Please Walk Clockwise - Part 1

  • 1 April 2020

On my morning walk this morning, I came across a sign that read 'Please Walk Clockwise'.

I walk daily on a 4km loop track and over the past week I have become increasingly nervous when facing runners or others approaching from the opposite direction, especially at points in the track where it is less than 1 m in width.

Even worse was the experience of encountering a cyclist at another point in the track who 1 metre in front of me, performed a projectile nasal clearance technique. Ewww.

I have become nervous for two reasons:

  1. Is the air contagious? (do droplets linger in the air?) and
  2. How do I acknowledge the other person? Do I smile (facing them in direct line of potential droplet fire), do I say hello (mouth projected exhale and inhale even worse), or do I turn away (rude and anti-social)?

I want to walk, I want to move, runners want to run, cyclists want to cycle.

As a physiotherapist and one who specialises in breathing, I know this is good for not only my physical health, respiratory system, immune system, cardiovascular system etc… but also for my mental health and well being. Plus outdoors in daylight ensures I get a Vitamin D fix for my airway health.

Knowing a thing or two about Breathing Matters, I thought to myself “Please Walk Clockwise” - this actually makes sense to me. I like this for many reasons but from my clinical experience there are three main reasons I feel this is important and they are:

  1. The Mechanics of breathing (covered in this blog post)
  2. The Psychology of breathing (will be covered in part 2 of “Please Walk Clockwise”)
  3. The Biochemistry of breathing (will be covered in part 3 of “Please Walk Clockwise”)

Let’s start with the mechanics

What we know from science:

One: This is a droplet-based virus.
For a point in time droplets maybe airborne so droplets could stay in the air momentarily and yes, we could inhale them.

This is a droplet-based virus. For a point in time droplets maybe airborne so droplets could stay in the air momentarily and yes, we could inhale them.A clear image to understand droplet’s in the air is when we step outside on a cold morning and exhale,(breathe out ) you can see your breath. The water vapor in your breath condenses into tiny droplets of liquid water that you can see in the air.  

In medical terms we call this "Exhaled Breath Condensate (EBC)".

We know from reports in the acute hospital setting we can breathe in these airborne droplets and potentially become infected. We know this occurs predominantly in environments where the virus is in high concentrations, the contact time is high and there is limited airflow in the environment– (hence the percentage of front-line heath workers contracting the COVID19 virus).

Two: The projection of droplets depends on the force of expulsion of the exhaled air i.e. relaxed breathing versus, a sneeze a cough or forced exhalation that occurs when we run or sing. So, a runner will project further than a walker, but an interesting point here is the runner also inhales (breathes in) harder than the walker.

Firstly, let’s look at the exhaled projection chart, this is the reason we are asked to distance ourselves at approx 2.0m. The mechanics of Droplet projection is visually easy to see in this article by Dr. Sui Huang a molecular and cell biologist  working from the University of Zurich "how far projections may travel".

COVID19: WHY WE SHOULD ALL WEAR MASKS — THERE IS NEW SCIENTIFIC RATIONAL posted on March 30th, 2020 Dr. Sui Huang molecular and cell biologist University of Zurich. This is a great read and also discusses the big debate at present surrounding the wearing of masks.

SecondlyVolume and Force
When runners are breathing in and out of their mouths and at force not only could they potentially be projecting droplets higher in concentration but also inhaling droplets deeper into their lungs.

To quote from Twitter, Dr Howard Luks, an orthopaedic surgeon and trailer runner "perhaps a deep respiratory seeding occurs due to respiratory effort". He has a point. A runner can move up to 120-150 Litres of air a minute (L/Min) and on average an adult  at rest moves 5-8 L/min. 

So the volume of air moved is massive in a runner. Breathing large lung volumes compared to walkers or when we are at rest, a runners breath is deep and big.

Three: Mouth versus nasal breathing & projection when walking running / exercising

When you breathe in through your mouth,  the air is moistened, but not filtered. And when you breathe through your nose the air is warmed, moisturised, filtered and sterilised.

In this case I am interested in a couple of facts:

  • Nasal breathing filters and sterilises the air. The nose produces a chemical in the nasal cavities called NO nitric oxide which helps sterilise the air, helping to kill viruses and bacteria.
  • When we move large amounts of air and in particular via the mouth this can have a drying effect on the lower airway, we know this can cause a phenomenon called exercise induced bronchospasm which can occur in part due to the lack of moisture in the airways, this drying effect can also open the runner up to exposure of infection, and a sensation of breathlessness due to tightening of airways. Hydration helps reduce this, as it does to help move mucus – hydration thins the viscosity of mucus.
  • We know and this applies to the more serious runner, post a long run or marathon the immune system can be compromised for a few hours afterwards, so awareness post running is important. For everyone if you are feeling off color DO NOT exercise the immune system will be compromised.

Our suggestion is to all walkers, and in particular runners:

  1. If you are out of sorts, DO NOT GO OUT.
  2. Keep your distance 2m or more for a runner up to 6m.
  3. When passing others breathe in and out of your nose. For a runner this may mean a temporary reduction in cadence to allow nasal breathing.
  4. DO not forcefully clear the nose or lung mucus in the vicinity of others.
  5. Wear a bandanna to mitigate further risk for both droplet spread but also for runners to assist with airway drying and irritation particularly in cold weather which may trigger coughing.
  6. And yes, to reduce further risk when possible:

Please Walk Clockwise.

Sign written by 8 year old Minnie.
Her mother is a G.P who understands the importance of social distancing during these times.

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