A marathon is a serious physical test not only for the elderly, but also for young people. Sports doctors and cardiologists are not sure of the "usefulness" of such exercises. Recent studies have revealed the mechanisms underlying the dangers of a marathon. Scientists also proposed new methods for the prevention of heart attack in marathon runners.
What is the danger of a marathon for the heart muscle?
A dangerous consequence of extreme sports is an increase in the concentration of heart markers that are observed with myocardial infarction and heart failure. These include troponin I or T, which are secreted from dead cells of the heart muscle into the blood.
Other markers are creatine kinase (especially the MB isoenzyme) and myoglobin.
Both substances are also found in skeletal muscle, so an increase is not a sure sign of damage to the heart muscle.
What blood markers most often increase in athletes?
A team of Madrid scientists examined heart markers in 63 amateur runners before and after a long distance run. Researchers have chosen athletes who are similar in age, body weight, and experience. Athletes were divided into 3 groups based on running distance: ten-kilometer race, half marathon or marathon.
A marker of chronic heart failure is the hormone NTproBNP. OH is secreted from the atrium into the bloodstream with an increase in physical activity. Blood samples were taken before and after the competition.
According to del Coso, after the run there was an increase in specific indicators of a heart attack. Troponin was elevated particularly distinctly. The measured values were orders of magnitude lower than after a heart attack.
However, the results show that stress causes short-term damage to the heart muscle.
NTproBNP is a marker of heart failure, an increase in the concentration of which indicates overload of the heart muscle. The increase in this hormone was dose dependent. A ten-kilometer run affected the heart less than a marathon.
After the run, normalization of all cardiac markers was observed.
Permanent damage could be detected using magnetic resonance imaging of the heart. The method is relatively new, and the amount of research is still small. However, some extreme athletes experienced increased fibrosis.
Due to the popularity of marathons, this question will sooner or later become the subject of epidemiological research.
How common are cardiac arrests?
At last year's Boston marathon 3 people collapsed beyond the finish line. Cardiologists in all 3 were diagnosed with acute coronary thrombosis in the clinic - i.e. myocardial infarction.
In the first 45-year-old man, coronary angiography showed 70% arterial stenosis. This section of the left coronary artery was completely closed in the second 55-year-old man.
The third 49-year-old man even had a severe 3 vessel disease with a displacement of the left peripheral coronary artery. This patient was supposed to be reanimated in case of heart shock, but after 8 days he was able to leave the clinic with three stents. 2 other patients received only one stent.
Three cases reported by Navin Kapoor from the research center are an exception.
The database, which was studied by specialists, included all marathon and half marathon competitions in the USA for 2000 - 2010. Among 10.9 million participants, 59 sudden cardiac arrests were detected.
40 of them, according to Aaron Baggish from the Massachusetts Hospital, were due to the marathon and half marathon. This leads to an incidence rate of 0.54 per 100,000 participants, which is not a noticeably high indicator.
Is it possible to prevent heart damage caused by stress?
The HDAC4 fragment can protect the heart from damage caused by temporary physiological stress.
The secret, scientists say, is the constant breaks between running.
If there is less rest, then the activity of protein kinase A is significantly reduced. As a result of continuous loading, the HDAC4 fragment disappears. The metabolism of heart muscle cells uses more sugar than fat for energy.
But it is not the altered energy production that makes the heart sick, but the sugars associated with proteins. Some of these sugar modified proteins ultimately upset the calcium metabolism in the heart.
