Pancreas & Insulin Production for Athletes - Function & Resistance

You don't need to be an expert in endocrinology to manage insulin levels, but it will help you to know some basics about the subject.

The effects of insulin are similar in the liver and in muscle tissue. When insulin levels rise, the liver and muscles increase their uptake of glucose and their synthesis of glycogen (the storage form of glucose). At the same time, insulin reduces the breakdown of glycogen in the muscles and the liver; it also decreases the synthesis of glucose from amino acids, lactate and glycerol in the liver. In muscle, insulin also raises the uptake of amino acids (especially the branched-chain amino acids leucine, valine and isoleucine) and decreases protein breakdown. Therefore, your muscles grow.

Insulin tends to affect most hormones in the body. When insulin goes up, the levels of catabolic hormones (such as cortisol and glucagon) fall. Additionally, insulin is required for (and stimulates) the production of insulinlike growth factor-I (IGF-l) in the liver and may be involved in regulating IGF binding proteins.

When insulin drops, the levels of catabolic hormones, such as cortisol, tend to rise.

Also, as insulin goes down and catecholamine (adrenaline and noradrenaline) levels go up, fat cells release free fatty acids into circulation to be burned for energy. IGF-l production is decreased and there may be negative effects on IGF-binding proteins.

Insulin decreases the use of fatty acids for fuel and cuts down the production of ketones in the liver. When insulin levels drop, the opposite effects occur: Uptake of glucose from the blood by various tissues is reduced; glycogen is broken down to glucose and used for fuel; and the burning of free fatty acids for fuel increases (this can lead to the production of ketones in the liver under certain circumstances). Additionally, the liver may start using amino acids, lactate and glycerol to make glucose. Of course, all this depends on the level of insulin sensitivity of the cells.