Reference values for the six-minute walk test in obese Indian population

Abstract

INTRODUCTIONThe Six Minute walk test (6MWT) is a useful performance based measure of functional exercise capacity in obese individuals. This test measures the distance that a patient can quickly walk on a flat hard surface in a period of 6 minutes (6MWD).1 Various studies have found reference values for SMWD in healthy individuals but very less is known for healthy obese individuals. The aim of this study is to find reference values for 6MWT in adult obese population.• Correlation of anthropometric measures with SMWD • To find the Reference equation to predict the distance walked during SMWT in obese individuals. Six-minute walk testIn the early 1960s, Balke developed a simple test to evaluate the functional capacity by measuring the distance walked during a defined period of time.2 There are several modalities available for the objective evaluation of functional exercise capacity. Walking is an activity performed daily by all but the most severely impaired patients. A recent review of functional walking tests concluded that "the 6MWT is easy to administer, better tolerated, and more reflective of activities of daily living than the other walk tests."3 The 6MWT is a practical simple test that requires a 100-ft hallway but no exercise equipment or advanced training for technicians. ABSTRACT Background:The six-minute walk test is one of the most powerful test used to measure the functional capacity in various chronic conditions such as in Obesity. There are very few reported studies on SMWT on Obese population all over the world, and there is no reference equation for SMWD. The aim of present study is to propose a Reference equation which could predict the distance walked in SMWT by obese individuals. Methods: 150 obese individuals free from any cardiorespiratory disease were randomized into 2 groups. SMWT data from group A was used to propose the reference equation and SMWD for Group B was predicted. Significance of difference between predicted and original values for group B was found. Results: Mean SMWD for Group A was 304.56 (SD= 68.28) which significantly correlated to (by using linear regression method) age (r = -0.32, p <0.001), BMI (r = -0.43, p <0.001) SpO2* (r=-0.35, p<0.001). These could explain 56% of the total variance in 6MWT. Though the difference between predicted and original values for group B wasn't found to be statistically significant. The proposed Reference equation is: 6MWT distance = (6.8) O2 saturation-(4.3) BMI-(0.6) age-170.64. Conclusions: SMWT is a simple, safe and powerful test to assess the functional status. The standardized SMWD values for Indian obese population would serve as benchmark to assess baseline functional capacity, prescribe proper and safe exercise intensity and monitor changes after rehabilitation interventions.