also, FWIW, I’ve found the 2+ hour endurance rides to be quite potent. So I really try and do at least 2 hours as a minimum, twice a week.
Today somebody posted this on the forum: Construction and breakdown of mitochondria
And I downloaded and skimmed the PDF translation of that Dutch article. Regarding my “2 hour rule” there was this:
References:
5. Booth F (1977). Effects of endurance exercise on cytochrome c turnover in skeletal muscle. Annals of the New York Academy of Science, 301, 431-439.
9. Fitts R et al. (1975). Skeletal muscle respiratory capacity, endurance, and glycogen utilization. The American Journal of Physiology, 228(4), 1029-1033.
I haven’t read those studies, and without any context that table summarizes that 60 minute “training units” resulted 40% increase in mitochondria content, versus 60% increase for 90 minute units, while 120 minutes resulted in 90% increase.
So that seemingly supports my 2 hour rule.
And FWIW #1 - in 2014 and 2015 when I was doing spin classes, I plateaued at 45 minute class so I started going earlier and bumped my sessions to 60 minutes and months later I pushed it even more and my rule became 5am arrival and 75-90 minutes total (I didn’t always make it at 5am).
And FWIW #2 - using TR I felt (feeling, not data) more benefit from doing an extended (repeated) TR Traditional Base with 2-3 hour workouts versus the short 60-90 minutes workouts.
I’ll go read those references at some point, and you can take my 2 hour rule for what its worth.