Don’t shuffle on slippery surfaces, Clemson University, Charleston researchers say

CLEMSON, SC – March 24, 2011 – Biomechanics researchers Timothy Highamof Clemson University and Andrew Clark of the College of Charlestonconclude that moving quickly in a forward, firm-footed stance across aslippery surface is less likely to lead to a fall than if you moveslowly. Approaching a slippery surface slowly hinders the necessary taskof shifting the center of mass forward once foot contact is made.

The researchers studied helmeted guinea fowl strutting along asix-meter runway that either had a rough-surface section (150-gritsandpaper) or a slippery one (polypropylene shelf liner). High-speedvideo recorded the action. The experiment is reported in the Journal of Experimental Biology, “Slipping, sliding and stability: locomotor strategies for overcoming low-friction surfaces,” pages 1369-1378 (vol. 214).

Above Photo: Researcher Andrew Clark sends a helmeted guinea fowl along a slippery surface. image by: Timothy Higham 

Helmeted guinea fowl react to slips much in the same way humans do,making them good test subjects, according to Higham. He and Clark areinterested in how animals move and avoid injury when making their waythrough their environments.

Finding out how animals can respond rapidly to unexpected changes intheir habitat, the scientists’ stated that their research would“ultimately yield important information regarding the flexibility ofphysiological and behavioral systems,” according to their article.

“The findings can be useful in helping humans, especially older ones,make their way across surfaces that are wet, icy or oily,” said Higham.“The key to avoiding slips seems to be speed and keeping the body massforward, slightly ahead of the ankles after the foot contacts theground.”

Slips are a major cause of falls that can cause injuries and evendeaths. Slips accounted for about 44 percent of fatal and nonfatalwork-related falls, according to a U.S. Bureau of Labor Statics reportin 1992.

Clark and Higham not only saw that speed, foot position and bodyalignment made a difference, but also the slip distance. For a guineafowl to fall, it needed to slip a minimum of 10 centimeters — just underfour inches. The distance is the same for humans, said Higham. 

Guinea fowl leg joints and human knees and ankles function in similarways: the position of the knee relative to the foot can create jointangles — wide or narrow — that can cause or prevent loss of balance onslippery surfaces, the scientists said. Once the knee passes the ankleduring contact with slippery ground, slipping stops.

“Our study shows that there are common limb-control strategies onslippery surfaces in helmeted guineas and humans,” said Higham.