Victor Zuniga Dourado

The six-minute walk test and body weight-walk distance product in healthy Brazilian subjects

We assessed the 6-min walk distance (6MWD) and body weight x distance product (6MWw) in healthy Brazilian subjects and compared measured 6MWD with values predicted in five reference equations developed for other populations. Anthropometry, spirometry, reported physical activity, and two walk tests in a 30-m corridor were evaluated in 134 subjects (73 females, 13-84 years). Mean 6MWD and 6MWw were significantly greater in males than in females (622 +/- 80 m, 46,322 +/- 10,539 kg.m vs 551 +/- 71 m, 36,356 +/- 8,289 kg.m, P < 0.05). Four equations significantly overestimated measured 6MWD (range, 32 +/- 71 to 137 +/- 74 m; P < 0.001), and one significantly underestimated it (-36 +/- 86 m; P < 0.001). 6MWD significantly correlated with age (r = -0.39), height (r = 0.44), body mass index (r = -0.24), and reported physical activity (r = 0.25). 6MWw significantly correlated with age (r = -0.21), height (r = 0.66) and reported physical activity (r = 0.25). The reference equation devised for walk distance was 6MWDm = 622.461 - (1.846 x Ageyears) + (61.503 x Gendermales = 1; females = 0); r2 = 0.300. In an additional group of 85 subjects prospectively studied, the difference between measured and the 6MWD predicted with the equation proposed here was not significant (-3 +/- 68 m; P = 0.938). The measured 6MWD represented 99.6 +/- 11.9% of the predicted value. We conclude that 6MWD and 6MWw variances were adequately explained by demographic and anthropometric attributes. This reference equation is probably most appropriate for evaluating the exercise capacity of Brazilian patients with chronic diseases.

Manifestações sistêmicas na doença pulmonar obstrutiva crônica

Chronic obstructive pulmonary disease is progressive and is characterized by abnormal inflammation of the lungs in response to inhalation of noxious particles or toxic gases, especially cigarette smoke. Although this infirmity primarily affects the lungs, diverse extrapulmonary manifestations have been described. The likely mechanisms involved in the local and systemic inflammation seen in this disease include an increase in the number of inflammatory cells (resulting in abnormal production of inflammatory cytokines) and an imbalance between the formation of reactive oxygen species and antioxidant capacity (leading to oxidative stress). Weakened physical condition secondary to airflow limitation can also lead to the development of altered muscle function. Chronic obstructive pulmonary disease presents diverse systemic effects including nutritional depletion and musculoskeletal dysfunction (causing a reduction in exercise tolerance), as well as other effects related to the comorbidities generally observed in these patients. These manifestations have been correlated with survival and overall health status in chronic obstructive pulmonary disease patients. In view of these facts, the aim of this review was to discuss findings in the literature related to the systemic manifestations of chronic obstructive pulmonary disease, emphasizing the role played by systemic inflammation and evaluating various therapeutic strategies.

Equações de referência para os testes de caminhada de campo em adultos saudáveis

OBJECTIVE: To develop regression equations for predicting six-minute and incremental shuttle walk distances (6MWD and ISWD, respectively), based on demographic characteristics, anthropometric variables, and grip strength. METHODS: We evaluated 6MWD and ISWD in 98 healthy adults. Height, weight, and grip strength were also assessed. Using data from 90 of the participants (40 males; 60 ± 9 years of age), we devised linear equations adjusted for age, gender, height, and weight, and we developed alternate models that included grip strength. We prospectively applied the equations in the 8 remaining participants (4 males; 59 ± 10 years), who had been randomly separated from the initial sample. RESULTS: Age, gender, height, and weight collectively explained 54.5% and 64.9% of the variance in 6MWD and ISWD, respectively, whereas age, height, weight, and grip strength collectively explained 54.4% and 69.0% of the respective variances. There was no significant difference between the measured and predicted 6MWD using equations with and without grip strength (14 ± 57 vs. 13 ± 67 m). Similar results were observed for ISWD (25 ± 104 vs. 25 ± 93 m). CONCLUSIONS: Grip strength is a determinant of ISWD and 6MWD; however, it could not improve the power of equations adjusted by demographic and anthropometric variables. The validity of our models including grip strength should be further evaluated in patients with skeletal muscle dysfunction.

