Sweet spot intervals are threshold intervals!
That note is exactly what I’m feeling. “we feel these steady-state workouts with lots of time spent right at the lactate threshold are not as effective as the two designs above, and provide a fairly small adaptive response for the level of fatigue they can create”
I don’t think food or fueling is an issue. Basically I’m 57 and don’t recovery quickly from 45 minutes at threshold. When doing the workout, it’s fine, completely achievable, could even do more, etc.
I use WKO and a long form KM style test.
I’m pretty sure I could do a 3x20 today without too much problem. I started at 3x10 and then bumped it up to a 3x15 and it took 4-5 days before my legs were feeling good again.
Maybe one workout every 5 days is just fine?