Foot movement in a shoe. How much is too much?
I have been saying for a long time that a so-called "pronating foot", will quite happily continue to pronate inside a running shoe, even a "motion control" shoe.
It certainly appears clear that whilst running footwear may offer some constraint to frontal plane movement of the calcaneus, an indicator of subtalar joint pronation, this constraint is likely to be very limited.
A new paper will be presented at the Footwear Biomechanics Group meeting next month on The Gold Coast, Australia, and I will be there to report on it for you.
However, for the moment, this abstract from Peter Bruggermann's group in Cologne gives a teasing glimpse.
The calcaneus adducts more than the shoe's heel during running
Matthieu B. Trudeau, Carl Jewell, Eric Rohr, Katina Mira Fischer, Steffen Willwacher, Gert-Peter Brueggemann, Footwear Science, Published online: 15 Jun 2017
Only a few studies have measured the movement of the calcaneus inside the shoe during running, and those that have done so have focused on the frontal plane of motion. This study's objective was to determine the three-dimensional (3D) movement of the calcaneus inside the shoe during running. A secondary objective was to determine if calcaneus movement differs between neutral and support shoes. Ten participants ran at 3.5 m/s in two shoes: a neutral and a support shoe. Right rearfoot kinematics were measured using reflective markers affixed to the shoe heel counter and to the skin of the rearfoot inside the shoe. 3D segment angle ranges of motion were calculated and compared across the shoe heel and calcaneus conditions, and across the two shoe conditions. The movement of the calcaneus compared to the shoe heel was not different in the frontal plane, but was significantly different in the transverse plane, with the calcaneus adducting by 4° more than the shoe heel. The calcaneus also moved significantly more than the shoe in the sagittal plane. Results were similar across the shoe conditions except in the frontal plane where less rearfoot eversion was measured in the support compared to the neutral shoe. The results from this study highlight an opportunity for the development of footwear technologies that can guide calcaneal adduction. Additionally, markers on the shoe heel counter may be appropriate for measuring motion of the foot inside the shoe in the frontal plane, but not the transverse plane.
This is interesting because movement of the calcaneus in both transverse and sagittal planes was greater than the shoe. In addition, the so-called support shoe did offer a degree of reduction in calcaneal eversion, although I have as yet no indication of the effect size.
The thing that really piques my interest is the comment about the opportunity to "guide calcaneal adduction", music to my ears and very much in keeping with my "Forward Transition" paradigm, of which you will hear more very soon.
Director of Bartold Clinical