What is the Cori Cycle? Gluconeogenesis Explained

Jul 09, 2022

Photo Credit: Kafeel Ahmed

If glucose isn't available, your body can convert other substrates into glucose to power brain & muscle function, here's how:

The Cori Cycle is named after Carl Ferdinand Cori and Gerty Cori who discovered this metabolic pathway.

The Cori Cycle itself is the process of turning lactate (a by-product of glycolysis - the splitting of a glucose molecule into 2 pyruvate molecules) back into glucose. 

There are other forms of gluconeogenesis as well, but the Cori Cycle specifically focuses on the lactate component. 

Gluconeogenesis

  • = gluco (glucose) neo (new) genesis (creation)

The Cori cycle is specifically broken down as follows

  • An athlete consumes a donut, then a short while later goes for a run
  • The donut is broken down into glucose, the glucose enters the muscle cell (by way of insulin) to be utilized for energy
  • When the glucose is oxidized (broken down), a by-product of this metabolism is lactate 
  • The lactate leaves the muscle cell and is transported to the liver
  • In the liver, the lactate is converted back into pyruvate and then reformed back into glucose to be utilized for energy again

 "Can you clear lactate in other ways?" 

Yep. 

 The muscle fiber can clear lactate itself. Type I muscle fibers can actually clear lactate themselves as they have high mitochondrial density & oxygen availability. 

"How long does it take to clear lactate?"

Following a hard interval workout (an anaerobic one), it takes about 1 hour to clear lactate. Your athletes may experience better clearing through active recovery like walking at 65% max heart rate. 

"What else goes through gluconeogenesis?"

 Glycerol and amino acids can both be converted into glucose. 

"How does gluconeogenesis interact with the endocrine system & hormones?"

The Cori Cycle is initiated because the brain senses a drop in circulating blood glucose. When this occurs, cortisol, glucagon, epinephrine, norepinephrine, thyroid hormone, or growth hormone may all be involved in this process. 

The Liver

The Cori Cycle is just one process that occurs in the liver. The liver is also involved in clearing cholesterol, hormones, and drugs from the bloodstream. Plus, the liver is also involved in the storage of nutrients like glycogen and breaking down glycogen into glucose to be released back into the blood. 

Summary 

The Cori Cycle occurs in the liver, it takes lactate and turns it into pyruvate, and then into glucose that can go back into the bloodstream to be utilized for energy through glycolysis. 


Support & Courses Available

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Edited by Danielle Abel, MSN, FNMS(c) CSCS(c)

https://www.instagram.com/danielle_s_abel/?hl=en

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