More asymmetrical thoughts

Again, in this study, like the last we discussed here, we are looking at experienced (and in this case, young) runners; sprinters specifically. Again, they ran relatively short distances (20 meters). More than 1/2 the runners had “large” asymmetries, and they all had asymmetries of some type. Some athletes had injuries and some did not.

There wasn’t a difference in sprint performance over this short distance. This is not surprising in light of the previous paper we discussed; asymmetries seem to worsen over time (Hanley 2018). The level of compensation present (since these are experienced runners) may also be better; the folks that were uninjured having compensation patterns that were more in line with their anatomy, than the injured ones.

• The asymmetries did not change. Thinking about anatomy, especially with hard deformities like torsions or versions, why would they? You can’t change the stripes on a tiger.

• Injured and non injured athletes did not differ in asymmetry before or after the study. Again, why would they? We are talking about gait changes (or perhaps compensations). What is significant for one individual (tibial torsion, femoral retroversion, leg length discrepacy) may not be as significant as it for another, depending on the compensation present.

The study concludes “... kinematic asymmetries in the stride cycle were not associated with neither maximal sprint running performance nor the prevalence of injury among high-level athletic sprinters.” Note that they are talking about prevalence of injury, not incidence of injury.

We still think that asymmetry matters...

Haugen T, Danielsen J, McGhie D, Sandbakk Ø, Ettema G. Kinematic stride cycle asymmetry is not associated with sprint performance and injury prevalence in athletic sprinters. Scand J Med Sci Sports. 2018 Mar;28(3):1001-1008. doi: 10.1111/sms.12953. Epub 2017 Aug 15.

Mouthguard's and improved performance?

This paper looks at the concept or preloading motor neuronal pools. We have written about this before on the blog. 

The Temporomandibular joint (TMJ) is blessed with many mechanoreceptors and receives innervation from Cranial Nerve V (trigeminal nerve) and the upper cervical spine. There is physiological overlap through the trigeminocervical nucleus (in the upper midbrain or mesencephalon, the principal sensory nucleus) which receives the same innervation from the trigeminal nerve distribution and the upper 4 cervical neuromeres(nerve levels) (so double input into same pathway). Nicoli Bogduk published abody of research on this, along with Susan Lord and Leslie Barnsley.

The upper 4 cervical nerve root levels also directly input into the flocculonodular lobe of the cerebellum (which coordinates alot of motor activity, especially of axial extensor muscles). This preloads the motor neuronal pool (just like contracting your muscle slightly, or clenching to get a better response from a reflex exam). By optimizing input (through a bite guard), you optimize mechanoreception, which optimizes cerebellar activity, which in turn pre loads the motor neuronal pool.  You would get SIMILAR ( and better tasting!) results with having them clench or bite down on gum, though not as good due to possible imperfect mechanics.

We have not seen all of the research but we are sure it is legit. It’s like an orthotic for the mouth. Keep in mind changing bite mechanics closer to symmetrical occlusion will be helpful ( ie. Orthodontics, invisalign etc).

There you have it. Next time you want to get some extra performance, or are trying to accomplish an especially difficult exercise, try clenching hard to preload those neuronal pools.

Ivo and Shawn…Preloading your neuronal pools to make learning this stuff easier for you….one pathway at a time.

http://lermagazine.com/cover_story/mouthguard-mysteries-can-wearing-one-really-improve-athletic-performance

The effect of footwear and sports-surface on dynamic neurological screening (click for link)→

Shoes make the man, or in this case, the athlete. This study shows that shoes (much like skis) allow us to perform faster than our brain is able to compensate ( in other words, we lack the skill) and allow us to sometimes stretch our  abilities, often at the cost of an injury. We must remember that technology must keep pace with the rate of neural learning, not the opposite.

J Sci Med Sport. 2010 Jul;13(4):382-6. Epub 2010 Mar 15.