Relationship between the work developed in maximal and submaximal exercise capacity tests and the degree of airflow obstruction in individuals with Chronic Obstructive Pulmonary Disease

Este estudio tuvo como objetivo investigar la relación de labor desarrollada en dos tests de capacidad de ejercicio, un máximo y otro submáximo, con el grado de obstrucción del flujo aéreo en individuos con Enfermedad Pulmonar Obstructiva Crónica (EPOC). Los 53 individuos con EPOC (29 hombres, 70±9Años, 65±14kg, volumen espiratorio forzado en el primer segundo [VEF1] 38 [31-54]% previsto) tuvieron evaluadas su función pulmonar, a través de espirometría, y capacidad máxima de ejercicio en por el Incremental Shuttle Walking Test (ISWT), y submáxima, por el test de caminata de seis minutos (TC6min). El trabajo desarrollado en los tests fue calculado por el producto de la distancia recorrida con el peso corporal del individuo (P). Para evaluar la contribución del peso en el rendimiento de los tests, los individuos fueron separados en dos grupos : de alto peso (n=32) y bajo peso (n=21). Se observó una correlación del VEF1 con la distancia recorrida en el ISWT y con el ISWT*P (r=0,43 y r=0,49, respectivamente; PObjetivou-se investigar a relação do trabalho desenvolvido em dois testes de capacidade de exercício, um máximo e outro submáximo, com o grau de obstrução ao fluxo aéreo em indivíduos com Doença Pulmonar Obstrutiva Crônica (DPOC). 53 indivíduos com DPOC (29 homens, 70±9 anos, 65±14 kg, volume expiratório forçado no primeiro segundo [VEF1] 38[31-54]% previsto) tiveram avaliadas sua função pulmonar, por meio de espirometria, e capacidade de exercício máxima, pelo Incremental Shuttle Walking Test (ISWT), e submáxima, pelo teste de caminhada de seis minutos (TC6min). O trabalho desenvolvido nos testes foi calculado pelo produto da distância percorrida com o peso corporal do indivíduo (P). Para avaliar a contribuição do peso no desempenho dos testes, os indivíduos foram separados em dois grupos: maior peso (n=32), e menor peso (n=21). Observou-se correlação do VEF1 com a distância percorrida no ISWT e com o ISWT*P (r=0,43 e r=0,49, respectivamente; pThe aim of this study was to investigate the relationship between the work in two exercise capacity tests, a maximum and a submaximal exercise, and the level of airflow obstruction in patients with Chronic Obstructive Pulmonary Disease (COPD). Fifty-three subjects with COPD (29 men, 70±9 years old, 65±14 kg, forced expiratory volume in the first second [FEV1] 38[31-54]% predicted) had their lung function assessed by spirometry, and maximal and submaximal exercise capacity were evaluated by the Incremental Shuttle Walking test (ISWT) and the 6-Minute Walk Test (6MWT), respectively. The work in the tests was calculated by multiplying the covered distance and the individual's body weight (W). To evaluate the contribution of weight on the developed work, subjects were separated into two groups: higher weight (n=32), and lower weight (n=21). FEV1 correlated with the distance on the ISWT and with the ISWT*W (r=0.43 and r=0.49, respectively;

Cutoff points for the 1-RM test and their association with mortality in COPD

Introduction: There is no available cutoff for the 1-repetition maximum (1RM) test of knee extensor muscles associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). Aims: To determine 1RM cutoffs for the knee extensors and to verify their association with mortality in COPD. Methods: In a preliminary analysis of a multicenter study, 170 patients performed the 1RM test of knee extensors (52%♂; 66±8yrs; FEV1 46±15%pred). Cutoffs for 1RM and 1RM/Body Weight ratio (1RM/BW) were identified by ROC curve analysis in a subgroup of patients (n=114; 68 from Brazil; 46 from Portugal). They were classified as either normal (≥80%pred) or low (<80%pred) strength by their maximum voluntary isometric contraction of knee extensors. Vital status was retrospectively ascertained for four years in the remaining sample (n=56). Results: The best discriminative cutoffs (1RM♀: 22kg; 1RM♂: 34kg; 1RM/BW♀: 25%; 1RM/BW♂: 48%) were tested in Kaplan-Meier analysis (Figure 1). Respectively, 40% and 41% of patients classified as ‘low strength’ according to 1RM and 1RM/BW cut-offs died in 4 years, in comparison to 0% and 20% in those with normal strength (P>0.05). Cox regression adjusted for confounders was not statistically significant. Conclusion: New gender-based knee extensors 1RM cutoffs adjusted or not for body weight were provided, although they were not yet statistically associated with mortality in this preliminary analysis.publishe

Are thirty minutes of rest between two 6-Minute Walk Tests enough for cardiovascular and symptomatic recovery for patients with chronic obstructive pulmonary disease?

