If you prefer to run on a treadmill or use an elliptical
machine for training, you may feel nauseous when you stop using the
machine. This is likely due to the perpetual motion of the treadmill belt. When your body is sustaining a constant motion, such as running, and you attempt to participate in other activities, like watching television or reading magazines, your eyes have trouble focusing. This leads to a sensation akin to feeling sick after being in the car for too long.