The influence of cognitive load on metabolic cost of transport during overground walking in healthy, young adults.

PURPOSE: Our aim was to examine whether cognitive processing during walking increases the metabolic cost of transport in healthy young adults. METHODS: Twenty healthy, young adults completed five conditions: (1) walking at a self-selected speed (spontaneous single-task), (2) seated resting (baseline), (3) performing cognitive task while seated (cognitive single-task), (4) walking while simultaneously performing the cognitive task (dual-task), and (5) single-task walking at a speed that matched the participant's dual-task gait speed (matched single-task). Rate of oxygen consumption (V̇O2) was recorded during all conditions. Gait speed and cost of walking (Cw; oxygen consumed per distance traveled) were recorded during all walking conditions. Reaction time and accuracy of responses in the cognitive task were recorded during all cognitive task conditions. Data from the fifth minute of each 5-min condition were analyzed. RESULTS: There was no difference in V̇O2 between the dual-task and matched single-task walking conditions. V̇O2 in the seated cognitive condition was significantly smaller than both walking conditions, but was not significantly different than zero. Cw was significantly greater during the matched single-task walking condition than during the dual-task walking condition. However, the difference in Cw was so small that it is unlikely to be clinically significant (0.008 mLO2/kg/m, 95% CI 0.002-0.014). CONCLUSIONS: Cognitive processing while walking may not increase energy demands of walking in healthy young adults. Maintaining non-preferred gait speed (matched speed) overground continuously for 5 min may require attentional resources, and thereby increase metabolic costs relative to walking at habitual speed.