Hi Scott just picked up your book the other week and couldn’t put it down! What a great resource. To that end I scheduled myself some gas exchange fitness testing to get some accurate baselines. Total time on treadmill was right around 20 minutes. I seemed to have gotten some confusing results or it may just be in the terminology. You mention using raw data (RER) to determine AeT. I started as low as 0.69 and crossed over 0.85 RER at 150HR.The data showed this to be the 50/50 point between fat and carbs. My anaerobic threshold/LT/VT2 was pegged at 155HR with an RER of 0.88 or 60/40 carb to fat. Using your 10% test I am within 3% is that correct? The confusing part is the lab labeled my AeT at 123HR with a RER of 0.76 or roughly 20/80 carb to fat which is a 26% spread. Which marker should I be using for my AeT? As an ultra runner I know I’ve spent almost all of my time in aerobic so I was expecting to be fat adapted. Other markers provided were a Max VO2 of 63.84 ml/kg/min and a VO2 at Threshold of 56.4 ml/kg/min. I’m 48 years old. Do I need to be suspicious of the results or be happy in having a big vacuum and working on other areas? I can attach files if needed.