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Those who are well-versed with rock-climbing (and other variants of climbing) are aware of the dangers posed by Suspension Trauma.

Here at The Great Outdoors there had been a healthy discussion on rare usages of Full body harnesses. Please see: Why are full body harnesses uncommon in mountaineering?

Prima facie, with the full body harness, the load gets distributed as compared to just the waist harness.

Can a full body harness reduce chances of suspension trauma?

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    I don't know enough to answer, but I think the problem is blood pooling in the lower body because of prolonged immobility in an upright position, rather than any kind compression. I don't think a full body harness will help with this. It can reduce the risk of traumatic spinal injury from falling in a prone or inverted position. – aucuparia May 4 at 10:08
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    Here's a good (and professional) German article about the suspension trauma. They only discuss sit harnesses, so I won't make it an answer, but having personally seen someone getting unconscious in a chest harness, I doubt it helps. – phipsgabler May 6 at 14:46
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    The main point the article makes about prevention is that a well-adjusted, comfortable, and ideally broad sit harness won't squeese any large blood vessels and is as good as it gets. – phipsgabler May 6 at 14:47
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    In addition to @phipsgabler, a full body harness might be even worse, since often they do not allow you to sit in them, but force you to some upright hanging position. This leaves less possibility to change your posture or move your legs to keep the blood flowing. – Benedikt Bauer May 7 at 19:39
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The cause of suspension trauma isn't fully known but is thought to be due to a lack of returning blood from the lower limbs. It is known that hanging immobile in a vertical position can lead to Suspension Trauma and this can happen surprisingly quickly as has happened when investigating the problem in France: Proposal of an Effective Algorithm to Manage Suspension Trauma in the Field.

In 1973, Amphoux performed a short series of suspension tests, which ended rapidly due to all subjects almost reaching the point of unconsciousness with disturbing hemodynamic data. In 1979, the medical commission of the French Federation of Speleology studied reports of 15 unexplained deaths among trained cavers during rope ascents. They first thought that the cause of the death was hypothermia, yet as they examined each case, they realized that the delay before loss of consciousness was too short to be compatible with hypothermia. These data where mentioned in 1992 in an article of Bariod who performed tests on healthy volunteers wearing a caving harness.

This study conducted under medical supervision and monitoring, was quickly stopped due to the occurrence of phases of severe bradycardia with loss of consciousness in two subjects after 7 minutes of suspension for the first and 30 minutes for the second. The experiment was repeated two years later in three healthy volunteers but was ended equally abruptly following the occurrence of severe malaises including a loss of consciousness. These two studies, although aborted, ruled out the possibility of hypothermia as the key role in the deaths, as had originally been thought.

As stated in the Wikipedia article referenced in the question: Suspension Trauma:

Suspension trauma (Syn. "orthostatic shock while suspended"), also known as harness hang syndrome (HHS), suspension syndrome, or orthostatic intolerance, is an effect which occurs when the human body is held upright without any movement for a period of time. If the person is strapped into a harness or tied to an upright object they will eventually suffer the central ischaemic response (commonly known as fainting). Fainting while remaining vertical increases the risk of death from cerebral hypoxia. Since there is no evidence that these effects are specifically due to trauma, or caused by the harness itself, climbing medicine authorities have argued against the terminology of suspension trauma or harness hang syndrome and instead termed this simply "suspension syndrome".

People at risk of suspension trauma include people using industrial harnesses (fall arrest systems, abseiling systems, confined space systems), people using harnesses for sporting purposes (caving, climbing, parachuting, etc.), stunt performers, circus performers, and occupations that require the use of harnesses and suspension systems in general. Suspension shock can also occur in medical environments, for similar reasons.

So a full body harness would not make any difference as this is what is used anyway in industrial applications and Suspension Syndrome is known to have occurred in such situations as well.

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  • @PaulPydon: Good data! Thanks +1. I was wondering if the full body harness is used, one can loosen the straps on the thighs/groin to allow better circulation blood (Although, as a standard practice, the straps should remain fastened as long as the harness is being used). Any thoughts on this? – WedaPashi May 5 at 7:23
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    The problem is NOT due to tight straps. It is due to remaining motionless in an upright position for some time. Think of soldiers on parade fainting: there's a problem with blood getting to the brain, so they faint and collapse to the ground. Blood returns to the brain and they recover. If you are held in a vertical position, you cannot collapse to the ground if you faint. As a Cave Rescue team member we have to not only know how to treat someone with Suspension Syndrome, but also remember to keep our own legs moving while suspended in a harness on a rope if we are not moving fr some time. – Paul Lydon May 5 at 11:20
  • Thanks for explaining it. You being a member of a Cave Rescue team, I have huge respect for you the content you contribute here! Thanks :-) – WedaPashi May 5 at 15:44

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