was randomized. Ventilation and related parameters were measured directly by gas exchange analysis via a metabolic measurement system. RESULTS: A third-order polynomial regression analysis showed that MVV = - 0.0001(fR)3 + 0.0258(fR)2-1.38(fR) + 96.9 at preselected fR and increased up to approximately 100 breaths·min- 1 (r2 = 0.982, P < 0.001). Paired t-tests indicated that average MVV values obtained at all preselected fR values, but not fRself, were significantly lower than the average maximum value across all participants. A linear regression analysis revealed that tidal volume (VT) = - 2.63(MVV) + 300.4 at preselected fR (r2 = 0.846, P < 0.001); however, this inverse relationship between VT and MVV did not remain true for the self-selected fR. The VT obtained at this fR (90.9 ± 19.1% of maximum) was significantly greater than the VT associated with the most similar MVV value (at a preselected fR of 100 breaths·min- 1, 62.0 ± 10.4% of maximum; 95% confidence interval of difference: (17.5, 40.4%), P < 0.001). CONCLUSIONS: This study demonstrates the shortcomings of the current lack of standardization in MVV testing and establishes data-driven recommendations for optimal fR. The true MVV was obtained with a self-selected fR (mean ± SD: 69.9 ± 22.3 breaths·min- 1) or within a preselected fR range of 110-120 breaths·min- 1. Until a comprehensive reference equation is established, it is advised that MVV be measured directly using these guidelines. If an individual is unable to perform or performs the maneuver poorly at a self-selected fR, ventilating within a mandated fR range of 110-120 breaths·min- 1 may also be acceptable.

El peso corporal, la estatura, variables del estilo de vida y cardiovasculares predicen el VO2 máx. en estudiantes universitarios / Body weight, height, lifestyle and cardiovascular variables predict the VO2 max in college student

Introducción: se puede utilizar medios simples para predecir el VO2 máx., como a través de las características corporales y el estilo de vida. Objetivos: elaborar una ecuación para estimar el VO2 máx. en base al peso, estatura, variables del estilo de vida y cardiovasculares en estudiantes universitarios. Métodos: participaron 35 hombres y 35 mujeres de 22,5±1,9 años a quienes se les midió el peso corporal, estatura, se registró el consumo de alcohol, tabaco y medicamentos, variables cardiorrespiratorias en reposo y el VO2 máx. en una prueba en cicloergómetro hasta el agotamiento. Se determinó la correlación entre variables, se incluyeron en una ecuación multivariada y se verificó la concordancia del modelo con el diagrama de Bland-Altman. Se asignó una significancia de p<0,05 con el programa SPSS v.20. Resultados: la ecuación de predicción es VO2 máx. (ml.min-1) = -1268,945 + (1305,94 × Sexo [Mujer= 2; Hombre= 1]) + (17,868 × Peso) + (1034,204 × Estatura) + (-97,223 × Medicamentos [SI= 1; NO= 2]) + (3,867 × Presión arterial sistólica [PAS]) + (-5,574 × frecuencia cardíaca reposo [FCr]) (r= 0,892; r2= 0,795; p<0,001). Según Bland-Altman no hay diferencias entre la ecuación y el test en cicloergómetro (p= 0,644) y ningún valor del VO2 máx. estuvo fuera de los límites de concordancia. Discusión: el principal hallazgo es que el peso y la estatura tienen el mayor poder predictivo, junto al sexo, y las demás variables lo aumenta, además, es un estudio pionero en Chile. Algunas investigaciones utilizan características corporales y estilos de vida para predecir el VO2 máx., pero solo dos incluyen el tabaquismo, una la FC y ninguna la presión arterial. Conclusiones: variables antropométricas, del estilo de vida y cardiovasculares predicen el VO2 máx. Se puede utilizar el modelo predictivo considerando las diferencias entre las características de las personas y entre países

Introduction: To predict VO2 max it can be used simple means such as body characteristics and lifestyle. Aim: To elaborate an equation to estimate the VO2 max based on body weight, height, lifestyle and cardiovascular variables in college students. Methods: In a sample of 35 men and 35 women of 22.5±1.9 years body weight, height, consumption of alcohol, tobacco and medications, cardiorespiratory variables at rest and VO2 max in a cycle ergometer test until exhaustion were measured. A correlation between variables was determined, which were included in a multivariate equation and the agreement of the model with the Bland-Altman diagram was verified. A significance of p<0.05 was assigned with the SPSS v.20 program. Results: the prediction equation is VO2 max (ml.min-1) = -1268.945 + (1305.94 × Sex [Female = 2, Male = 1]) + (17.868 × Weight) + (1034.204 × Height) + (-97.223 × Medications [YES = 1, NO = 2]) + (3.867 × Systolic blood pressure) + (-5.574 × Resting heart rate [HRr]) (r = 0.892, r2 = 0.795, p<0.001). According to Bland-Altman there are no differences between the equation and the cycle ergometer test (p = 0.644) and no values of VO2 max were outside the limits of agreement. Discussions: the main finding is that weight and stature have the greatest predictive power, along with sex, and the other variables increase it, in addition, it is a pioneering study in Chile. Some research uses body characteristics and lifestyles to predict VO2 max, but only two include smoking, one HR and none blood pressure. Conclusions: Anthropometric, lifestyle and cardiovascular variables predict VO2 max. The predictive model can be used considering the differences between the characteristics of people and between countries

