Metabolic Health 10 MIN READ

Activity fueling score: Everything you need to know

The human body provides energy through a combination of carbohydrates and fat-based fuels. High-intensity workouts rely dominantly on carb-based sources while the body depends more on stored fat during long, slow burn exercise.

Written by Alina Gufran

Nov 18, 2021
activity fuelling score

The human body provides energy through a combination of carbohydrates and fat-based fuels. High-intensity workouts rely dominantly on carb-based sources while the body depends more on stored fat during long, slow burn exercise.

activity score know

Highlights

  • The fueling score signifies how well-fueled you were during your activity window and ranges from 0 to 10 on a scale. The higher your fueling score, the more optimally fueled you were during your activity,
  • There are three Glucose Zones are: Overfueled [> 140 mg/dL] ,Optimal zones [80-140 mg/dL] (Superset of High & Low intensity) & Underfueled [< 80 mg/dL],
  • When the figures are high for the fueling score and slope, it’s an indication that you were able to maintain appropriate glucose levels during your workout.

Pre-exercise glucose intake and suitable feeding strategies ensure that your body is equipped with the right amount of glucose to sustain your dream performance through the session.

It prevents blood glucose levels decline during exercise and restores glycogen reserves. We call this ‘being optimally fueled’ for your High-Intensity Glucose Zone.

Consistently maintaining glucose levels at an optimum range helps you sustain the intensity of your training. This maximises your performance gain and allows your body to adapt to physical stress.

Sustaining your Glucose Zone is a key factor in maximising your training. You have to fuel your body adequately >60 mins before your exercise to maintain the necessary glucose levels.

We introduced a special metric that helps you manage the fueling of your workout and deliver peak workout performances called the Fueling Score.

The fueling score signifies how well-fueled you were during your activity window and ranges from 0 to 10 on a scale.

The higher your fueling score, the more optimally fueled you were during your activity. If your score is consistently low, we recommend that you re-examine your fueling strategy.

Different metrics contribute to the overall fueling score. It is calculated based on the percentage of the time spent in different glucose zones, the number of falls, and the slope.

Contributors to the Fueling Score

Part 1: Glucose Zones

Glucose Zones help determine your fueling score. They build a comprehensive picture of your glucose levels during exercise. Your fueling score is affected directly by how much time you spend on each glucose zone.

The three glucose zones are

Overfueled [> 140 mg/dL] Glucose Zones

An overfueled state doesn’t affect the performance of your workout but can cause inflammation and is not considered ideal.

Lesser time spent in the overfueled state in your activity window and a lesser proportion of over fueling will help you to inversely achieve a higher fueling score.

When your glucose levels go above 140 mg/dL, your body produces excessive insulin in an attempt to regulate your glucose levels. Excess insulin can cause abrupt changes in your metabolic homeostasis.

The frequency and duration of a hyperglycemic event (>140 mg/dL) can result in long-term consequences for your health such as chronic inflammation, insulin resistance and lipogenesis. Over time, this can have detrimental effects on the body.

Before you begin your workout, insulin secretion induced by a glucose spike (>140 mg/dL) may interfere with your body’s ability to depend on fat as fuel during exercise, affecting the metabolic flexibility you may require in that specific workout session.

Optimal zones [80-140 mg/dL] (Superset of High & Low intensity)

Being optimally fueled means that you have enough glucose supply to flawlessly power your activity. A higher percentage of the optimally fueled state and its longer duration in your activity window will help you achieve a higher fueling score.

1.High Intensity [110-140 mg/dL]

The high-intensity glucose zone (110-140 mg/dL) is ideal for high-intensity and long-duration activities for which you need optimum levels of glucose so that you can sustain your peak performance.

Some of the exercises that can be performed under the high-intensity glucose zones include HIIT, Resistance Training, certain CrossFit programs etc. This parameter also enables athletes to stay aware of the zones that can help them compete at their best and possibly have an edge in their performances.

2.Low Intensity [80-109 mg/dL]

The low-intensity glucose zone (80-109 mg/dL) is ideal for low-intensity activities such as walking, short-distance cycling, yoga, etc. These activities do not require high fueling and can be sustained with a moderately fueled state.

3.Underfueled [< 80 mg/dL]

Being in an underfunded state (<80 mg/dL) during a high-intensity workout can mean that you are hindering the availability of glucose to your muscles. Glucose is also the fuel of the brain.

Being under-fueled during your activity may affect your brain’s optimal functioning. Your overall glucose uptake may also be impacted due to being underfunded.

Adequate glucose supply is critical for sustaining your peak performance, especially during high-intensity activities. In your activity window, a lower percentage of under-fueling and a shorter duration of the under-fueled state will help you achieve a higher fueling score. 

Part 2: Slope Glucose Zones

Slope refers to the trend of your glucose line. A negative slope line can mean lower energy and poorly managed dietary intake.

positive slope workout

Positive Slope during your workout

A 0% slope is desirable and a positive slope is favoured over a negative slope. It gives you an indication of the quality of your fuel.

negative slope activity

Negative Slope during your workout

At the end of your workout or activity, the cognitive energy demand is at its highest. Especially when you are an athlete training for an event that has a deciding factor towards the end.

Ensuring that you consume good quality fuel that provides a sustained level of glucose till the end of your activity can be decisive for your overall performance.

If you notice a negative slope for your workouts, try increasing your glucose intake prior to or during the workout.

