Attentional requirements of walking according to the gait phase and onset of auditory stimuli

Abstract

A dual-task paradigm was used to examine the influence of an attention demanding cognitive task on each phase of gait. Twenty-three participants (aged 18-27) walked on a treadmill at a 20% increase of their self-selected speed, either alone or while performing a cognitive task. Muscle activity was measured with electromyography (iEMG) for eight muscles of the dominant leg. The cognitive task consisted of subtracting one (EASY) or seven (HARD) from orally presented numbers. Reaction time (RT) and accuracy were recorded. iEMG events were selected according to stimulus onset (0-150 ms, 150-300 ms and 300-450 ms) prior to phases of gait (double-leg stance, single-leg stance and swing). There was a decrease in iEMG amplitude of fibularis longus (p=.013) and a trend in the same direction for vastus lateralis (p=.065) while walking and performing the cognitive task. When stimulus onset was considered, iEMG of medial gastrocnemius (p=.021) and lateral gastrocnemius (p=.004) were reduced during single-leg stance, when stimuli occurred between 300 and 450 ms prior to this phase. Cognitive performance was affected by task difficulty (RT, accuracy) and by dual-task load (RT). Dual-task costs were observed in both the motor and the cognitive tasks, suggesting that walking requires attention. There was a specific moment (300 ms after stimulus onset) during single-leg stance when dual-task costs were most pronounced, corroborating supraspinal involvement in the control of normal walking. Time-based approaches should be considered when analyzing attentional demands of a dynamic task such as gait.

Do cognitive tasks during gait increase the risk of accidents with pedestrians? A study based on electromyographic parameters

“…Our results on the muscle activation pro ile while performing the dual task do not support the results presented by Abbud et al (11) as, in our study, the muscle…”

“…The execution of gait should not be considered an exclusively automatic act or a mere re lex, but a process that requires association between cognitive and muscle reactions to produce an appropriate action (11,17,18). Thus, this study intended to identify electromyographic changes during the gait of young individuals, executed concomitantly with cognitive tasks that can predispose these individuals to a higher accident risk.…”

“…Abbud et al (11) proposed the association between gait and the solution of mathematical expressions, identi ied competition for executive resources during their association, denigrating the execution of the motor task and the cognitive task, with a signi icant increase in mistaken response patterns and in the latent time for reactions while executing a dual hard task. These authors considered that the muscle responses indicated the distribution of neural resources to execute the activities proposed, raising the hypothesis that the increase in the cognitive demand leads to a reduction in the muscle responses associated with the motor tasks proposed.…”

“…During the DHT, the volunteers answered complex subtraction counts verbally (subtraction of seven number), involving igures between 1 and 99. For the DMT, the participants answered simple and complex subtraction counts verbally, involving randomly chosen igures between 1 and 99 (11).…”

“…The dual task is a frequently used method to assess gait, as it permits the division of a primary motor performance task, which is the main focus, and a secondary task, both executed at the same time (10). Studies appoint that, when the gait happens concomitantly with another cognitively demanding activity, the performance of both tasks can be negatively affected, as gait requires attention and high levels of cognitive resources for planning, monitoring and coordination (11,12,13).…”