The six-minute walk distance is a marker of hemodynamic-related functional capacity in hypertension: a case-control study

This study investigated the association between hemodynamic variables and the 6-minute walk distance (6MWD) in adults with and without hypertension and explored the role of hemodynamic variables as predictors of 6MWD. Patients undergoing antihypertensive medication therapy (n = 41) and sex-matched healthy subjects (n = 41) were evaluated for their clinical status and cardiovascular risk factors. Two 6-minute walk tests were performed along an 18-m corridor with a 30-minute rest interval. The intraclass correlation (ICC) was high among patients (ICC = 0.984 (0.965; 0.992), P<0.001) and controls (ICC = 0.987 (0.832; 0.996), P<0.001). The patients presented 6MWD values that were significantly lower than those of healthy controls (338.8 +/- 112.8 vs. 388.0 +/- 66.7 m, P = 0.010). In patients, the 6MWD was significantly and positively correlated with sex (0.737; P<0.001), height (0.502; P<0.001) and weight (0.303; P = 0.027). In addition, negative and significant correlations were observed between 6MWD and the mean ( 0.577; P<0.001), systolic ( 0.521; P<0.001), diastolic ( 0.505; P = 0.001) and pulse (-0.353; P = 0.015) pressures after simultaneous adjustment for age, body height and weight. The same behavior was observed in healthy controls (except for pulse pressure), albeit with lower correlation values. A regression model with sex, age, height and weight explained 52.2% (P<0.001) of the variance. The highest explained variance in patients (64.8%; P<0.001) and controls (56.5%; P<0.001) was observed after replacing the body weight with mean pressure in the model. The 6MWD is inversely associated with hemodynamic variables in both groups and is lower in patients with hypertension compared with healthy controls. Hemodynamic variables, particularly the mean pressure, should be included in prediction equations for 6MWD.