Aerobic intensity and pacing pattern during the six-minute walk test in patients with multiple sclerosis.

Objective: To examine the aerobic intensity level and pacing pattern during the 6-min walk test (6MWT) in persons with multiple sclerosis, taking into account time of day, fatigue, disability level and multiple sclerosis subtype.

Design: Cross-sectional study.

Subjects/patients: Eighty multiple sclerosis patients (Expanded Disability Status Scale, EDSS ≤ 6.5).

Methods: Participants performed the 6MWT at 3 different time-points (morning, noon, afternoon) during 1 day. Heart rate and pacing strategy (distance covered every minute) were registered. A sub-group analysis determined the effects of fatigue, disability level and multiple sclerosis subtype.

Results: The relative aerobic intensity was constant throughout the day (67 ± 10% of estimated maximal heart rate). In all sub-groups heart rate increased and distance walked declined after the first minute (p < 0.001). The mild EDSS sub-group showed a slightly larger increase throughout the 6MWT in heart rate development, while no differences were seen in sub-groups of fatigue and multiple sclerosis subtype. In most sub-groups walking speed was fastest in the first minute and constant during the final 4 minutes.

Conclusion: In patients with multiple sclerosis aerobic intensity is moderate during the 6MWT and unaffected by time of day. Disability may have some influence on aerobic intensity, but not on pacing strategy during the 6MWT, whereas neither fatigue nor multiple sclerosis subtype has any effect.