Are your running shoes bad for your health?

Running shoes on a road

Shoes are your body’s biggest support. We need shoes to be in their best shape to live our best
life or, in fact, to live our life at our best – both pain-free and injury-free. Every pair of shoes we
wear needs to be in good condition, and this is especially important if you run regularly because
running shoes take a lot of punishment; when you run, your shoes are subjected to the equivalent
of almost 300% of your body weight.

Investing in a good pair of running shoes is a smart move – but only if you don’t let them get too
old, and only if you never run two days in a row. If you run every day (or almost every day),
have at least two pairs of running shoes, and switch pairs each day. This is necessary because the
foam used in the soles needs up to 48 hours to get back in shape (remember, you’re applying
pressure of up to three times your bodyweight). That is why many brands tend to add some
encapsulated air (Nike), gel (Asics) or other technologies to speed up the process of the shoes
getting back into shape and provide adequate support.

So, even with brand new running shoes, you need to thing about the work they do for you and
how much time they need to recover to be at their best. With older shoes, you need to be extra
cautious. Keep in mind that the soles of your running shoes last longer than their cushion; just
because your soles aren’t worn out, doesn’t mean your shoes are in an adequate condition to
ensure they keep absorbing shocks and protecting joints. The risk you take running (or walking)
in an out-of-shape pair of shoes (running, or regular) is that those shoes mislead your foot, put
your posture out of alignment and your gait out of balance. All this in turn can damage your

There’s little point in paying attention to the quality of your running shoes if you don’t apply the
same standards to your other shoes, so the following tips apply to all footwear.

Purchasing Shoes

The shoes you buy are important. Some people like to change their shoes often, which is a
strategy with many advantages, but not if you opt for style over support, or if you tend to choose
cheaper shoes.

The thing about trying not to spend too much money on a product is that the consumer accepts it
will likely have a short lifespan. The manufacturers know this, and they adapt their production
costs accordingly, dragging down the quality of your footwear, which is concerning because
shoes are the first point of support for your whole body. Light, soft and minimalistic shoes are
the cheapest to produce and, therefore, the cheapest to buy, but the reduction in support for your
feet means the risk of damage to your body is increased.

Just because you’re paying a reasonable sum of money for your shoes doesn’t mean they’re good
shoes. Look out for defects at the point of purchase:

  • Asymmetry around the heel counter (the support at the back of the heel of the shoe). This
    will negatively affect your alignment, balance and posture.
  • A sharp spur sticking out. This might simply hurt or, more seriously, harm you, potentially
    being a source of infection and leading to an antalgic gait (aka a limp).
  • Excess of glue. Beside the aesthetic issue, this weakens the shoe and leads to uneven wear
    and tear, significantly reducing the lifetime of your shoes.
Running shoes being laced up

Retiring Shoes

Wear and tear is inevitable, but there’s no need to be concerned until a few critical points are

Shoes or heel counter out of shape

A foot that rolls inward as you move (overpronates) or supinates (rolls the other way) will show
over time, on the shoe-heel, the toe box or on the whole shoe. This is unacceptable and a sign the
shoes are damaging your body. Get rid of those shoes! Get rid of them even if you are having
orthotics made, because a pair of orthotics placed in a pair of shoes that are out-of-shape and that
mislead your foot will simply not work – they will be uncomfortable and they will wear out more

Tip: Use a wooden shoe tree

Heel has worn to a sloping edge on the outside

As we are meant to walk ‘slightly duck-toed’, i.e., with feet pointing outwards with a 7-to-12-
degree angle (Fick angle), it is completely normal that the back of your shoes’ soles appear
bevelled on the outside corner of the heel.

If you plan to resole a pair of shoes, make sure you have this done them once the first layer of the
heel is worn. If you leave it too long this can affect your knees, increase any existing pronation
and impact your joints all the way up.

Tip: Wear more than one pair of shoes in rotation, to give the material some rest.

A smooth tread (the part of the shoes that contacts the ground)

This is unacceptable, quite simply because it increases your risk of slipping and falling on wet
floors, mud, loose gravel, etc.

Dirty or soaking wet

Those won’t damage your body but, shoes are dirtier than a toilet seat. In 2020, a study led by
researchers at the University of Arizona found nine different species of bacteria on the shoes of
participants. Over the course of two weeks, researchers discovered 440,000 units of bacteria on a
single pair of shoes. At any given time, millions of bacteria live in our shoes, along with fungi
and moulds. Bacteria like E. coli are extremely common on the outside of the shoes.

So, you simply need to clean your shoes, but avoid using a washing machine or tumble dryer as said shoes could shrink or bend at high temperatures or the glue could unstick with the amount of
water used.


  1. Stuff your wet shoes with newspaper to adsorb the water, drying them naturally around
    a decent shape.
  2. Store them in a dry place.

Shoes that have become rigid due to sticking mud

Cleaning your shoes after a muddy run or hike is a bit like cleaning your barbecue immediately
after use – easier to do and you’ll keep both for longer.

The materials used to make the upper of your shoes are supposed to give so that your feet feel
comfortable and so the shoes can adapt to your foot shape and flex. The alternative is them
becoming a source of inflammation, corns and / or blisters for the skin on your feet.

Muddy running shoes

Don’t be fooled by appearances

Even if the shoe treads look good, that doesn’t mean the cushion hasn’t gone. The shoes might
look alright from above when you look down at your feet, but if you check them on a flat surface
from behind, you will realise that this posture is what people see when they follow you.

The Bottom Line

Wearing worn-out shoes is dangerous for your foot, ankle, knee, hip, back and neck health.
The list of signs in this article is not exhaustive but sum up what we see the most when dealing
with foot health, posture and biomechanics.

Be aware that stepping around the house on hard floors with bare feet puts far more weight on
our feet (around 120% of our body weight) than when walking outdoors with a proper arm swing
that offloads our feet from our own weight, putting around only 80% of our body weight on
them. Of course, being barefoot is great to keep the muscles working whenever and wherever
they can (sand, grass, carpet, etc.), but as soon as you need shoes, make sure they are supportive
and in a good shape.

The padding and support provided by your shoes are essential to protect your body when
walking or running on hard surfaces. So, wear your shoes and be very aware of the state of your
footwear. Spend plenty of time checking them in-store at the point of purchase. Then check them
regularly on a flat surface and get rid of any pair that you associate with any form of body pain.
Finally, consult a biomechanics professional if you have any concerns.

About the Author

Christophe Champs is an expert in Biomechanics, and the founder of PODO Clinic and
Workshop. Christophe works with clients to help correct postural and biomechanical issues that
are causing pain or putting a client at risk of injury. By testing both the moving gait and the still
posture Christophe can correct misalignment and asymmetry through creating custom-made
orthotics to suit the exact needs of each individual client.

Twitter: @PodoLondon

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