03
Freediving – where to start (Part II)
In the last posting I mentioned the Eight different disciplines of Freediving.
When considering taking up Freediving as a sport or favourite pastime it is very important to pay attention to Safety.
There are certain things that have to be considered when learning about safety; which are contractions, black-out, sambas (LMC), laryngospasm, the buddy system, the safety procedures and underwater rescue.
Safety
This section gives info on safety; contractions, black-out, sambas (LMC), laryngospasm, the buddy system, the safety procedures and underwater rescue.
Contractions
Some people may experience abdominal contractions at some point during a static. This is a natural reflex caused by the urge to breath (usually due to elevated CO² levels). Contractions don’t mean you immediately have to surface and breathe, you can do a while longer. It is common for people performing static holds for the first few times to want to let air out to make themselves feel more comfortable. You should never do this as it is depriving your body of vital oxygen supplies and is a common sign of a black out. If your buddy exhales any air then you should bring them up out of the water.
Samba or LMC (Loss of Motor Control)
A loss of motor control (LMC) (also known as a “samba”) is a short fit triggered by low oxygen levels (hypoxia). The technical term is ‘Hypoxic Fit’. At the end of the breath hold your buddy should encourage you to breathe and look at your lips (or tongue if the water is very cold) for signs of cyanosis. If they are blue, purple or very pale then this is a sign you have reached or are near your limit.
Black-out
During a descent, the increased pressure causes more oxygen to dissolve into the blood. On ascending the lungs expand and the remaining partial pressure of oxygen in the alveoli drops off rapidly and most people will lose consciousness when the ppO2 in their lungs falls below 0.1 bar
This drop in the level of oxygen causes a sudden loss of consciousness. The greatest proportional pressure changes occur in the top few metres, making black out more likely in the top 15m. Remember also that blackout can also occur without depth – after any breath hold.
(Video from Freediving.biz)
Your limits will change every day and are based on your fitness, what you have eaten (or not) that day, how tired you are and so on. You should never assume that your performance can be automatically repeated or bettered in the next session. Sustaining a samba or black out is not a sign that you have ‘reached your limits’ but that you have vastly exceeded them. A samba or a black out will tire your body more than you realise and it is important to avoid them.
Shallow-water Black-out
Shallow-water blackout is a sudden unconsciousness; can occur while practicing depth disciplines. The lungs expand (due to a pressure differential on ascent) and “suck” oxygen from the blood.
Black-outs in the Pool
You can also pool black-out during or after a static when your oxygen level is way too low because of a long breath hold. Any time any Apnea is taking place each person must have a buddy to monitor them throughout the training. Agreed signals must be established before the training takes place. Usually after a pre-determined time (within the expected breath-hold time), a tap from the safety diver should be acknowledged by a hand signal. The system of tapping should be employed at 30 second intervals for the first minute then at 15 second intervals thereafter.
Laryngospasm
Laryngospasm is a protective reflex that protects the airway by closing off the vocal cords preventing water from entering the lungs. This is usually stimulated when water hits the back of the throat. The laryngospasm reflex temporarily prevents drowning by tightening the throat and keeping out water. This allows a last ditch effort to save the blackout victim. This is just one potential incident that exemplifies why a diving buddy is essential. One should do two rescue breaths (mouth to nose) and the airway should open and spontaneous breathing begins. During a Freediving course with a qualified instructor you will learn in depth the correct rescue techniques for dealing with laryngospasms and other physical failures on the surface and at depth.
The Buddy system
The buddy system is a system for Freedivers to dive safely, never dive without a buddy!! Your buddy should know all safety procedures and your buddy should never attempt a dive deeper than your own limit. Be honest and open with your buddies about your abilities and condition on the day. Use the “one up, one down” system when doing constant weight dives and keep an eye on your buddy at all times. You should meet your buddy at a preagreed depth and follow the diver to the surface and complete surface protocol to ensure correct recovery.
In Dynamic Apnea training the buddy should either swim alongside the partner or meet the partner in the water at an agreed distance towards the end of their dive. This must be at least the last quarter of the expected minimum distance. As mentioned above, during Static Apnea training each person must have a buddy to monitor them throughout the training. Agreed signals must be established before the training takes place.
Remember this, if nothing else:
Take your task as a buddy as seriously as your own diving.
Never, ever freedive alone
Listen to your body carefully and pay heed to signs
Relax and enjoy yourself!
