Glucose Monitoring and Exercise (CGM Part 2)
Glucose Monitoring and Exercise (CGM Part 2)
What happens to your glucose levels when you exercise?
Hello everyone,
Today’s newsletter continues from last week’s. I kept using a CGM (Continuous Glucose Monitor), and I want to share with you what happens to your glucose levels when you exercise (specifically in a spin class).
A few of us from the newsletter are planning to do a CGM experiment together 👯♀️. This means joining a WhatsApp group, we all buy the sensor together and share what we find for 2 weeks. The sensor is painless to use and it can be purchased as a one off for £48.29 directly at Abbott. If you are keen to join, hit reply with your number and I will add you (there is no additional cost than the sensor).
If you have missed what a CGM is and how it can help PCOS, head to Part 1 here.
To illustrate what happens to your glucose levels whilst you exercise, I am going to use my Saturday morning spin class as a case study (I am a big fan of spinning 🚴🏻♀️).
Rising Heart Beat
This was a 40-min class that had quite a lot of sprints and climbs throughout. My heart rate looked like this:
Every organ in our body requires oxygen to survive. Your breathing increases, so your lungs can take in more oxygen, and the heart rate increases, so the oxygen gets transported through the blood faster to the organs needed. Oxygen is required because it’s a key component of the equation that creates energy (ATP). The other key component is Glucose.
As you can see below, Glucose + Oxygen creates ATP, Water and Carbon Dioxide.
.
As you exercise, the muscles are the organ that demands more oxygen and glucose. The muscles tell the heart to start pumping harder to receive more oxygen and Glucose to make ATP. The muscle requires ATP so they can contract and carry out the activity you are putting them through (like my spinning class).
Rising Glucose levels
Because the muscles require more Glucose, this is what happened to my glucose levels whilst I was spinning:
You can see how throughout the exercise class, my heart rate increased, and so did my glucose levels. This combination allows the muscle to receive the two most important raw materials to make ATP (energy): glucose and oxygen.
Even at rest, each muscle cell contains roughly 1 billion ATP molecules, all of which will be used and replaced every 2 minutes; during intense exercise, muscle ATP production can increase 1000-fold to meet the demands of intense muscle contraction, which explains the spike in Glucose and Heart rate.
Where does the Glucose come from?
Glucose (technically converted to glycogen for storage) in our body is stored in 3 places within the cytosol part of the cells:
In the muscles 💪🏼 - this is one of the main places where Glucose gets stored, as muscles need a constant supply of Glucose.
In the liver 👻 - the body uses the glucose storage from the liver to keep balanced glucose levels in the blood. Given all organs are dependent on ATP and Glucose, there needs to be a constant supply of Glucose in the blood. This is why we burn energy, primarily from the liver, even when we sleep.
In fat cells 🫓 - if the two above are pretty full, excess Glucose will be stored in fat cells.
Each gram of glycogen is stored with at least 3 g of water. This is why we lose weight in the first week of going on a “low-carb” diet. The water gets lost by burning the stored glycogen, not actual fat loss. Our scale might also show an increased weight after a few carb-heavy days. It is not actual fat but water 💧.
The capacity of your body to store muscle and liver glycogen is limited to approximately 1,800 to 2,000 calories worth of energy. After that, it gets stored in adipose tissue.
The muscles prefer pure Glucose for high-intensity exercise as it is quicker to convert to ATP. For lower-intensity exercise or when fasting, muscles will start burning fat to keep their glycogen storage stable. This is why some people recommend training “fasted”, as your body will burn through stored glucose levels and turn to fat cells for energy.
I hope you enjoyed this one. As usual, ping me with any questions you might have.
See you next Sunday,
Francesca
1 Sources
Murray, B., & Rosenbloom, C. (2018). Fundamentals of glycogen metabolism for coaches and athletes. Nutrition Reviews, 76(4), 243–259. https://doi.org/10.1093/nutrit/nuy001
The body’s fuel sources . Human Kinetics. Retrieved August 5, 2023, from https://us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources
Disclaimer: We are all unique in our ways, so this information is for educational purposes only. In my communications, I summarise research data and bring my experience. This shouldn’t be viewed as medical advice at any point. Please further consult your healthcare provider about your health needs.