Blood glucose response to different exercises

You may have noticed that when you exercise, your blood glucose levels (BGLs) don’t respond exactly the same way with the same exercise, let alone different types of exercise. Sometimes blood glucose levels go up and sometimes they might go down. Sometimes there may be very little change at all. This is because different intensities and durations of exercise impact on the way our bodies use glucose.

Other factors that can affect your blood glucose response to exercise include your fitness level in a particular type of exercise, time of day, hydration, insulin which may be active in your system, whether you’ve had a recent hypoglycaemic event and carbohydrate intake.

Aerobic/Moderate Intensity Exercise

For the most part, moderate intensity aerobic exercise leads to a decrease in blood glucose levels both in the short and long term. This includes activities such as walking, swimming and bike riding where you reach a “lightly puffing” intensity. When we move our bodies continuously at a moderate intensity, our muscles use glucose to fuel this movement. As a result, blood glucose levels decrease and this response can be greater for activities that are longer in duration. It is recommended that Australian adults include 30 minutes of moderate intensity exercise on most day of the week. When regular exercise is established and maintained, your muscles use more glucose. This makes the insulin in your body work better.

Anaerobic/High Intensity Exercise

Activities such as high intensity interval training, sprinting or lifting weights are considered anaerobic. These are activities where your heart rate can increase quite high and you may not be able to talk while you complete it. The increase in your heart rate and the fast-paced movement you complete causes the release of different hormones like adrenaline. These hormones stimulate the release of glucose from the liver as well as using glucose stored as glycogen in the muscles in order to fuel this high intensity movement. As a result, you may see a short-term increase in your blood glucose levels. However, the long-term response (over one or two days) results in a sustained decrease in blood glucose levels.

If you’ve ever completed exercise and seen a short-term increase in blood glucose readings then this is not a cause for alarm, but a natural response. Try checking a few hours later and see where your levels are.

Mixed Intensity Exercise

Mixed intensity activities usually have a combination of both moderate and high intensity components, along with intermittent rest periods. This can be seen in team sports, such as soccer, netball or hockey where there are periods of sprinting and changing direction, followed by periods of pausing or resting. As a result, activities where there is mixed intensity, can either increase or decrease your blood glucose levels.

The best way to determine whether an activity impacts your blood glucose levels is to check before, during and after. This is particularly useful for new activities to best identify your blood glucose response and to plan accordingly. Checking your blood glucose levels is an important part of exercise in the management of diabetes, and can give you a great level of feedback. It’s beneficial to understand how your glucose levels can fluctuate relative to the type of activity you’re performing. This will also allow you to make informed decisions about the timing of exercise, changes to medication regime and meal planning around your exercise.

 

By Hayley Nicholson, Ex Phys CDE

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