Glossary Of Terms

Below is a list of terms commonly mentioned in the various manuals. If you come across a term which is not mentioned – please feel free to add it in the comments section below. Alternatively – you can mention this to your instructor which will then update the page.

Apnea – Breath-hold (Latin)
AAT – Aquatic Ape Theory. This controversial theory emerged in the 1960’s and claimed that many features that distinguish humans from their nearest evolutionary relatives emerged because the ancestors of humans underwent a period when they were adapting to a semiaquatic existence, but returned to terrestrial life before having become fully adapted to the aquatic environment.

Aerobic metabolism – Using O2 and Sugar to generate ATP. High volume, low intensity and short recovery.

Anaerobic Alactic metabolism – Using Stored ATP to fuel the muscles. High intensity, low volume and long recovery.

Anaerobic Lactic metabolism – Using Glycogen to produce ATP. High intensity, medium volume and long recovery as the waste product is Lactic acid.

ATP – Adenosine triphosphate. An energy rich molecule that is used to store energy in the cells.

Bradycardia – Slowing of the heart rate. This is related to the Dive response (See DR). Freedivers recorded HR lower than 20bpm during dives.

BO – Black Out. Loss of consciousness caused primarily by a drop in the partial pressure of O2 during a dive. (p.58)

Barotrauma – Pressure related injury which is caused to an airspace due to an increase or decrease in pressure.

CWT – Constant weight – Swim as deep as possible using ns / Mono n.

CNF – Constant weight No Fins – Swim as deep as possible without ns.

DCS – Decompression sickness. a condition that results when sudden decompression causes nitrogen bubbles to form in the tissues of the body. It is suffered particularly by divers (who often call it the bends), and can cause pain in the muscles and joints, cramps, numbness, nausea, and paralysis.

Diaphragm – a dome-shaped, muscular partition separating the thorax from the abdomen in mammals. It plays a major role in breathing, as its contraction increases the volume of the thorax and so in ates the lungs.

DYN – Dynamic Apnea. Swim as far as possible in a pool using ns / Mono n DNF – Dynamic No Fins. Swim as far as possible in a pool without fins

DR – Dive response.

ET – Eustachian Tube. A narrow passage leading from the pharynx to the cavity of the middle ear, permitting the equalisation of pressure on each side of the eardrum.

Epiglottis – a ap of cartilage at the root of the tongue, which is depressed during swallowing to cover the opening of the windpipe.

FIM – Free Immersion. Dive as deep as possible using the rope to pull down and up.
Fluid goggles – Swim goggles that have been modi ed by embedding a corrective lens that allows the Freediver to see underwater once the goggles are ooded with fluid.
Frenzel – An equalisation technique using the tongue to push air into the eustachian tubes. FRC – Functional residual capacity. Exhale diving is done on FRC.

Hook breath – Recovery breathing. Passive exhale followed by strong inhale and hold. Used to decrease the risk of BO/LMC at the end of the dive (P.26)

HR – Heart rate
Hemoglobin – A red protein responsible for transporting oxygen in the blood of vertebrates. Its molecule comprises four subunits, each containing an iron atom bound to a heme group.

Intercostals – a muscle situated between the ribs. Used for breathing.

LMC – Loss of motor control / Samba. Partial loss of consciousness caused primarily by a drop in the partial pressure of O2 at the end of a dive. (p.57)

Mouth-fill– Inflating the cheeks with mouth from the lungs in order to enable deeper equalisation.

Neck weight – A weight that is used on the neck usually in the DYN discipline. Used to offset the weight of the lower body against the oatation of the chest cavity.

NLT– No Limits – Dive as deep as possible using any means to descend and ascend.

N2 – Nitrogen

Nose Clip – Used to block the nose allowing hands-free equalisation. Can not be used in conjunction with a mask.

O2 – Oxygen

Partial pressure– the pressure that would be exerted by one of the gases in a mixture if it occupied the same volume on its own.

Recovery breathing – See Hook Breath

Samba – Refer to LMC

SWB – Shallow water blackout

Soft Palate – the eshy, exible part toward the back of the roof of the mouth.

SP – Surface protocol. Airways clear of the water, remove mask, Signal OK, verbal OK

STA – Static Apnea. Holding the breath for as long as possible without moving

Lung Squeeze – A pressure related injury caused by increase in pressure on the airways. Can be Upper (Trachea) or Lower (Bronchi and Lung tissue).

Trachea – a large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs; the windpipe.

VWT – Variable weight. Dive as deep as possible using a weight to descend and ns / rope pull to ascend