The athlete in question – Ben Smith who is an elite crossfit athlete – is seen to be hyperventilating and then swimming a length underwater. The acronym EMOM means “Every Minute On the Minute” which encourages athletes to continue this exercise as quickly as possible and repeat every minute with no or little rest.
Freediving safety basics show that with hyperventilation and no rest period will lead to
Shallow Water Blackout Hypoxic Blackout – which if practicing by yourself can be fatal.
Elite athletes with training, aware of the dangers and supervised properly (as it seems Ben was in this case) are not the danger – the concern from the Freediving community is encouraging hyperventilation and then swimming consecutive lengths of a pool with little or no training or supervision is designed to end in tragedy. Proper education and awareness of risks is what we would like to see from Crossfit.
The video has garnered 600 comments on Facebook already, many from Freedivers explaining how dangerous the video and exercise is.