Cardiorespiratory Responses During the 6-Minute Walk and Ramp Cycle Ergometer Tests and Their Relationship to Physical Activity in Stroke.

The 6-minute walk test (6MWT) is applied to measure exercise capacity following stroke. The authors sought to compare cardiorespiratory responses during the 6MWT with responses to a ramp cycle ergometer test (CET) in community-dwelling individuals with stroke. A secondary objective was to determine the relationship between cardiorespiratory responses during each test and daily physical activity. Participants completed 3 evaluation sessions. The CET and 6MWT were conducted in 2 separate sessions at least 72 hours apart. Participants wore a portable gas analysis unit (Cosmed K4b2), which also measured heart rate (HR) during the 6MWT. A uniaxial accelerometer (activPAL) was employed to measure time spent upright (standing and stepping) over 5 days as an estimate of daily physical activity. Complete CET and 6MWT data were obtained for 16 participants (14 men), a mean ± standard deviation of 2.0 ± 1.1 years after stroke and 71.1 ± 9.7 years of age. Compared with the 6MWT, the CET elicited a higher VO2peak (P = .032), VCO2peak (P = .005), respiratory exchange ratio (P = .015), and self-reported perceived breathing (P < .0001) and leg heaviness (P < .0001) at test completion and a lower HRpeak (P = .029). Except for the first minute, VO2 during the 6MWT was, on average, 80% to 85% of VO2peak from the CET. Among 15 participants, average time spent upright per day was not significantly related to 6MWT distance (r = 0.447, P = .096) or VO2peak from the CET (r = 0.388, P = .153).

The study found that exercise intensity achieved during the 6MWT appeared sufficiently high for aerobic training, assuming CET VO2peak accurately reflects aerobic capacity. The 6MWT could be useful for prescribing aerobic exercise following stroke.