Electric Muscle Stim Article by Charlie Francis

Selection of Muscle Groups
Maximum strength EMS is applied to the quads, hamstrings, glutes, and the erector spinae. These muscle groups play the main role in power development around the hip joint, where, at maximum speed, the power output is seven times higher than around any other joint. The abs play a major role also, and they can be treated as well, but their rotational movement and primary support, rather than power role, favor traditional high rep training. More on this later. The soles of the feet can even be treated in cases of insufficient foot strength.
Individual Sessions - Preparation
EMS works best as the last training element of the day, separated from other work by at least two hours. This is usually done at night before bed, as it can be done at home and the supra-maximal stimulus it provides is excellent for promoting the release of growth hormone during sleep.
Use a hot shower as warm up preparation, being careful to remove any oils or creams from the areas to be treated to ensure proper conductivity (oils left on the skin can cause the current to jump around the skin surface causing considerable discomfort). The increased blood flow in the muscles after the shower heats the muscle motor neurons, lowers electrical resistance, and makes them more receptive to EMS.
Start the EMS session with a gentle pulsing mode for three to five minutes to complete the warm-up before starting the maximal contractions. Warm down using the same pulsing method.
Contractions - Timing
Each muscle group is stimulated maximally for ten reps of ten seconds duration with a fifty second rest period between contractions. It’s critical to maintain the rest periods as prescribed as this is the absolute minimum recovery time needed to maintain a maximal contraction on the next rep. A shortened rest period may, in fact, change the nature of the exercise so that it enhances the wrong fiber type.
Sprinters use the full ten second contraction time, though shot putters and linemen find that six seconds is about the longest they can maintain a maximal contraction. In either case, the same fifty second rest period must be maintained.
Procedure
Though modern stim equipment allows for a number of muscle groups to be stimulated simultaneously, never work more than two muscle groups at a time. The athlete must be able to determine where the stimulus is coming from. Keep the limbs straight and unsecured. Never stimulate antagonists at the same time for safety reasons. This also allows the athlete to concentrate on the contraction in isolation for learning reasons.
When stimulating the soles of the feet, have the athlete stand on the pads to prevent cramping. The athlete must always control the intensity of the contraction as the amount of current necessary for a maximal contraction varies widely between individuals depending on fiber type, fat distribution (fat is an insulator), muscle size, and injury history.
As a rule, sprinters require much less current to achieve a maximal contraction because their higher percentage of white fiber provides less resistance. The better the sprinter, the more this is so. EMS units have a “rise-time” feature (the time it takes to ramp up the contraction from zero to max) that is either preset or adjustable. Where it’s adjustable, choose the shortest time the athlete can tolerate, usually half to three-fourths of a second.