1.   As for elliptical motion trainers, which require the legs to move in an elongated circle, the manufacturers do not push the backward motion feature.

2.   Nearby, several exercisers were striding on elliptical motion trainers, switching the direction of their leg movements from forward to reverse and back again every couple of minutes.

3.   Precor Inc., of Bothell, Wash., was the first to develop an elliptical motion machine, a cross between a treadmill and a step machine.

4.   Rippe cautioned that elliptical motion is not natural, since it combines stepping and walking.