I don’t doubt that they are slower, I doubt that it’s the pool depth. To be more accurate, i have no idea if it the pool depth, but a swimmer saying that it is doesn’t tell me a lot. I’m not sure if the intuition of a swimmer can differentiate between the pool depth effect and other effects that could influence performance. I don’t doubt that something is making them slower, but i don’t believe it’s pool depth until there’s better evidence.
It's pretty amazing that people here are willing to wade into a field and contest what is accepted amongst practitioners. Olympians literally spend around 40 hours a week in the pool if not more. Places like team USA and other well funded teams have an army of coaches and scientists trying to eke out every basis point of performance as their full-time job.
As a swimmer, I remember everyone lauding over how cool the Beijing Water Cube was because it was a uniform 3m deep which made it excellent for racing in - this was 16 years ago in 2008.
Since the Paris Olympics were accepted the regulation recommendation for pool depth has been revised from 2m to 2.5m
So clearly people vested in the sport and live and breathe it have seen enough evidence (including the sleepy regulatory board) to advise deeper pools.
If you wanted another possible explanation for how depth may affect the swim - a crucial part of the swim is the dive and also the underwater kicking. Both of those may have separate dynamics to swimming on the surface.
Looks like they don’t if you look at the quotes in the article. Nobody said “I can feel the turbulence reflected from the bottom of the pool slowing me down”, they just said they notice they are slower and the article claims they think it might be depth-related.
