What is the difference difference between "Muscle Stim" and "Functional Electrical Stim."(FES).

    In a previous article on muscle stimulation  we discussed what is generically referred to as "muscle stim."   Muscle  stimulators for functional use are referred to as Functional Electrical Stimulators and are used for rehabilitation, not muscle pain.

    One of the things you have on good stimulators is what is called  "rise and fall" time.  As an example you would not want a FES unit to come on and immediately ramp up to it's full power. If this happens then the person jerks their arm/leg whatever from full resting position to the end result or a completely involuntary motion that can cause harm.  If you want to hold a coffee cup you would not jerk it up from the table to your lips in half a second, but you would gradually lift it up over an elapse of time and then tilt it to drink.

   The "rise time" is the time it takes for the unit to come on and go to full power.  This allows the muscles to contract more naturally and achieve a smooth movement, not a jerky response.  After the rise time is over then the unit has what is referred to as a "Hold" time which is nothing but an interval of time in which the contractions are held to keep the cup close to the mouth.  After the hold time is done then we have what is called the "fall" time and that is when the FES unit slowly decreases the power so the arm/hand can lower the cup back to the table. 

   The process I've referred to above is the "duty cycle" or actual time the unit is on and holds power until it turns off and rests for the next "duty cycle".  Clinically the therapist uses the duty cycle to not only help the patient regain control but also as a gauge of the strength the patient is recovering during the rehab. process.

   When one starts the rehab. the patient may not be able to do more than a few repetitions before fatiguing or do only a few treatments per day.  With time and use the duty cycle becomes more aggressive ( greater time unit is on ) and the repetitions during the day more frequent.