During the past few trainer rides I've noticed something a bit strange (to me anyway)... I'll do 5 minute intervals and during the interval my power drops as much as 20-25 watts even though I don't shift or change my cadence. It's a bit frustrating when you have a certain wattage you're trying to hold for the interval. Today I did a 20 minute interval and gradually lost power over the entire ride. Again, no shifting so I assume my speed would be the same...

So what's going on here? Am I just settling in and maybe gaining some efficiency or is this an over training issue or something else? I would think using less power at the same speed is a good thing, right?

Thanks!