For example: there is record in 46 A. D. use of an electric discharge from a torpedo fish used to reduce pain and in the 18th century Luigi Galvani (Italian Physicist) recorded muscle contraction by touching an electric current to a frog muscle. Use of "E Stim"; for pain control is on the premise of the Gate Control Theory (Melzack and Wall), however E Stim is also used clinically today for muscle strengthening, wound healing and tissue repair, resolution of edema (or swelling) and even trans-dermal (skin) drug delivery. Physiological effects of E Stim are derived by depolarizing nerve membranes and creating "action potentials".
Electrical currents with enough amplitude and sufficient duration will cause an action potential, and once generated the body responds the same way it does to an action potential that is generated physiologically, with a muscle contraction. These muscle contractions are how you can use E Stim to speed up the recovery process between workouts! By dilating blood vessels, the muscle contractions work to actively flush metabolic waste products (for example: components of muscle breakdown, and that which makes you sore) by bringing fresh oxygenated blood and nutrition to the front lines. This process is done without causing fatigue (especially to the neuromuscluar system) and helps with lymphatic drainage which carries most of the waste out of the system. So be sure to apply the electrodes as soon as possible after your training session to speed up the recovery and flushing process to help impede the bottle necking of metabolic waste.
How else can we use this modality to improve our training? By applying the over load principle, we can further stress the same muscles we just hit in our WOD to further increase the muscular stress and thus forcing further adaptation. Once again this acts as a burn out set, but without the time, physical and mental effort required for the added stressor. Also, research has shown that regular use of an E Stim unit (3+ x week) can cause the formation of additional blood vessels, which acts to improve conditioning as there becomes a need for increased vascularity to the area of stress. By being more vascular there is a more readily available and faster delivery of oxygenated blood which allows for a potential of increased performance on the muscular endurance side of the coin.
As always you should check with your doctor before utilizing any product or device that will alter your health and although there are a lot of benefits of recovery please be aware of the contraindications (or warnings of when NOT to use) of E Stim. It is important NOT to use electric stimulation in individuals that have cardiac pacemakers (or any implanted electrical device), during pregnancy, with a cancer, or by placing electrodes on the face or chest.