Spearfishing Freediving Physiology for Spearfishing

Question 1

What physiological reflex helps divers conserve oxygen during a breath-hold dive?

Accepted Answer

The mammalian dive reflex, which slows heart rate and redirects blood to vital organs

Answer

Adrenaline rush

Answer

Increased respiratory rate

Answer

Muscle relaxation response

Question 2

What happens to air volume in a diver's lungs as they descend to greater depth?

Accepted Answer

Air volume compresses according to Boyle's Law, decreasing as pressure increases with depth

Answer

Air volume increases proportionally

Answer

Air volume stays constant

Answer

Air converts to liquid at depth

Question 3

What is 'lung squeeze' and at what depths does it typically become a risk for spearfishers?

Accepted Answer

Pulmonary barotrauma from exceeding the lung's minimum compression volume, typically at depths greater than 100 feet for most divers

Answer

A feeling of fullness after eating before diving

Answer

Mild chest compression felt at any depth

Answer

Air trapping in the sinuses

Question 4

Why do experienced spearfishers pack-breathe (inhale in stages) before a dive?

Accepted Answer

To maximally load the lungs beyond tidal volume, increasing oxygen stores for the dive

Answer

To hyperventilate and extend dive time

Answer

To equalize ear pressure at the surface

Answer

To reduce anxiety before descending

Question 5

What is the 'urge to breathe' physiologically driven by during a freedive?

Accepted Answer

Rising CO2 (carbon dioxide) concentration stimulating chemoreceptors in the brain

Answer

Dropping oxygen levels in the blood

Answer

Nitrogen buildup

Answer

Lactic acid accumulation

Question 6

How does equalization failure during a descent affect a spearfisher's dive?

Accepted Answer

Inability to equalize middle ear pressure causes pain and can rupture the eardrum, forcing an aborted dive

Answer

It has no practical effect

Answer

It increases bottom time

Answer

It only affects hearing temporarily