Abstract: An exercising device which employ the principle of isotonic exercise in conjunction with isometric impact exercise. The exercising device comprises two spaced apart pivotably mounted levers to which the exerciser applies a rotational force; an adjustable resilient force, such as a spring, selectively opposing the rotation of the levers. The resisting force varies during the pivoting of the levers such that as the levers pass dead center the force applied by an exerciser reaches a maximum value and after passing dead center thereby permitting the levers to be rapidly rotated by the resisting force; and a lever stopping member for suddenly stopping the rapidly rotating lever.