Paralympic runners with left-leg prostheses are at a disadvantage

New Scientist : When running races on a curved track, most athletes go slower on the curves than on the straight stretches. However, for athletes with unilateral leg amputations, there is an additional impediment: Amputees whose affected leg is on the inside of the curve run about 3.9% slower. That was the finding of a recent study published in the Journal of Experimental Biology. Because track competitions are run in the counterclockwise direction, those with a prosthesis on the left leg will be at a disadvantage. Researchers recorded the race times of 17 runners, both amputees and nonamputees. The scientists found that the fastest runners exert the most force on the ground in the shortest possible time and that on curves the inside leg of all runners spends more time in contact with the ground than the outside leg. Running prostheses are lighter than biological legs and thus create significantly less force. Moreover, prostheses can’t flex to adjust for curves the way biological ankles can. To help even the odds, the researchers say, sprinters with left-leg prostheses could race in the outer lanes or in special heats in which the participants run in a clockwise direction.