For runners, here comes a treadmill that automatically changes speed to match the pace of the runner. The automated treadmill uses sonar technology to tell exactly where the runner is on the treadmill.

If the runner picks up pace and moves toward the front of the running belt, the speed automatically increases. If the runner slows down and moves toward the back, the speed decreases.

"The result is a treadmill experience that is much closer to walking or running outdoors," said Steven T. Devor, associate professor of kinesiology at the Ohio State University.

"If you are running outside and you want to speed up or slow down, there is no button to push. It is the same with this new automated treadmill," Devor noted.

The researchers started with an inexpensive sonar range finder which is used to measure the distance between an object and the sonar device.

They attached it to a microcontroller and a computer, which was linked to the electronics in the treadmill. The sonar is set up behind the treadmill and aimed at the runner’s back, just between the shoulder blades.

When the runner is in the middle of the running belt (measured from front to back), the speed of the treadmill stays the same.

If the sonar senses that the runner is moving farther away, that means the runner is picking up speed, then the sonar microcontroller sends a signal to the treadmill to speed up the belt in varying increments of speed.

The speed increases until the runner returns to the middle of the belt.

If the sonar senses the runner is getting closer to the device, a signal tells the treadmill to slow down until the runner returns to the middle.

"It is all seamless and the runner does not even know that it is happening," Devor pointed out.

Devor and Scheadler also found that the automated treadmill did a better job than standard treadmills at providing an accurate measure of an athlete’s aerobic capacity.

The device is a finished prototype and is nearly ready for commercialisation. Ohio State recently filed a patent application covering the treadmill’s novel features.

The researchers revealed the automated treadmill in a study published in the journal Medicine & Science in Sports and Exercise.