a blast from the past wrote:
Please point to the part of jecht's sentence which implies that lower intensity training is ESPECIALLY effective at enhancing mitochondrial biogenesis.
"Wouldn't you still want EZ days for mitochondrial growth".
In fact, in already trained individuals "easy days" won't do anything to improve muscle respiratory capacity.
Just off the top of my head... don't make me dig for the references,:
1) hauling a sledge across the polar icecap for many hours per day didn't improve the muscle respiratory capacity of the (already more fit) leg muscles (Jannson et al.?)
2) riding a bike 5-6 h/d through the Rockies didn't improve muscle respiratory capacity in trained cyclists (work from Brent Ruby's lab);
3) exercising for 2 h at somewhat higher intensity didn't stimulate AMPK in trained cyclists (work by Glenn McConell).
Etc.
TL,DR: intensity matters.
ETA: Tying things back to the thread topic, based on folks description of what they're doing I see nothing but the cogent application of basic training principles, especially specificity (i.e., focusing on developing muscular metabolic fitness by doing lots of "sweet spot" training instead of shorter, gut-busting intervals) and progression (i.e., never digging yourself into too deep of a hole so that you can't keep overloading the system). From an exercise physiology perspective, it's really a no-brainer.