Recently I retrieved some pilot EMG studies that we carried out on sit-up
exercises using the ball some years ago and feel that the results may be
interesting to members here.  First let me begin with some of the background
to this research.   Initially using the time-tested methods of "eye-balling"
(visual analysis) and palpation (feeling with the fingers), I noticed that,
during supine crunching or so-called "lower ab" exercises over the ball with
feet touching the ground or being restrained, or with the arms holding the
uprights on suitable machines, the ball did not appear to cause as great an
increase in trunk muscle activity as in limb muscle activity - contrary to
what most ball teachers maintain.

However, appearances can be deceiving, so I carried out some surface EMG and
myotonometer (indirect muscle tension) recordings to estimate increases in
muscle tension and activity in those muscles which looked and felt as if they
were changing their levels of activity.  Lo and behold, there was little
change in the activity of the abdominal and lower spinal musculature,
compared with concentration crunches over an AbMat or flat on the floor, but
a very significant increase in activity of the muscles in the legs (when feet
were in contact with the ground or being restrained) and marked increase in
activity of the muscles of the forearms, chest and lats (when the hands were
gripping apparatus to keep one from falling off the ball.)

In other words, contrary to all the beliefs and claims, ball abdominal
training does not produce marked increase in activity of the "core
stabilisers" or "core muscles", but large increases in activity of the
muscles that are responsible for PERIPHERAL stabilisation.  This supports
what I have written repeatedly about the major role that the periphery plays
in stabilising the body in most sport and the misleading concept that "core
stability" can be trained separately from "peripheral stability".   This
means that a lot of so-called "core training" does not even focus on the
core, but strongly implicates peripheral muscle action.   Once again, it
emerges that human movement takes place in an integrated fashion and that
attempts to single out isolated muscle regions, while sometimes appropriate
for various pathologies, are misguided and largely unnecessary.

Now, some of you may recall my mentioning the fact that some bellydancers and
bodybuilders show that some people can acquire the skill to preferentially
activate certain regions of the abdominals (upper, middle, lower, left and
right sides).  Some may use this information to state that I consider that
one should do different exercises for "lower" and "upper" abs, but that would
not be entirely accurate.   It is inaccurate because it is impossible or
extremely difficult (without plenty of biofeedback practice) to recruit one
part of the abs and allow the other parts to remain dormant.  Moreover, there
is no scientific or practical evidence that more isolated ab region training
offers any significant performance or shaping advantages than more general ab
training or training with exercises that do not even focus intentionally on
the abs (such as squats, standing press, tricep pushdowns and bench press).

If you do "lower ab" exercises, then all other parts of the abdominal muscles
(yes, including the obliques) will also become active.  Similarly, if you do
"upper ab" exercises, then the lower and all other parts of the abs will also
become active.  If you do any form of natural movement or stabilisation
against large or suddenly imposed loads, then the entire abdominal
musculature will become involved, with the degree of overflow throughout the
abdominal region and to many other adjacent and distant muscles being
determined by the load being handled by the body.   Generally, it is a matter
of overkill or redundancy to do numerous exercises for the abs, using various
 free standing and toy assisted drills.  One can enhance abdominal strength
and shape by means of a very small inventory of exercises, most of which you
need to experiment with to determine those which best suit you physically and
mentally.

Dr Mel C Siff
Denver, USA
http://groups.yahoo.com/group/Supertraining/