pain (11). Moreover, individuals with
low back pain often have existing im-
balances beyond that of asymptomatic
person’s, further suggesting risk (13).
In addition, evidence has suggested
that individuals who are athletic or
perform routine resistance training
present similar muscle imbalances
favoring the ﬂexors when compared
with extensors (5,8,12). These imbal-
ances, however, must be interpreted
with caution as the performance of
abdominal crunches alone cannot be
tied to these imbalances and most of
the studies have not presented details
with regard to training patterns. One
may consider the possibility, albeit
theoretical, that trained individuals
may develop a remodeling response
that would afford their disc tissue
a certain remodeling response to the
stresses of a crunch, offering a degree
of protection. Nevertheless, if an
imbalance exists, performing abdomi-
nal crunches in the absence of bal-
anced extensor training would
seemingly perpetuate one’s risk. Thus,
the solution resides in a balanced
training program as opposed to avoid-
ing exercises such as the crunch.
With regard to speciﬁc recommenda-
tions, a rule of avoiding crunches is
not supported by the evidence. Cer-
tainly among individuals with a current
or history of disc pathology, these exer-
cises would be considered a precaution
and left to the decision of a healthcare
practitioner. Evidence does support the
position that sustained or repeated ﬂex-
ion is likely to cause a worsening of
symptoms among individuals with
a symptomatic lumbar disc herniation,
as a result of intradiscal pressure in-
creases and the nature of repeated ﬂex-
ion (6,18,19,23). Assuming there are no
precautions to performing abdominal
crunches, a balanced exercise program
that includes both strengthening of the
spinal ﬂexors and spinal extensors would
seemingly mitigate injury risk from mus-
cle imbalances and subject the spine to
more balanced forces. However, this
recommendation may generate the
question of whether extension exercises
are safe and effective.
Conﬂicts of Interest and Source of Funding:
The authors report no conﬂicts of interest
and no source of funding.
Morey J. Kolber is a Professor in the
Department of Physical Therapy, Nova
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