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Mess Trick - The life saving excuse

The story of healing comes intertwined forever with the story of suffering and so the history of medicine’s most brilliant discoveries is often temporally related to the world's bloodiest wars and deadliest diseases. Unfortunately, it is a perpetual yin-yang relationship.

Today I'm am going to tell you a story, the core of which is rooted in physiology and medicine, but the implications reach deep into politics, philosophy and ethics.

The First World War fought between 1914 to 1918 was the first large scale war of the modern era to see a clash of that magnitude. The war brought with it numerous technological advances and along with the advances came an awesome killing power. Machine guns and aviation technology saw leaps and bounds in development. While this advance in engineering is often seen as a positive outcome of the industrial revolution, in reality, it was a grim, death and disease ridden time to be alive in.

Historians today claim the WWI witnessed some of the worst forms of warfare known to man during it's course. To give you an idea, let's look at some numbers. Within the first six weeks of the war, 300,000 men were wounded. That's about 7,150 men a day or about 300 men an hour! Suffering ran rampant. And where suffering runs, medicine follows. The Thomas splint, widespread use of typhoid vaccines, mobile X Ray units, powerful antiseptics, new and improved prosthetics are just some of the changes that WWI brought along with it.

But our story today does not involve the front lines. Today's story is about the quiet trainees who were being pruned to enter the war. About the kids, barely out of high school, being drafted by the army. Some went in and returned with their mind in fragments, yet others returned with their limbs severed and many of them never returned at all.

The loss of life was senseless. Some historians describe WWI as a “diplomatically botched negotiation.” Soldiers saw this. They understood that they were laying down their lives for the egos of men that will never even see a battle field in their lives. And so they decided to boycott it. In many countries however the military service wasn't voluntary: there was a draft in effect. So the only way out was to find a health condition that excused you.

This ladies and gentlemen, is the story of the mess trick.

The mess trick is a self imposed manoeuvre, that causes the person to lose consciousness and have uncontrolled jerky movements that looked like he had a seizure. Its simple to do, really. To pull it off, the person squats and takes about twenty quick deep breaths. Then the person quickly stands up, closes his mouth and nose with his hand and breathes out hard. This causes the person to lose consciousness and puts his muscles into overdrive causing jerky movements which can be mistaken for a seizure. And this phenomenon is seen in normal individuals without any neurological or cardiac problem!

So now we know the history and the philosophy behind this curious phenomenon. This was explained for the first time in a study published by the British Medical Journal in August of 1951. Let us now understand the physiology and medicine behind it.

The subject material that has been presented here is for the purposes of education and information only. We do not encourage anyone to attempt these manouvres for any reason. Please use and share this information responsibly. 
- Team Firstclass

The phenomenon consists of four parts.

  1. Squatting
  2.  Hyperventilation
  3. Standing up quickly
  4. Valsalva manoeuvre

The basic principle is to reduce the blood supply to the brain to the point where consciousness is lost. So how do these three things accomplish that?


The squatting is done to reduce blood flow to the muscles because it's a position that keeps most of the big muscles of the body relaxed. This allows more blood to be available for the heart and the brain.


The hyperventilation does two things. Hyperventilation, as you all know causes washout of carbon dioxide and increases the amount of oxygen in your body. So the low amount of carbon dioxide is the cause for the effects of hyperventilation: peripheral vasodilation and cerebral vasoconstriction. Peripheral vasodialation means that the blood vessels in the muscles dialate so that they can get more blood. Cerebral vasoconstriction is the shrinking of the blood vessels in the brain which means the brain will get less blood.

Standing up quickly

Standing up quickly from a sitting down or lying position makes everyone light headed. It is something we have all experienced. It occurs because when you stand up quickly all the blood goes down to your legs due to gravity which means less blood for your brain which leads to lightheadedness. Remember, however, that from the previous step, the blood vessels in the brain are already small and the blood vessels of the muscles are larger than normal which means on standing up, even more blood goes to the muscles and even less blood reached the brain.

At this point the brain is already low on oxygen due to low blood supply.

Valsalva maoeuvre

This is something that is known to everyone and done by everyone. It is defined as forceful expiration against a closed glottis and it is accomplished by pinching your nose, closing your mouth and breathing out hard. What does it do though? The changes of valsalva are described in four phases but we need to understand only the basics.

When you try to breathe out hard we try and create high pressure inside our chest by contracting our chest wall muscles. This pressure, when higher than the atmospheric pressure, allows air to move from inside the lungs to outside. But when you do the Valsalva, there is no where for the air to go, so the pressure inside the chest just keeps building.

This high pressure inside the chest causes two problems. Firstly it prevents the blood in the muscles from coming back to the heart. This means less blood to pump to the brain. Secondly, it prevents the heart from pumping blood effectively. This means that the already starved brain gets even less blood.

Mess trick.jpg

So at the end of these four phases, there is excessive pooling of blood in the peripheries and very little blood in the brain. On top of that, the ability of the heart to pump blood to the brain is also reduced. All of these result in the brain reaching a critical level of hypoxia which causes loss of consciousness.

Now once the person loses consciousness, the person generally falls to the ground and effect of gravity is lost and the high pressure in the chest are relieved. This results in a slow return of the blood supply to the brain. When the blood supply returns to the parts of the brain responsible for motor functions, the muscles go into overdrive and start twitching which looks like a seizure to the people looking.

However remember that there is no harm that comes from this, except, maybe injury from the fall. The person regains consciousness and can go about living normally.

So there is it, the mess trick, demystified.

Author: Narendran Sairam (Facebook)

Sources and citations

1.Clarke, Owain. “World War One: Medical Advances Inspired by the Conflict.” BBC News, 7 Aug. 2014,
2.Wilcox, Vanda. “Combat and the Soldier's Experience in the First World War.” World War One, British Library, 29 Jan. 2014,
3.Howard, P, et al. “The ‘Mess Trick’ and the ‘Fainting Lark.’” British Medical Journal, vol. 2, 18 Aug. 1951,