We know that exercise burns glucose, but the bigger picture of how it helps our blood sugar metabolism is a lot more complex than that.
For a start, whereas insulin is necessary to get glucose into most types of cells in our bodies, the cells of our skeletal muscles - the ones we use to propel ourselves - can take in sugars for fuel, without needing insulin.
Those muscle cells have complex work-arounds that enable them to take in sugars in response to muscular action. This is collectively called exercise-meditated glucose transport. It makes sense: if you are running for your life from a predator, muscles are the most important thing to fuel, and you need that fuel sucked into those muscles as fast as possible! We don’t fully understand these mechanisms, but we can see them work, and researchers are looking into how they do that.
176 genes have been found that affect glucose uptake by muscles, and exercise regulates more than half of these genes. These include many genes that previously have not been associated with exercise-induced insulin sensitivity. Interestingly, the genetically driven changes triggered by endurance exercise and resistance exercise have little overlap: they are mostly different. It’s a complex field of research that is important in the modern world because of the twin epidemics of obesity and diabetes.
Because this is exercise-meditated glucose transport rather than insulin-dependant glucose transport, it works in all of us, including people whose tissues have become somewhat insulin resistant, as well as in Type 2 diabetics. And our muscles continue to uptake extra glucose in the post-exercise recovery period: a bonus for lowering blood sugars and for weight loss!
In our day-to-day life, our skeletal muscles also use insulin: indeed skeletal muscle is the primary tissue for maintaining glucose regulation. Exercise actually improves the insulin sensitivity of glucose uptake in skeletal muscle: ongoing regular exercise helps reduce insulin resistance and makes your metabolism work better in the long run!
You can see why exercise is considered an essential cornerstone of treatment for insulin resistance and Type 2 diabetes, and how it helps healthy folk prevent those conditions!
Muscle fibre: Are you fast-twitch or slow-twitch?
Have you ever tried a new way of exercising, thoroughly enjoyed it and felt it really worked for you? Or conversely, have you ever found that something that sounded great just wasn’t for you, or you didn’t feel good afterwards? That could be because of your muscle fibre type. There are two types of muscle fibres, fast-twitch and slow-twitch. We all have some of both, but those of us with a preponderance of fast-twitch fibres will be better at sprints: olympic track stars are born that way! Those of us with more slow-twitch fibres will prefer walking, jogging or yoga.
If you eat salmon you will have seen the different coloured muscle fibres: there are some that are browner, and they are closer to the skin, and more prominent close to the tail. They are the fast twitch fibres: they do the hefty work of pushing the salmon upstream when they go home to spawn. The other fibres are great for cruising in the ocean. And think of chicken legs: they are darker because chickens are runners!
If you are interested in finding out more about your muscle composition, a genetic test can help you do that, and tell you what kind of exercise might suit you best.
Just do it!
Exercise at a time that works for you. Exercise sets some people up for the day, so they like to hit the running trail or the gym early. Others do better exercising later in the day, when it can help burn off steam and promote relaxation. If you have been sedentary all day you may find that 15-30 mins exercise at the end of the day helps you sleep better.
Exercising with a friend is more fun for most of us. If you want to be spurred on, go with someone competitive. If you want gentle pleasant company, pick someone who enjoys the game itself more than the end score. If you have the time and space for a dog in your life, they are a great incentive to get out regularly. Or, if you have a friend who has a dog, they might be glad of company on walks, or appreciate your help to walk the dog for them sometimes.
Isn’t it funny how people say “I have to take the dog for a walk” because they recognize it’s good for the dog. But you don’t often hear people say “I have to take myself for a walk!”
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