An exchange between Tony Schwartz and Barry Ross regarding Weyand study from Supertraining:
"<schwartztony@h…> wrote:
<<<"So all we need to know is the amount of force? Not when it was
applied, what phase it was applied in, what actions contributed to
the force, etc.? I can see why you agree with Weyand as it seems
you both value an incomplete data set in making wide-ranging
conclusions.
You criticize Dr. Yessis’ book for not giving ground reaction force
data. Why don’t you start by telling us what that data would add?
If ground reaction forces are so critical, can you tell us the
forces that you measured with Allyson? I assume you must be
measuring them, since they are of so much importance to you. Can
you give us some averages for your other runners? What differences
in this data did you find between runners?
If you can’t answer my questions don’t tell me that the Weyand study
is great and Dr. Yessis’ book is “old and dreary.” If you can’t
answer any of these questions then you don’t give anyone a reason to
read your book.
I am responding to your questions, so how about responding to mine
instead of changing the topic or giving some poor excuse? We cannot
hope to have an exchange of ideas if you refuse to give a response.
This is what a discussion is. If you don’t know it, say you don’t
know it. There is nothing to be ashamed of in this regard. These
topics are not taught in universities or most books, so it is not
expected that people know these topics. It is deplorable that this
knowledge isn’t readily available, but pretending that we know these
things will not get us anywhere.>>>>
***First, for both you and Jon Haddan, I did not present any of my own theories
on what makes people run faster, the study by Peter Weyand, et. al., did that.
Secondly, I’m not a sprint coach, I’m a strength coach. The
only “theory” I would put forward is that it is possible to
dramatically increase strength with minimal increase in mass. This
would increase the effects of mass-specific force.
In answer to your “how do you train” question, as it relates to
Weyand’s theory and study, it’s quite simple: Focus on increasing
maximum leg strength, while keeping gains in mass to a minimum. This
can be done through any of the several well known exercises that
address leg strength. I use the deadlift because the time under load
is more readily controlled, and I believe that this is a major
factor in keeping mass gains to a minimum. In addition, add
plyometric exercises to train for greater rate of force
development. Most of this is well known by all of us. Nothing new
here, besides the mass issue.
However, the results of this study from 2001, may not be as well
known, “Effects of isometric training on the elasticity of human
tendon structures in vivo.(Kubo, K. Kanehisa, H., Ito, M. Fukunaga,
T.) Department of Life Sciences(sport science), University of Tokyo
Japan,” stated that “Furthermore, as suggested by Wilson et al. , an
increase in the stiffness of the muscle-tendon complex should result
in a higher force and rate of force development. A stiffer muscle-
tendon complex would also transmit force to the bone more rapidly,
and thus a higher rate of force development would be expected.” The
study also stated, “The main result of this study was that isometric
training increased the stiffness and Young’s modulus of human tendon
structures as well as muscle volume and strength. To our knowledge,
this is the first evidence that shows the effects of strength
training on the elastic profiles of human tendon structures in
vivo,” and, “These (previous) findings suggest that the elastic
profiles of human tendon structures will be changeable through the
execution of regular exercises, as observed in the animal
experiments.”
The study concludes that strength training increases rate of force
development and stiffness of the tendons. This has a direct
relationship to the Weyand study, which concluded, “…human runners
reach faster top speeds not by repositioning their limbs more
rapidly in the air, but by applying greater support forces to the
ground.”
The study also stated, “If the mechanical energy to reposition limbs
is provided largely passively through elastic recoil and energy
transfers between body segments, rather than actively by power
generated within muscles, minimum swing time would be affected
minimally by muscle fiber speeds.”
I believe that “greater support force” in Weyand’s study would
include minimal muscle mechanical work. I also believe that Weyand,
or one of his co-researchers, used the example of a bouncing
superball to further clarify this point. If you drop a superball
vertically,it rebounds vertically. If you throw it down harder,
it rebounds faster. If you throw the ball at an angle between
vertical and horizontal, it will bounce at that angle. It does this
by elastic recoil since it has no muscles.
My personal take on Weyand’s theory is as follows: Speed increases
as greater amounts of force are applied to the ground. Early speed
requires muscle mechanical work in an effort to offset inertia and
most of this force is directed horizontally. Stride length begins to
increase as greater amounts of force are applied. To run more
economically, the runner begins to change vectors toward the
vertical rather than continuing with the initial short, choppy
strides required by the horizontal, which also uses enormous amounts
of muscle mechanical energy to maintain. The change in vector allows
greater stride length because of increased air time. The vector
change has it’s own cost in offsetting the effects of gravity, so
the runner naturally (not by consious effort) selects a vector that
has the lowest energy cost. At this point, the most efficient system
is one that would use the least amount of mechanically produced
energy to sustain a high rate of speed. The more efficient system is
Weyand’s elastic recoil concept because it requires minimal muscle
mechanical work. The effects of mass, speed, and gravity store
significant amounts of elastic energy from ground force support
during the eccentric contraction of muscles and tendons occuring in
the initial phase of ground contact as the body continues its
forward momentum. The recoil occurs as COM begins to move through
the contact point, releasing the stored energy at a rapid pace and
propelling the body both vertically and horizontally, the same way a
spring would react ( or perhaps a superball?). The ground force
support creates energy from the elastic recoil, not muscle
mechanical work.
The alternative theory is using muscle mechanical force during the
entire run. Besides being inefficient from an energy use standpoint,
I cannot get by the apparent contradiction of increasing muscle
mechanical force while ground contact time diminishes. It seems to
me this suggests if one dropped a 40 lb medicine ball on someone
lying on the ground it could be pushed back to the one who dropped
it at a faster rate than a 30 lb ball. Would that mean they would
merely slap back a 150 lb ball? In almost 39 years of being involved
with strength training I have never seen anyone move greater amounts
of weight (create more force) faster than lesser ones by conscious
effort. Certainly you can increase rate of force development through
all amounts of force, but it is still in a linear fashion. It will
take a longer time to mechanically create more force then less. To
imply that one can create greater amounts of force in a shorter
duration of contact time would imply that the greatest amount of
force could also be delivered at any duration of contact time. If
this is the case, why don’t runners do just that? Why ramp up to
speed? Why does research show diminishing contact times at greater
speeds instead of equal contact after the first few strides? There
are several other apparent contradictions in the muscle mechanical
theory (paw back) as well, but this one is enough to make it
unreliable, in my opinion, as a rational model for training effort.
Barry Ross
North Hills, California.