Blog

You are currently viewing Fueling Exercise

Fueling Exercise

During endurance exercise (anything longer than 2 minutes of repetitive motion), energy is made available for use by the muscles predominantly by burning fat and carbohydrate. As intensity increases, the proportion of carbohydrate (CHO) increases, and vice versa. Even the leanest among us has considerable stores of fat (more than 20,000 calories stored as body fat), but CHO storage is small (only 800-1500 calories stored as glycogen). Because of the higher rates of use at higher intensities and low storage of CHO, it is possible for “CHO availability” to decline to levels which hinder the athlete’s ability to maintain high intensity exercise in efforts longer than 45-60 minutes. 

Thus, maintaining CHO availability is a key factor in maximizing endurance performance. We can maximize CHO availability for strenuous efforts in three main ways: 

1. Make sure “storage tanks” of glycogen are filled before the effort.

    • Do this by decreasing strenuous training in the days before the effort
    • Eat a high-carbohydrate meal the night before the effort 
    • Eat a high-carbohydrate meal 2-3 hours before the effort
    • Take in 20-30 grams of CHO 15 minutes before the effort starts

2. Consume CHO during exercise.

    • Easy exercise <90 minutes in length: Take in 20-30g CHO to help you feel better, and help you recover faster, but it is not necessary to have a good workout
    • Easy exercise >90 minutes in length: Take in 60g of CHO per hour (including the first hour) during the workout
    • Hard exercise (like a race) <60 minutes in length: Take in 20-30g of CHO about halfway through the workout
    • Interval training <90 minutes in length: Take in 30-50g of CHO during the workout (this can be a good time to practice the skills/logistics of eating during a race)
    • Race >90 minutes: Take in 80-100g CHO per hour during the workout
      NOTE: As you get up above 60g per hour, the KIND of CHO will start to matter. We recommend 2:1 Glucose to Fructose blend. See the note below for some products that fit this concept. 

3. Refill glycogen after exercise. 

    • Immediately following exercise there is a “window” where CHO is taken in faster. This window isn’t as important if you have 24 hours to refill your glycogen stores. If you have less than 24 hours, you should eat 1g of CHO/kg body weight for 4 hours following the effort. 

Untitled design (2)

Some general guidelines 

  1. We say “take in” because CHO can be consumed either in a drink or as food. 
  2. All guidelines above are for SIMPLE carbs (high in the glycemic index, meaning sugar). In order for your body to process the CHO fast enough, it needs to be something that can break down FAST.  
  3. In efforts longer than 10 hours, it’s possible to consume more complex carbs (lower in the glycemic index, something like a potato or bread) early in the effort. Because the intensity will be lower, CHO demand will be lower, and you will be able to keep CHO availability higher even with ‘slower burning’ carbs. Something like a sandwich in a 100 mile race might be great, but that same sandwich in a short race will just sit in your gut like a stone because your body can’t process it fast enough to be useful. 

Some high CHO products to consider

  1. Scratch Superfuel
  2. Maurten drink powder
  3. Science in Sport Beta Fuel
  4. UCANNow that you have a plan for nutrition during workouts, click below to read about choosing a training plan.


How to Pick a Plan

Tags: