Predicted VO2 on 6 minutes walk test for FAP liver transplanted patients

Physical function is limited post-liver transplantation and exercise training can improve exercise capacity following transplantation but previously assessment of functional capacity is necessary. The 6 minute walk test (6MWT) is routinely used for studying patient’s exercise capacity and is less expensive and time consuming than a Cardiopulmonary Exercise Test (CPXT). There have been some studies looking at the relationship between 6MWT and peak VO2 in patients but few presented an adequate equation for predicted peak VO2 from 6MWT to transplanted patients and none for Familial Amyloidotic Polyneuropathy (FAP) liver transplanted patients (FAPTx). The aim of this study was to compare the validity of 6 equations as predictors of VO2 from the 6MWT and compare it with directly measured VO2 in patients FAPTx.

Does 6-minutes walk test predict functional capacity in elderly people?

Portugal has an accentuated aging tendency, presenting an elderly population (individuals with more than 65 years old) of 19.2%. The average life expectancy is 79.2 years. Thus, it’s important to maintain autonomy and independency as long as possible. Functional ability concept rises from the need to evaluate the capacity to conduct daily activities in an independent way. It can be estimated with the 6-minute walk test (6MWT) and other validated test. This test is simple, reliable, valid and consists in a daily activity (walk). The goals of this study was to verify associations between functional capacity measured with two different instruments (6MWT and Composite Physical Function (CPF) scale) and between those results and characterization variables.

Does the 6-minute walk test predicts functional capacity in a sample of elderly women? A pilot study

Introduction: Functional capacity is the capacity to conduct daily activities in an independent way. It can be estimated with the 6-minutes’ walk test (6MWT) and other validated functional tests. Objectives: Verify associations between functional capacity measured with two different instruments (6MWT and Composite Physical Function (CPF) scale) and levels of physical activity and between those and characterization variables. Methods: This sample consisted of 30 apparently healthy elderly women from Loures municipality. Essentially they should be independent and community-dwelling. Characterization data were collected, containing characterization of physical activity levels and anthropometric data. Functional capacity was assessed with CPF scale and distance walked by the 6MWT. Results were analysed using a SPSS v21.0 through correlation tests. Results: The walked distance in 6MWT was positively associated with height (r = 0.406; p = 0.026), physical activity level (r = 0.594; p = 0.001) and functional capacity (r = 0.682; p = 0.000). For each point more obtained in CPF, the distance walked increases on average by 7.5 meters. Relatively to sedentary participants, being insufficiently active increases, on average, the distance walked in 85.8 meters; and being active increases, on average, the distance walked in 108.8 meters. No other associations were observed in our sample. Conclusion: Based on the collected sample, walked distance in 6MWT has a high correlation with results in CPF scale, so this test can be used to predict functional capacity. More attention should be taken to promote strategies to increase walking in older adults.

Improvements in the 6-Min Walk Test and Spirometry Following Thoracentesis for Symptomatic Pleural Effusions

Background: Impairment in pulmonary capacity due to pleural effusion compromises daily activity. Removal of fluid improves symptoms, but the impact, especially on exercise capacity, has not been determined. Methods: Twenty-five patients with unilateral pleural effusion documented by chest radiograph were included. The 6-min walk test, Borg modified dyspnea score, FVC, and FEV, were analyzed before and 48 h after the removal of large pleural effusions. Results: The mean fluid removed was 1,564 +/- 695 mL. After the procedure, values of FVC, FEV and 6-min walk distance increased (P<.001), whereas dyspnea decreased (P<.001). Statistical correlations (P<.001) between 6-min walk distance and FVC (r=0.725) and between 6-min walk distance and FEV, (r=0.661) were observed. Correlations also were observed between the deltas (prethoracentesis X postthoracentesis) of the 6-min walk test and the percentage of FVC (r=0.450) and of FEV, (r=0.472) divided by the volume of fluid removed (P<.05). Conclusion: In addition to the improvement in lung function after thoracentesis, the benefits of fluid removal are more evident in situations of exertion, allowing better readaptation of patients to routine activities. CHEST 2011; 139(6):1424-1429

Can the Cardiopulmonary 6-Minute Walk Test Reproduce the Usual Activities of Patients with Heart Failure?

