What is the Glucose Score?

The Glucose Score combines all relevant metrics associated with glucose control and builds a clear picture of your glucose levels during exercise. It takes into account your Glucose Performance Zone, steep changes in your glucose levels, the overall trend of your glucose line, and low glucose levels.

The score is provided on a scale of 1 to 100. The higher your score, the more optimal your glucose control was, illustrating whether or not your circulating glucose availability was optimal during exercise. A lower number may indicate that you need to adjust your fueling strategy.

How is my Glucose Score calculated?

Four factors are considered in calculating your score. These parameters are combined and weighted with a proprietary algorithm.

Note that you may have a bad workout even with a high score and vice versa. There are multiple variables that impact performance in addition to glucose. Context and understanding are important. The goal of the score is to help you avoid fueling from being your limiting factor.

Here are the factors that influence your Glucose Score. Use this as a guide to learn how to improve your Glucose Score.

Glucose Performance Zone

The percentage of time you spend in your GPZ. Ensuring that you are well-fueled for high intensity and long duration workouts is critical. Maintain your glucose levels within your GPZ to improve your score. 100% of time in GPZ is ideal.

Glucose Lows

The percentage of time spent below 80 mg/dL. Low glucose levels can impact your fuel availability during high intensity and long duration training. Experiment with increased glucose intake to avoid glucose lows. Avoid time below 80 mg/dL during your workout to improve your score. 0% of time with Lows is ideal.

Glucose Drops

The number of times your glucose drops by at least 10 mg/dL within a 5-minute time frame. Steep drops in your glucose levels can result in fatigue, lack of focus, and overall lack of energy. Optimize the timing and amount of glucose intake to ensure adequate energy. Limit steep drops in your glucose levels over the duration of your workout to improve your score. 0 Drops is ideal.

Glucose Slope

The overall trend of your glucose line. A downward sloping glucose line could indicate mismanagement and non-optimized energy levels. Experiment with increasing your glucose intake. Maintain your glucose levels during your workout to improve your score. 0% Slope is ideal, and a positive Slope is better than a negative Slope.

How do these factors impact my performance?

Glucose Performance Zone

Spending more time in the glucose zone that you feel best in is a good way to know you are supplying your muscles with the amount of glucose they need to operate at peak performance. Higher glucose levels during exercise increases glucose uptake in the muscle.1 Additionally, as exercise duration increases and glycogen stores deplete, interstitial glucose takes a predominant role in contributing to energy expenditure sustaining the energy for the muscular work required.2 Glucose up-regulation depends on a variety of factors3 (carbohydrates intake, exercise intensity, hormonal responses, etc.) and how these factors impact glucose regulation varies on an individual basis. One should experiment how to potentially maintain a stable and relatively higher glucose level during exercise to optimize performance. Type, amount, and timing of carbohydrate intake also affect the ability to maintain a certain level of glucose (time in GPZ) during exercise.

Glucose Lows

If your glucose is too low, you may be impacting glucose availability for your muscles, especially if you are trying to exercise at higher intensity. During exercise, low glucose levels might impair your brain’s functions, overall glucose availability to the working muscles, and total glucose uptake. Ensuring a sufficient and stable supply of glucose to the working muscle is critical to support energy expenditure during extensive endurance exercise.2 Any low glucose level (<80 mg/dL) might impact this.

Glucose Drops

A sudden negative change in your glucose level during exercise might signal a misalignment of glucose delivery to glucose uptake, and will potentially cause feelings of lack of energy. The steepness and frequency of drops indicate an instability of glucose supply. Drops can be multifactorial, but having many drops, steep drops, or long duration drops indicates either unstable/variable intake or intensity changes. Many drops is a good indication that an athlete is trying to fuel but is struggling to maintain glucose level, so intake should be increased in frequency, volume, or both.

Glucose Slope

A negative trend in your glucose line indicates that you have a decreasing amount of glucose being delivered to your working muscle compared to the amount being used across the duration of the workout. This may indicate the depletion of your glycogen stores and readily available fuel. A negative slope should be a prompt to adjust your nutrition strategy and intake fuel at a higher rate.

Should my Glucose Score always be high?

Not necessarily. The aim of the Glucose Score is to provide you with an indication to use during moderate-to-high intensity sessions where ensuring proper glucose availability is key. And also during longer endurance sessions where the role of maintaining glucose levels is associated with performance outcomes. During low intensity sessions, your aim might be to ensure a low Glucose Score to train the body for mental and physical adaptations.

How do I optimize my Glucose Score?

Having visibility and fueling to your glucose trend to ensure a stable and sustainable glucose level is the easiest way.

Without this, the best strategy is to use a feeding schedule designed for the type of training you are doing to ensure a proper glucose availability to your working muscle.

General guidelines exist and the Glucose Score will provide you the ability to adjust these based on your own physiology and glucose control during exercise. This is personal fueling.

Don’t forget, good glucose availability isn’t just about what you do during your training, it is also about your fueling outside of training hours, particularly in the hours before training (Priming).

What the score is not:

Performance is a multifactorial phenomenon. That means that multiple variables influence exercise capacity and tolerance, glucose availability and glucose control included. The Glucose Score is intended to help minimize poor glucose availability as a negative factor on your performance.

Note that you may have a bad workout even with a high score and vice versa. There are multiple factors that impact your performance. One can feel great and have a low Glucose Score as well as feeling tired or underperform with a higher Glucose Score.

What affects the score?

External Physical Factors

External Nutritional Factors

  • Intensity - workload

  • Altitude

  • Temperature

  • Carbohydrate dose, type and timing

  • Fat intake

  • Protein intake

  • Diet composition

  • Caffeine

Internal Physical Factors


  • Training Adaptations

  • Insulin sensitivity

  • Liver and Muscle glycogen stores

  • Dehydration

  • Infection/Inflammation

  • Fatigue

  • Stress


How do you use the score?

The Glucose Score can be used to help manage your training or race. When the number is high it’s an indication that you were able to maintain and properly control glucose level during exercise.

Conversely, when the value is low, it may be a good idea to review your feeding strategy during training to make sure that glucose availability isn’t a limiting factor in your ability to perform. The adjustment(s) you decide to make will likely be impacted by which parameter of the score you are working to address. Are you trying to get your glucose higher, more stable or prevent it slowly dropping? Strategies to address these are all slightly different.  

The score can also be used to learn how the body reacts to various situations and stimuli.

For example, if your score is consistently low during exercise, you notice that the past few days of cumulative measurements to identify a pattern that may have been the cause.

Conclusion

Your glucose control just got an upgrade. Now that you’re armed with an improved feedback loop, you’re more empowered than ever to optimize your fueling strategy. Stop guessing, discover what works best for you, and evaluate how different fueling protocols impact your Glucose Score. Welcome to the world of true personal fueling.

References

  1. Institute of Medicine (US) Committee on Military Nutrition Research; Marriott BM, editor. Fluid Replacement and Heat Stress. Washington (DC): National Academies Press (US); 1994. 8, Timing of Carbohydrate Supplementation During Prolonged Strenuous Exercise.
  2. Coyle, E F et al. “Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate.” Journal of applied physiology (Bethesda, Md. : 1985) vol. 61,1 (1986): 165-72. doi:10.1152/jappl.1986.61.1.165
  3. Suh, Sang-Hoon et al. “Regulation of blood glucose homeostasis during prolonged exercise.” Molecules and cells vol. 23,3 (2007): 272-9.