RE: [RC] Understanding Saddle Tissue Physiology - Mike Sofen
Robert Ferrand wrote: "The following experiment was made to
determine the relationship of external pressure on blood flow by using a
radioactive isotope 133Xe. The amount of radioactivity was measured as
external pressure was applied. One can observe that as external pressure
increases the blood flow reduces. What is most notable is that pressures as
low as .25 P.S.I. or 4 ounces can reduce flow by as much as 60%. This
is a significant point when related to saddle fit, especially with a bridging
saddle that does significantly increase pressures."
Let's do some
simple math: the weight bearing surface area of a perfectly fitting saddle
is perhaps 100 square inches - 2 strips of about 3" wide by 16" long (the area
of the saddle tree). A rider weighing only 100 pounds places 1 Pound per
Square Inch (PSI) across that entire surface, while a 200 pound rider places
double that (2 PSI). Remember, we're talking perfectly uniform weight
distribution from a perfectly fitting saddle here.
If only 0.25 PSI
can cause such significant blood flow reductions, then no one could ever ride a
horse without causing damage. Clearly, imperfect saddle fit doesn't
prevent most riders from completing 50-100 mile rides with a sound horse
(including the horse's back) at the end of the ride.
I don't disagree
that poorly fitting saddles are highly problematic and the cause of many issues
- both behavioral and physical - my point is there is not necessarily a
direct relationship between actual measured pressures and
physiological functioning, damage or change.
