When new research is published, its always intriguing to watch how different communities respond to it and the interpretation or spin that gets put on it¹. I already discussed the The ‘Running Shoes Causing Knee Osteoarthritis’ Debacle in a previous article and how the spinning and re spinning of false headlines lead to a myth. This paper was recently published:
Impact reduction during running: efficiency of simple acute interventions in recreational runners.
Giandolini M, Arnal PJ, Millet GY, Peyrot N, Samozino P, Dubois B, Morin JB.
Eur J Appl Physiol. 2013 Mar;113(3):599-609.
Running-related stress fractures have been associated with the overall impact intensity, which has recently been described through the loading rate (LR). Our purpose was to evaluate the effects of four acute interventions with specific focus on LR: wearing racing shoes (RACE), increasing step frequency by 10 % (FREQ), adopting a midfoot strike pattern (MIDFOOT) and combining these three interventions (COMBI). Nine rearfoot-strike subjects performed five 5-min trials during which running kinetics, kinematics and spring-mass behavior were measured for ten consecutive steps on an instrumented treadmill. Electromyographic activity of gastrocnemius lateralis, tibialis anterior, biceps femoris and vastus lateralis muscles was quantified over different phases of the stride cycle. LR was significantly and similarly reduced in MIDFOOT (37.4 ± 7.20 BW s(-1), -56.9 ± 50.0 %) and COMBI (36.8 ± 7.15 BW s(-1), -55.6 ± 29.2 %) conditions compared to NORM (56.3 ± 11.5 BW s(-1), both P < 0.001). RACE (51.1 ± 9.81 BW s(-1)) and FREQ (52.7 ± 11.0 BW s(-1)) conditions had no significant effects on LR. Running with a midfoot strike pattern resulted in a significant increase in gastrocnemius lateralis pre-activation (208 ± 97.4 %, P < 0.05) and in a significant decrease in tibialis anterior EMG activity (56.2 ± 15.5 %, P < 0.05) averaged over the entire stride cycle. The acute attenuation of foot-ground impact seems to be mostly related to the use of a midfoot strike pattern and to a higher pre-activation of the gastrocnemius lateralis. Further studies are needed to test these results in prolonged running exercises and in the long term.
It certainly got those in the Chi Running community excited as the midfoot strike pattern that was used was the same as used by Chi runners. There were are number of blog posts (eg) applauding the study, but as usual, it exposed a common problem with the reading, appraisal and interpretation of research by those who are not familiar with the reading, appraisal and interpretation of research. All the usual trope of fallacies such as confirmation bias were on display.
It was good study, but I will make these comments.
- There were only 9 subjects (which I do not necessarily have a problem with as I understand the concepts of sample size calculation, power analysis and effect sizes; and with a ‘within subjects’ comparison you can get away with smaller sample sizes). Interestingly no one on any the Chi running websites I checked even raised this 9 as an issue; yet if you check back to some older posts on those sites they were certainly very critical of the sample size if they do not like the results of a study! Why not also criticize a study that they like because it also had a small sample size? (Ironically, those who do not like the results of the study I wrote about here, are criticizing its sample size of 36 as being too small…don’t figure!)
- It was an acute intervention. The same results may or may not be applicable to those who are habitual midfoot strikers (see postscript added below for more).
- Tibial stress fractures, that only make up around 4% of running injuries, is the only injury linked to impact forces, so going to midfoot striking is not going to be a panacea to reduce injuries! Yet, that is exactly how many on Chi running websites interpreted this study as evidence that you get less injuries with Chi running, when it was not even a study on injuries! (for more on impact forces and injury, see this post).
- It is also what I like to call a ‘zero sum game’ or “Law of Conservation of energy”, which means that the total “energy” in the system remains the same. This implies that you can not change the load in one part of the gait without increasing it somewhere else. In order to run with the midfoot stike to lower the impact forces you have to have certain muscles working harder (which the study sort of showed: “higher pre-activation of the gastrocnemius lateralis“). This has the theoretical effect of exposing those muscles, tendons to a higher risk for injury, so you just trade one risk for another.
I have already discussed Chi running here and have a previous rant about it….and I actually have nothing against Chi running! Its just the claims that are made for it (eg the second coming of the messiah) and the misuse, misrepresentation, misquoting and misinterpretation of the science and the reaction to this research on the Chi Running websites that I checked just reaffirms those views.
As always, I go where the evidence takes me until convinced otherwise.
POSTSCRIPT: I just reported on a similar study that did a 3 month intervention to midfoot striking rather than the acute intervention of the above study. In that study, they reported a significant difference in a number of the impact parameters at 1 month, but most had returned to baseline by 3 months. This suggests that the results of the above study are not valid.
¹Nothing to do with running, but I just read these two posts on Left Brain/Right Brain about how the anti-vaccine cranks spun research to show what it didn’t show! (No, the autism prevalence did not go down in Denmark after the removal of thimerosal and No, the autism “rate” in California did not go down after removing thimerosal from vaccines) and this one on Quackometer: How media reports of electrosensitivity may be responsible for electrosensitivity. They do show how the gullible get taken in.
Giandolini, M., Arnal, P., Millet, G., Peyrot, N., Samozino, P., Dubois, B., & Morin, J. (2012). Impact reduction during running: efficiency of simple acute interventions in recreational runners European Journal of Applied Physiology, 113 (3), 599-609 DOI: 10.1007/s00421-012-2465-y