Are Over-unders Threshold workouts really, or rather VO2max?

[Brennus]

@Kuttermax

An important consideration with O/U’s is they can have a different training effect compared to steady threshold intervals by helping to develop the “lactate shuttle”

I mean, it’s better than nothing…but a typical over/under workout like picket guard where you’re at 90% for a couple minutes than 105% for a couple minutes…we’re not exactly talking about a flood of lactate oozing out of the cells. We’re talking 3, 4, 5 mmol concentrations. So the difference between blood lactate during the ‘over’ and blood lactate during a regular 2 minute threshold effort is not a lot. Probably 1mmol or less.

If you believe (as I do) that MCT1 and/or MCT4 upregulation is greatest when the concentration INSIDE the cell is much, much greater than the concentration OUTSIDE the cell…then the additional utility of over/unders for adaptation is de minimis vs just sustained threshold efforts.

If you really want to upregulate that shuttle, see my post regarding Green’s work:

True or False: No threshold work I do today is going to help me at the race this weekend

Ha! Yes! It’s tough to power a study that much, though. You may not recall when I was futzing around with the ‘day of MCT upregulation’ based on Green’s paper. In that paper they saw MATERIAL upregulation of monocarboxylate & glucose transporters w/in hours of training stimulus. So you could at least hypothesize that adaptation could happen in days…but I think that hypothesis goes of the rails if you instead first train the subjects for ~20 weeks and then do the Green MCT/GLUT upregulation…

Or just read the paper:

https://journals.physiology.org/doi/full/10.1152/ajpregu.00699.2007

@Kuttermax

Some athletes, myself included, find the O/U’s more manageable than the steady threshold work.

Yeah. I think that’s 100% valid. If you like them, do them. But don’t do them because you think they provide some sort of special stimulus that you otherwise will miss out on.