Watch your step when the going gets rough

Placing your foot accurately is a complicated process. If something moves where you plan to place your foot then you can adjust your step while your foot is swinging through. Experts thought previously that if nothing changed in the path, or in your plans, then the place where your foot will land is fixed before it even leaves the ground. In this case, you would make no use of immediate visual information during each step.

Researchers monitored the accuracy with which subjects could step onto a target. In 50% of the attempts they blocked subjects' vision just at the point when they were lifting their foot off the ground. On the occasions when vision was blocked, the subjects were less able to step accurately on the target.

"Because vision was blocked only after the foot had left the floor, this research shows that we use visual information to adjust our footfall while our foot is moving forwards – it is not simply predetermined at the beginning of the step," says Dr Raymond Reynolds, who along with Dr Brian Day conducted the work at the Institute of Neurology, Queen Square, London. The research is published this week in the Journal of Physiology.

This research models the sort of situation people encounter when rambling over rough terrain, where they need to accurately place their feet on well defined targets. Getting it right may avoid your slipping or twisting an ankle. "This visual guidance mechanism could also help gymnasts on the beam, or acrobat walkers on a tightrope, as in these situations accurate foot placement becomes crucial," says Reynolds.

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