Image may be NSFW.
Clik here to view.
Year after year, day after day, the athletes are faced with bigger demands so the limits of human possibilities are moved forward everyday. The proof of that is the fact that juniors today surpass the results of seniors from 30 years ago.
Changes in the organism that intensive training evokes are big and can be functional and anatomic, as short-term – during the training and shortly after, also long-term – after a few years of training.
Body activity of high intensity is enabled by correct functioning and cooperation of number of organs and organ systems, and cardiovascular system in this process has the central role. To get a large enough amount of oxygen to the active muscles during repeated efforts of high intensity, the heart is subjected to morphological, functional and electrophysiological changes that we call athletic heart syndrome or just athletic heart, or sport heart.
Athletic heart is a complex phenomenon, still under-researched, as in anatomic and functional sense, also from an aspect of its relation towards health. It is the “grey zone” between physiology and pathology, so unknown and subject to various interpretations. During the last few years, we were witnesses to a few sudden deaths of prime young athletes that have been connected to training. The interest aroused by these tragic events, caused many discussions. Could have these tragic events been prevented and what has caused them?
Athletic heart is a benign enlargement of heart mass with specific morphological changes and it represents a physiological adaptation for load caused by athletic training. It is characterized by heart enlargement in the whole, with enlargement of its cavities and thickness of heart muscle, and by increase of heart rate economy while resting and in the conditions of physical effort with increasing its maximal functional capacities. Also, besides enlargement of the heart muscle in the whole, capillarization and content of myoglobin in myocardum are also enlarged.
Doing sports also leads to decrease in arterial blood pressure, as systolic, also diastolic, so the increases of work capacity, and achieving a faster recovery after acute loadings. Heart oxygen consumption in effort is smaller, which enlarges heart reserves, and pumped heart function is improved. Blood supply is increased in skeletal muscles, improved insulin resistance and lipid status.
Athletic or sport heart phenomenon in modern sports medicine and medicine in general represents an important issue. The very fact that within the “athletic heart” syndrome enlargement and thickening of heart muscle occurs, there are questions asked about differentiation of this physiological hypertrophy from pathological that is seen in a number of cardiology and non-cardiology diseases.
The concept of athletic heart has been described for the first time in the bygone year 1899. by a Swedish doctor S. Henschen, taking into account that in that time the controversies about this phenomenon had already taken the momentum. Doctor Hope, one of the highest authorities in researching heart diseases in the 19th century, published in that time that he didn’t know of such an original heart disease such as the one caused by intense rowing.
In sports population the heart frequency is not increased, it is even lower in relation to non-trained population. Heart frequencies that have been registered at rest go from 30 beats per minute (most commonly in cyclists), but the usual frequency in athletes is 40 beats in a minute. An important difference appears regarding the pounding volume that is significantly larger in trained individuals. In a non-trained individual, minute volume of the heart increases with the increase of heart frequency, while in trained athletes minute volume increases with the increase of pounding volume. Minute volume at rest in trained and non-trained individuals is significantly different.
The biggest athletic hearts we find in endurance sports. In the first place are skiers, racers and cyclists, with heart volume over 1100ml, swimmers, canoeists, wrestlers and long-distance runners with around 1000ml, then rowers and football players with heart volume around 900ml. Sprinters and gymnasts have a heart that is big around 800ml, and the smallest volume, below 700ml have golf players. In female athletes there are no significant volume changes. Weight of the heart of an athlete is 300-400g (normal weight 300g). If the heart would get to so called critical mass of 500g, then it would be endangered because parallel with hypertrophy, not enough number of capillaries are made which would supply myocardum with sufficient oxygen.
Will the athlete get a heart enlargement and in which stage, depends on the type of the activity, training intensity, length of sports internship, gender and constitutive characteristics.
Morphological adaptation changes characteristic for athletic heart are different for different sport activities. The main difference in the type of sport is reflected in the mechanism of heart hypertrophy development.
In continuous dynamic load (aerobic sports), that is characterized by rhythmic isotonic contractions of large muscle groups, and which result is visible movement in space, muscles act like a muscle pump, getting the blood back to the heart, loading it the most with volume of blood that arrives to it and consequently with these kinds of sports the biggest heart muscle enlargement occurs. Because of the need for larger volume, a widening of left heart cavity occurs, while myocardium hypertrophies so it could adjust itself to increased stress on its wall.
As opposed to that, in sports where athletes are submitted to shorter, but more intense loads (e.g. weight lifters) a significant enlargement in heart mass can occur, but without enlargement of the heart cavity. Athletes that are submitted to isometric trainings also show a significant thickening of the wall. In speed and power training, the peripheral muscle hypertrophy is seen mostly, with small or no changes to the volume.
Genetic factors also have effect when myocardium mass enlargement is concerned, under the effect of sport training.
An interesting fact is that adaptation changes characteristically for athletic heart can be seen already in early ages, even in a 5-year-old.
Until the 30s in the last century, enlarged heart in athletes was considered a harmful phenomenon, so the enlargement was related to hypertrophy. Many researches showed that athletic heart is a healthy heart and definitely is not by itself the cause of sudden death in athletes. However, to avoid any kinds of incidents in sport fields, thorough physical examinations should be conducted so eventual existence of any kind of structural or functional heart anomalies could be discovered on time.