The cardiopulmonary exercise testing (CPET) is known to be the gold standard method for the assessment of functional capacity. However, the method is expensive, often not well tolerated by the patients, and may not be a good strategy to evaluate activities of daily living (ADL). Functional tests are indirect method to assess functional status or functional capacity of an individual to perform ADL and meet their metabolic demands. These tests are considered objective measures that can monitor the clinical course of several diseases as well as responses to interventional therapies.

Walking and running tests were originally developed to evaluate and estimate aerobic physical fitness of healthy individuals and correlate it with maximal aerobic power (peak VO₂). Balke, in the sixties, followed by Cooper and his 12-minute test, used to evaluate physical performance in healthy subjects, motivated, according to them, by the need of field tests for screening of large populations. These methods showed good correlation with laboratory measurements of aerobic capacity (peak VO₂ and anaerobic threshold).

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Abstract

Background:

The evaluation of the functional capacity of patients with chronic heart failure (HF) by means of the distance covered in the six-minute walk test (6MWT) has assumed great importance, since the 6MWD is a predictor of mortality and hospitalization in this population, however the determinants of better distance traveled in patients with HF are little explored, especially in the Brazilian population.

Objective:

To evaluate the determinants of 6MWD in patients with chronic HF.

Methods:

A cross-sectional study was performed with 81 HF patients in outpatient treatment. 6MWD was used as the outcome variable and sociodemographic, clinical, physical-functional and emotional data were submitted to multiple regression analysis using the stepwise method with a significance level of 5%.

Results:

Mean age of participants was 56.71 years; the 6MWD showed a bivariate correlation with age (r = -0.27, p = 0.01), maximal inspiratory pressure (r = 0.42, p < 0.01), maximal expiratory pressure (r = 0.36, p < 0.01), handgrip strength (r = 0.38, p < 0.01), Borg scale (-0.22, p = 0.04), Charlson index (r = -0.25, p = 0.02) and modified Medical Research Council (mMRC) dyspnea scale (r = -0.42, p < 0.01). In the multivariate analysis, the variables gender (p = 0.001), age (0.004), forced vital capacity (FVC) (p = 0.016) and mMRC (p = 0.001) simultaneously explained 37% of variance in the 6MWD.

Conclusion:

Higher levels of dyspnea on daily life activities, female sex, older age and lower forced vital capacity are determinants of a shorter 6MWD in patients with chronic HF.