Ian Pateyjohns wrote:
Yes I did mean loaded hyperextensions using the standard hyper bench
seen in most gyms and holding a dumbell to my chest. From what you
stated you think I should be using the valsalver maneuver to raise
IAP during this movement even with the spine flexed (and its not to
a great degree).
John Casler writes:
Hi Ian,
Actually if you examine the action, you will see the spinal extensors are
tensioned at the top of the action, as well as the gluteals, and if you are
holding a DB, the lats, traps, and scapular adductors.
All of these create a multi-layered muscular support to:
1) Keeping the posterior disc slightly compressed and
2) Form the spine/torso into a rigid unit
3) Create somewhat of a suspension system, that would require a detailed
diagram to be fully explained
Now a little IAP will not hurt, but the most important support mechanism is
the "supra" musculature that creates the protective posterior disc
compression, but as well causes the load to actually be more equally
distributed to the total disc body(s) (again a diagram would be needed to
totally explain) much like the cable systems of old style cranes.
Now the forces are not "fixed"during the action, and you will see that as
the torso is "lowered" that compressive loads to the "anterior" disc reduce
substantially due to the physics involved. In fact, at the very bottom, the
discs my experience de-loading of a sort.
That is why I suggest looking at all the various positions and forces in
those positions. And maybe even more important is the "transitionings" of
those forces. For example, if you go from deloaded discs to loaded discs
rapidly without the Torso Stabilizing needed for that variant, you may
experience problems.
Spinal Flexion at the bottom position would not necessarily be dangerous to
a healthy spine, since it is under reduced load and low compression.
However those with symptoms or history of disc pathologies should be
cautious.
The first things to always look for are the primary forces, and how they
will load the spine. Then you must look at the Torso in total, and how the
various muscles, pressures, and structures, can contribute (in a natural
way) to manage the loads safely and effectively.
Regards,
John Casler
TRI-VECTOR 3-D Force Systems
Century City, CA
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