This study that just turned up in my alerts and caught my eye. It was not on runners, but on children. I was not going to write about it for that reason, but all day it has been gnawing at me to write about it as it has direct relevance to some previous posts: The concept of ‘core stability’ of the foot and Does Barefoot Running Lead to a Higher Arch of the Foot? and adds some more evidence into the mix of what is discussed in those posts:
Toe Flexor Strength and Foot Arch Height in Children.
Morita N, Yamauchi J, Kurihara T, Fukuoka R, Otsuka M, Okuda T, Ishizawa N, Nakajima T, Nakamichi R, Matsuno S, Kamiie S, Shide N, Kambayashi I, Shinkaiya H.
Med Sci Sports Exerc. 2014 Jun 3
The aim of this study was to investigate the muscle strength and arch height of the foot in the standing position and the relationships between these indices and physical performances involving the lower limbs in children.
A total of 301 elementary school children (3rd grade, n = 158, age = 8.6 ± 0.5 yr; 5th grade, n = 143, age = 10.6 ± 0.5 yr; means ± standard deviation) participated. The maximal isometric toe flexor strength (TFS) in the standing position was measured using a toe flexor dynamometer. Foot arch height (FAH) was assessed as the distance between the navicular tuberosity of the foot and the floor in the standing position, and FAH relative to the foot length was represented by the foot arch index (FAI). For physical performance involving the lower limbs, 50-m sprint run, standing broad jump, repeated side-step and rebound jump were measured.
There were no significant correlations between TFS and FAI, and between relative TFS (rTFS = TFS / body mass) and FAI. rTFS was significantly correlated with all physical performance tests. No significant correlations among FAI and physical performances were found, except for rebound jump ability in 5th graders. After multiple regression analyses adjusting for gender and body mass, TFS was the only significant correlating factor for all physical performances involving the lower limbs.
This study showed that TFS was associated with enhancement of some measures of lower-limb physical performance in children. These results suggest that foot function should be evaluated with both the muscle strength and arch height of the foot in children.
Ignoring the performance issues for now, what this study did is measure arch height and measured toe flexor strength, which is probably a measure of both the long flexors and small intrinsic muscles and showed that their was no relationship between arch height and muscle strength, which is pretty much consistent with what most studies are saying in runners discussed in this post. I refer you to that post rather than re-litigate the issues here (its almost school pick-up time and I gotta get my girls!).
Nothing in the study jumps out at me as being an issue, except a minor concern with the reliability issues surrounding the measurement of the arch height. More data on that would have been helpful to help determine the trust in the correlations that they reported.
The other issue is that can we extrapolate from children (not the topic of this blog) to runners and the related issues (the topic of this blog)? ….hmmmm, I can’t see why not.
…so much for using muscle strengthening to increase the arch height in kids!
As always: I go where the evidence takes me until convinced otherwise, and this study in the context of the other continues to tell me that arch height is not related to muscle strength.
Morita N, Yamauchi J, Kurihara T, Fukuoka R, Otsuka M, Okuda T, Ishizawa N, Nakajima T, Nakamichi R, Matsuno S, Kamiie S, Shide N, Kambayashi I, & Shinkaiya H (2014). Toe Flexor Strength and Foot Arch Height in Children. Medicine and science in sports and exercise PMID: 24895943