Insulin (from Latin insula – island) is a hormone of peptide nature, formed in the beta cells of the pancreatic islets of Langerhans. It has a multifaceted effect on metabolism in almost all tissues. The main effect of insulin is to reduce the concentration of glucose in the blood. In bodybuilding, insulin is used because of its pronounced anabolic effect. Alternatives are oral hypoglycemic agents such as Diabeton.
Insulin increases the permeability of plasma membranes to glucose, activates key enzymes of glycolysis, stimulates the formation of glycogen from glucose in the liver and muscles, increases the synthesis of fats and proteins. In addition, insulin inhibits the activity of enzymes that break down glycogen and fat. That is, in addition to its anabolic action, insulin also has an anti-catabolic effect.
Two types of tissue are the most dependent on insulin for glucose transport: muscle tissue and adipose tissue, the so-called insulin-dependent tissues.
Effects of Insulin
Metabolic effects of insulin
- Enhancement of cellular uptake of glucose and other substances;
- activation of key enzymes of glycolysis;
- increase of intensity of glycogen synthesis – insulin boosts glucose storage by liver and muscle cells by polymerizing it into glycogen;
- decrease in intensity of gluconeogenesis – reduces the formation of glucose in the liver from various substances of non-carbohydrate nature (proteins and fats).
Anabolic effects of insulin
- increases cellular uptake of amino acids (especially leucine and valine);
- enhances the transport of potassium ions, as well as magnesium and phosphate, into the cell;
- enhances DNA replication and protein biosynthesis;
- increases synthesis of fatty acids and their subsequent esterification – in adipose tissue and the liver, insulin promotes the conversion of glucose into triglycerides; when insulin is deficient, the opposite happens – fat mobilization.
Antitabolic effect of insulin
- suppresses protein hydrolysis – reduces protein degradation;
- reduces lipolysis – reduces the flow of fatty acids into the blood.
The dangers of insulin use – a lethal dose
Perhaps the main factor in insulin’s bad reputation is the risk of developing hypoglycemia. On any forum, one can find posts of a cautionary nature, as if even a small overdose of insulin can be fatal. However, scientific and practical data tell a different story: Dr. G Kernbach-Wighton and colleagues have determined that the smallest lethal dose of insulin is 100 IU, that is, a full insulin syringe. Many people stay alive even after doses of 3000 IU! But in the case of a serious insulin overdose, there is no time to call an ambulance while clearly conscious. Depending on the degree of overdose, it takes anywhere from a few minutes to a few hours before a coma develops, so even lethal doses of insulin are not fatal if the timely flow of glucose into the bloodstream is started.
What kind of insulin is used in bodybuilding
Short-acting and ultra-short-acting insulin should be used in bodybuilding:
Short-acting insulin starts to work when injected subcutaneously in 30 minutes (so injected 30-40 minutes before meals), peaks in 2 hours, disappears from the body in 5-6 hours.
- Humulin Regular
- Actrapid NM
Ultra-short-acting insulin begins to act in 0-15 minutes, peaks in 2 hours, disappears from the body in 3-4 hours. It is more physiological and can be injected immediately before a meal (5-10 minutes) or immediately after a meal.
- Insulin aspart (NovoRapid Penfill, NovoRapid FlexPen).
- Insulin lispro (Humalog)
- Insulin glulisine (Apidra)-these are all semi-synthetic analogs of human insulin.
Advantages and disadvantages of insulin
- Low cost of the course
- Affordability – the drug can be freely purchased in the pharmacy
- High quality – fakes are virtually eliminated, unlike steroids
- Lack of toxicity, low frequency of side effects, almost no consequences of the course
- Minor relapse phenomenon
- A pronounced anabolic effect
- Can be combined with anabolic steroids and other agents
- No androgenic effect
- Insulin does NOT have any toxic effects on the liver or kidneys and does NOT cause sexual dysfunction (potency).
- Complicated regimen
- Significant fat gain
- Hypoglycemia, or a decrease in blood glucose concentration, which entails all other manifestations. Уpoglycemia can be easily prevented.
- Itching in the injection area
- Allergies – very rare
- Decreased endogenous insulin secretion – only found with very long courses of high-dose insulin