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ASICS ARTICLE
Dual Density Midsoles Dr. Chris Bishop PhD Is there a role for dual density midsoles in modern
range, despite evidence presented by Malisoux and co-
athletic shoes?
authors that some dual density designs are associated
Running is a popular activity. And despite a small popula-
with lower injury risk. So is there a role for dual density
tion that continue to support the barefoot and minimalist
midsoles in 2019? I want to delve into the best part of four
movement, most runners are wearing shoes. Each year,
years research to share our investigation findings and the
recreational runners purchase up to three pairs of running
two big lessons we learnt along the way.
shoes, with the purchases being in part motivated by the expectation of improved running performance. But how
Lesson 1: Not all dual density systems are the
do we identify the right shoe for an individual? Well de-
same.
spite the large number of running shoes sold each year,
I think its unfair to label dual density systems don’t work.
there are currently no criteria to help runners decide
Because the Brooks Adrenaline was a different design to
which is the best running shoe for them. This results in
the ASICS Kayano, which was then different to the NIKE
shoe selection based on subjective assessments of shoe
Structure Triax and New Balance 860. Some posts were
characteristics and anecdotally-based marketing literature
hard density. Some posts were different in geometric de-
and product information from shoe manufacturers, or vid-
sign. If we consider ASICS DUOMAX system, it is simply
eo gait analysis results from technical retail stores.
a thin (say 10mm thick) wall in the medial midsole in the midfoot that was never purported to act on the subtalar
Traditionally, running shoes have been categorised
joint, where as the former Adrenaline was a wall of stiffer
based on levels of support ranging from structured cush-
midsole material in the posterior heel of the shoe. Similar
ioning to motion control. Underpinning the concept of
concepts yet differing positions equals different purported
support is the presence of different midsole designs. Dual
function. Heck you could argue the Nimbus is a dual den-
density footwear (characterised by two differing density
sity system in the past with fluid ride midsole system actu-
layers of a midsole) has been a keepsake of athletic foot-
ally being composed of two differing midsole materials
wear design for the best part of 30 years. The long held
which will each respond in different ways.
belief was that dual density midsoles stopped the foot from pronating through loading response and midstance,
If we are going to make conclusive statements about
as well as providing medial stability to the shoe. Despite
something working/not working, you have to be comparing
this anecdotal categorisation of running shoes, evidence
apples with apples.
from the literature does not support the premise the foot-
wear can control motion [1]. However, runners continue
Lesson 2: The literature hasn’t actually properly in-
to purchase this shoe on the basis that it feels more com-
vestigated the effects of these designs on running
fortable and stable for them when they run.
biomechanics. When you look at the design of most studies investigating
There has no doubt been a lot of pressure with regards to
dual density footwear, the outcomes used are a result of
the effect of this type of footwear and whether it should
the instantaneous effects of the shoe, and it is therefore
still exist of recent times. Largely anecdotal and pseudo
unknown what the acquired effect of the shoe is overtime,
expert opinion without a huge amount of published evi-
whether that be after defined periods of running or accu-
dence to support such strong statements. There are cer-
mulative periods of wear.
tainly brands removing dual density systems from their CONTINUED ON NEXT PAGE >>
