Study reviewed by XPT Assistant Performance Director, Mark Roberts
This study takes a look at what happens to the stored red blood cells in the spleen (200-250ml of densely packed blood accounting for around 8% of the bodies red blood cell count) during breath holds. The study mainly focused on the size of the spleen post apnea to determine that it does in-fact contract and release its stored blood after the onset of apnea. Furthermore, it stays contracted during the subsequent 4 breath holds and was shown to only partially recover after 60min.
The researchers tested 27 males (10 trained free divers, 10 untrained, 7 men with spleens removed). They carried out 5 breath holds, 2 minutes apart with the subjects faces submerged in water.
Some things we can take away from this study are that:
a) The spleen seems to actively contract upon the breath hold apnea, staying contracted for more than an hour after the last hold. This indicates that the influx of red blood cells into the bloodstream remains there for a long time. This could have great implications for endurance athletes if intermittent hypoxic work was part of the “pre game” warm up.
b) There is only a slight (4%) difference in the amount the spleen contracted from the trained divers to the untrained population. Making the power of this breath exercise accessible to all, not just the experienced. What they saw was the trained divers being able to endure a longer apnea through mental fortitude, resulting in that extra 4% contraction (dump of concentrated red blood cells) of the spleen.
Read the full study: https://www.ncbi.nlm.nih.gov/pubmed/12819225