by Dr M. C. Siff
For newcomers, these P&Ps are Propositions, not facts or dogmatic
proclamations. They are intended to stimulate interaction among
users working in different fields, to re-examine traditional concepts,
foster distance education, question our beliefs and suggest new
lines of research or approaches to training. We look forward to
responses from anyone who has views or relevant information on the
Puzzle & Paradox 92
The debate about whether or not it is possible to separately exercise
the upper and lower abdominal erector muscles may not have been
definitively settled yet.
There is still considerable debate about whether or not it is possible
to exercise separately the upper and lower portions of the recti
abdominis muscles, especially since the recti constitute a single
band of muscle between origin and insertion. Numerous books and
fitness professionals refer to crunches and situps for the 'upper
abs' (with the pivot being the distal rectus attachment on the pelvis),
and pelvic curl or leg pushes into the air for the 'lower abs' (with
the pivot being the proximal rectus attachment on the lowest ribs
EMG studies show that both the 'upper' and 'lower' abs show considerable
electrical activity during both of these types of exercise, so that
some authorities dismiss the idea of separate isolation exercise
of the upper and lower abs.
Yet, a TV programme some years ago showed a belly dancer using
her highly skilled abdominal musculature to roll a few quarters
(US 25c pieces) up, down, diagonally and sideways across the belly.
She concluded her unusual display by successfully folding a dollar
bill placed on her belly. From this vaudeville display, it would
certainly appear that it is possible to activate different parts
of the abdominal musculature in skilled sequences. This might then
suggest to the skeptic that it may be meaningful to talk about separate
exercise of the upper and lower regions of the abs.
Of course, we must note that the effectiveness of most non-explosive
exercises depends primarily on the amount of concentrated focus
and voluntarily produced goal-directed muscle tension, so that one's
visualization of the exercise would appear to have a profound effect
on the pattern of activation of any muscle. This also depends on
the patterns of breathing and breath-cessation used during the exercise.
Some authorities state that, since the different regions of the
abdominals are separately innervated, one should certainly be able
to activate upper and lower regions of the abs separately.
However, in saying that the lower abs are separately innervated
we have to be cautious in misapplying this information. All of the
rectus abdominis and the obliques are innervated by branches of
the thoracic nerves T6 or T7 - T12, as is transversus (by the ventral
rami and L1). This would tend to imply that the lower abs and lower
obliques(?!) should be activated by stimulation of T6/7 - T8/9 and
the upper abs and upper obliques (if these exist!) by the remaining
thoracic nerves. In addition, an examination of their nervous innervation
would also suggest that there should be separate activation of upper
and lower transversus.
This clearly confounds the entire issue of trunk action and situps
for the supposedly different parts of the trunk muscles. We can
only resolve the issue if we stop talking about upper and lower
abs etc and analyze in terms of a graduated activation of all of
the trunk muscles progressing from the extreme top to the extreme
bottom (as defined by the appropriate nerves) - much in the way
that a caterpillar moves.
This would appear to offer a far more accurate and logical biomechanical
approach, since the current view of upper vs lower abs would imply
that there should be a somewhat jerky discontinuity somewhere during
a full crunch. The entire action of trunk flexion is smooth, well-controlled
and continuous, so this observation supports my view that there
is a smooth continuum of activation of the entire abdominal (and
erector spinae) group.
If one wishes to simplify, then it would be crudely accurate to
talk of upper, mid and lower abs, but this still tends to mask the
fact that there is really a continuum of muscle activation involving
all of the trunk muscles, each exhibiting a different level of involvement,
depending on the type and pattern of movement.
This means that it is highly unlikely that you will be able to
totally isolate the 'lower abs', since there is always accompanying
involvement of many other stabilizing and mobilizing muscles.
This, of course, has not answered the other issue which we raised
earlier. If there is differential innervation of the obliques and
transversus, must we then conclude that we should recognize upper
and lower portions of these muscles, too? We have to bear in mind,
even though essentially the same nerves are involved in activating
the abdominal musculature, that different movement patterns have
to be used to activate the different muscles.
Does this not imply then that one single exercise should be able
to exercise all of the trunk muscles? Another point - if one sits
up, then both the absand the obliques have to become involved in
flexion, as a consequence of basic biomechanics - but what about
transversus which is more strongly activated by coughing and forceful
expulsion of air from the lungs (or by initiation of walking)?
Give your views on the concept of upper vs lower exercise of the
abdominal musculature, including the obliques. Quote any relevant
references or personal findings to corroborate your reply.
Dr Mel C Siff
School of Mechanical Engineering
University of the Witwatersrand
WITS 2050 South Africa