The Incremental Shuttle Walk Test in Older Brazilian Adults

Background: Despite widespread use of the incremental shuttle walk distance (ISWD), there are no reference equations for predicting it. Objectives: We aimed to evaluate ISWD in healthy subjects and to establish a reference equation for its prediction. Methods: 131 Brazilian individuals (61 males; 59 ± 10 years) performed 2 walk tests in a 10-m long corridor. We assessed height, weight, body mass index, forced expiratory volume in 1 s, forced vital capacity and self-reported physical activity. Results: Mean ISWD was greater in males than in females (606 ± 167 vs. 443 ± 117 m; p < 0.001). ISWD correlated significantly (p < 0.05) with age (r = –0.51), height (r = 0.54) and weight (r = 0.20). A predictive model including age, height, weight and gender explained 50.3% of the ISWD variance. In an additional group of 20 subjects prospectively studied, the difference between measured and predicted ISWD was not statistically significant (534 ± 84 vs. 552 ± 87 m, respectively), representing 97 ± 12% of the predicted value calculated with our reference equation for ISWD. Conclusions: This reference equation including demographic and anthropomorphic attributes could be useful for interpreting the walking performance of patients with chronic diseases that affect exercise capacity.

Effect of three exercise programs on patients with chronic obstructive pulmonary disease

We compared the effect of three different exercise programs on patients with chronic obstructive pulmonary disease including strength training at 50_80% of one-repetition maximum (1-RM) (ST; N = 11), low-intensity general training (LGT; N = 13), or combined training groups (CT; N = 11). Body composition, muscle strength, treadmill endurance test (TEnd), 6-min walk test (6MWT), Saint Georges Respiratory Questionnaire (SGRQ), and baseline dyspnea (BDI) were assessed prior to and after the training programs (12 weeks). The training modalities showed similar improvements (P > 0.05) in SGRQ-total (ST = 13 +/- 14%; CT = 12 +/- 14%; LGT = 11 +/- 10%), BDI (ST = 1.8 +/- 4; CT = 1.8 +/- 3; LGT = 1 +/- 2), 6MWT (ST = 43 +/- 51 m; CT = 48 +/- 50 m; LGT = 31 +/- 75 m), and TEnd (ST = 11 +/- 20 min; CT = 11 +/- 11 min; LGT = 7 +/- 5 min). In the ST and CT groups, an additional improvement in 1-RM values was shown (P < 0.05) compared to the LGT group (ST = 10 +/- 6 to 57 +/- 36 kg; CT = 6 +/- 2 to 38 +/- 16 kg; LGT = 1 +/- 2 to 16 +/- 12 kg). The addition of strength training to our current training program increased muscle strength; however, it produced no additional improvement in walking endurance, dyspnea or quality of life. A simple combined training program provides benefits without increasing the duration of the training sessions.

Valores de referência para o teste de caminhada com carga progressiva em indivíduos saudáveis: da distância percorrida às respostas fisiológicas

