How Cortisol Influences Your Training

Many exercise enthusiasts and clients of personal trainers strive to optimize muscle gains with their workout programs. However, many people refrain from doing cardiorespiratory training because they were told that blood during aerobic exercise will increase protein catabolism, resulting in breakage, or loss, of muscles At fitness conferences, this topic is regularly discussed and debated by physical education professionals and personal trainers.

This evidence-based article aims to address many confusing questions about cortisol and muscle growth, discussing the newer concepts of how hormones work, the many functions of cortisol, the association of cortisol with aerobic exercise, and the possible catabolic effect of cortisol on muscle mass and strength muscular.

How do hormones work in the body?

There are two main types of hormones; amines and peptides versus the steroid. The biological differences between these types of hormones are caused by a combination of their chemical structures and their cellular mechanisms of action.

Amine hormones and peptides are composed of one or more amino acids (protein blocks). The more amino acids have small electrical charges on some of their atoms, molecules interact with these small charges found in water molecules, and thus can be dissolved in Water. However, since the cell membranes are mainly comprised of lipids, the amines and peptides can not cross the cell membranes to enter them.

Accordingly, amines and peptides bind to specialized protein receptors on the outer side of the cell membranes. Such binding causes changes in structure and / or distribution within the receptor, leading to the production of specific molecules that alter the metabolism of the cell. For example, the insulin released by the pancreas connects with a target cell receptor to increase the glucose into the transport of proteins to the cell membrane, thereby increasing the uptake of glucose by cells.

Steroid hormones are cholesterol derivatives that are soluble in lithium and repelled by water. This means that to be transported by blood, which is basically water, they must be connected to proteins. Steroid hormones do not need protein to connect with the cell membrane to influence cell function. Steroid hormones enter the cell's membrane where intra-cellular proteins help in their transport to the nucleus, where they carry out their functions. Steroid hormone functions are generally related to increased or decreased protein synthesis.

Some hormones do only one thing, and there is usually a need for hormones to interact with other molecules to perform their functions. This is especially true for steroid hormones. For example, testosterone stimulates increased protein synthesis, but to do so, requires the presence of molecules called somatomedins, produced in skeletal muscles. This interdependence increases muscle hypertrophy (growth) in strength training.

  • How is the Muscle Mass Gain in the Body?
  • What Is Anabolic Steroid and How Does It Work
  • What is Anabolism and Catabolism?
  • Taking Protein Before or After Training?

What are the functions of cortisol in the body?

Cortisol has several functions, one of which is the increased supply of amino acids in the liver, and thus the increase in protein catabolism stimulus. However, cortisol functions are complex and simple interpretations can be misleading. For example, cortisol, like many other steroid hormones, is released in a complex way through a daily cycle of 24 hours, with clear changes in the release caused by feeding, sleep and exercise.

As the release and presence of the bulk of cortisol in the blood occurs during the hours of sleep, the daily release profile of cortisol may be more important for the daily hormonal regulation of body metabolism than its response to training. This makes research on the responses of hormones to exercise very difficult, since the acute cortisol response may be totally different to the nocturnal release profile, which may be when cortisol has its most striking impact on the balance between muscle protein and catabolism.

What is the function of Cortisol in aerobic exercise?

During exercise, regardless of whether it is a strength or aerobic workout, cortisol is released in proportion to the intensity of the exertion. That way, even when you train in excess, cortisol is released, and even more so to compensate for aerobic exercise! With elevations in exercise intensity, other hormones also elevate, such as glucagon, adrenaline, noradrenaline and growth hormone.

The concentration of other hormones in the blood, such as insulin, decreases during exercise. To accurately interpret the influence of hormones on body metabolism during and in response to exercise, you need to know how all the hormones that influence a given metabolic function are answering (ex. Muscle Catabolism). As explained earlier, for some hormones, this may also require blood samples taken over the 24-hour cycle.

When related to prolonged aerobic exercise, cortisol clearly works to preserve the body's carbohydrate stores. Cortisol increases the alternative fuels of muscles, such as fatty acids and amino acids (from muscle reserves and catabolism of prevents the entry of glucose into skeletal muscle, and provides the fuels (amino acids) to the liver, to glucose.

All of these functions are elevated during low carbohydrate nutrition hours in the body, such as when glucose lowers. Thus, when doing prolonged aerobic exercise, the catabolic effects of cortisol on muscle can be reduced blood glucose, which is best performed by carbohydrate intake (liquid and / or solid).

Alternatively, when an aerobic exercise is performed for a short enough time not to reduce muscle or liver glycogen (eg. <45 min), the exercise-induced release of cortisol will probably be irrelevant to muscle protein balance. Also, the theoretical effects on the metabolism of this increase in cortisol can be overcome by the simultaneous increase of growth hormone, testosterone, and muscle-specific somatomedins. The net result is the preservation of muscle mass.

What else could explain the difficulty of increasing muscle mass when aerobic exercise is added to resistance training?

This is a crucial question that needs to be answered. Additional explanations have two sides. First, aerobic exercise adds a caloric expenditure to your workout that needs to be adjusted to the appropriate energy consumption. If an insufficient amount of carbohydrate is consumed, what many people who practice strength training can do because their diets are richer in protein and low in carbohydrate, these situations are conducive to generating the low carbohydrate conditions that lead to the action of cortisol as a carbohydrate store, a catabolizing hormone protein. The problem here is not aerobic exercise, but inadequate carbohydrate intake!

The additional explanation lies in the counterproductive effects of aerobic training on muscle strength and hypoertrophic cell stimuli. Although scientists do not know what these stimuli are yet, muscle gain (and hypertrophy) may be inhibited if strength training occurs too early near aerobic exercise (ex. on the same day). This has nothing to do with a hormonal response mechanism, although it is easy to blame cortisol.

Instead, we believe that the signals given to the working muscle that induce adaptation both strength and resistance are diluted when combined with strength and resistance training (aerobic). This is how to give muscle massages various.

On the other hand, we are telling the muscle to build more proteins to increase mitochondrial mass (by increasing the organelles of the cells involved in the production of energy) during exercise, and then we tell the muscle not to focus on the mitochondria, to now increase muscle contracting protein synthesis during exercise resistance. No matter what the training order, both exercise conditions can end with a reduced response.

Summary and practical applications

Here are some lessons to take from this article. First, do not look at a single response of a hormone in the body to be interpreted as the cause of the hormonal effects. The body's metabolism is the balance of many hormonal regulation in response to variations in metabolic states. Second, adding aerobic exercise to the workout routine will not greatly affect muscle strength and / or hypertrophy while carbohydrate intake is adequate.

However, if you are a professional (or aspiring) bodybuilder or athlete trying to maximize muscle growth, then careful advice must be given about how much and how aerobic exercise should Be done. Finally, for many who wish to achieve changes in body composition, aerobic exercise to the training program will be an essential component to the development of program

Aerobic exercise can help you achieve your goals while at the same time taking advantage of benefits of improved health in a balanced physical state (strength, endurance, flexibility, etc).


Is your carbohydrate intake adequate? Do you think that cortisol influences much or little in your daily workout? Comment below!

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