Loss of counciousness:

By Rik Rösken

Scope of this article:

A black-out could look very frightening for a bystander. But how does the atlete perceive it? A freediver speaks about what happened during a breath-hold diving competition during an competition.

"Standing on a submerged table I tried to concentrate myself on my breathing. In the distance, I heard someone saying: Look! He is so much shaking of the cold, that it seems that he has a loss of motor controll before even started!"

"I dive below the 1 meter line and start a symtetric swimming pattern with my arms in front and my head looking down. Within several strokes I reach the required speed and try to maintain the right level while the swimmingpool gets deeper. The turning at the other side of the pool happens without much problems. While I do regain the planned speed fast, it seemed that my stroke became larger. It is getting more difficult at 75 meter and I start swimming a bit slower. Looking at the bottom, I can see from the tiles that I lost almost all of my speed. At the second turning point (100 meters) I become aware that I feel a bit disbalanced and I need al of my concentration to make the second turningpoint."

"During the turningpoint my last thoughts where just to make three more strokes. After the third stroke I arive at the side of the pool and see how my hands catch the side and how I surface."

"When I regain conciousness, I see one of the jurymembers before me. "Breathing, just try to focus on breathing he tells me" I breath slowly without any difficulty. I wonder what this man is doing so close to me and then I realised that I just had my first black-out and feel that I am on the knee of the safetydiver. Joking a bit I give a OK sign and the jury can laugh about it"

From the side of the pool was seen how the diver colapsed during breathing after his attempt. The safetydiver in the water catched him and kept him above water while a member of the jury encouraged him to breath. The diver regained fully counciousness after 5 to 10 seconds.

"The black-out was for me a new experience. It doesn't hurt, you don't remember anything of it and you don't have any effects after it. No tiredness and I felt fine when I gave the OK signal to the jury. Looking afterwards to it, I was probable better to remain at the same speed and stop at 100 meters.

Experiences with black-out are different, but the most athletes doesn't experience it as frightful. Sometimes divers have long dreams, with a pleasant feeling. Afteraffects, when the safetydivers acted rightly, are seldom. Sometimes a headache and severe tiredness is reported, oxygen can solve this when given in time.

The danger of black-out and loss of motor controll is that the diver doesn't have any control of his (or her) body and without assistance will drown. While swimming causes that divers have more dificulty to feel their contractions, it should also noted that some divers doesn't seem to have them. Finally it is important to underline that black-out and loss of motor controll can happen at the start of dive at specific situations. Hyperventilation can play a role in some cases.

Knowledge of breath-hold diving and trainingstechniques are vital to dive safely as possible. With required knowledge during courses incidents like these can be averted.

Also read:
Loss of Consciousness: The confusion around Shallow Water Black-out
Lempert T, Bauer M, Schmidt D., Syncope: a videometric analysis of 56 episodes of transient cerebral hypoxia. Ann Neurol. 1994 Aug;36(2):233-7.