OBJECTIVE: To determine reference values for incremental shuttle walk distance (ISWD) and peak physiological responses during the incremental shuttle walk test (ISWT), as well as to develop a series of predictive equations for those variables in healthy adults. METHODS: We evaluated 103 healthy participants > 40 years of age (54 women and 49 men). We fitted each participant with a gas analysis system for use during the ISWT. Oxygen consumption (VO2), carbon dioxide production, minute ventilation, heart rate (HR), ISWD, and maximal walking velocity (MWV) were obtained as primary outcomes. We also assessed hand grip strength (HGS) and lean body mass (LBM). RESULTS: The regression analysis models, including physiological variables, ISWD, and MWV (adjusted for age, body mass, height, and sex), produced R2 values ranging from 0.40 to 0.65 (for HR and peak VO2, respectively). Using the models including LBM or HGS, we obtained no significant increase in the R2 values for predicting peak VO2, although the use of those models did result in slight increases in the R2 values for ISWD and MWV (of 8% and 12%, respectively). The variables ISWD, MWV, and ISWD × body mass, respectively, explained 76.7%, 73.3%, and 81.2% of peak VO2 variability. CONCLUSIONS: Our results provide reference values for ISWD and physiological responses to the ISWT, which can be properly estimated by determining simple demographic and anthropometric characteristics in healthy adults > 40 years of age. The ISWT could be used in assessing physical fitness in the general adult population and in designing individualized walking programs.OBJECTIVE: To determine reference values for incremental shuttle walk distance (ISWD) and peak physiological responses during the incremental shuttle walk test (ISWT), as well as to develop a series of predictive equations for those variables in healthy adults. METHODS: We evaluated 103 healthy participants ≥ 40 years of age (54 women and 49 men). We fitted each participant with a gas analysis system for use during the ISWT. Oxygen consumption (VO2), carbon dioxide production, minute ventilation, heart rate (HR), ISWD, and maximal walking velocity (MWV) were obtained as primary outcomes. We also assessed hand grip strength (HGS) and lean body mass (LBM). RESULTS: The regression analysis models, including physiological variables, ISWD, and MWV (adjusted for age, body mass, height, and sex), produced R2 values ranging from 0.40 to 0.65 (for HR and peak VO2, respectively). Using the models including LBM or HGS, we obtained no significant increase in the R2 values for predicting peak VO2, although the use of those models did result in slight increases in the R2 values for ISWD and MWV (of 8% and 12%, respectively). The variables ISWD, MWV, and ISWD × body mass, respectively, explained 76.7%, 73.3%, and 81.2% of peak VO2 variability. CONCLUSIONS: Our results provide reference values for ISWD and physiological responses to the ISWT, which can be properly estimated by determining simple demographic and anthropometric characteristics in healthy adults ≥ 40 years of age. The ISWT could be used in assessing physical fitness in the general adult population and in designing individualized walking programs.

Usual gait speed assessment in middle-aged and elderly Brazilian subjects

OBJECTIVES To evaluate the usual gait speed of asymptomatic adult and elderly Brazilians with a 10-meter walk test and to compare the results with foreign reference values. METHODS Seventy-nine asymptomatic volunteers ≥40 years old of both genders were assessed. After anamnesis, anthropometry and the application of a habitual physical activity questionnaire, the volunteers were submitted to a 10-meter walk test at usual speed by means of which gait speed, the number of steps and length of stride were calculated. RESULTS Except for age, all study variables were significantly lower in women. Subjects ≥70 years old presented a significantly lower gait speed than subjects between 40 and 49 years old and between 50 and 59 in both men (1.09±0.18 m/s, 1.35±0.11 m/s and 1.34±0.22 m/s, respectively) and women (1.02±0,10 m/s, 1.27±0.20 m/s and 1.27±0,15 m/s), respectively). Gait speed showed moderate correlations with age (r=-0.41, p<0.001) and height (r=0.35, p=0.001). After multiple regression analysis, age and gender were selected as relevant attributes of gait speed in that they explained 24.6% of this variable. The gait speed values in this study were significantly lower than foreign reference values (p<0.05). CONCLUSIONS The gait speed presented age-related decline and values significantly lower than those described for foreign populations. This finding indicates the need for comprehensive investigation of gait speed reference values for the Brazilian population.

Equações de referência para a predição da força de preensão manual em brasileiros de meia idade e idosos

O objetivo deste estudo foi avaliar os valores normais da forca de preensao manual do membro superior dominante (FPM-D) e nao dominante (FPM-ND) em sujeitos de meia idade e idosos assintomaticos e elaborar equacoes de referencia para a predicao da FPM. Foram investigados 54 voluntarios (51,9% homens) com idade >50 anos, medindo-se massa corporal, estatura e perimetria do braco direito e esquerdo, e calculando-se o indice de massa corporal. A FPM-D e FPM -ND foram avaliadas por dinamometria mecânica. O indice de atividade fisica habitual (IAF) foi avaliado pelo questionario de Baecke. A FPM-D foi superior a FPM-ND em ambos os sexos e em todas as idades (p<0,05). Foram encontradas correlacoes significativas entre a FPM e idade, estatura, massa corporal e perimetria do braco. As melhores equacoes de referencia foram as seguintes: FPM-Dkgf =39,996 - (0,382 x idadeanos)+(0,174 x pesokg)+(13,628 x sexohomens=1;mulheres=0) (R2ajustado=0,677); e FPM-NDkgf=44,968- (0,420 x idadeanos)+(0,110 x pesokg)+(9,274 x sexohomens=1;mulheres=0) (R2ajustado=0,546) A diferenca consistente entre a FPM-D e FPM-ND torna necessario o uso de dados normativos especificos para cada mao. Atributos simples de serem obtidos, tais como idade, estatura, massa corporal, perimetria do braco e sexo, podem pois prever adequadamente os valores esperados da FPM para adultos e idosos assintomaticos.

