I'm familiar with cycling power training and the TSS, CTL, ACL metrics, and am kinda' intrigued with my new Ambit2's calculation and tracking of recovery hours. Damn, when I got into a 100hr recovery deficit, I was seriously fatigued and all my running injuries popped up. this morning's run I was at a 30hr deficit- and wasn't too bad, but still on the down side. Is there any information about how this metric is calculated and how to use it for training? Training for an ultra, and this, conceivably, could be used as a guide to help me push my fatigue load, but not too high?