Tuesday, March 2, 2010

Gymnastics and Microfractures

Scientists consider sprinting and gymnastics to be high impact activities.  Surprisingly, they only consider weight lifting to be a medium impact activity.  Tell that to a strongman competitor.  Given equal acceleration increasing the amount of mass will increase the impact.  However, scientists seem intent on focusing their attention on performing studies on bone with people using normal bodyweight loads.  The problem is that scientists focus only on sports that currently exist rather than inventing new exercises for the purposes of their experiments.  But, we can still analyze these articles relating to cortical bone to find evidence that cortical bone microfractures can increase height and then develop our own exercises to induce tensile strain microfractures.

Comparison of pQCT parameters between ulna and radius in retired elite gymnasts: the skeletal benefits associated with long-term gymnastics are bone- and site-specific.

"19 retired artistic gymnasts, aged 18-36 years, were compared to 24 sedentary women. Bone mineral content (BMC), total and cortical bone area (ToA, CoA), trabecular and cortical volumetric density (TrD, CoD) and cortical thickness (CoTh) were measured by pQCT at the 4% and 66% forearm. RESULTS: At the 4% site, BMC and ToA were more than twice greater at the radius than ulna whereas at the 66% site, BMC, ToA, CoA, CoTh and SSIpol were 20 to 51% greater at the ulna than radius in both groups (p<0.0001). At the 4% site, the skeletal benefits in BMC of the retired gymnasts over the non-gymnasts were 1.9 times greater at the radius than ulna (p<0.001), with enlarged bone size at the distal radius only. In contrast, the skeletal benefits at the 66% site were twice greater at the ulna than radius for BMC and CoA (p<0.01)."

We can see the increase in the cortical area from gymnastics(20 to 51%).  Again, the study was not taken place over a period of time so no change in height could be detected.  However, the retired gymnasts had an average height of 161.3 versus 164.5 this is similar to the running study where runners had a shorter height.  However, it's possible that shorter people would favor going into gymnastics.  Both the retired gymnasts and non-gymnasts had approximately the same forearm length within the standard deviation so perhaps the height increase is due to wear and tear rather than an inhibition of bone length increase or compressive forces causing bone length decrease.  The article also mentions that gymnasts have a high incidence of damage in the growth plate of the distal radius.

In the article the retired gymnasts had a mean cortical area in the ulna of 118.6 whereas the non-gymnasts had a cortical area of 94.5.

Mechanical loading during growth is associated with plane-specific differences in vertebral geometry: A cross-sectional analysis comparing artistic gymnasts vs. non-gymnasts.

"Gymnastic exposure was associated with shorter, wider vertebral bodies, yielding greater axial compressive strength and lower fracture risk, despite no BMAD advantage. Our results suggest the importance of plane-specific vertebral geometric adaptation to mechanical loading during growth."<-Though this may not be a causal relationship.

"There was a strong trend toward greater height and waist circumference among non vs. ex/gym"<-The study mentioned that there was no sign of delayed puberty in gymnasts.

"non had taller vertebrae than ex/gym, even after accounting for stature and age effects. The overall difference in vertebral shape was reflected by distinct ratios of latDepth/paWidth, which had profound effects on BMAD, as observed in different planes and by different methods. "'

" this is a cross-sectional analysis in which pre- and post-menarcheal subjects are not the same individuals"<-Maybe shorter individuals stay in gymnastics longer.

The study Sustained skeletal benefit from childhood mechanical loading. found no difference in height between gymnasts and non-gymnasts.

It seems clear from the running study and the gymnastics study that compressive impact forces cannot increase height and only has other benefits on the bone.  In fact they may even decrease height.  It is extremely difficult to decrease bone length.  Much more difficult than increasing length.

1 comment:

  1. I don't mind whether gymnastics can increase or decrease height. I will still enroll my ten year old daughter in a gymnastics class. I firmly believe that this sport can give her lots of benefits.

    Kids Gymnastics