Why Do I Need to Manage My Blood Sugar When I Exercise or Play Outside?

When you exercise or play outside, your muscles work hard to help you move. To do that, your muscles need fuel (energy) in the form of carbohydrates (carbs) from food. Eating the right number of carbs also helps keep your blood sugar within a normal range.

When you exercise, your muscles release glucose (sugar). Your muscles also become more sensitive to insulin. This can happen during or after exercise. It can also last for up to 36 hours (about a day and a half). Your muscles also use glucose that is already in your body. Managing your blood sugar while you exercise helps your muscles use glucose better.

What Should I Do to Manage My Blood Sugar Before I Exercise?

You should keep track of the following things before you exercise:

  • Your blood sugar levels before you exercise
  • How hard your exercise will be (Scroll down to see the different types of exercise.)
  • How long you will be exercising

What Should I Eat or Drink Before and After I Exercise?

You should drink lots of water before, during and after you exercise. You should also eat snacks that are high in carbs and protein.

Below are some examples of snacks you can eat before and after you exercise. Carb counts can be different, depending on the brand. Read the nutrition labels before you exercise:

Snack Grams of carbs Grams of protein
Nature Valley® Protein chewy bar 14 10
Yoplait® Light vanilla fat-free yogurt 16 5
KIND® bar 18 8
6 peanut butter crackers 23 3
KIND® Healthy Grains bar 24 3
8 ounces (oz.) of chocolate 1% milk 24 8
Yoplait® Original vanilla low-fat yogurt 33 5
Peanut butter sandwich (1 tablespoon of peanut butter) 33 8

 

How Many Carbs Should I Eat Before Exercising?

The charts below show you how many carbs you should eat, based on the type of exercise you do.

Low-Intensity Exercise

Low-intensity exercise is easy and gets your body moving a little more than usual. Examples include going for a short walk or playing outside. My blood sugar level before exercising Grams (g) of carbs to eat
  Under 100 mg/dl
  • 15-30g
  100-200 mg/dl
  • 15g
  200-300 mg/dl
  • 0g
  • Drink lots of water before, during and after exercising

 

Medium-Intensity Exercise

Medium-intensity exercise (also called moderate intensity) gets your body moving more than usual. It can also be certain types of sports, playing tennis, riding your bike, or walking quickly. My blood sugar level before exercising Grams (g) of carbs to eat
  Under 100 mg/dl
  • 15-30g
  • 15g for every hour of exercise
  100-200 mg/dl
  • 15g for every hour of exercise
  200-300 mg/dl
  • 0g
  • Drink lots of water before, during and after exercising
  300 mg/dl or more
  • 0g
  • Drink lots of water before, during and after exercising
  • If you have ketones, do not exercise until the ketones are clear.

 

High-Intensity Exercise

High-intensity exercise (also called strenuous activity) gets your body as much as possible. It can also include playing many sports, such as soccer, baseball, football, swimming, kickboxing or field hockey. My blood sugar level before exercising Grams (g) of carbs to eat
  Under 100 mg/dl
  • 15-30g
  • 15g for every hour of exercise
  100-200 mg/dl
  • 15g for every hour of exercise
  200-300 mg/dl
  • 0g
  • Drink lots of water before, during and after exercising
  300 mg/dl or more
  • 0g
  • Drink lots of water before, during and after exercising
  • If you have ketones, do not exercise until the ketones are clear.
Rev. 12/2016. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.