I can't find the study but the latest I read was that they impair or do nothing for performance but assisted in recovery somehow. More work needs to be done.
If it does indeed help recovery then on a multi-day race that's as good as gold. My point was that the study eliminated or at least cast doubt on any performance improvements whilst riding, ie. necking a bottle ain't gonna knock 1min off your 25 PB.
https://www.frontiersin.org/articles/10.3389/fphys.2017.00806/full
I can't find the study but the latest I read was that they impair or do nothing for performance but assisted in recovery somehow. More work needs to be done.