I usually hydrate with bottles and I can manage them on the trainer, road group rides, and solo gravel rides.
But in gravel races, I find that I don’t drink enough when I am on someone’s wheel under sketchy gravel conditions.
So this past race I wore a hydration pack. I hydrated much better, but I also felt a lot of unusual strain in the muscles that go between my glutes and lower back. It was very windy so I had a bent elbow aero position on the tops.
But regardless, that hydration pack and aero position completely changed the muscle groups that were working (or at least complaining) vs my training muscles.
Should I be training with a hydration pack if I am going to race with one?