Fitness Matters: Insulin Sensitivity Linked To Muscle Mass

What is Insulin Resistance?

The hormone insulin works to regulate the amount of sugar (glucose) in your blood. Basically, we eat food, the pancreas releases insulin into the bloodstream to escort glucose to your muscles, fat and cells, and as a result energy is created. For those that are insulin sensitive, this process is efficient and works well. If someone is insulin resistant, their insulin isn’t ‘sensitive’ to this process, meaning their insulin is unable to effectively ferry glucose to those areas and complete that energy production transaction. This leads to a buildup of glucose in the blood, later this can turn to fat, and eventually this impaired process can lead to type 2 diabetes. The body will attempt to overcompensate for having low insulin sensitivity and excess glucose in the bloodstream by producing even more insulin. This excess insulin is associated with damaged blood vessels, nerve damage, high blood pressure, obesity, amongst other serious health problems.

Take away point:

Insulin Sensitive = good (more responsive insulin, efficient energy production)

Insulin Resistant = bad (less responsive insulin, glucose & insulin build up leading to many different health complications)

Insulin resistance typically has no symptoms. Regular exercise, specifically weight bearing and high intensity interval training can help reverse insulin resistance. Often those who are insulin resistant are overweight. Losing weight by increasing daily activity and eating at a deficit to your maintenance calories can also reverse this issue.

Nowadays we’re seeing an increase in insulin resistance and very low muscle mass is a risk factor for it. Higher lean muscle mass is correlated to better insulin sensitivity, and in turn lower risk of type 2 diabetes. Exercise, more specifically weight training, can develop muscle tissue, expanding the storage space for blood sugar in the muscle, and therefore improving insulin sensitivity.

Take away point: More muscle mass = more storage capacity for glucose = less likely to have a build up of glucose in the bloodstream = can access and use this stored energy (glucose) later.

Glycogen is the storage form of carbohydrates. Glucose is stored in the form of glycogen in our muscles and in our liver. So the glucose is escorted by the insulin away from the blood and into the cell and becomes glycogen. We rely on these stores of glycogen for energy throughout the day and during exercise, but without optimal insulin sensitivity we’re losing out on this energy! It sounds counter productive to say that exercise gives you energy, but it literally does!

Take away point: Weight bearing exercise = increase muscle mass = improve insulin sensitivity = greater storage capacity for glycogen = more energy stores to access.

Unfortunately we can’t choose where the carbohydrates are stored within the body. Glycogen can only be depleted from the muscle it’s stored in, but glycogen stored in the liver can be used throughout the body. So you can’t expect to go for a long run or do countless squats without depleting the glycogen stores in your leg muscles, and then hope to rely on the glycogen stores in your biceps to carry on running and squatting! It just doesn’t work that way. Exercise, specifically resistance training, really is one of the best ways to train the body because it can easily target the whole body and different muscles through a variation of movements.

Take away point: We need to exercise in a variety of ways in order to work ALL our muscles to ensure we’re utilising all the energy (glycogen) we’ve stored in our muscle tissue.

Insulin sensitivity can result in the dilation of blood vessels, which in turn can decrease blood pressure; this is known as vasodilation. In the conditions of insulin resistance, the opposite can happen – vasoconstriction, which can impact both blood flow and blood pressure negatively. What if we could increase the formation of blood vessels that surround a muscle, therefore enhancing blood flow and supplies of oxygen and nutrients, effectively raising energy levels?! Oh, but wait…. WE CAN!!!!! WITH EXERCISE!!!! Increased formation of blood vessels is called capillarisation. When capillarisation increases, our muscles are able to work for longer without fatiguing because we have essentially created more avenues for the blood to flow.

Take away point: Increased muscle mass helps with insulin sensitivity. Exercise helps to increase both muscle mass and the formation of new blood vessels that carry blood, oxygen and nutrients to our muscles.

In summary:

Load bearing exercise = gains in lean muscle mass.

More muscle mass = more insulin sensitive.

More insulin sensitive = more dilated blood vessels.

More dilated blood vessels = improved blood flow and blood pressure.

Improved blood flow / pressure = more energy! #MoveMore!