OBJECTIVE: The 6-minute walk test is an way of assessing exercise capacity and predicting survival in heart failure. The 6-minute walk test was suggested to be similar to that of daily activities. We investigated the effect of motivation during the 6-minute walk test in heart failure. METHODS: We studied 12 males, age 45±12 years, ejection fraction 23±7%, and functional class III. Patients underwent the following tests: maximal cardiopulmonary exercise test on the treadmill (max), cardiopulmonary 6-minute walk test with the walking rhythm maintained between relatively easy and slightly tiring (levels 11 and 13 on the Borg scale) (6EB), and cardiopulmonary 6-minute walk test using the usual recommendations (6RU). The 6EB and 6RU tests were performed on a treadmill with zero inclination and control of the velocity by the patient. RESULTS: The values obtained in the max, 6EB, and 6RU tests were, respectively, as follows: O2 consumption (ml.kg-1.min-1) 15.4±1.8, 9.8±1.9 (60±10%), and 13.3±2.2 (90±10%); heart rate (bpm) 142±12, 110±13 (77±9%), and 126±11 (89±7%); distance walked (m) 733±147, 332±66, and 470±48; and respiratory exchange ratio (R) 1.13±0.06, 0.9±0.06, and 1.06±0.12. Significant differences were observed in the values of the variables cited between the max and 6EB tests, the max and 6RU tests, and the 6EB and 6RU tests (p<0.05). CONCLUSION: Patients, who undergo the cardiopulmonary 6-minute walk test and are motivated to walk as much as they possibly can, usually walk almost to their maximum capacity, which may not correspond to that of their daily activities. The use of the Borg scale during the cardiopulmonary 6-minute walk test seems to better correspond to the metabolic demand of the usual activities in this group of patients.

Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing

The 6-minute walk test (6MWT) is a simple field test that is widely used in clinical settings to assess functional exercise capacity. However, studies with healthy subjects are scarce. We hypothesized that the 6MWT might be useful to assess exercise capacity in healthy subjects. The purpose of this study was to evaluate 6MWT intensity in middle-aged and older adults, as well as to develop a simple equation to predict oxygen uptake ( V ˙ O 2 ) from the 6-min walk distance (6MWD). Eighty-six participants, 40 men and 46 women, 40-74 years of age and with a mean body mass index of 28±6 kg/m2, performed the 6MWT according to American Thoracic Society guidelines. Physiological responses were evaluated during the 6MWT using a K4b2 Cosmed telemetry gas analyzer. On a different occasion, the subjects performed ramp protocol cardiopulmonary exercise testing (CPET) on a treadmill. Peak V ˙ O 2 in the 6MWT corresponded to 78±13% of the peak V ˙ O 2 during CPET, and the maximum heart rate corresponded to 80±23% of that obtained in CPET. Peak V ˙ O 2 in CPET was adequately predicted by the 6MWD by a linear regression equation: V ˙ O 2 mL·min-1·kg-1 = -2.863 + (0.0563×6MWDm) (R2=0.76). The 6MWT represents a moderate-to-high intensity activity in middle-aged and older adults and proved to be useful for predicting cardiorespiratory fitness in the present study. Our results suggest that the 6MWT may also be useful in asymptomatic individuals, and its use in walk-based conditioning programs should be encouraged.

Estimation of Maximal Work Rate Based on the 6-Minute Walk Test and Fat-Free Mass in Chronic Obstructive Pulmonary Disease

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Do muscle strengthening exercises improve performance in the 6-minute walk test in postmenopausal women?

Background: Walking speed seems to be related to aerobic capacity, lower limb strength, and functional mobility, however it is not clear whether there is a direct relationship between improvement in muscle strength and gait performance in early postmenopausal women. Objective: To evaluate the effect of muscle strengthening exercises on the performance of the 6-minute walk test in women within 5 years of menopause. Methods: The women were randomized into control group (n=31), which performed no exercise, and exercise group (n=27), which performed muscle strengthening exercises. The exercises were performed twice a week for 3 months. The exercise protocol consisted of warm-up, stretching, and strengthening of the quadriceps, hamstring, calf, tibialis anterior, gluteus maximus, and abdominal muscles, followed by relaxation. Muscular strength training started with 60% of 1MR (2 series of 10-15 repetitions), reaching 85% until the end of the 3-month period (4 series of 6 repetitions each). Results: The between-group comparisons pre- and post-intervention did not show any difference in distance walked, heart rate or blood pressure (p>0.05), but showed differences in muscle strength post-intervention, with the exercise group showing greater strength (p<0.05). In the within-group comparison, there were differences in final heart rate and quadriceps and hamstring strength pre- and post-intervention in the exercise group (p<0.05). Conclusion: The results suggest that muscle strengthening of the lower limbs did not improve performance in the 6-minute walk test in this population of postmenopausal women. Trial registration ACTRN12609001053213.

