Continuous Glucose Monitoring (CGM) has revolutionized the way athletes, including endurance athletes, optimize their performance and nutrition. Originally developed for diabetics, CGM devices are now being embraced by professional athletes to track their glucose levels and make informed decisions about their training and nutrition. In this article, we will explore the benefits of CGM for endurance athletes, with a specific focus on swimming, cycling, and running. We will delve into how CGM can help athletes dial in their performance, enhance their endurance, and improve their nutrition, all while leading a healthier lifestyle.
What is CGM?
CGM is a cutting-edge technology that enables athletes to continuously monitor their glucose levels throughout the day. It consists of a circular glucose monitoring apparatus, about the size of a quarter, which includes a hair-thin needle and a transmitter that pairs with a companion app via Bluetooth or NFC. The sensor, which usually lasts for 14 days, is inserted into the upper arm using a special applicator. It measures the concentration of glucose in milligrams per deciliter (mg/dL) in the interstitial fluid surrounding the body’s cells.
Originally designed for diabetics to replace traditional finger-prick tests, CGM has now found its way into the training and nutrition routines of endurance athletes. By providing real-time data on glucose levels, CGM helps athletes make informed decisions about their fueling strategies and optimize their performance.
Fueling Strategies for Endurance Athletes
For endurance athletes, maintaining optimal glucose levels is crucial for sustaining energy levels during training and competitions. When working out at high intensities, the body relies on glycogen, stored glucose, to fuel the muscles. The liver also releases glycogen to raise blood sugar levels. However, glycogen stores are limited, and athletes need to continually replenish their fuel to keep performing at their best.
CGM helps athletes fine-tune their fueling strategies by providing insights into how their glucose levels respond to different types and quantities of carbohydrates. While general recommendations suggest consuming 30 to 60 grams of carbs before exercise and 80 to 100 grams for racing, CGM allows athletes to pinpoint their individual needs.
Pre-Training and Pre-Race Fueling
Timing and composition of pre-training or pre-race meals play a crucial role in optimizing performance. When athletes eat, their glucose levels rise, triggering the release of insulin to regulate blood sugar. However, exercising during this window can lead to a decrease in blood glucose levels, potentially impacting performance.
Using a CGM, athletes can experiment with different timing and composition strategies for their pre-exercise meals. Some may find they perform better by consuming their meal a few hours before training to allow insulin levels to decrease. Others may prefer eating closer to the workout or fueling as they go. CGM provides valuable feedback to help athletes determine the best approach for their individual needs.
Nutritional Timing and Macronutrient Balance
In addition to timing, the balance of macronutrients in an athlete’s diet also plays a significant role in glucose regulation. Consuming simple carbohydrates without fiber or other macronutrients that slow digestion and absorption can cause insulin spikes and crashes throughout the day. This repeated process can lead to insulin resistance and chronically high glucose levels, increasing the risk of developing Type 2 diabetes.
To stabilize digestion and avoid glucose spikes and crashes, athletes can pair carbohydrates with protein and dietary fat. CGM helps athletes monitor the impact of different macronutrient combinations on their glucose levels, enabling them to make more informed choices about their nutrition.
My Personal Experience
So far so good! I have seen improvements in my health and training fueling as well. It’s another way to see what is really going on inside my body, and being a science geek, I love it!
Changes in Training
I realized I was fueling a bit too much during my shorter, easy z2 sessions. My blood glucose wasn’t rising that much without nutrition, adding workout nutrition drinks with a high glycemic load resulted in unnecessary sugar spikes.
For harder sessions or longer sessions, I haven’t made a lot of changes yet, as part of the focus is to make sure I get enough calories, and I find liquid carbs the easiest way, consuming a maltodextrin/fructose blend of anywhere between 60 to 70grams/hour.
I find that I feel better when I start training at baseline glucose, meaning I have stopped eating an hour before training. Since I train in the mornings, this means starting with a small snack right before my workout or starting nutrition during my workouts.
Changes in Lifestyle
One of the most surprising benefits was in my afternoon mood. I realized that I was eating carb-heavy meals that lead to spikes and subsequent crashes. After discussed with a doctor, he assured me it wasn’t an issue – if blood glucose reverts to a baseline of 70-100mg/dL 2 hours after a meal, its healthy.
I decided to track glucose levels with my mood, and was able to reduce the impact by a few things:
- Control the quantity of carbs by a little, can also help to break meal into two parts rather than one large meal.
- Have a tablespoon of Apple Cider Vinegar (any vinegar works in this matter) before my meal
- Eat vegetables (or salad) and proteins before carbs
Taking these steps I was able to reduce the spike but more importantly – control the glucose levels in the subsequent hours. This means that there was no crash after a spike. Blood glucose returned to a baseline level more slowly rather than a rapid increase and rapid decrease.
