Controversy: Is Harness Suspension Trauma (HST) still a thing?

Dangling in a harness, 50 feet above the ground. Your fall is arrested in time and the ground still looks very, very far away. As your heartbeat is rising, your body’s survival instinct kicks in. In this situation it is of utmost importance to alert your co-workers, think about your training and preparation and above all.

Do not panic.

Harness Suspension Trauma

After a fall is arrested, the danger is not passed, but takes shape in the form of harness suspension trauma (or HST). The symptoms of HST can become noticeable in a matter of minutes. They may involve lightheadedness due to a disruption of the circulatory system. Furthermore, the leg straps from the harness will press deep in your skin and will probably squeeze your veins. Squeezing veins can lead to blood flowing back to your brains with the result of passing out.

At least, that’s the theory behind this phenomena.

The controversy

As you already saw by reading the title of this blog, there is quite some controversy about Harness Suspension Trauma. I think it is safe to say that HST is one of the most criticized subjects in the entire work at height industry.

So, there it is, out in the open.

There are different opinions we would like to address about Harness Suspension Trauma.

Suspension Trauma (also medically referred to as Orthostatic Intolerance or Harness Hang Syndrome) continues to be the subject of many scientific papers. Papers that study the blood flow of a worker in suspension, and the amount of blood flow to the brain, leading to syncope (or fainting). Check out the opinions of proponents and opponents.


  • Proponents of this theory point out the different research papers which show the effects on human body, when strapped into a vertical situation, highlighting the bad blood flow and lack of oxygen to the brain and other vital organs in such a position.


  • Opponents of the theory use arguments about little empirical defensible data and don’t take other side effects of a fall into account.  One of their arguments is, nobody died from Harness Suspension Trauma alone (leaving fall trauma and other injuries out of the equation).

Taking both parties into account, there is definitely a huge amount of discomfort for the suspended workers. The physical effects of a fall can lead from minor to probable life-threatening injuries. In combination with a number of factors involved, such as hitting a structure or other objects during the fall. Everybody agrees about one thing, rescue needs to be done as soon as possible!

Minimize the side-effects of a fall

Letting the discussion be a discussion, there are certainly a number of easy things you can do to prevent the chance of HST and minimize the side-effects of a fall. There are a few simple rules.

Check your harness for a proper fit and use a relief straps;

It is important to ensure that a full-body harness is used and that the fitting is not too tight or too lose. A flat hand should fit between the strap and your arm/leg, a closed fist should not. Nowadays, most harnesses are equipped with relief straps attached to the harness near the user’s hips. When suspended, the user needs to manually deploy these straps, and place his feet in the created loops. This allows him to stretch his legs and relief the pressure of his thighs so that his blood circulation is not impeded. Before using a harness, always check if the relief straps are present. A set of simple (and mostly cheap) relief straps can mean all the difference when suspended and increases the chance that a user is rescued before losing consciousness.

Setting up a rescue plan;

Make sure you have everything in place in a rescue plan.

  • Know who to call in the event of a fall.
  • Document training.
  • Know where the rescue anchors are located.
  • Know how emergency services can reach a suspended worker in the shortest amount of time possible.

To improve the emergency response time, always remain within a co-workers eyesight and never work alone!

Conclusion and download

Despite the discussion, hanging in suspension is no joke and can lead to very serious injuries. We also want to emphasize that the fall arrest is just the first half of the story and that a rescue plan to follow up is absolutely crucial.

Take our advice; be prepared. Follow training. Never work alone and make sure your harness has relief straps. To help you remember these simple rules, we established a safety poster with 3 simple instructions that can help users prevent HST when their fall is arrested. The poster is free for you to use. Hang it in a place where it is visible for workers. A good position is near the roof entrance, or at the location where the PPE is kept.

If you require more information about harness suspension trauma or safety in general, please contact us.

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