I typically don’t pay any attention to supplements like this but I hear the promotion every week on the IM Talk podcast so figured I’d dig for a little info and user experience. So - real deal, worth trying?
I have used it the last few years during racing season. It’s one of those things that I’m not sure whether it’s truly a physical thing or mental thing. It’s not like you can switch it on or off. It takes a bit of time for it to kick in, so if you stop using it, you won’t know for a little bit. I have ran out of it a week or so ago, so I haven’t been using it since. I can’t say I feel any different really, but I’m also out of my Ironman build and not doing IM length workouts. I can say that when I was using it, I didn’t have much in terms of muscle soreness after long runs. I just can’t say whether that was the Extreme Endurance or just the training adaption. Try it out and see how it suits you.