Since reading your new book (fantastic job BTW) I have been spending essentially all of my time training at or below AeT. I have been adhering to the program for roughly the last 4 weeks. I have a rather significant aerobic and endurance sports base before entering the program outlined in your book. I guess I would call myself an enthusiastic and committed 48 year old, Cat 1.5 athlete ( per your definitions at the end of the book), as I’m not a professional athlete, have a full time job, and a family. But I do pretty well in age-class, and I’m actively trying to get better. Prior to starting I tested the AeT and AnT the best I could, and there was roughly a 10-11% ( 15 beat HR difference) between the two…not perfect but also not fulminantly aerobically deficient. OF course, these are estimates, based off what I believe were reasonable tests.
I have been focusing on mountain running as we are now out of skimo season. I am handling runs at a very easy, up to AeT pace, and I am increasing distance and tolerating vertical. I have done essentially no speed/high intensity work-outs the last 4 weeks ( which I normally would have done heading into race season). I jump into a handful of mountain/skyraces each season generally ranging 13-26 miles (most in the 2-4 hour range), which all have significant vertical gain/loss. While these races are not super fast, they do require a faster pace than ultras to be competitive.
How do I know my AeT is improving, thus allowing myself to train to an increased AeT HR? Pace improvements are difficult to gauge when running in the mountains and not on a track. When is it reasonable to retest of AeT and AnT? Is there a time or way of knowing when intensity should be incorporated into the training plan, as it seems rather clear in your book to not overdo Zone 3-4 workouts until at least the AeT/AnT difference is well below 10%?