The muscle stimulators create a dynamic signal which comfortably contracts muscles and then slowly releases them over a period of time. This allows the muscle fibers to properly relax, and move fluids in and out of the area without causing fatigue to the muscle. This will help you recover, build endurance, or maintain performance. The stimulation units feature various programs so you can tailor your training program to suit your exact needs, whether that be endurance, strength, recovery, maintenance or performance.