Abstract: An exerciser has a base, a pair of parallel guide rails disposed on the base, a pair of driven units mounted slidably and respectively on the guide rails, and a friction-type resistance device mounted on the base and connected operably to the driven units to resist movement of the driven units. The resistance device includes a friction wheel mounted rotatably on the base, a friction belt trained on the friction wheel, a tension spring interconnecting one end of the friction belt and the base, and first and second transmission rollers mounted rotatably on the base at two sides of the friction wheel. First and second clutch units couple a respective one of the first and second transmission rollers and the friction wheel only when the respective transmission roller rotates in a first direction to drive rotatably the friction wheel in the first direction. The friction wheel applies a force to the friction belt in a compressing direction of the tension spring while rotating in the first direction.