Six-minute walk test: functional capacity of severely obese before and after bariatric surgery

Background: The 6-minute walk test (6MWT) is a well-known instrument for assessing the functional capacity of a variety of groups, including the obese. It is a simple, low-cost and easily applied method to objectively assess the level of exercise capacity. The aim of the present study was to study the functional capacity of a severely obese population before and after bariatric surgery. Methods: A total of 51 patients were studied. Of the 51 patients, 86.2% were women, and the mean age was 40.9 +/- 9.2 years. All 51 patients were evaluated preoperatively and 49 were evaluated 7-12 months postoperatively. The initial body mass index was 51.1 +/- 9.2 kg/m(2), and the final body mass index was 28.2 +/- 8.1 kg/m(2). All patients underwent Roux-en-Y gastric bypass. The 6MWT was performed in a hospital corridor, with patients attempting to cover as much distance as they could, walking back and forth for as long as possible within 6 minutes at their regular pace. The total distance, Borg Scale of perceived exhaustion, modified Borg dyspnea scale for shortness of breath, and physical complaints at the end of the test were recorded. In addition, the heart rate and respiratory frequency were assessed before and after the test. Results: The tolerance was good, and no injuries occurred at either evaluation. The patients` mean distance for the 6MWT was 381.9 +/- 49.3 m before surgery and 467.8 +/- 40.3 m after surgery (p < .0001). Similar results were observed for the other parameters assessed. Conclusion: The 6MWT provided useful information about the functional status of the obese patients undergoing bariatric surgery. A simple, safe, and powerful method to assess functional capacity of severely obese patients, the 6MWT is an objective test that might replace the conventional treadmill test for these types of patients. (Surg Obes Relat Dis 2009;5:540-543.) (C) 2009 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Relationship of upper-limb and thoracic muscle strength to 6-min walk distance in COPD patients

Study objectives: This study was developed to investigate the influence of thoracic and upperlimb muscle function on 6-min walk distance (6MWD) in patients with COPD.Design: A prospective, cross-sectional study.Setting: the pulmonary rehabilitation center of a university hospital.Patients: Thirty-eight patients with mild to very severe COPD were evaluated.Measurements and results: Pulmonary function and baseline dyspnea index (BDI) were assessed, handgrip strength, maximal inspiratory pressure (Pimax), and 6MWD were measured, and the one-repetition maximum (1RM) was determined for each of four exercises (bench press, lat pull down, leg extension, and leg press) performed on gymnasium equipment. Quality of life was assessed using the St. George Respiratory Questionnaire (SGRQ). We found statistically significant positive correlations between 6MWD and body weight (r = 0.32; p < 0.05), BDI (r = 0.50; p < 0.01), FEV, (r = 0.33; p < 0.05), PImax (r = 0.53; p < 0.01), and all values of 1RM. A statistically significant negative correlation was observed between 6MWD and dyspnea at the end of the 6-min walk test (r = -0.29; p < 0.05), as well as between 6MWD and the SGRQ activity domain (r = -0.45; p < 0.01) and impact domain (r = -0.34; p < 0.05) and total score (r = -0.40; p < 0.01). Multiple regression analysis selected body weight, BDI, Pimax, and lat pull down IRM as predictive factors for 6MWD (R-2 = 0.589).Conclusions: the results of this study showed the importance of the skeletal musculature of the thorax and upper limbs in submaximal exercise tolerance and could open new perspectives for training programs designed to improve functional activity in COPD patients.

Comparison between actual and predicted postoperative stair-climbing test, walk test and spirometric values in patients undergoing lung resection

OBJETIVO: Verificar se os testes: Volume Expiratório Forçado no 1º segundo (VEF1), Teste de Caminhada de 6 minutos (TC6) e Teste de Escada (TE) se alteram proporcionalmente ao pulmão funcionante ressecado. MÉTODOS: Foram incluídos pacientes candidatos a toracotomia para ressecção pulmonar. No pré-operatório (pré) e no mínimo três meses após a cirurgia (pós), realizaram espirometria, TC6 e TE. O TE foi realizado em escada com 12,16m de altura. O tempo para subir todos os degraus o mais rápido possível foi chamado tempo de escada (tTE). Os cálculos dos valores dos testes preditos para o pós-operatório (ppo) foram realizados conforme o número de segmentos funcionantes perdidos. Os valores pré, ppo e pós foram comparados entre si para cada teste. Estatística: foi utilizada a análise de variância para medidas repetidas (ANOVA), com significância de 5%. RESULTADOS: Foram estudados 40 pacientes. A ressecção pulmonar variou desde o ganho de dois segmentos funcionantes até a perda de 9. Os valores pré, ppo e pós foram respectivamente: VEF1 -pré = 2,6±0,8L, ppo = 2,3±0,8L, pós = 2,3±0,8L (VEF1pré > VEF1ppo = VEF1pós), TC6-pré = 604±63m, ppo = 529±103m, pós = 599±74m (TC6pré = TC6pós > TC6ppo), tTE-pré = 32,9±7,6s, ppo = 37,8±12,1s, pós = 33,7±8,5s (tTEpré = tTEpós < tTEppo). CONCLUSÃO: Nas ressecções pulmonares, este grupo de pacientes perdeu função pulmonar medida através da espirometria, mas não perdeu a capacidade de exercício, medida através dos testes de escada e caminhada.

