Study: Excessive exercise training causes mitochondrial functional impairment and decreases glucose tolerance in healthy volunteers

Does anyone have access to Cell, it would be great if you could share the pdf. :grinning:
It would be interesting to know what happens after four weeks. Maybe these researchers can be on the science of getting faster.

Here is the summary of the study:

Exercise training positively affects metabolic health through increased mitochondrial oxidative capacity and improved glucose regulation and is the first line of treatment in several metabolic diseases. However, the upper limit of the amount of exercise associated with beneficial therapeutic effects has not been clearly identified. Here, we used a training model with a progressively increasing exercise load during an intervention over 4 weeks. We closely followed changes in glucose tolerance, mitochondrial function and dynamics, physical exercise capacity, and whole-body metabolism. Following the week with the highest exercise load, we found a striking reduction in intrinsic mitochondrial function that coincided with a disturbance in glucose tolerance and insulin secretion. We also assessed continuous blood glucose profiles in world-class endurance athletes and found that they had impaired glucose control compared with a matched control group.

9/10 for the graphics lol

They discovered the rest week. :+1:


No Sh*t!


I find this bit sort of interesting. I would assume that it’s quite important to know when they were tested (rest week or training block) to know whether that has any relevance at all though.

More detail here…

Max week had 152 mins of HIIT interval time (not ride time) designed to simulate excessive training…seems they might have used SPBHV :rofl:


Except it’s a bit of an exaggeration. Performance didn’t actually decline during week 3, it merely plateaued. VO2max continued trending upward.

More details and a bit of commentary starting here.

Perhaps the practical takeaway is: when doing Vo2Max blocks: do 2 on, 1 off.

Why, when VO2max was still headed upwards?


Sure, but that’s a simplistic view, specifically in light of the information highlighted by the article. My point is that you might get 90% of the gains (or higher) in V02 with very little of the metabolic cost the researchers highlighted during week 3.

Well if always being slightly short of your full potential as an athlete is your goal, sure.

But then again, if your goal isn’t to be as good as you can be, why do VO2max intervals in the first place? There are certainly far more pleasurable ways to spend your time, both on and off a bicycle.


Yeah that’s right! Why bother training! Just imagine what you could do with all that free time! You could even learn how to communicate without sneering condescension. Wouldn’t that be fun?!


I’d rather win races.

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Here it is… for academic / learning purposes only! Hope I don’t violate forum policies… ** captain flies away **

1-s2.0-S1550413121001029-main.pdf (3.4 MB)


Really interested to hear what others take away from this.

For me:

They’re not trying to study an optimal workout plan - they were trying to study what happens in the mitochondria of people doing super-overloaded exercise. So they ran these folks through a program of increasing intensity loads that they was purposefully excessive and looked at what happened to their mitochondria. The glucose stuff comes in because there’s been a chicken/egg thing in the metabolism literature with mitochondria being funky in Type 2 Diabetes - are the mitochondria funky in T2D folks because the glucose level is too high, or is the glucose too high because the mitochondria are funky? So they say, “hey, here we have people where we made their mitochondria mad through exercise, and now their glucose tolerance is worse.” So that points to a directionality.

And then they thought, “well, if we messed with people’s mitochondria by making them work hard for just a few weeks and that gave them changes in glucose tolerance, what’s going on in elite athletes?” I’m not a metabolism person, but Figure 7D, it looks like the elite athletes’ blood glucose differences come from 1) their bodies “letting” them sit at lower glucose for longer during sleep/before breakfast, and 2) peaking a little higher around lunchtime. It doesn’t seem crazy to me that endurance athletes end up training greater tolerance of hyper/hypoglycemia, by running glucose stores down a bunch from time to time, and by fueling with super-purified sugars. I don’t actually know what the T2D version of this graph looks like, but I’d be surprised if it’s the same, and also surprised if these differences translate to HA1C differences.

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You really made me laugh this time :joy:

And don’t forget the exclusion criterion was commitment to more than 5h weekly endurance training and/or regular high-intensity training. Tbh I lost my interest in the study when I read this :woman_shrugging:

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