The purpose of the Shock Absorber device is to stop a moving load with minimum load rebound, with minimum shock to the load, and minimum shock to surrounding equipment. Pneumatic shock absorbers are used in conjunction with cushions and springs.
From a design consideration, when designing or choosing a shock absorber, is where that energy will go. In most shock absorbers, energy is converted to heat inside the viscous fluid. In air cylinders, the hot air is usually exhausted from the atmosphere.