Respirar en altitudes extremas - Proyectos científicos "EVEREST" (Segunda parte) / Breathing at extreme altitudes - Scientific projects "EVEREST" (Second part)

Escalar el punto más alto de la Tierra, el Mt. Everest (8.848 m), sin equipos de oxígeno conlleva una demanda fisiológica que está próxima a la máxima capacidad de tolerancia humana. Exponerse a altitudes extremas condiciona drásticamente la función pulmonar, el nivel de oxígeno y el rendimiento físico. Esta revisión reúne interesantes aspectos respiratorios, de gases sanguíneos y ejercicio aeróbico aportados por aquellos proyectos científicos que han llevado a cabo mediciones fisiológicas entre 8.000 m y 8.848 m, en altitud real o simulada, como las Operaciones "Everest I" (1946), "Everest II" (1985) y "Everest III-COMEX" (1997), y las Expediciones "AMREE" (1981), "British 40th Anniversary Everest" (1993) y "Caudwell Xtrem Everest" (2007). Estos fascinantes eventos de investigación, junto a otros destacados proyectos biomédicos realizados a más de 5.500 m, muy especialmente las Expediciones "Silver Hut" (1960-61), "Italiana all’Everest" (1973) y "British Everest Medical" (1994), incluyendo aquellas pioneras observaciones científicas llevadas a cabo en el s.XIX hasta los más recientes proyectos de investigación realizados, han sentado las bases del conocimiento sobre la tolerancia humana ante niveles de hipoxia hipobárica extrema, donde el pulmón y la cadena respiratoria adquieren un trascendente protagonismo requiriéndose de finos ajustes fisiológicos que garanticen la oxigenación celular. Asimismo, se exponen ciertos aspectos geofísicos, factores climáticos y otros condicionantes ambientales que limitan la viabilidad biológica y pueden afectar la salud respiratoria de los alpinistas situados en las cotas superiores de la troposfera a la latitud subtropical donde se encuentra ubicada dicha montaña. Actualmente cientos de alpinistas intentan alcanzar la cumbre del Mt. Everest todos los años, pero solo algunos consiguen su objetivo sin inhalar oxígeno suplementario, entre ellos algunos excepcionalmente dotados nativos Sherpa, protagonistas de insospechadas hazañas en la montaña más elevada de la superficie terrestre, cuya cima roza el límite fisiológico de supervivencia para el ser humano

Climbing to the highest height on Earth, the Mt. Everest (8.848 m), without supplementary oxygen equipment involves a physiological demand that is close to the maximum human tolerance. Exposures at extreme altitudes drastically conditions lung function, stores of oxygen and physical performance. This review brings interesting aspects about respiration, blood gases and aerobic exercise reported by those scientific projects that have carried out physiological measurements between 8,000 m and 8,848 m above sea level, under real or simulated altitude: the Operations "Everest I" (1946), "Everest II" (1985), "Everest III-COMEX" (1997), and the Expeditions "AMREE" (1981), "British 40th Anniversary Everest" (1993), and "Caudwell Xtrem Everest" (2007). These fascinating scientific research events, along with other outstanding biomedical expeditions performed above 5,500 m, like especially the "Silver Hut" (1960-61), "Italiana all’Everest" (1973), and "British Everest Medical" (1994), including those pioneer scientific reports made on the XIX century until the most recent research projects performed, have laid the foundations and knowledge on the human tolerance to such extreme levels of hypobaric hypoxia, where the lung, breathing and respiratory chain takes on a major role requiring fine physiological adjustments to ensure cellular oxygenation. Geophysical aspects, climatic factors and other environmental conditions that limit the biological viability and can affect the respiratory health of climbers on the upper troposphere zone at the subtropical latitude where that mountain is located are likewise reviewed and analyzed. Every year, hundreds of climbers try to reach the top of Mt. Everest, but only a few of them achieved their goal without inhaling supplemental oxygen, including some exceptionally gifted Sherpa natives, protagonist on unsuspected exploits in the highest mountain on terrestrial surface, whose summit touch the physiological limit of survival for the human being