One of the pioneers of tech diving, Michael Menduno is a legendary figure in the technical diving world. Watch out as he writes about a different topic that most people like me had never heard about – technical freediving.

Briefly going over the history of tech diving at the start of his talk, Michael talked about how the navy had pioneered helium gas diving in the 1930s and commercial divers had developed their own protocols in the 1960s for deep sea oil field diving. He also talked about how mix technology optimized a diver’s breathing mix, which enabled tech divers to dive down to unprecedented depths in the ocean.

Then prefacing his love for swimming and diving, he started to explain how he stumbled upon something that was kind of in between the two sports – technical freediving – as it allowed him to dive without the gear. The concept of technical freediving is similar to that of technical diving. By using the principles established by technical diving about mix gases and its effects on human anatomy, technical freediving involves pre-breathing an enhanced oxygen gas mix to improve the freediver’s safety and performance underwater.

Two individuals are responsible for the development work that is being done on technical freediving, a term coined by Kirk Krack, founder and CEO of Performance Freediving International (PFI) and a former tech diving instructor trainer. In addition to Kirk, there is also former freediving world record holder and engineer Eric Fattah. Michael revealed that pre-breathing and post-breathing oxygen gave freedivers better times holding their breath underwater compared to just breathing air. The world record for a breathhold after pre-breathing oxygen is over 24 minutes compared to slightly over 11 minutes when just pre-breathing normal air. When used conservatively, pre-breathing oxygen before freediving can reduce risk of decompression illness (DCI) in freedivers and can reduce end of day fatigue as well.

While it sounds like a fantastical idea, the science behind how it works is rooted in the way the human anatomy works. Pre-breathing oxygen loads your body with oxygen and flushes out carbon dioxide in your body, thereby changing the blood chemistry in your body, enabling the freediver to hold his breath and dive longer. The major risk of freediving is hypoxia. Mixed gas pre-breathing may reduce the risk of hypoxia in freedivers. It also enables them to lengthen their breathhold time underwater. As such, there are plenty of freediving applications for technical freediving such as enhancing the ability of competitive safety divers, increasing the safety and bottom time of film crew and actors who need to freedive on screen and hunting. In Tom Cruise’s 2015 movie Mission Impossible: Rogue Nation, Tom Cruise’s character of Ethan Hunt had to hold his breath for more than three minutes to retrieve a chip in an underwater vault. For the scene to be shot, Cruise had to be trained to hold his breath for more than six minutes and he was trained by Kirk Krack. Kirk, who also worked on The Cove and Avatar, went to Truk Lagoon with the PFI crew in 2017 to freedive, hitting depths of 30 to 60 metres, nearly doubling their freediving time and or shortening their surface intervals by practicing technical freediving. Michael also went through the risks of technical freediving, which includes:

  • Central nervous system oxygen toxicity
  • Carbon Dioxide narcosis
  • Gas switching errors
  • Surface interval (SI) miscalculations
  • Oxygen handling n servicing
  • Lung volume reduction buoyancy changes

There are also still areas that are unknown, including the limits of CNS oxygen toxicity? How much SI is required? The current procedures were developed experimentally. Are air breaks needed? What is a decompression model for freediving? Hypoxia limits? And how pre-breathing oxygen enriched gas impacts carbon dioxide. There also many challenges on the research front regarding technical freediving. First of course is money, but there are also questions regarding the ethics of experimenting on freedivers to find the limits.

For the moment, PFI has an education programme about technical freediving – it’s not really a consumer product but for working divers.

As a parting shot, Michael also mentioned about the potential abuse of technical freediving. Only less than 10 percent of freedivers today are trained. Globally, there are 100-120 scuba deaths a year, and 20 to 25 tech diving deaths a year with most of these mostly rebreather related. These compare to 50-60 breathhold diving fatalities a year, which experts say is under reported.

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