ABC | Volume 114, Nº3, March 2020

Original Article Farah et al. Effort during 6-minute walk test Arq Bras Cardiol. 2020; 114(3):486-492 Table 1 – Characteristics of patients with intermittent claudication included in the study Variables Did not achieve VT (n = 28) Achieved VT (n = 42) p Age, years 66.1 ± 9.9 66.9 ± 10.2 0.745 Body mass index, kg -1 m 2 29.9 ± 6.0 29.0 ± 5.6 0.486 Ankle brachial index 0.85 ± .21 0.71 ± .21 0.013 Claudication onset time, seconds 297 ± 192 271 ± 191 0.572 Peak walking time, seconds 576 ± 266 541 ± 219 0.542 Six-minute pain-free distance, meters 189 ± 144 214 ± 96 0.417 Six-minute walk test, meters 382 ± 73 399 ± 67 0.332 VO 2 at VT, mL.kg -1 .min -1 12.0 ± 2.4 10.1 ± 1.9 < 0.001 VO 2 peak, mL.kg -1 .min -1 13.9 ± 3.7 13.5 ± 3.4 0.627 Sex, % women 52 48 0.109 Diabetes mellitus, % yes 46 54 0.419 Hypertension, % yes 41 59 0.789 Dyslipidemia, % yes 38 62 0.436 Coronary artery disease, % yes 13 88 0.093 COPD, % yes 53 47 0.211 VT: ventilatory threshold; VO 2: oxygen uptake; COPD: chronic obstructive pulmonary disease. Some practical messages can be draw from this study. The 6-minute walk test is harder for men and patients with low cardiorespiratory fitness. Is recommended that exercise training intensity should be performed above VT in order to improve cardiovascular function in cardiac patients and the elderly. 33,34 Considering that the 6-minute walk test simulates an over-ground walk, the current results support its use as an exercise mode to increase both daily physical activity and cardiorespiratory fitness in men and in patients with low cardiorespiratory fitness. However, in Table 2 – Multiple logistic regression model predicting achieved ventilatory threshold during the 6-minute walk test in patients with intermittent claudication Dependent variable Independent variables β (EP) OR 95%CI p Achieved VT Sex, men = reference -1.72 (0.65) 0.18 0.05 – 0.64 0.008 Oxygen uptake at VT, mL.kg -1 .min -1 - 0.58 (0.17) 0.56 0.40 – 0.77 < 0.001 VT: ventilatory threshold; β (EP): Regression coefficient (error-standard); OR: odds-ratio. 95%CI: 95% confidence interval. Hosmer-Lemeshow test: χ 2 = 9.607, p = 0.298. Table 3 – Comparison of clinical parameters of intermittent claudication between men and women included in the study Variables Women (n = 28) Men (n = 43) p Age, years 64.9 ± 9.5 67.6 ± 10.3 0.265 Body mass index, kg -1 m 2 31.1 ± 6.6 28.3 ± 5.0 0.044 Ankle brachial index 0.80 ± .23 0.75 ± .22 0.258 Claudication onset time, seconds 241 ± 164 306 ± 203 0.330 Peak walking time, seconds 507 ± 196 585 ± 256 0.180 VO 2 at VT, mL.kg -1 .min -1 10.3 ± 2.3 11.3 ± 2.2 0.035 VO 2 peak in treadmill test, mL.kg -1 .min -1 12.0 ± 2.9 14.7 ± 3.4 0.001 VO 2 peak in 6-MWT, mL.kg -1 .min -1 11.1 ± 3.0 12.5 ± 2.1 0.034 6-MWT: 6-minute walk test. women and in patients with higher cardiorespiratory fitness, over‑ground walking may not be enough to improve activity and fitness levels. The cross-sectional design of this study is a limitation, as no causality can be inferred. Patients with severe cardiac disease and asymptomatic PAD or PAD more severe than claudication were excluded in the screening; therefore, the results can be extended only to our current sample of patients with claudication. Given we were not able to precisely identify VT in patients who stopped during the 6-minute walk test, generalization is also 489