Studies of dual tasks (i.e. situations during which an individual performs two tasks simultaneously) and the subsequent inter-task interference have shown that locomotion and posture involves motor and cognitive components. Dual tasks therefore constitute a promising avenue for improving the diagnosis, prevention and management of falls or cognitive impairment in populations at risk. However, tackling these major public health concerns with dual-task interventions requires a better understanding of the mechanisms underlying dual-task interference. In this context, we review (i) the main dual-task theories proposed to date and (ii) the factors that can influence dual-task interference effects in healthy young individuals and might therefore explain the current lack of consensus on the mechanisms of dual tasks. We also consider cognitive-motor dual tasks in which the motor task is a less frequently studied transition movement (such as gait initiation or turning), rather than only the often-studied gait and posture tasks. In general, the review focuses on the behavioral effects of dual tasking.

We studied relations between eye movements and postural control. In two experiments, participants were asked to shift gaze to follow horizontal oscillation of visual targets. Postural sway variability was reduced during target oscillation, relative to sway with a stationary target. Target displacement amplitude was within the range that normally does not elicit head rotation, and measured head rotation did not increase during target motion. Eye movements made when the eyes were closed did not yield a reduction in body sway (relative to sway when the closed eyes were stationary). The amplitude and frequency of eye movements matched the amplitude and frequency of target motion. The results undermine the view that eye movements and postural control compete for limited central processing resources, and document a functional integration of postural control with visual performance.Tasks or behavioral goals that are superordinate to the control of posture may be termed suprapostural tasks (Stoffregen,

In 2 experiments, the authors independently varied the degree of cognitive and perceptual difficulty of suprapostural tasks. Participants were 23 students in Experiment 1 and 15 in Experiment 2. Increases in perceptual difficulty tended to be correlated with decreases in the variability of postural sway, consistent with the hypothesized functional integration of postural control with suprapostural tasks. Sway variability was not influenced by changes in the cognitive difficulty of tasks when perceptual difficulty was held constant, contrary to predictions derived from the perspective that postural and suprapostural activities compete for a limited pool of central processing resources. The results underscore the need for researchers to differentiate between suprapostural tasks that require perceptual contact with the environment and those that do not.

Among the complications associated with diabetes mellitus is postural control. The authors reviewed 28 studies in the literature that focused on the magnitudes of postural sway that people with and without diabetes exhibit. The general observation is that postural sway is greater for people with diabetes, especially if their condition includes neuropathy. Peripheral sensory neuropathy seems to be the primary factor, but the available evidence does not rule out diabetes per se, other neuropathies (central, autonomic, motor), or an inability to exploit fully optical and inertial information about posture. The authors' review raises the issue of foot disorders and the possibility of increased sway as a useful adaptation; it also calls for better neuropathy assessments, postural tasks, and measures.