Xpedition:

AeT improvement depends on two things primarily:

1) Your genetics. The distribution of adaptability is like a bell curve. Luckily, we humans are genetically predisposed towards endurance rather than speed and power. So, the bell curve for this has rather short tails. That means that while there are definitely fast responders and non-responders the vast majority of folks will fall in the middle with decent response to this type of training. Since you can’t control your genetics you’ll just have to find out by doing an experiment of one.

2) VOLUME: This the biggie and it is a universal rule no matter your genetics. For those with ADS the higher the volume of training you can handle just below your AeT (Z2) the faster the improvement will come. Caveat- DON’T TAKE THIS TO MEAN YOU SHOULD JUMP TO RUNNING 100MILES/WEEK. But the volume of this stuff is the main stimulus to improvement.

My TYPICAL observations: For those training under 8 hours/week of Z2 it is going to take 4-6 months to appreciably move the needle. Once over about 12 hours/week decent gains can come in 8-12 weeks.

I hope this helps.
Scott

Hi @jeff,

Just some anecdotal reference data from my own experience:

I started working with a UA coach back in Feb 2018 while in the depths of ADS. My first metabolic test indicated my AeT at 120-125 and AT about 165. Fast forward to Jan 2019, I had lost 30 lbs and logged about 275 hours of training (>95% of which was Z1-Z2, and a good chunk of that was fasted training) and my AeT had risen to about 150 with virtually no change to AT. A couple of months ago I did my own aerobic decoupling test to test AeT and concluded it had increased a bit further to 155.

As Scott said, VOLUME and FASTED TRAINING in the low aerobic regime will pay the biggest dividends in increasing AeT. Once fat adaptation is well-established, the benefits of fasted training begin to wane and volume becomes king.

Happy training,
Adam