PDA

View Full Version : thank you electrical muscle stimulation



Sandra Hirschberg
10-16-1996, 03:09 PM
To all

thank you all a million for your invaluable input to my questions regarding
electrical muscle stimulation (EMS). I was overwhelmed by the response. I
will wait a while longer for more responses, and then I will post all
responses for all to read.

I will explain in a little more detail my study, and answer some of the
questions I received.

I want to quantify the activation deficit (AD), and hope to do this by
measuring on an isokinetic dynamometer, peak forces of maximal voluntary
contractions (MVC), obtained without EMS, and peak forces obtained with
EMS. The AD will be the difference between the two for that particular
subject at that particular knee angle. Of course I will only be able to
quantify the AD if the subject will allow me to go to maximal, meaning
increasing the amplitude of stimulation until a plateau in the force is
observed. Having determined every subjects individual "absolute" force,
and subtracting the MVC force from it, I will have a percentage for the AD
for that subject at that knee angle (probably 65 degrees).

I will consequently attempt to reduce this AD, not through long term
training, but ACUTELY (instantaneously), using various interventions (ie.
heavy squats), in an attempt to potentiate and disinhibit various parts of
the nervous and skeletal system and thus allow the subject to produce a
greater MVC force. I will then measure again (as above) the AD and see if a
change has occured. I am also looking at possible transfers of any
significant changes to a 6s sprint cycle, (ie. possible, immediate
performance improvement).

I am currently using a 600ms square wave pulse (DC), 2ms pulse width, 250Hz
frequency, and have gone up to 100mA in amplitude (max. on our stimulator).
I have observed (although only on myself), an increase in peak force of up
to 15-20% with EMS. This was achieved using large (3" by 5") electrodes,
(stimulating transcutaneously) and at a 65-70 degree knee angle (isometric).
Cathode was placed 1/3 and the anode 2/3 of the distance between the
anterior superior iliac spine and the upper border of the patella. I
certainly did notice patellar irritation!!! I think using femoral nerve
stimulation (as many of you suggested) may be too painful, but I will give
it thought.

If you have any suggestions or comments about my study, please reply, I
value all input, and constructive criticism. I will reply to all of your
questions individually next week. Thanks too for all the reference help.
Thanking you again,
regards Sandra Hirschberg
shirsc10@scu.edu.au