We think about maximising athletic performance in two categories: On-Hours and Off-Hours.
On-Hours = training or performance. Off-Hours = recovery and preparation.
In this article, we'll discuss:
- What is Glucose Variability?
- How can I experiment to find what fuel sources work best for me?
- What are some potential risks of high Variability to my health and performance?
What is Glucose Variability?
Glucose Variability is a key metric you can use to validate how your fuel provides stable and sustainable energy (or not) in a specific time frame. It represents the degree of movement (ups and downs) of your glucose levels on the Live Graph. To be more precise, it's a summary metric that indicates the "dispersion" of glucose data or how widely your glucose levels are spread around your Average Glucose.
Overall, Glucose Variability is a good way to understand how much your glucose levels vary. Analyzed in conjunction with your Off-Hours Glucose Zones and you will get a precise representation of both the amplitude and frequency of your glucose levels over time outside of training.
Movement of the line on the Live Graph is normal as your body naturally regulates glucose levels with an average variability of 10-12 mg/dL during rest (unpublished evidence). However, during rapid drops (and even rapid increases) in glucose, you may experience fatigue, lethargy, lack of focus, and lack of energy. Significant changes (steep and large upward or downward movements) can impact energy levels, feeling, key training adaptations and performance in general.
Determining which type of food and amount of fuel to consume to help prevent a dip or a steep spike in your glucose levels is critical. It’s the difference between sustained energy and feeling sluggish.
How can I experiment to find what fuel sources work best for me?
To experiment, start by eating a banana. See immediately how your body reacts to it. From this, you can start to discover which foods provide the most stable and sustainable energy. (Hint: It may or may not be a banana.)
Look at the two graphs below. This is about limiting the steep "spikey" nature of the line on the graph—stable and sustainable (optimal) means relatively flat. The goal would be to find fuel sources that result in the graph on the right.
What are some potential risks of high Variability to my health and performance?
Variability is also sensitively associated with vascular health and oxidative stress. And it can potentially increase the risk of developing cardiovascular events long term. A series of published evidence has demonstrated that vascular function is strongly linked to endurance capability. In fact, most of the key parameters around endurance capacity (like VO2max and the anaerobic threshold) are molecules-delivery dependent (like glucose or oxygen) that rely on vascular functionality.
In the context of optimising performance, variability can be a good proxy to understand the level of metabolic perturbations and change your body is facing. For example, consuming simple sugars (e.g., concentrated high-glycaemic carbohydrates) immediately before exercising might cause blood sugar to rise rapidly—often triggering peak insulin release and potentially affecting endurance performance due to: i) rebound hypoglycemia, ii) depressed fat metabolism and iii) early depletion of glycogen stores.
Therefore, a low Glucose Variability before exercise would imply an ideal source of glucose that stabilises blood sugar and sustains muscle metabolism. Reducing Glucose Variability in the hours leading up to an event by consuming a low-glucose response food would provide a relatively slow rate of glucose absorption into the blood. This results in a stable glucose supply to the muscle as exercise progresses while reducing the impact of insulin release on subsequent performance. A relatively normal insulin level allows to preserve blood sugar availability and optimises fat oxidation while sparing glycogen reserves.
Discover fuel sources and other techniques to lower your Glucose Variability to support stable and sustainable energy. Validate your current strategy or discover a better plan. Over time, you will learn what works best for you. And remember, what works for you may not work for someone else, and vice versa.
Data visualisation is key. We make it easy for you.
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- Zhou, Z., Sun, B., Huang, S., Zhu, C., & Bian, M. (2020). Glycemic variability: adverse clinical outcomes and how to improve it? Cardiovascular Diabetology, 19(1), 102.
- Jeukendrup, A. E., Raben, A., Gijsen, A., Stegen, J. H. C. H., Brouns, F., Saris, W. H. M., & Wagenmakers, A. J. M. (1999). Glucose kinetics during prolonged exercise in highly trained human subjects: Effect of glucose ingestion. Journal of Physiology, 515(2), 579–589.
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- Hearris, M. A., Hammond, K. M., Fell, J. M., & Morton, J. P. (2018). Regulation of muscle glycogen metabolism during exercise: Implications for endurance performance and training adaptations. Nutrients, 10(3), 1–21.
- Figueira, F. R., Umpierre, D., Bock, P. M., Waclawovsky, G., Guerra, A. P., Donelli, A., Andrades, M., Casali, K. R., & Schaan, B. D. (2019). Effect of exercise on glucose variability in healthy subjects: randomized crossover trial. Biology of Sport, 36(2), 141–148.