The cause of an overuse injury in running is that the cumulative load on the tissues is beyond what the current state of the tissues can tolerate, so it breaks. Historically the focus has always been on the cumulative load and its only been more recently that the focus has been on the state of the tissues to take the loads. I am aware of almost a dozen publications on the genetic risk factors for Achilles tendinopathy and presume that those genetic issues affect the state of the tissues to take the load, perhaps making the tissues more vulnerable or making the tissues less likely to be able to adapt to the loads being applied. I had never thought about those genetic issues affecting the elasticity of tendons and the energy cost of running until this:
Is the COL5A1 rs12722 Gene Polymorphism Associated with Running Economy?
Rômulo Bertuzzi, Leonardo A. Pasqua, Salomão Bueno, Adriano Eduardo Lima-Silva, Monique Matsuda, Monica Marquezini, Paulo H. Saldiva
PLoS ONE 9(9): e106581. doi:10.1371/journal.pone.0106581
The COL5A1 rs12722 polymorphism is considered to be a novel genetic marker for endurance running performance. It has been postulated that COL5A1 rs12722 may influence the elasticity of tendons and the energetic cost of running. To date, there are no experimental data in the literature supporting the relationship between range of motion, running economy, and the COL5A1 rs12722 gene polymorphism. Therefore, the main purpose of the current study was to analyze the influence of the COL5A1rs12722 polymorphism on running economy and range of motion. One hundred and fifty (n = 150) physically active young men performed the following tests: a) a maximal incremental treadmill test, b) two constant-speed running tests (10 km•h−1 and 12 km•h−1) to determine the running economy, and c) a sit-and-reach test to determine the range of motion. All of the subjects were genotyped for the COL5A1 rs12722 single-nucleotide polymorphism. The genotype frequencies were TT = 27.9%, CT = 55.8%, and CC = 16.3%. There were no significant differences between COL5A1 genotypes for running economy measured at 10 km•h−1 (p = 0.232) and 12 km•h−1 (p = 0.259). Similarly, there were no significant differences between COL5A1 genotypes for range of motion (p = 0.337). These findings suggest that the previous relationship reported between COL5A1 rs12722 genotypes and running endurance performance might not be mediated by the energetic cost of running.
Th energy return from the elasticity of the tendons is an important component of running and running efficiently. The current dogma states that anywhere from 50% to 95% of the energy absorbed by tendons is returned as ‘free energy’. Most of those numbers are just made up, extrapolated from previous research and it is not clear just how much the tendons do actually return. The number tends to morph over time, depending on what point is trying to be made. I do eagerly await the publication of the details of a study that puts it at only 2% being returned from the Achilles tendon to see what that was based on and if it is valid.
I won’t comment on the above research as it speaks for itself and the full text is here. I have already litigated the running technique and economy issues here, here, here, here, here, here, here, here, here and here and my conclusion from all that is that the issue of running technique or foot strike pattern and running economy is that it is subject specific. I offered up one possible explanation for that, ie variations in joint axes positions affecting the lever arms for tendons and hence how hard or not particular muscles have to work. What the above study offers up is a discussion of the potential of genetic variation affecting the energy return from the elasticity of the tendons as another possible explanation of the subject specific differences in running economy for different running techniques (just not the one they tested). That is also likely to be affected by joint axis and lever arm variations as to how efficiently that energy can be returned.
As always, I go where the evidence takes me until convinced otherwise ….
Bertuzzi R, Pasqua LA, Bueno S, Lima-Silva AE, Matsuda M, Marquezini M, & Saldiva PH (2014). Is the COL5A1 rs12722 Gene Polymorphism Associated with Running Economy? PloS one, 9 (9) PMID: 25188268