After reading that, I’m going to abandon Sweetspot and go back to a polarized approach. Also looked at the low volume polarized level plan. Their “endurance” rides are in my recovery zone. Back to building my own plan.
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After you finish the intervention today, do you have before/after metric(s) in mind? My coach looks at a couple things, I’ve never thought about measuring it.
I don’t think you can measure it without a biopsy. I could observe blood lactate levels but that’s just the intermediate condition of three determinants: how fast does lactic acid get produced in the sarcoplasm (in other words, at what work rate does the cori cycle really start to ramp up), how fast does MCT4 transport lactate across the membrane, and how fast does lactate get cleared by heart/liver/kidney but also skeletal muscle…here’s where MCT1 starts to matter.
So if blood lactate is higher it might just mean I’m not clearing it as well. Or it could mean I’m just producing a ton of it. Who knows? Probably the best I can do is just subjective guesswork.
The main thing about the results form the original study that caught my eye is that they make pretty good sense. Seems to me like I should get the best adaptation for shuttling lactate across the membrane when the concentration gradient across the membrane is highest. So, generate a lot of lactic acid in the muscle after a long period of rest. That way there isn’t a lot of lactate OUTSIDE of the muscle and there is a lot of lactic acid INSIDE the muscle.
And their results seemed to reflect that. MCT4 up-regulated immediately. MCT-1 seems to take much longer.
Here’s where a classic 5x5 approach might not be effective. A 5x5 workout lowers blood pH materially by the start of the 2nd interval. So the gradient across the membrane is much less than it would be from a rested state.
However, I have some reservations about the work that came out of that lab. Some are just the usual whining…these were untrained individuals. Not our of shape necessarily but mid-to-low 40s VO2, college student-type subjects. I suspect the subject mix was mostly composed of hey-i’ll-be-a-subject-for-your-study-you-be-a-subject-for-my-study sort of people. Untrained individuals are going to have outsized reponse to any stimulus (ask any juicehead how they responded to the 1st cycle).
Also, they did workout #1, workout #2 (and associated biopsies), then waited 4 weeks, then did workout #1 - workout #16 with associated biopsies at #9 and #16. There is a LOT of discussion to be had regarding this choice of protocol…although I totally understand the practical consideration of not taking 4 real-deal biopsies of the vastus lateralis in one day.
Those are just the normal, whiny, egghead complaints that are normally bandied about when it comes to exercise science…but there might be something more serious going on at that lab. Here we have a group of subjects that are untrained. They performed a GXT. Then they rolled into a lab and cranked out 16 repetitions of 6 minutes at 90% VO2peak. 12 subjects. 0 reports of difficulty completing an interval at a given work rate. No data from the GXT included in the study. No data from individual workouts included in the study.
Does that sound legit to you?
Here’s another study from the same lab. Participants performed either 30 minute or 60 minute workouts at either 70% or 86% of VO2peak. Just average college age dudes with mid-40s VO2. Does anybody stop for a minute and ask: ONE HOUR AT 86% OF VO2PEAK??? No mention of failure to complete the workout?
So part of my motivation was just to see how hard is this, really? The answer for me is that it’s pretty hard! 
I can definitely feel something adapting this morning. I think I must not understand what GXT VO2peak means. 
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There was also one more confound when I did these: warm up time for the trainer. My trainer takes 20 minutes to warm up depending on ambient temperature. When I hop on the trainer power at the pedal will be 15 to 20 watts higher than power recorded at the optical torque sensor. That will eventually normalize down to 5 to 7 watts over the course of 20 minutes of riding.
(ever wonder why the 2nd interval feels a little easier than the 1st? It might not be just VO2 kinematics!)
So each of these workouts as I constructed them did not provide sufficient warm up time for the trainer but also did not contemplate the higher work rate. Meaning my average workrate was really 18 watts higher than what I should have targeted.
That was my own dumb fault. 
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More TrainerRoad thoughts on over/unders in Meghan Kelley’s recent blog post:
Again, I think traditional over/unders are an ok workout but not the best way to improve lactate clearance. Especially among trained athletes the most adaptation to MCT4 in the membranes of the muscle occurs when the difference in lactate concentration across the membrane is maximized. We’re all producing lactate even as we walk around the house but that doesn’t lead to MCT4 up-regulation. But when we produce a LOT of lactate in the muscle while there isn’t much lactate outside the muscle then lactate transport really has to work hard, hard, hard to move that stuff out. That is what stimulates adaptation.
Once concentration on either side of the membrane gets to be about equal adaptive stimulus is less. I think Green’s work supports this notion. Athletes get some adaptation even in Z2 but athletes got a lot more adaptation by doing a few minutes of intense work…hanging out for an hour…doing another few minutes of intense work…hanging out…repeat…repeat. Intense work generates a lot of lactate in a short time so stimulus to transport is maximized. And those were untrained athletes. It’s reasonable to assume that as athletes attain a more trained state they would have to whack the transport mechanism harder and harder to achieve adaptation.
Just something to think about. Everybody should click on that article and give it a read.
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