I occasionally go free diving for rock lobster or fish with a speargun and I've distinctly noticed an increase in the ease and length of breath-hold since going keto-paleo. I understand that diet can affect this, and I'm wondering if any other paleo divers here have noticed this? Also, anyone have any idea what physiological mechanisms related to holding your breath might be affected by abstaining from Neolithic foodery?
This study(http://www.ncbi.nlm.nih.gov/pubmed/17406888) came to the conclusion that you can hold your breath longer when fasted and carbohydrate free but its more dangerous because your blood has less oxygen carrying potential. Its a little confusing though so I could be wrong. I'm fairly certain low carb diets lower co2 levels in the body which probably increases breath holding time because breath holding is normally terminated due to the urge to breathe, mainly caused by the increasing carbon dioxide level.
Prolonged periods of physical work deplete the carbohydrate stores (glycogen) in the body, which forces the body to compensate by increasing the rate of lipid (fat) metabolism. When the human body burns fat to produce energy, it uses 8% more oxygen than when metabolizing carbohydrates. Also, 30% less CO2 is produced by fat metabolism. Thus a breath-hold hold diver who has depleted the glycogen stores will become hypoxic faster, and, making the situation worse, the CO2 driven stimulus to breathe will be delayed. A dive that could safely be performed in a rested and well-fed state may be dangerous after a long day of exertion from diving or land-based activities.
I would be careful after reading this, lots of great info if your read through the whole thing.
I haven't measured 'before and after' but it seems my breatholding has improved since going paleo. But, my body composition has changed since then too. I'm looking to compare notes with someone on freediving nutrition, hit me up if you're interested. I also posted about my insane case of oxygen debt at http://paleoinmalaysia.tumblr.com/post/12381997642/the-4000-calorie-day-i-wake-up-starving-at-1am
My guess is that it is related to your body being more efficient in using its energy/oxygen. That said, I don't know that I would push it longer than normal if alone. You don't want shallow water blackouts.