Are My Shoes Dead?

Many of you have questions regarding the importance of a good running shoe - it's HUGE. Improper footwear worn repeatedly can cause a whole mess of aliments. Make sure when purchasing a new shoe to visit a reputable athletic and sport store and have one of their specialists take a look at your feet. They can access which shoe will give you the proper support. Below is a good article I came across, to help you better understand the bio-mechanics of a running shoe, and help you choose the right one for you!

REMEMBER: picking the 'pretty' pair isn't necessarily the best fit for you!



ARE MY SHOES
DEAD?

By Phil Moore


One of the most frequently asked questions from
fitness instructors and participants is…how long
should my shoes last? Obviously this will vary
from one person to the next, but there are some
general rules of thumb that do apply.

The midsole or material between the upper and
the outersole is generally composed of pre-
compressed foam called Compression Molded
E.V.A. It is a very lightweight material that has
excellent resilience (or the ability to absorb shock
and return it to its original shape before the
impact). Constant pounding compromises the
resilience of the foam and its ability to attenuate
shock.

The midsole also acts as a housing for such high
tech materials as AIR, GEL, ABSORB, etc. Yet,
often with so little of these celebrated impact
absorbers in the shoe, they have a negligible
effect on the life of the midsole.

Therefore, the long term cushioning responsibility
falls on the foam. This compression set E.V.A.
has a well documented lifeline of about 500
running miles. After this amount of pounding, the
foam “tires” and the resilience is significantly
compromised to the point where the shoes fell
like it “blew a tire”. Often, this “flat” is not obvious
until you try on a new pair of shoes and realize
immediately why your knees or arches have been
acting up.

But “running miles” are a poor measuring cup for
aerobic activity. So to try and create a gauge
that was meaningful to fitness enthusiasts, I
tracked a group of instructors who did a
consistent number of high impact classes per
week and who also felt their shoes were
“finished” when various body parts began to cry
out for help (for example, shin splints, plantar
fascia, Achilles, knees).

With this group of thirty or so instructors, we
observed a consistent pattern of wear. Here are
a few examples:

a) A person doing 4 classes per week
felt their shoes were “dead” within 6
months.

b) A person doing 8 classes per week
felt their shoes were “dead” in 3
months.

c) A person doing 2 classes per week felt their
shoes were “dead” in 12 months.

So based on 500 miles worth of wear, the reverse math
meant that each class is equivalent to about 5 running
miles worth of wear and tear.

# classes/week X 5 miles X 4 weeks Approx # of week (= miles/ (= miles/ months to week) month) get to 500 running miles

2 10 40 12 months
3 15 60 8 months
4 20 80 6 months
5 25 100 5 months
6 30 120 4 months
7 35 140 3 1/2 months



When comparing aerobic wear and tear with
running miles, we need to keep in mind two
important points:

1. With fitness and aerobic exercise,
there is a great deal of lateral
movement, which stretches the
upper more than the linear activity
of running. The upper therefore
may get sloppy and lose support,
further limiting the life of the shoe.

2. The impact in aerobics is
concentrated on the forefoot area of
the shoe. Running, on the other
hand, involves a heel to toe gait
pattern, which spreads the impact
more evenly across the midsole.

Do not change your shoes based totally on this
chart! Use the chart as a gauge, listen to your
body and compare it with a new pair of the same
shoes before you decide.