All who practise sport know the relevance of physical activity for hormone balance. Concentrations of individual hormones differ considerably, depending on the type of the activity. What do you need to know to effectively build up your muscles and body mass and not to spoil the effect? We are going to focus on the most important hormones: testosterone, cortisol and insulin.

What is testosterone?

Testosterone is a hormone secreted by the hypothalamus and the frontal lobe of the pituitary gland. The hormone is responsible for:

1. androgenic features:

  • development of secondary male characteristics (development of sex organs, libido, male voice, body hair)
  • increase in the size and mass of muscles; key role in protein economy

2. and anabolic features:

  • related to increase in body mass
  • which, theoretically, are not hormone-induced

A male body produces daily c.a. 7 mg of testosterone, with the peak concentration between 6 and 9 in the morning. As much as 98% of testosterone binds with proteins, 55% with globulin (which is responsible for sex hormone binding) and 2% of the hormone determines biological activity.

Functions of testosterone:

Testosterone is an anabolic, meaning that it binds proteins, thus leading to muscle development. It causes insignificant retention of sodium, potassium, calcium, sulphates, phosphates and water. Plus, it has an effect on a number of the body’s most vital organs:

  • kidneys, liver, heart, skeletal muscles, bulbospongiosus muscle, bones, marrow, salivary glands, urinary bladder, skin, sebaceous glands and hair, by supporting their functions,
  • thymus, spleen and lymphatic tissue (may compromise immunity).

Among the main functions of testosterone are:

  • muscle (body mass) building – accelerates protein binding and inhibits protein degradation
  • energy supply for muscles – accelerates glycogen replenishment after exercises
  • enhancement of erythrocyte (red blood cell) multiplication.

What is the effect of physical activity on testosterone?

It all depends on what activity we are talking about:

  • short, intense activity increases blood testosterone
  • long-lasting effort leads to testosterone drop for as many as several days
  • maximum effort causes short-term increase in testosterone concentration immediately after workout

Strength trainings usually increase blood testosterone levels.

The growth of blood testosterone concentration depends on the intensity of the workout, weight and muscle mass. The results are similar for both men and women, although in women they are less prominent. Other indicators suggest that working out reduces resting blood testosterone (from 25 to even 75%).

Researchers are unable to fully explain why blood testosterone grows physiologically after training. Some attribute it to the activity of the sympathetic system, which participates in testicle stimulation to produce testosterone. When it comes to blood testosterone concentration after workout, different results were observed for two groups:

  • hard-training athletes: reduced hormone secretion, probably caused by many years of efforts, overtraining and decreased anabolic effect
  • those who train recreationally: increased testosterone production, stimulated testosterone secretion after workout

To obtain anabolic effect and develop body mass, high doses of the preparation are needed. Yet, whatever you decide, mind the side-effects.

What is cortisol?

Cortisol is a catabolic hormone, which causes degradation of contractile proteins in skeletal muscles. The highest concentration of cortisol is observed between 8 and 9 in the morning and between 2 and 4 at night. The hormone has a considerable impact on carbohydrate, protein and fat metabolism and on the metabolism of virtually all nucleated cells.

What is more, together with insulin, glucagon, adrenaline and the growth hormone, cortisol is responsible for proper blood glucose through gluconeogenesis, participates in glycogen synthesis and influences protein metabolism.

Functions of cortisol

Since the growth of cortisol leads to negative protein balance, it seems natural that the hormone inhibits muscle proliferation. But this is not true. Cortisol boosts growth. Catabolic processes provide the body with numerous nutrients making it capable of performing a hard workout.

If you want to build up muscles, what you should pay attention to is the duration of the training and the time of the day when the cortisol level is elevated.

  • The best effects are obtained with high doses of cortisol during intense effort and subsequent lowering of the dose right after the training.
  • Providing the body with cortisol over an extended time will have a negative effect on the health and body composition, as muscles will degrade and insulin resistance will develop. You may start gaining weight and your sensitivity to cortisol may deteriorate. Additionally, too high blood cortisol leads to immunity issues.

Changes in blood cortisol levels depend on the number and quality of trainings. Those who do strength and endurance trainings tend to have low cortisol,which may indicate overtraining. Post-workout cortisol concentration also depends on your fitness, adaptation to effort and the total work done.

As a standard, after a resting phase (24h), cortisol level drops to the value from before the training. Insignificant strain (including short training and moderate intensity training) after workout has no effect on cortisol secretion. In conclusion: the bigger the effort, the higher the blood cortisol level (higher values are reported in less trained people).

What is insulin?

Insulin is an anabolic hormone, with even higher anabolic properties than the growth hormone. These properties do not translate so much into muscle development or fat loss as into inhibition of carbohydrate, fat and protein decomposition.

Insulin secretion is strictly connected with blood glucose. The primary function of insulin is to maintain proper blood sugar, i.e. at the level between 80 and 100 mg/dL. As the threshold of 100 g/dL is exceeded, insulin leaves the pancreas to collect excess glucose and store it safely.

Excess glucose is stored in:

  • muscle glycogen
  • liver
  • adipose tissue (gaining weight)

What is the effect of physical activity on insulin?

Physical effort, other than short and low-intensity trainings, decreases blood insulin levels. When does insulin level drop?

  • during moderate effort
  • sub-maximum effort
  • maximum trainings
  • strength training
  • gradually growing effort

Insulin synthesis drops as a result of training. If you want to reduce the basal blood insulin concentration and insulin secretion, you should consider endurance workout.

What is the effect of insulin on protein synthesis?

Insulin stimulates protein synthesis through ribosomal activity (ribosomes produce increasing amounts of protein). Insulin “orders” the ribosomes to work. Without the order, they remain inactive. This means that insulin is indispensable for muscle mass building.

Anabolic activity of insulin is equally important as its anti-catabolic activity. How does it work?

  • the body synthesises and decomposes proteins every day. If you want to build up your muscles, you need a positive protein balance, i.e. the amounts of synthesised protein should exceed the amounts of decomposed proteins
  • additionally, insulin delivers amino-acids to muscles and directly to muscle cells, making you only one step away from beautiful muscles.

How does insulin stimulate muscle mass building?

Insulin promotes the development of muscle mass by increasing glycogen synthesis, i.e. by making the muscles more effective. Insulin delivers glucose to muscle cells, thus enhancing their performance and recovery.

If you want to build up your muscles, you need to remember to keep high insulin levels all day long. The crucial moment, however, is right after training, when your body is sensitive to insulin and glucose will not immediately transform into fat, but into glycogen instead. Then, you can safely eat a large portion of carbohydrates.

Insulin is a signal for the body of whether you want to build up muscles or burn fat. What does it mean?

  • if your blood sugar is high, insulin is secreted and glucose gets to the liver in the form of muscle glycogen
  • if your blood sugar is low, the insulin level is low, too, and the body uses fat as a fuel

If you want to both build up your muscles and burn fat, you can choose certain times of the day when you will decide about your blood sugar levels, knowing what you will achieve. In order to accelerate muscle proliferation, increased insulin secretion is necessary. It is good, however, to prepare such portions twice a day at most (post-workout and in the morning) and eat lighter meals during the day. Then, the body will switch into burning fat.