All Abdominal Exercises are Not Created Equal!
by J. R. McNeal, M. S., C.S.C.S. and W.A. Sands, Ph.D.
The fitness industry is replete with exercise devices designed to
enhance fitness or sculpt the body. They are marketed to the unsuspecting
and often gullible consumer, promising quick fixes and effortless
results. Oh, if only it was that easy! Considering the amount of
money Americans spend on fitness gadgets, we should be the fittest
nation in the world instead of the fattest! One of the most recent
trends in the industry is the emergence of the various abdominal
conditioning devices, designed to "isolate" the abdominals
(as if that were possible!), reduce neck strain, and in general
make exercising the abdominal muscles an enjoyable experience. Are
all of these devices created equal? How do they compare to a regular
crunch, or the "forbidden" situp? The purpose of our investigation
was to answer these questions. We decided to compare 6 different
commonly performed exercises and devices to see if indeed there
are differences in muscle activation and range of motion. By comparing
the amount of muscle activation achieved, we can make recommendations
regarding the relative value of one exercise over another with respect
to force generated by the target muscles (the abs). Range of motion
meanwhile, is a variable that has been virtually ignored in the
fitness research literature. Watch virtually any throwing activity
for example, and you can see that the range of motion of the trunk
during such movements is large indeed.
We asked 20 active, college-aged students to participate in this
investigation (10 females, 10 males). The exercises selected were
1) a regular crunch from the floor, 2) a regular situp with feet
constrained, 3) a situp with the addition of the AbMat™ pad, 4)
a crunch performed with an ab-roller type device, according to the
recommendations of the manufacturer, 5) a crunch performed with
the ab-roller combined with the AbMat™ pad, and finally 6) trunk
flexion utilizing the Ab Bench resistive device. The exercises were
demonstrated to the subjects, and they were allowed to practice
each until they were comfortable with their performance. They were
then videotaped with high-speed video while performing 3 trials
of each exercise. Various anatomical structures of the subject were
marked with reflective tape so that they were evident on the screen.
This allowed the videotaped performances to be digitized and analyzed
for specific kinematic information; in this case, angular displacement.
Electromyography electrodes were placed on the upper and lower abdominals
to assess muscle activity.
Findings:
For the lower trunk angle, the AbMat™ and Ab Bench achieved significantly
greater ranges of motion than did the ab-roller exercises, the situp,
or the regular crunch, although the traditional situp was significantly
better than the ab-roller exercises and the regular crunch. At the
hip and upper trunk angles it was again discovered that the AbMat™,
Ab Bench, and the traditional situp were better than the ab-roller
devices or the regular crunch at moving through a large range of
motion. In most cases, the ab-roller exercises and the regular crunch
did not differ from eachother, making the purchase of an ab-roller
for specifically conditioning the abdominals questionable when compared
to the regular crunch, which doesn't cost anything! However, if
the goal is exceptional conditioning of the abdominals through a
large ("functional") range of movement, then devices such
as the AbMat™ and Ab Bench, which place the abdominal muscles in
a slightly stretched position prior to each repetition, may be a
wise equipment investment.
The muscle electrical activity provided even more insight into
the efficacy of these particular exercises. It was of particular
interest to us that the recordings from the abdominals could be
described by different characteristic recordings; the regular crunch,
ab-roller exercises, and the AbMat™ were characterized by a continuous
activation pattern with a low amplitude (low force output), while
the Ab Bench and situp were described by two distinct phases, concentric
and eccentric which were of much higher amplitude. We did not feel
we could adequately compare the two groups of exercises against
each other due to these differences and thus the results basically
compare exercises within each group. This is one example of the
problems that can influence the results of electromyography studies
of the abdominals, and any study not accounting for these differences
should be considered with some reservation. Another problem which
is inherent in electromyography investigations of the abdominals
(but rarely if ever acknowledged by researchers in their results!)
is the problem of skin and fat rolling that occurs whenever the
trunk flexes. This makes the nature of the muscle electrical activity
change as the electrode moves farther from and closer to the muscle.
We feel that it is important to be aware of such shortcomings in
this type of research so that you can become a more knowledgeable
consumer.
The continuous activation exercises were not different in their
activation of the upper abdominals. However, for the lower abdominals
the AbMat™ elicited significantly more activity than did the ab-roller
exercises. The regular crunch was superior only to the ab-roller
exercise used simultaneously with the AbMat™. Therefore, the AbMat™ seems to be the superior exercise of this group for eliciting
muscle activation, especially when the lower abdominals are considered.
The situp and Ab Bench exercises as stated earlier, were different
in their EMG patterns. Because the EMG was greater in these exercises,
but occurred over a shorter time period, these exercises may be
better choices if large force production is desired, rather than
muscular endurance. For both the upper and lower abdominals the
situp produced greater activation than the Ab Bench. It is critical
to note, however, that due to the limitations of this study and
these typical subjects, we were not able to approach any kind of
maximal load on the Ab Bench. The Ab Bench allows resistance to
be added to the exercise, which would cause an increase in muscle
activation to move the increased load. In other words, one should
be able to get any level of activation up to a maximum with the
Ab Bench. The situp is constrained by the weight of the individual's
upper body. This was likely a major drawback in the ability of this
study to properly distinguish between these two exercises. Common
sense would tell us that if we were able to increase the resistance
provided by the Ab Bench, the muscle activation results would have
been different.
In conclusion, it can be recommended that ab-roller devices may
not be any better than the regular crunch in conditioning the abdominals.
For specificity of movement, equipment such as the AbMat™ and Ab
Bench which place the spine in a slightly hyperextended position
prior to abdominal contraction may be better choices, especially
for sport performance. The situp appears to also be a good choice
for both range of motion and activation, although it is limited
in the amount of resistance and thus less muscle activation which
can be achieved
J. R. McNeal, M. S., C.S.C.S.
W.A. Sands, Ph.D.
Dept. Of Exercise
SLC, UT. 84112 |