Abstract: An arm wrestling machine including an operating arm pivotally mounted on a base and two assemblies for exerting forces on the operating arm urging the operating arm toward a vertical position. One assembly includes a spring connected between the operating arm and a spring support mounted on a screw for linear movement toward and away from the operating arm so that such assembly provides an adjustable, continuous force on the operating arm. The other assembly includes a pneumatic cylinder connected between the operating arm and the base and intermittently receiving bursts of compressed air from a valve that is mounted on the operating arm so that the case of the valve moves with the operating arm and having a weight attached to the valve member of the valve so that movement of the operating arm intermittently opens the valve.