The term core conjures up a lot of different
images for people. Many think of six
pack abs and training sessions that include hours of sit ups. The term core training has been over utilized
in the training literature and yet it is probably the most misunderstood area
and region. It is this misunderstanding which
tends to lead to core training that is performed incorrectly a majority of the
time. With the increased focus on
functional training, many envision incorporating throwing a medicine ball at the
floor as an appropriate form of core training.
But what is the core and is it really that important?
The definition of the core varies from author
to author. This is often due to the
complexity of this region. This
complexity comes from all the variables which influence loading and stability
of the region. J. Porterfield & C. DeRosa,
in their textbook, Mechanical
Low Back Pain: Perspectives in Functional Anatomy provide a
comprehensive review of the core as well as all the structures which contribute
to loading and stability of this region.
Considering from a musculoskeletal perspective, this review indicates
that there are ~30 muscles which directly or indirectly provide some stability
to the lumbar spine. Knowing this, when considering
the core, we should consider superiorly anything from the pecs/upper thoracic
spine to inferiorly the quadriceps/hamstrings.
Although the hamstrings and quadriceps’ contribution is somewhat
controversial, when you consider the facial envelop for the quadriceps and
hamstrings and its continuation into the abdominal fascia and thoracolumbar
fascia we can see its influence here.
When you also consider the origin for both of these muscles, you can
easily see the how both the fascia and origin would influence position of the
pelvis and hence impact the core.
It has been well understood and vetted in the
research the importance of core stability to prevent low back pain. However, what has not been as well understood
is the impact that core stability has on performance. Biomechanically and logically, it makes sense
but there has not been an abundance of research showing it. Butcher et al, where
one of the first to correlate core stability with performance measures. In 2007, they looked at the impact of core training
on vertical takeoff velocity.
Methods: Fifty five athletes were
selected from various sports including basketball, dance, running, football,
hockey, martial arts, rowing, rugby, slow pitch, soccer, swimming and
volleyball. None of them had previous
history of low back pain (in last 12 months) or lower extremity injury. Subjects were assigned to one of four groups:
trunk stability training (TS), leg strength training (LS), combination trunk
and leg strengthening (TL) and non-training group (CO). Training groups were given a periodized
program for 9 weeks and instructed to train 3xs/week. Vertical takeoff velocity was determined from
performing countermovement jump onto a force plate.
Results: All three training groups experienced
improvements in vertical takeoff velocity when compared to the control
group. The truck stability group had the
most significant increase in vertical takeoff in comparison to the control
group at 3 weeks; however, at 9 weeks, the combined trunk and leg strengthening
group had the most significant gain. Based
on the results, it indicates that trunk stability training does have an impact
on vertical takeoff velocity. Since
vertical takeoff velocity has a direct correlation to vertical jump height,
this would indicate that core stability would increase vertical jump.
Discussion: This
is a great article and begins to make the case for core stabilization training to
improve athletic performance. This said,
when looking at the training or specifically the exercise selection, the core
stabilization exercises could be considered very low grade/intensity for the level
of athletes. All of the exercises
selected (with the exception of one) were in supine, prone or sidelying. Therefore, would the training effect be even
greater if these were done in combination with exercises in more upright, sport
like, or full weight bearing positions?
When looking at the leg strengthening exercise selection, these would
also be considered low grade/intensity.
None of the exercises selected where full weight bearing and were sitting,
supine or prone. With the change in
length tension relationships in standing versus prone/supine/sitting, is the
full training effect carried over to the activity? So
although this study gave us some good indication that stability training can in
fact improve performance, are we only seeing half the picture? Had the exercises selected been more
representative of the positions needed for upright sport participation, would we
have seen even greater impact on vertical jump?
In part II, we will look at recent study which
also evaluates the impact of core stabilization on vertical jump in soccer
players.
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