Just reading Jesse Fortson’s article ‘5 Indoor Cycling Workouts to Get Faster’. Good article. Linked below. At #1 were ‘Over/Unders’ in the classic sense…a few percent above threshold for a little while, a few percent below threshold for a little while, repeat. I’ve said in the past that these aren’t my favorite workout for the stated purpose because ramp-test derived FTP has a margin of error that exceeds the variation in work rate of these classic over/under intervals. Heck, day-to-day variation in FTP might have greater variation than a classic over/under. So you don’t know, you might just be doing a sweetspot workout instead…or you might just be exploring how the VO2max long-component affects you.
But, also, there are much easier ways to achieve the stated purpose of the workout! From the article:
“The primary objective of over-unders is to increase your ability to tolerate and utilize the metabolic byproducts that accompany riding above your FTP”
Ok. So that’s monocarboxylate transporters, primarily, right? MCT-1 and MCT-4 specifically. Anybody ever ask themselves: how long does it take to up-regulate a monocarboxylate transporter? It takes, like, an afternoon. And you don’t have to grind out big long intervals at or around threshold. Further, like so many transporters in the human body, I suspect that the gradient of up/down regulation is dictated by the gradient of concentration at the boundary. In other words, you are going to up-regulate faster if there is a LOT of lactic acid on one side of the membrane and not to much on the other side…not if you’re just a little bit above the point where you can comfortably clear the lactic acid produced.
So if you want to up-regulate MCT-4, try this novel approach: warm up for 10 minutes, then do 5 or 6 minutes at a pace where you maintain 90% or more of you resting heart rate plus 90% of the difference between your max heart rate and your resting heart rate. Then get off the bike and go about your day. 45 minutes later get on the bike and do it again. Do that 15 times. You’ll well & truly up-regulate increase your ability to tolerate and utilize the metabolic byproducts that accompany riding above your FTP by doing that.
But, doing over/unders? I don’t know. Maybe. Somebody would have to show me the biopsy. Doesn’t mean over/unders aren’t a good workout, though. They’re a good threshold type workout. And good for cultivating mental toughness.