A simple approach to assess VT during a field walk test.

We aimed to examine whether the ventilatory threshold (VT) during an incremental shuttle walk test (ISWT) could be determined using heart rate variability (HRV) analysis. Further aims were to assess variables capable of predicting performance in the ISWT and the intensity of this test. Beat-to-beat RR intervals and gas exchange values in 10 healthy subjects (31-83 years; 7 men) were collected during the ISWT. The ventilatory equivalent was used to assess VT from respiratory components. To determine the HRV threshold (HRVT), the instantaneous beat-to-beat variability values of the RR intervals at each stage of exercise were graphically plotted against walking speed (WS). The oxygen consumption at HRVT was calculated (VO2HRVT). No significant differences were found between walking speed (WS) at VT and WS at HRVT (5.04±1.00 vs. 5.10±1.04  km/h; p=0.89). Linear regression analysis revealed a strong correlation between VO2VT and VO2HRVT (r(2)=0.896). The Bland and Altman plot analysis revealed an agreement between VO2VT and VO2HRVT (-0.05; 95%CI: -0.30-0.20  L/min). Thus, the VT can be assessed during the ISWT using a simple heart monitor. The ISWT may be a useful tool to assess exercise capacity and prescribe walking programs.

Reference equations for the 6-minute walk test in healthy individuals

El test de caminata de 6 minutos (TC6) ha sido ampliamente utilizado en el ambiente clinico. Algunas ecuaciones de referencia para la prevision de la distancia recorrida en el test (DTC6) estan disponibles en la literatura. Esta revision tuvo como objetivo discutir criticamente los hallazgos de la literatura, publicados en portugues y en ingles (LILACS, SCIELO, MEDLINE y PUBMED), que evaluaron los valores normales y elaboraron ecuaciones de referencia para la prevision de la DTC6 en individuos sanos, comparandolos a los resultados recientemente obtenidos en individuos brasilenos. Edad, genero, peso, estatura e indice de masa corporal fueron los atributos demograficos y antropometricos mas frecuentemente correlacionados con la DTC6. Las ecuaciones resultantes de esos atributos fueron capaces de explicar entre 25 y 66% de la variabilidad total de la DTC6. Lamentablemente, las ecuaciones extranjeras no son adecuadas para la poblacion brasilena. Aun cuando el test es realizado bajo estandarizacion rigurosa, la diferencia de performance en el TC6 entre extranjeros y brasilenos permanece, indicando la necesidad de los valores de referencias especificos para cada poblacion y/o etnia. En ese sentido, las ecuaciones desarrolladas recientemente en el Brasil son, probablemente, las mas apropiadas para interpretar la performance de caminata de nuestros compatriotas con enfermedades cronicas que afectan su capacidad para realizar ejercicios. Estudios futuros con muestras substancialmente mayores (p.e. multicentricos) y con tecnica de muestreo randomizada son necesarios para que los valores de referencia de la DTC6 sean mas representativos.The six-minute walk test (6MWT) has been broadly used in clinical settings. Several reference equations for prediction of the total distance walked during the test (6MWD) are available in literature. The present review aimed to critically discuss studies, published in Portuguese and English (LILACS, SCIELO, MEDLINE, PUBMED), which evaluated normal values and created reference equations for predicting 6MWD in healthy subjects, comparing them with the results that were recently obtained in Brazilian individuals. Age, sex, weight, height and body mass index were the main demographic and anthropometric features more often correlated with 6MWD. The equations derived from these characteristics were able to explain between 25 and 66% of the total variability in the 6MWD. Unfortunately, the foreign equations were not applicable to the Brazilian population. Even when the 6MWT was performed following strict standardization, the difference in 6MWT performance between foreign and Brazilian individuals remains, indicating the necessity of providing specific reference equations for each population and/or ethnic group. Accordingly, these equations developed in Brazil are probably the most appropriate for interpreting 6MWT performance in Brazilian patients with chronic diseases affecting the exercise capacity. Future studies are necessary with larger sample sizes (e.g. multicentric ones) and randomized design for the reference values of the 6MWD to be considered reliable.