FOOTWEAR SOLE STRUCTURE
di Sergio SEGALIN
***CERTIFIED BY THE UNIVERSITY OF PADUA
To ascertain the effects of the prolonged, regular use
of a shoe fitted with a sole having the above-described
characteristics, a study was conducted on a group of
volunteers (adult males and females aged between 21
and 72 years old) who normally suffered from a sense
of fatigue in their legs and sometimes even pain in
their feet by the end of the day.
|These volunteers were asked to wear
a shoe specifically designed for the test (hereinafter
called the "Segalin shoe" for the sake of brevity)
continuously for at least two months and a series of clinical,
radiographic and electromyographic tests were performed
at the baseline and at the end of the test period to evaluate
At the baseline, all the volunteers underwent a clinical
assessment to ascertain any pre-existing clinically pathological
An X-ray was taken of the static arrangement of the foot
before and after the trial period in the same static/dynamic
conditions, wearing both the usual shoes (with no fixed
or removable insole) and the Segalin shoe. The X-rays
showed that, at the end of the test, all individuals retained
their original, specific static arrangement unchanged
- both those originally presenting with an absolutely
normal articulation and those revealing anatomical variations
at the baseline. This result was comforting in that it
confirmed, not only experimentally (as in the past) but
also clinically, that a prolonged use of the Segalin shoe
did not affect the static arrangement and articulation
of the foot.
The volunteers also underwent electromyographic assessment,
usually conducted in two stages, i.e. once at the baseline,
wearing their normal footwear, then again after the test
period spent wearing the Segalin shoe continuously for
at least two months. During each test, a prolonged recording
was obtained bilaterally to study the activity of the
posterior tibial muscle (which is mainly responsible for
bearing the weight of the body while standing), with the
individual in three different positions: (a) standing
to attention, (b) with the body leaning forwards and the
legs extended to the limit before the individuals lost
their balance; and (c) with the body leaning backwards
and the legs extended to the limit before the individuals
lost their balance.
None of the cases examined showed any signs of "trace
enhancement"(*) after continuously wearing the Segalin
shoe, so muscle fatigue never increased when this shoe
was used. Conversely, in all cases and in all positions
considered, the recording obtained after wearing the Segalin
shoe for 2 months showed a reduction in "trace intensity"
by comparison with the trace obtained at the baseline,
leading us to the conclusion that wearing the Segalin
shoe always induced a more limited muscle contractility
and consequently also less limb fatigue.
The "trace amplitude" parameter also showed
a reduction in muscle contractility and a greater relaxation
after prolonged use of the shoe being tested, in all the
positions examined. This reduction was sometimes particularly
evident and the muscle contraction practically disappeared.
None of the cases showed any increase in mean trace amplitude
after wearing the test shoe. Surprisingly, the beneficial
effect was quite remarkable in some individuals, as illustrated
in the graphs below.
* Electromyographic activity was assessed on the basis
of two different parameters, i.e. "trace intensity"
and "trace amplitude", which are different ways
to evaluate and express the muscle's contractile activity.
In the light of these positive findings, in the words
used by the testers themselves, it can be claimed that,
"using the Segalin shoe, the posterior tibial muscle
suffers less fatigue thanks to the more limited contractile
effort required both in the primary position and in the
activation phase, thanks also to the improved relaxation
in the inhibition phase". In other words, the continuous
use of the Segalin shoe coincided with less fatigue in
the lower limbs than when the individuals were wearing
their normal footwear.