Post-workout insulin spike: what’s all the fuss about?

By James Rutherford BSc Hons

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The topic of insulin is one of the most spoken about topics in the sport of bodybuilding, but not a huge amount of people actually fully understand it. First thing’s first, there is a common misconception that insulin is blood sugar (glucose), however, this is not the case, insulin is simply a hormone that regulates blood glucose levels, it is not blood glucose itself.

There are two hormones that regulate blood glucose levels, glucagon and insulin. The role of glucagon is to increase blood glucose levels and the role of insulin is to decrease blood glucose levels, simple. Now the way insulin works are that the brain senses when blood glucose levels are too high and it then sends signals to the beta cells in the pancreas to secrete insulin. This insulin then binds to glucose in the blood and removes it via two main pathways. It transports the glucose either to the liver to be converted into glycogen for storage via a process called glycogenesis or it is shuttled via the GLUT4 transporter (a type of glucose transporter) to muscle and fat cells for them to absorb; this results in a reduction of blood glucose.

The latter of these two main pathways is what we’re interested in as this is the pathway in which the glucose is taken to muscle and fat cells, and it will be the muscle cells that will be much more receptive of this glucose. This is because after training the muscles will be drained of nutrients after having used them up for continuous muscular contractions during training and will want to replenish whatever nutrients they can as quick as they can.

This is where the insulin comes in! Ingesting fast acting carbs and simple sugars post workout will cause a sudden increase in blood glucose which will of course signal a sudden release of insulin to counteract this. As described above this insulin will then attempt to remove the glucose from the blood as efficiently as possible by shuttling it to muscle and fat cells, but the insulin release causes muscle cells to become hypersensitive and at this point the muscle cells will be far more receptive than the fat cells as they have a greater need for the glucose and therefore the insulin secreted will shuttle the majority of the glucose to the muscle cells, which will also be readily absorbing amino acids to stimulate muscle protein synthesis. Once inside the cells the glucose is then phosphorylated (a process that involves protein enzymes being switched on) to form glucose-6-phosphate, a compound that can be either converted into glycogen for storage within the muscle or enters the metabolic pathway glycolysis, which involves the glucose being converted into pyruvate, resulting in the production of ATP (adenosine triphosphate) which is then readily available to facilitate muscular contraction.

All in all the process of insulin spiking after training and the effect it has on muscle cells is a very complex biological process that can be made simple by these three easy to remember steps…
Increase blood glucose by ingesting simple fast acting carbs

Insulin secreted shuttles glucose to the muscle cells and causes these cells to increase their uptake of amino acids for enhanced protein synthesis

Muscle cells absorb the glucose and use it for anabolic processes to facilitate future muscular contractions
So in conclusion, make sure that your post-workout supplementation contains some form of simple carbs, high-quality whey protein and BCAA’s as all of these nutrients will be rushed to the muscles to stimulate recovery, growth and most importantly GAINS!

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