Part 3: Falls Glucose Zones

This refers to the number of times your glucose drops by at least 10 mg/dL within a 5-minute time frame. If you have 1 or more falls, your fueling score will be penalised.

activity score slope
Multiple Falls

The glucose dips of real concern occur with longer, more difficult sessions when glycogen stores get depleted.

With a high-intensity workout, there can be a rapid descent in glucose levels. You may experience dizziness and fatigue, especially if the levels hit the hypoglycemic range (below 70 mg/dL).

falls during workout
Zero Falls

Optimising timing and the amount of glucose intake can ensure good energy levels. Limit steep falls in your glucose levels over the duration of your workout to improve your fueling score. 0 falls is considered the paradigm.

How can you Optimise your Fueling Score?

Optimise your fueling score by staying in the optimal zone (80-140) during the workout. Strategic fueling systems that ensure adequate glucose availability to your working muscles during workouts are also essential for an abiding fueling score.

Don’t forget: good glucose intake isn’t about what you do during your training; it’s also about how you fuel outside of training hours, particularly right before the exercise.

1.Pre-workout fueling

lady eating healthy

Glucose intake plays a major role both before and after a workout. Before your workout, glucose serves as the main energy nutrient or “fuel” to:

  1. Maximise muscle and liver glycogen stores,
  2. Provide glucose for intestinal absorption during exercise,
  3. Supply all the energy required in the transition from rest to activity.

Quickly eating carbs can restock diminished glycogen reserves. In fact, the most decisive factor in recovery time is the rate of glycogen repletion.

Quickly eating carbs can restock diminished glycogen reserves. In fact, the most decisive factor in recovery time is the rate of glycogen repletion.

Therefore, once you’re getting ready for or are recuperating from a high-intensity exercise, it’s useful to consciously consume carbs.

The idea is to fill up your liver and muscle glycogen stores. As your carb intake increases, your average glucose will trend upwards. This helps to increase the supply of glucose and glycogen in your system to better prepare for these workouts.

When you carb load ≤ 60 min before workout, insulin, and blood glucose levels are reported to be elevated immediately and they may even negatively impact your performance later. Your last food intake should be ideally timed before the hours that define your specific training.

The amount you eat and what you eat will also affect the timing of your workout.

2.In-workout fueling

Glucose levels that hover around 70 mg/dL can affect your muscles. They may not get the required amount of glucose for performance or for recovery. It is recommended to keep your blood glucose levels above 80 mg/dL for activity.

You can also replenish your levels during the training. During moderate or high-intensity training exercises, when your aim is to hit peak performance, make sure you provide ample glucose to your muscles. This will help with metabolic efficiency and give you enough fuel for your working muscles.

It is also important to pay attention to your glucose levels. Ensure they don’t plunge below 70 as this will lead to the unavailability of glucose. As your glucose nosedives, your abilities like balance and stability might get impaired.

Research shows that episodes of hypoglycemia lead to cognitive decline, difficulty in focus, mental weakness, impaired judgment and a lack of precision and accuracy in complex motor tasks.

Not a good place for good performance. Fuel enough in-workout to ensure your levels are not dipping below 80 mg/dL.

How to Interpret the Activity Fueling Score?

Performance during a workout is affected by multiple factors or variables such as exercise capacity, glucose availability and glucose control.

You can have a bad training session even with a high score and vice versa. Various factors impact your performance. You can feel great and have a low fueling score or feel tired and underperform with a higher fueling score.

The score can give you the awareness of the ways in which you can time your workout and how intense your workout can be based on your fueling trend.

How to use the Activity Fueling Score?

The fueling score can be used to manage the fueling of your workout or training. When the figures are high for the fueling score and slope, it’s an indication that you were able to maintain appropriate glucose levels during your workout.

Similarly, when the value is low, it might be a good time to rethink your fueling strategy during your workouts to ensure that your glucose is sufficiently elevated and doesn’t adversely impact your ability to perform.

The changes you decide on will be impacted by which aspect of the score you choose to address. Are you attempting to raise your glucose level, make it more stable or prevent it from slowly dropping? The strategies will vary depending on your goal.

The score can also be interpreted to understand how your body responds to various situations. For instance, if your score is consistently low during exercise, you may observe the metrics over the past few days to see a pattern that potentially may be the cause.

Factors that affect the Activity Fueling Score

The fueling score can be affected by a host of factors which are a mix of physical, dietary, and internal. Parameters like the intensity of the workout, altitude, and temperature can potentially affect your workout and, thus, the score.

Nutritional yardsticks such as carb dose, type and timing, fat intake, protein intake, diet composition, and caffeine consumption also impact the workout.

Training adaptations, insulin sensitivity, liver and muscle glycogen stores, dehydration, infection/inflammation, fatigue, and stress that naturally impact your workout can affect the fueling score in various ways.

Conclusion

Your fueling score can serve as a useful indicator for your workout routine, and optimising it by using various fueling protocols can help improve performance, calorie-burning, and overall health and fitness levels. Monitoring your slope, falls and glucose zones allows you to manage the timing and amount of glucose loading to ensure optimal energy during your workouts.

The fueling score can help you understand how your body uses glucose during activity. It can aid in identifying diet and exercise combinations that can allow you to train and adapt better to activity. It helps you discover the best fueling strategies suited to your personal needs.

Disclaimer:The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns before undertaking a new healthcare regimen including making any dietary or lifestyle changes.

References

  1. Inflammation: Definition, Diseases, Types, and Treatment
  2. Nutrition rules that will fuel your workout – Mayo Clinic
  3. Diabetes and exercise: When to monitor your blood sugar – Mayo Clinic
  4. Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis

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