Effects of an exercise training program in physical condition after liver transplantation in familial amyloidotic polyneuropathy: a case report

Introduction: Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disease that leads to sensory and motor polyneuropathies as well as functional limitations. So far, liver transplantation is the only treatment for FAP because the mutated protein causing the disease is mainly produced in the liver. With the increasing survival of transplant recipients, functional and cardiovascular problems as consequences of immunosuppressant side effects are increasing associated with sedentary lifestyles and/or retransplantation status. We sought to analyze the impact of exercise training programs on 1 FAP patient’s course long-term after liver transplantation. Methodology. A FAP patient (female; 49 years of age; body mass index 18.8 kg/m2) underwent a liver transplantation 133 months before assessment. She was assessed for body composition, isometric quadriceps muscle strength, functional capacity, fatigue, and levels of physical activity before and after a 6-month period of combined exercise training. Results: After the exercise training program, almost all variables were improved, namely, total body skeletal muscle mass, proximal femoral bone mineral density, quadriceps strength, maximal oxygen consumption on 6 minutes walk test (6mwt) or VO2peak, total ventilation on 6mwt, and fatigue. The improvement in distance on 6mwt (69.2 m) was clinically significant. Preintervention the levels of physical activity were below international recommendations for health; after the program they achieved the recommendations. Conclusion: The results showed an improvement in functional capacity with a decrease in future disability risk associated with a better lifestyle with respect to physical activity levels in 1 patient.

Strength, muscle quality and functional capacity in liver transplanted familial amyloidotic polineuropathy patients

Liver transplantation is the unique treatment for several end stage diseases. Familial Amiloidotic Polineuropathy (FAP) is a neurodegenerative disease related with systemic deposition of amyloidal fibre mainly on peripheral nervous system, clinically translated by an autonomous sensitive-motor neuropathy with severe functional limitations in some cases. The unique treatment for FAP disease is a liver transplant with a very aggressive medication to muscle metabolism and force production. To our knowledge there are no quantitative characterizations of body composition, strength or functional capacity in this population. The purpose of this study was to compare levels of specific strength (isometric strength adjusted by lean mass or muscle quality) and functional capacity (meters in 6 minutes walk test) between FAP patients after a liver transplant (4.1±2 months after transplant surgery) (FAPT) and a healthy group (HG).

Contribuição para o estudo da fibromialgia : análise de variáveis de aptidão física, de composição corporal e capacidade funcional

A presente dissertação pretendeu verificar o efeito de um programa de exercício supervisionado versus domiciliário, de intensidade moderada, com a duração de 16 semanas, na aptidão física de pessoas com fibromialgia. Houve necessidade de ajustamento dos objetivos e analisaram-se os dados obtidos no primeiro momento de avaliação, pretendendo-se analisar a relação entre variáveis de aptidão física, contribuindo para a compreensão da aptidão física de pessoas com fibromialgia. Apresentam-se e analisam-se variáveis de aptidão física e os resultados do efeito do exercício a nível de composição corporal, capacidade cardiorrespiratória e capacidade funcional. Neste âmbito realizaram-se 5 estudos. No estudo I analisou-se a precisão de diferentes equações preditivas de consumo de oxigénio, que utilizam a distância caminhada no teste de marcha de 6 minutos e propõe-se uma atualização para a equação específica para esta população. No estudo II observou-se a relação entre o consumo de oxigénio, composição corporal e força muscular. No estudo III avaliou-se a precisão de equações preditivas de composição corporal utilizando pregas adiposas e a densitometria de raio-X de dupla energia como método de referência. No estudo IV verificou-se qual o índice que melhor reflete a composição corporal destas mulheres. No estudo V analisou-se a associação entre a frequência cardíaca de recuperação, após um teste de esforço máximo e o consumo de oxigénio. Os principais resultados reforçam os resultados anteriores de que a população estudada apresenta diminuição da aptidão física, da capacidade funcional e valores de composição corporal indicativos de excesso de peso. Não apresentaram alterações autonómicas e verificou-se que a distância caminhada durante o teste de marcha de 6 minutos, a idade, percentagem de massa gorda e a massa magra apendicular são preditores do VO2 pico. Após a intervenção as participantes apresentaram alterações positivas a nível da aptidão física.