Doing this for dinner had a surprising effect – I was sleeping better.
My recommendation: yes. Do try a CGM for at least a month. If you think it will help then continue. If you feel you have somewhat optimized your diet and workout nutrition in that period, and can manage to do so in the future without a CGM, discontinue it.
Is it for you? That’s a question you have to ask yourself while your weight the pros & cons.
Cons of CGM
The way I see it there are three drawbacks of a CGM.
- If you have struggled with eating disorders, or struggled with disordered eating of any form, CGMs can add a layer of unneeded complexity. Do you want to see yourself resort to self-negative talk after a small glucose spike? Or stop eating just to get a positive glucose score? In such cases a CGM will result in negative athletic performance, and eventually lead to REDs or injury.
- Cost – As an endurance athlete, be it runner, cyclist, cross-country skier or triathlete, there is always a plethora of gadgets to choose from on a limited budget – choose wisely!
- Drowning yourself in data. If you are comfortable with managing your nutrition, understand the metrics, are looking to learn or have a coach to guide yourself, then it’s a great tool. However if you are collecting data from your watch, power meter, HR, HRV, etc. then it’s just another number to further get lost in training.
CGM and Endurance Sports: Swimming, Cycling, and Running
Now let’s explore how CGM specifically benefits endurance athletes participating in swimming, cycling, and running. These sports require sustained effort, making glucose regulation and optimal fueling strategies essential for performance.
CGM for Swimmers
Swimmers face unique challenges when it comes to maintaining glucose levels during training and competitions. The water environment can affect insulin sensitivity, potentially leading to fluctuations in blood sugar levels. CGM provides swimmers with real-time data on their glucose levels, allowing them to adjust their fueling strategies accordingly.
By monitoring glucose levels before, during, and after swimming sessions, swimmers can fine-tune their carbohydrate intake to maintain stable energy levels. CGM also helps swimmers identify any potential issues, such as hypoglycemia or hyperglycemia, and take appropriate actions to prevent them.
CGM for Cyclists
Cycling is a demanding endurance sport that requires sustained effort over long distances. Maintaining glucose levels is crucial for cyclists to avoid bonking and perform at their best. CGM provides valuable insights into how the body utilizes glycogen during cycling and helps cyclists adjust their nutrition and hydration strategies accordingly.
By tracking glucose levels in real-time, cyclists can determine the optimal timing and quantity of carbohydrates to consume during long rides. CGM enables them to strike the right balance, ensuring a steady supply of fuel without overwhelming the body with excessive glucose.
CGM for Runners
Running places significant demands on the body’s energy systems, making glucose regulation essential for optimal performance. CGM allows runners to monitor their glucose levels during training runs and races, helping them fine-tune their fueling strategies.
With the help of CGM, runners can experiment with different carbohydrate intake strategies before, during, and after runs. By analyzing the impact of various fueling approaches on their glucose levels, runners can optimize their nutrition to sustain energy levels and enha nce their endurance.
Lifestyle Changes with CGM
CGM not only benefits athletes during their training and competitions but also leads to positive lifestyle changes. By providing real-time feedback on glucose levels, CGM helps athletes develop a better understanding of the impact of their dietary choices on their overall health.
Optimizing Post-Meal Glucose Levels
CGM enables athletes to track their glucose levels after meals and make adjustments to their dietary habits. By controlling the quantity of carbohydrates, consuming vinegar before meals, and prioritizing vegetables and proteins before carbs, athletes can stabilize their post-meal glucose levels.
Maintaining a more stable glucose profile after meals can lead to improved energy levels, reduced mood swings, and better overall health. CGM serves as a valuable tool for athletes looking to optimize their nutrition and lead a healthier lifestyle.
Improved Sleep Quality
The impact of glucose levels on sleep quality has been explored extensively. By maintaining stable glucose levels throughout the day, athletes may experience improved sleep patterns and overall sleep quality. CGM allows athletes to identify any glucose spikes or crashes that may disrupt their sleep and make necessary adjustments to their nutrition and lifestyle.
Conclusion: Embrace the Benefits of CGM
In conclusion, CGM offers a multitude of benefits for endurance athletes, including swimmers, cyclists, and runners. By providing real-time data on glucose levels, CGM helps athletes optimize their performance, enhance their endurance, and improve their nutrition. It enables athletes to fine-tune their fueling strategies, adjust their macronutrient balance, and make informed decisions about their training and competitions.
Moreover, CGM encourages athletes to lead a healthier lifestyle by promoting better dietary choices and helping maintain stable glucose levels throughout the day. By embracing the benefits of CGM, endurance athletes can unlock their full potential, achieve their performance goals, and embark on a journey towards optimal health and well-being. So, why not give CGM a try and experience the transformative power it can bring to your athletic journey?
