the possibilities of the heart known today. Its main purpose is to create blood flow in all tissues of the body with its pressure, to pump blood. Here are the mechanical characteristics of this pump.
The heart works on average with a frequency of 80 beats per minute, in children - a little more often, in the elderly and the elderly - less often. In one hour, the heart performs 80 x 60 = 4800 contractions, in a day 4800 x 24 = 115200 contractions, in a year this number reaches 115200 x 365 = 4 2048000. With an average life expectancy of 70 years, the number of heart contractions - a kind of engine operation cycles - will be about 3 billion
Let's compare this figure with those of the machine cycles. The motor allows the car to pass 120 thousand km without major repairs - these are three trips around the world. At a speed of 60 km / h, which provides the most favorable engine operation, its service life will be only 2 thousand hours (120,000). During this time, he will make 480 million engine cycles.
This number is already closer to the number of heart contractions, but the comparison is clearly not in favor of the engine. The number of contractions of the heart and, accordingly, the number of revolutions of the crankshaft is expressed by a ratio of 6:1.
The duration of the heart's service life exceeds that of the engine by more than 300 times. Note that in our comparison, the highest indicators are taken for a car, and average indicators for a person. If we take the age of centenarians for calculation, then the advantage of the human heart over the engine will increase by 10–12 times in the number of working cycles, and by 500–600 times in terms of service life. Is this not evidence of a high level of biological organization of the heart!
The heart has enormous adaptive capabilities, which are most clearly manifested during muscular work. At the same time, the stroke volume of the heart almost doubles, that is, the amount of blood ejected into the vessels with each contraction. Since this triples the frequency of the heart, the volume of blood ejected per minute (minute volume of the heart) increases by 4–5 once. Of course, the heart at the same time expends much more effort. Работа основного – левого – желудочка увеличивается в 6–8 once. It is especially important that under these conditions the efficiency of the heart increases, measured by the ratio of the mechanical work of the heart muscle to all the energy expended by it. Under the influence of physical activity, the efficiency of the heart increases by 2.5–3 times compared to the level of motor rest. This is the qualitative difference between the heart and the engine of a car; with an increase in load, the heart muscle switches to an economical mode of operation, while the engine, on the contrary, loses its efficiency.
The above calculations characterize the adaptive capabilities of a healthy but untrained heart. A much wider range of changes in his work is acquired under the influence of systematic training.
Physical training reliably increases the vitality of a person. Its mechanism is reduced to the regulation of the relationship between the processes of fatigue and recovery. Whether a single muscle or several groups are being trained, a nerve cell or a salivary gland, the heart, lungs or liver, the basic patterns of training each of them, like organ systems, are fundamentally similar. Under the influence of the load, which is specific for each organ, its vital activity intensifies and fatigue soon develops. It is well known that fatigue reduces the performance of an organ; less well known is its ability to stimulate the recovery process in a working organ, which significantly changes the prevailing idea of ​​fatigue. This process is useful, and one should not get rid of it as something harmful, but, on the contrary, strive for it in order to stimulate recovery processes!
In conditions of intense activity, working capacity gradually decreases, fatigue increases. As soon as the work stops, the balance of the main processes that ensure the vital activity of the working organ changes in the direction of the predominance of restoration. Being strongly “accelerated” by fatigue, the recovery process at first proceeds very intensively, and then, as it approaches the initial level, it weakens. And here we note a very important point. If the work was sufficiently (but not excessively!) intense, then after reaching the initial level performance for some time rises higher than before the load. This period, called the supercompensation phase, when fatigue and the changes in tissues caused by it are replenished in excess, means the transition of the body to a qualitatively new state of increased readiness to perform work. If during this period the load is repeated, then subsequent changes in the functional state of the organ in the recovery period raise the working capacity even higher. With each load, the level of performance rises higher and higher. This is what happens with the ideal functioning of the training mechanism. The training that takes place in real life often gives "failures" if the load exceeds the body's capabilities, if it falls on the period of insufficiently recovered or already slightly decreased after the phase of supercompensation of working capacity.
Knowledge of the mechanism of training makes it possible to understand the main mechanism of disorders that can develop with repeated loads. If significant work is performed under conditions of incomplete restoration of working capacity caused by excessive or too early applied loads, then the opposite process occurs - a decrease in working capacity.
Repeated fatigue seems to accumulate, creating a state of long-term, persistent chronic fatigue. This condition in sports is called overtraining. It is characterized by the loss of the body's ability to quickly recover from functional stress. Reduced intensity of recovery during the performance of the work itself is manifested in rapid fatigue, muscle weakness, or reduced endurance during physical exertion.
The transition of the training mechanism to the opposite is very easy. Sometimes it intersperses into the training process as a short-term failure and remains almost unnoticed by a person, sometimes it drags on. A prolonged or disease-complicated period of overtraining can dramatically undermine a person’s strength. Due to the deterioration of the general condition of the body, incompletely cured pathological processes, chronic tonsillitis, bronchitis worsen, the work of the heart, liver and other organs worsens.
The above diagram allows you to understand the mechanism of detraining, when minor physical activity that is not capable of stimulate recovery processes, gradually lead to a decrease in the overall level of human muscle performance. Unfortunately, a significant part of young people and even more people of mature age follow this path.
The development of the training effect under the influence of systematic physical activity leads to an increase in the efficiency of not only the neuromuscular apparatus, including the higher cortical centers of movements, but also the heart and the entire cardiovascular system. Equally, "failures" in the mechanism of training, detraining or especially overtraining lead to a deterioration in the functional state of the heart, the entire circulatory system.
The point of training is that by a system of physical activity that stimulates recovery processes in the skeletal muscles, in the muscle of the heart itself and in the muscle elements of the walls of blood vessels, to increase the efficiency of the circulatory organs so much that even a small, economical work of them is sufficient to meet the needs of metabolism. in the body. It is easy to understand that the higher the level of recovery processes in the working tissues themselves (for example, in the muscles of the legs when running), the less the need to supply them with blood, and therefore, the work of the heart to service these tissues decreases. This is the essence of the economization that develops under the influence of training.
Economization in the work of the circulatory system is combined with similar changes in the respiratory system: the frequency of respiratory movements decreases and their depth increases, relative to (per 1 J of work performed), pulmonary ventilation, the amount of oxygen consumed and carbon dioxide released by the body decrease. "Economic effects" in the circulatory and respiratory systems develop in parallel, because both of them work in close interconnection, providing joint delivery of oxygen and nutrients to the working organs, as well as the removal of metabolic products.
All organs and tissues of our body, without exception, are capable of training. The central nervous system is always included in some part of the process of training any function. Often, however, the training process is limited to the central nervous system itself, without affecting other organs. So, it is possible to train memory, thinking, perception, ability distinguish between stimuli that are close in their properties, for example, for musicians - sounds and their combinations, for tasters - the taste of drinks, etc.
Able to train and the system of the digestive system. Unfortunately, for a modern person, this training is one-sided due to the use of concentrated, high-calorie foods, their excessive consumption. A typical overtraining here is frequent diseases of the digestive system.
Donation, for example, enhances hematopoietic function by the training mechanism. Staying in the mountains basically works the same way, where oxygen starvation stimulates the work of mechanisms that ensure the delivery of oxygen to the tissues. Each system is able to train with the help of “its own” influence.
Unlike local training effects, physical activity, in addition to the development of the motor system (muscles, ligaments,