Article

The distance walked in 6 minutes (6MWD) has been reported to be
linearly related to peak oxygen uptake (VO2) in cardiac diseases and in lung
diseases. In these patients, the VO2 during a 6-min walk test (walkVO2) has been
found to be nearly equivalent to peakVO2, but with a lower respiratory exchange
ratio (RER). Whether these observations translate to the less functionally
impaired patients or healthy control subjects is not exactly known. METHODS:
Thirty-two healthy control subjects and 15 chronic heart failure (CHF) patients
performed a 6-min walk test and a maximal cardiopulmonary exercise test (CPET)
both with measurements of gas exchange. RESULTS: The 6MWD and peakVO2 were
linearly correlated, but with an increased slope appearing above 532 m. In CHF
patients, walkVO2 was similar to peakVO2, but with lower heart rate and
ventilation than measured at peak exercise. In healthy control subjects, VO2,
ventilation and heart rate were lower during the 6-min walk than at maximal
exercise but higher than at the anaerobic threshold. The RER during the 6-min
walk remained <1 in both groups. CONCLUSIONS: Above 500 m, 6MWD becomes less
sensitive to any increase in peakVO2. Furthermore, CHF patients and healthy
control subjects exercise respectively at maximal and high VO2, but below the
anaerobic threshold (as assessed by a CPET) during the 6-min walk test.
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Langue : ANGLAIS