Aerobic Base Training: Mitochondrial Density vs Lactate Shuttle

[ryanarifin134]

Hello! I was reading this blog post on the physiology of aerobic base training, and I had a question: does the “lactate shuttle” part of the aerobic energy pathway ever become the limiting factor of aerobic performance? In other words, is there a point in which the mitochondrial density of your slow twitch muscle fibers (in which training below your aerobic threshold improves) aren’t being fully utilized, and the bottle neck of your aerobic energy system is the speed/efficiency in which the molecules can transport lactate to the mitochondria dense slow twitch fibers (this efficiency which can be trained by training near your lactate threshold, but is also largely based on genetics)?

Thanks so much for your insight, and I hope that question makes sense. And if you think any part of my above understanding of what is happening physiologically is incorrect – please let me know!

[Scott Johnston]

Ryan:

The lactate shuttle does become the limiter to your endurance at the lactate threshold.  By definition, the lactate threshold or anaerobic threshold occurs when the lactate removal rate just equals the lactate production rate.  Since this metabolic threshold represents your endurance limit and since the removal rate is dependent on the shuttle the shuttle becomes the limiter to your endurance.

I hope this helps.  You might want to read this article https://evokeendurance.com/126579-2/

Scott

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