The benefits of exercise don’t just stop at improving your cardio or building a stronger body to offset pain and osteoporosis. There are other seriously positive side effects, such as reducing your risk of some cancers and improving your blood sugar control.

Blood sugar used to be a topic reserved for diabetes discussions, but the subject has now moved into mainstream wellbeing and fitness circles. More and more brands now allow us to check on our levels from home, and it’s now possible to link your blood sugar to your workout routines via various bits of fitness tech. But how does exercise impact our blood sugar?

Blood sugar levels refer to the amount of glucose in our bloodstream. “Your blood sugar has the important job of supplying all the cells and tissues within our body with energy to do their jobs, but it’s particularly important for our muscle and brain cells,” says sports nutritionist Janina Gelbke.

Unless you have diabetes, the body is able to finely balance the blood glucose levels. “It is incredibly well maintained in a tight range, between 3.5-7.8 mmol,” adds Gelbke. However, things can influence our blood sugar within these well-set levels.

When, what and how we eat most kinds of food will impact your glucose levels, while exercise and physical activity, sleep, stress, hormones, illness, medications, the weather and hydration “are just some of the things that change our blood glucose levels instantly or over the coming hours or days,” Gelbke adds.

Because of glucose’s role in muscle activity, having the right levels of blood sugar is essential when exercising. That is why there’s been a lot of talk on social media and many products coming out to help people track, monitor or enhance their blood sugar levels.

“Exercise affects our blood sugars differently depending on the type, intensity, duration and time of day,” explains Gelbke. For instance, some studies show that exercising in the evening improves glycemic control more than morning workouts – but it’s worth noting that most of this research has been done in men, and often in men with diabetes.

As for the type of exercise you do, “low-to-moderate intensity or aerobic exercise makes blood sugar levels decrease as it is utilised for fuel and energy,” Gelbke explains. Essentially, when you’re doing a brisk walk or medium-intensity circuit, you’re using up the sugar in your blood and lowering the levels. 

But while you might think you should run off the sugary impact of a bag of sweets, high-intensity exercise actually doesn’t lower your glucose in the short term. “It can make blood sugar levels temporarily increase, as the body will release glycogen stored in the muscles into the bloodstream for extra fuel. Adrenaline will also be released during stressful exercise which can too increase blood glycogen levels,” says Gelbke.

In healthy populations, that spike is nothing to worry about. Research shows that the long-term benefits of all exercise, including HIIT, include an overall reduction in blood sugar levels.

In those with diabetes, consulting blood sugar levels before exercising is important. “People with the condition need to maintain blood sugar levels within the normal range during exercise to both feel good, stay safe from hypoglycaemia and perform at their best. If blood sugar levels are low or very high, you should treat this first and not exercise,” says Gelbke.

People without diabetes can rely on their pancreas and liver to control their blood glucose levels, meaning you don’t need to go on a walk after eating carbohydrates to lower your glucose levels.

“It’s become increasingly trendy for non-diabetics to use glucose monitors during exercise as a way to further enhance performance and optimise sports nutrition and fueling strategies, but this is a very new and upcoming area and definitely not essential for health at all,” says Gelbke.

However, if you feel like your blood sugar may be on the low side – feeling dizzy, shaky, hungry or tired - it’s probably a good idea to eat before exercising. And if you’re worried about your blood sugar, talk to your doctor about it; they’ll be able to do a series of quick tests that’ll see whether your levels are within the healthy range both fasted and after eating. For the majority of healthy people, however, fueling well around your training and doing regular exercise is probably all you need to worry about. 

Images: Getty