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What Happens When You Hold Your Breath

Mermaid Iara underwater shared at AquaTails home of quality mermaid tails for swimmingWhat Happens When You Hold Your Breath, explains AquaTails.  This explains the science behind Mermaid Iara’s 3-1/2 minute breath hold video:

In this video model Iara Mandyn holds her breath for about 3 minutes 20 seconds for this underwater mermaid shot. Some of the scientific and physiological changes while holding your breath could be:

  • Heart rate rises initially, then drops gradually throughout (bradycardia)
  • Blood vessels in the arms and legs constrict (vasoconstriction), to pool blood for brain/heart, where it is needed
  • CO2 levels increase, which trigger defense mechanisms
  • CO2 eventually causes involuntary abdominal contractions (usually just termed contractions), which increase blood flow to the brain
  • Elevated CO2 levels cause oxygen to be more easily released from the blood (Bohr effect
  • When arterial blood oxygen saturation (SaO2) drops below around 30% (in elite divers), a blackout occurs (BO for short, or ‘samba’ which means hypoxic seizure)
  • If exercising while holding breath (i.e. swimming), then the vasoconstriction in the arms and legs forces anaerobic metabolism to occur there = build up of lactic acid, and causes myoglobin in the muscles to release oxygen.

For motionless breath holding, the time you can hold your breath for is determined by:

  1. Psychological resistance to the urge to breathe
  2. Total oxygen storage capacity (= lung volume + blood volume + hemoglobin concentration in blood)
  3. Oxygen consumption rate ( = metabolic rate), determined by body temperature, fitness level, vasoconstriction level, and relaxation level; also requires an empty stomach for lowest metabolic rate
  4. Resistance to low oxygen levels (better resistance to low oxygen = longer breath hold)

See more underwater Iara Mandyn videos.

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