Tuesday, February 16, 2010

The Implications of the Mechanostat Theory on growing taller

This article is incredibly outdated right now and I don't know how to fix it as of yet.

The mechanostat theory is problematic to theory of creating microfractures in the cortical bone to increase height.  The mechanostat theory essentially states that it takes a 1.5% change in bone length to cause a fracture in the cortical bone.  The Mechanostat theory does not distinguish between fracture and microfracture.

The mechanostat theory states that bone modeling is incited when the bone changes in length by .15%.  It's not clear whether the adaptation is a result of a change in the width of the periosteum or is it a case of trabecular microfracture.

It is more likely to be a healing of trabecular microfractures thus resulting in decreased porosity of the bone.  The three determinants of bone density being size(what we want), porosity, and bone mineral content.  It's pretty clear that bone modeling is possible with average weights and exercise.  If the bone modeling range is achieved by say 20lbs dumbell bench which could compress the bone by .15%, then it would take a 200lbs dumbell bench to compress the bone by 1.5%.  Using 200lbs dumbells on the bench is elite level.

So, we either have to find exercises that change the bone length by 1.5% or we have to prove that the mechanostat is flawed.  Given that the mechanostat theory was developed in 1960 and that bone research remains heavily flawed even today, I choose the latter option.  It's hard to believe that all the bone microfractures would occur in the trabecular bone and none would occur in the cortical bone in the bone modeling range.

The Utah paradigm of skeletal physiology: an overview of its insights for bone, cartilage and collagenous tissue organs.

"...adding them to the 1960 paradigm led to the still-evolving Utah paradigm of skeletal physiology that concerns, in part, how load-bearing skeletal organs adapt to the voluntary mechanical loads on them."

So it is possible that cortical microfractures occur in the bone modeling range and therefore it is possible to perform plausible exercises to cause them.  Crisis averted.

We have to encourage scientists to look less at stress-strain laws and the growth of bone and more on microfractures.

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