You’ve probably heard that exercise is good for your health. But what’s the effect on blood glucose? Does it cause your levels to drop or spike? And what does this mean?

It may come as a surprise, but both is true.

Understanding why and when what happens, is a key part of managing your health. 

Exactly how exercise alters glucose levels can be different for everyone. Some may notice bigger effects, whereas others will only see small changes in their blood sugar curves.
A general rule of thumb is that how your glucose changes (up or down) depends on the type, duration, and intensity of the physical activity as well as your diet and overall health status. So, when it comes to blood sugar and exercise, the relationship is complex.

The best way to understand the relationship between exercise and blood sugar is to jump right into science. So let’s have a look at one glucose curve.

When you exercise, your body relies on two sources of fuel: glucose and fat. So how your blood glucose changes during exercise depends on the intensity level of your workout and the fuel source your body is using.

Steady-state cardio exercises, like yoga, easy jogging, or gentle swimming, don’t require quick bursts of energy. In these cases, it gets more of its energy from fat, so your blood glucose will usually stay at the same level or decrease. 

During high-intensity exercises, your body doesn’t have the supply of energy on hand to fuel your workout. So, it provides glucose from the storage to immediately fuel your workout. This extra burst of glucose causes a sharp increase in blood glucose. 

While you might be worried about the sudden blood sugar rise during high-intensity exercise, you shouldn’t be. The acute blood sugar increase during high-intensity exercise is a completely different physiological response than eating a cookie that spikes your glucose. The rise in blood sugar during high-intensity training actually improves both fasting glucose and insulin sensitivity over time. These adaptations support your metabolic health and blood sugar management.

By continuously measuring your blood glucose levels before, during, and after exercise, you will analyze your body’s response. Seeing how your glucose levels change during exercise helps you to find the right exercise for your situation, and meet your health goals.