Exercise is good for health. It can make muscles and bones stronger, help improve mood and emotions, and most importantly for those with type 2 diabetes, it can help control blood glucose levels (BGLs).
But how much exercise is right, what type of exercise should you be doing and how hard should you be working? These factors can be broken down with the FITT principle– the frequency, intensity, type, and time of exercise.
Frequency – How often should you be exercising?
When you exercise, the muscles start to use the glucose in your bloodstream as a form of energy. This occurs without the help of insulin, and is called a non-insulin mediated glucose uptake. The benefits of exercise don’t stop when you stop either, they can keep going for hours afterward. When you exercise, the body becomes more sensitive to insulin, the hormone that helps glucose enter your body’s cells. This increased insulin sensitivity means that your body is more efficient at using the blood glucose, which lowers your BGLs. This sensitivity can last for up to 72 hours!
For this reason, the Australian guidelines recommend that you go no more than two consecutive days without exercising. This can include any type of exercise, and the goal is to build up to 210 minutes of moderate activity (or 125 minutes of vigorous activity) each week. This should include two resistance sessions and an enjoyable form of aerobic training.
Intensity – So how hard should you be working?
The intensity of exercise refers to how hard you are working while you exercise. This can be measured in several different ways, but the most common is a rating of perceived exertion (RPE) scale. This is a simple 1-10 scale, where 1 indicates super light exercise you could do all day, and 10 indicates working so hard you don’t think you can do any more. While doing moderate exercise, you should aim to be around 4-6 out of 10 on the RPE scale.
Another way to measure intensity is using the talk-sing test. Light exercise means you can sing while exercising, moderate intensity means you would be able to talk but not sing and vigorous exercise happens when you are unable to hold a conversation while exercising.
These intensities matter while exercising as they can affect how your blood glucose levels respond to exercise. When exercising at a high intensity (or for a long time) some people will find that their blood glucose levels rise. This happens because the body releases adrenaline, a hormone that triggers your flight or fight response. Adrenaline triggers the release of glucose from the body’s stores, so the amount of glucose in the blood increases. This causes a higher BGL reading at the end of exercise. However the muscles are still taking glucose from the blood, so your BGLs will keep coming down even when you have finished exercising.
Its important to check your BGLs before exercising, as if they are already high it can be best to keep exercise at a low-moderate intensity to avoid possibly having a spike from vigorous exercise.
Type – what exercise should you be doing?
There are many different forms of exercising; walking, weightlifting, soccer, swimming, netball, lawn bowls – and not everyone will enjoy the same activities. Exercise can be grouped into two main types: aerobic exercise (eg: walking, swimming, rowing, social tennis, bowling) and resistance exercise (lifting weights, using machines, group classes, home programs with equipment or bands).
Aerobic exercise can be described as exercise for the heart and lungs. It is important to find a form of aerobic exercise you enjoy doing, as this makes it easier to incorporate into your everyday activities. Aerobic exercise is an effective way to lower BGLs, as it uses large muscle groups, so there is a higher uptake of glucose while exercising at a moderate intensity.
Resistance training is good for muscle and bone strength. Increasing muscle mass means there are more cells to uptake the glucose in your blood. Resistance training does not need to be done in a big gym, using common items you would find in your house or pantry, or just your own body weight can be enough to provide benefits to your muscles and bones.
Time – how long should you be exercising for?
The guidelines recommend 210 minutes of moderate exercise or 125 minutes of vigorous exercise each week. This number can sound like a lot, so it is important to remember that something is better than nothing, especially if you are just beginning exercise. While the duration (how long you spend doing an activity) of any exercise block will vary depending on what you are doing, aiming for around 30 minutes of moderate activity each day ensures you can build up to achieving the guidelines.
This does not have to be done in a full 30 minute block! Breaking exercise up into ‘exercise snacks’ can make it more manageable to fit into your day. For example, a 10 minute walk after breakfast, 5 minutes of sit to stands and calf raises in television ad breaks, 5 minutes of wall pushups and marching on the spot while cooking dinner and a 10 minute walk at the end of the day adds up to 30 full minutes of activity!
References:
Exercise is Medicine Australia. (2014). Type 2 Diabetes and Exercise. http://exerciseismedicine.com.au/wp-content/uploads/2018/06/2014-T2DM-BRIEF.pdf
American Diabetes Association. (2023). Why Does Exercise Sometimes Raise Blood Glucose (Blood Sugar)? https://diabetes.org/healthy-living/fitness/why-does-exercise-sometimes-raise-blood-sugar
Live Lighter. (2020). How to keep on track with (and keep track of) your exercise resolution. https://livelighter.com.au/news/how-to-keep-on-track-with-and-keep-track-of-your-exercise-resolution
