<<….. I stated that Heavy weights are far more dangerous than moderate
weights in children, and many studies have shown that you can get BETTER
gains…several of the studies that you, yourself have referenced. >>
*** It would be more accurate to restate everything that has been written or
implied about the risks of weight training and any other sports in this way:
“Greater forces, powers and work loads are potentially more dangerous than
moderate forces, powers and work loads, especially if the patterns of
movement are complex and involve the movement of implements that can readily
produce deviations from safe conditions.”
This more accurate statement is necessary because moderate weights can be
accelerated more rapidly than heavier loads or in ways that deviate further
form the body than heavy loads. This means that movement under these more
modest conditions can produce much greater forces on the body, which is
precisely what we are trying to minimise. We must not fall for the fallacy
that training with heavy weights necessarily imposes greater forces and
torques on the body. This simply is not true.
>>Of course, in both cases, the shock is transmitted via the legs to the
>>spine and rest of the body, but even then, the twin who is executing non-
>>maximal sporting actions is exposed to a force that is some 2.5 times
>>greater than that experienced by his brother who is squatting with nearly
twice
>>bodyweight. It does not matter where or how contact with the ground is
>>made the force is still transmitted to the whole body.
Again, not what I was talking about. I am talking about specific point of
pressure. Each step is slightly different than every other during a run and
the point of pressure changes. In, for example, a squat, the feet are
stationary and the point of pressure does not change.
*** In terms of biomechanics there is no such thing as a “point” of pressure.
Pressure is defined as Force per unit Area (P = F/A) and a point is defined
as an imaginary location which occupies no area or space. In other words, we
would be dividing by zero and pressure at a point would be infinitely large.
Putting that pedantic issue aside, yes, the locus of contact of the foot with
the ground changes during each stride, but so it also does in powerlifting.
The foot does not have to leave the ground for the line of action of the
centre of gravity of the effective load to move during a squat. “Centre of
pressure” studies like this have been carried out for many years on lifters
and runners and the centre of pressure does not remain in exactly the same
region during squats or pulls.
The force transmitted to the rest of the body has nothing to do with the
locus of the centre of pressure. No matter where the force acts on the foot,
it is transmitted to the rest of the body a fraction of a second later. And
the shock wave or impulse is then imposed on ankle, knee, hips, spine and so
forth.
<<Also a review of basic biomechanics, if you graph the vectors from a ground
reaction force in running and a squat (using squat as an example…don’t
mean to pick on it), you will find a significant difference in the
vectors…namely the weight is acting from a Top-down direction rather than
strictly a ground reaction force.>>
*** What you are trying to point out is that the force may be broken down
into various horizontal and vertical components (to be more complete, we
should also add rotational components, which are often dominant features in
the causation of lower extremity injury). In my earlier letter I was
referring to the vertical ground reaction force (I even mentioned reaction
forces) and it was THIS force that was far greater during running and jumping
than squatting. Sorry, there is no way out of accepting that the vertical
reaction forces imposed during many traditional school sports routinely
exceed those encountered in even heavy powerlifting and weightlifting. Visit
any biomechanics laboratory and check for yourself.
But now that we are on the issue of components of force, let us focus for a
moment on rotational components or torques about various joints in the body.
It is these types of action which cause a huge number of injuries in daily
life and typical school sports, far more than the vertical reaction forces
encountered in either light or heavy lifting. Thus, when a footballer,
soccer player, baseballer or basketballer plants a foot, turns suddenly,
accidentally allows the ankle or knee to twist excessively, the resulting
torque produces the host of injuries that all of us see daily in sport -
ruptures of ACL, collateral ligaments, menisci – and in the upper body, we
have the infamous rotator cuff syndrome.
So, if we are to make any cautionary comments about participation in sport,
let’s simply make a blanket statement about all sports and impress on
everyone the dangers of excessive magnitude and duration of force and torque
on the young or old body. Let us talk about what really causes the
problems, namely FORCE, TORQUE and WORK LOAD (Volume), not magnitude of load
alone.
While magnitude of load can produce large forces, etc, this is also true of
light loads, especially light loads acting over a long lever (e.g. as in
throwing and hitting). I know that this requires more sophisticated
education, but at least it does not produce generations of misguided, but
well-meaning coaches, parents and athletes.
<<once again, Mel…I am not comparing weight lifting to other sports…but
if you really want to, you might want to explain the documented increase in
weightlifting, running and track & field injuries in adolescents over the
last 10 years and the reduction in hockey, football and soccer injuries. I
can’t explain it. >>
***I either own or have read through many of those references that you listed
recently and, while a few referred to some trivial cases of weight training,
not one examined the injury history and patterns of youngsters who had
participated for a few years in Olympic Weightlifting and Powerlifting (where
heavy loads are part of competition). We all agree that poor technique in
any sport, including the lifting sports, is probably a major cause of injury,
there seem to be no references that anyone has produced in NSCA, ACSM or
medical situations which prove that competitive lifting in youngsters causes
a significant increase in musculoskeletal injury, especially if compared with
their peers who have participated in other traditional school sports.
<<We understand, Mel. I’m simply stating that moderation is important and
that we let the general public know that there IS risk and danger associated
with weightlifting, just like other sports. >>
***Fully agree. We must optimise training to suit the INDIVIDUAL
irrespective of age, gender or structure and any sage coach knows that. What
we simply need to do is to create a lot more sage coaches, parents and
athletes.
Dr Mel Siff