Influence of step length on 6-minute walk test performance in patients with chronic heart failure

ObjectiveTo investigate the influence of gait parameters including step length and walking speed during performance of the 6-minute walking test (6MWT) in patients with chronic heart failure (CHF).DesignObservational study.SettingSpecialist heart failure clinic.ParticipantsPatients with CHF and aged-matched, apparently healthy controls.InterventionsEach patient and control performed a 6MWT following a standardised protocol in a 15 m corridor. The number of steps (defined as step from left foot to right foot) taken every 15 m was counted, and reported as minute-by-minute changes in 6MWT performance. In addition, minute-by-minute changes in time taken to complete 15 m and mean walking speed throughout the test were calculated.Main outcome measuresWalking speed and step length.ResultsThirty patients with CHF {87% males; mean age 75 [standard deviation (SD) 8] years} and 10 healthy controls [80% males; mean age 77 (SD 11) years] undertook the 6MWT. For the CHF group, the mean distance walked was 309 (SD 48) m and the peak Borg score was 12 (SD 1). For the controls, the mean distance walked was 334 (SD 138) m and the peak Borg score was 12 (SD 1). Patients with CHF showed no significant minute-by-minute changes in step length or walking speed over the course of the 6MWT. In the first 5 minutes, healthy controls had a longer step length and faster walking speed than patients with CHF [step length: mean difference in the first minute was 0.03 m, 95% confidence interval (CI) of the difference 0.01 to 0.05 m; P = 0.02; walking speed: mean difference in the first minute 0.04 m/second, 95% CI of the difference 0.02 to 0.07 m/second; P = 0.01]. A multiple linear regression analysis demonstrated that body mass index (P = 0.02) was the most important predictor of 6MWT performance.ConclusionPatients with CHF have a shorter step length and walk more slowly than controls during the 6MWT. Altered gait mechanics may contribute to limited exercise capacity in patients with CHF.