Dos test de caminata de 6 minutos (TC6min) son necesarios para que se evalúe la capacidad funcional de ejercicio en pacientes con enfermedad pulmonar obstructiva crónica (EPOC). Aunque la American Thoracic Society (ATS) sugiere 1 hora de intervalo entre dos test, todavía se desconoce si puede utilizarse un periodo menor para normalización de las variables fisiológicas. En este estudio se comprobó que es suficiente el intervalo de 30 minutos de descanso entre dos TC6min para que las variables cardiovasculares y de síntomas vuelvan a sus valores de referencia. El estudio se llevó a cabo con 215 pacientes con EPOC (121H, 66±8 años; VEF1: 44[32-57]% previsto), que hicieron dos TC6min con intervalos de 30 minutos. Antes y después de los test se midieron la presión arterial (PA), la frecuencia cardíaca (FC), la saturación de oxígeno (SpO2) y el grado de disnea y de cansancio. Los pacientes caminaron una distancia más grande en el segundo test (TC6min1: 450 [390-500]m vs TC6min2: 470 [403-515]m; p;0,05 para todos. Aunque tenga diferencia estadística significante en la FC inicial entre el primer y el segundo test, el resultado no es clínicamente relevante, por lo tanto, los 30 minutos de descanso entre dos TC6min son suficientes para la recuperación cardiovascular y de síntomas en pacientes con EPOC.Two 6-Minute Walk Tests (6MWT) are required to evaluate functional capacity of exercise in patients with Chronic Obstructive Pulmonary Disease (COPD). Despite the fact that the American Thoracic Society (ATS) has proposed a one-hour interval between two tests, it is unknown whether a shorter period could be used for the normalization of physiological variables. We aimed to verify that an interval of 30 minutes of rest between two 6MWT is sufficient for cardiovascular and symptomatic variables to return to their basal levels. Two hundred and fifteen patients with COPD (121H, 66±8 years; FEV1: 44 [32-57]% predicted) performed two 6MWT with a thirty-minute interval between them. Before and after the tests, we measured Blood Pressure (BP), Heart Rate (HR), peripheral oxygen saturation (SpO2), degree of dyspnea, and fatigue. Patients walked the longest distance in the second test (6MWT1: 450 [390-500]m vs 6MWT2: 470 [403-515]m; p;0.05 for all). Although there are statistically significant differences in initial HR between the first and second test, this finding does not seem to be clinically relevant. Therefore, thirty minutes of rest between two 6MWT are sufficient for cardiovascular and symptomatic recovery in patients with COPD.Dois testes da caminhada de 6 minutos (TC6min) são necessários para avaliação da capacidade funcional de exercício em pacientes com doença pulmonar obstrutiva crônica (DPOC). Apesar de a American Thoracic Society (ATS) preconizar um intervalo de 1 hora entre dois testes, não se sabe se um período menor poderia ser utilizado para normalização das variáveis fisiológicas. O objetivo foi verificar se o intervalo de 30 minutos de repouso entre dois TC6min seria suficiente para que as variáveis cardiovasculares e sintomatológicas retornassem aos valores basais. Duzentos e quinze pacientes com DPOC (121H, 66±8 anos; VEF1: 44[32-57]% previsto) realizaram dois TC6min com intervalo de 30 minutos entre eles. Foram mensuradas antes e após os testes, pressão arterial (PA), frequência cardíaca (FC), saturação periférica de oxigênio (SpO2) e grau de dispneia e fadiga. Os pacientes caminharam maior distância no segundo teste (TC6min1: 450 [390-500]m vs TC6min2: 470 [403-515]m; p;0,05 para todos). Embora haja diferença estatisticamente significante na FC inicial entre o primeiro e segundo teste, tal achado não parece ser clinicamente relevante. Portanto, trinta minutos de repouso entre dois TC6min são suficientes para recuperação sintomatológica e cardiovascular em pacientes com DPOC