ATHLETIC HEART SYNDOME
An athlete’s heart includes all cardiac changes secondary to repeated, high-intensity physical activity. Hypertrophic cardiomyopathy is a disease in which the heart muscle thickens. It is one of the changes that can be observed.
Understanding this condition requires revisiting a few basics.
A Muscular Pump
The heart is a muscle that propels blood through the body with each beat, ensuring blood circulation. Several conditions can cause an increase in the volume and thickness of this muscle pump. This is known as cardiac remodeling.
In the same way that a person who exercises regularly will develop more prominent muscles, when the heart encounters resistance in ejecting blood, it will become more muscular and the thickness of the left ventricle muscle will increase. This change in the cardiac structure is called hypertrophy.
All Physical Activities Are Not Alike
Physical activity alone can cause remodeling of the left ventricular cavity, but beware, the type of activity that is being referred to is at the athletic level. For instance, jogging for an hour 3 times a week or weight training 4 times weekly is not enough to cause significant cardiac remodeling.
Who Can Be Described as an Athlete?
An athlete is an individual, young or old, who is engaged in regular physical training and participates in official competitions at various levels, both locally and internationally.
All athletes do not develop athlete heart or cardiac remodeling. In addition to practicing a sport regularly, the 2 following specific factors are to be taken into account:
- high-intensity training,
- high-load training.
High-intensity training is a form of strength training that requires sufficient effort to achieve a heart rate of at least 75% of the maximum age-dependent frequency.
What about the Training Load Required?
High-intensity workouts should be repeated significantly:
- at least 7 to 10 hours per week,
- for a minimum of 3 months.
Each Sport Has its Characteristics
Not all sports challenge the heart in the same way. Since the type of activity performed by a weightlifter differs markedly from that of a marathon runner, the impact or remodeling on the left ventricle is different.
The classic power training of a weightlifter is one of concentric muscle hypertrophy, i.e., the left ventricle develops a uniformly thickened muscle.
Endurance training in a marathon runner causes the left ventricular cavity to dilate and enlarge without thickening the ventricular muscle. This is referred to as eccentric hypertrophy.
Eccentric hypertrophy, or an enlarged cavity, allows a greater volume of blood to be ejected with each beat. This is why athletes often have a lower resting heart rate.
It is also possible that these athletes have a slightly reduced ejection fraction (contraction capacity of the heart) at rest, a phenomenon that can be objectified with a cardiac ultrasound or a cardiac magnetic resonance test. This occurs because more blood is ejected with each beat to maintain blood flow at rest. However, the ejection fraction quickly reverts to its normal value with effort.
A Wide Range of Options
In addition to these 2 opposed forms of sport, a wide range of sporting situations exist. Left ventricular remodeling will then take place according to the different levels of endurance (enlargement of the heart) and power (thickening of the heart) that these various efforts require.
Grouping Sports Is Necessary for a Better Understanding:
Sports and sports cardiology specialists have put forward a classification of sports into 4 groupings:
- power (wrestling, weightlifting, downhill skiing) - thickening of the heart muscle,
- endurance (cycling, triathlon, rowing) - enlargement of the left ventricle cavity,
- mixed (soccer, field hockey, American soccer) - thickening and enlargement of the heart muscle,
- skill (golf, curling, table tennis) - little remodeling.
Gender and Ethnicity Differences Were Observed
In general, myocardial remodeling appears to be more favorable in women versus men. Dilation of the left ventricular cavity is less marked and concentric hypertrophy, or thickening of the heart muscle, is of lesser magnitude.
A noticeable ethnic difference is also observed. It has been found that athletes of Afro-Caribbean descent may develop more secondary remodeling during training compared to athletes of other ethnicities.
To assess cardiac remodeling in relation to an athlete’s training and the presence of cardiac hypertrophy, the following factors should be considered:
- type of sports discipline,
- intensity and volume of training,
This diagnostic work is challenging because training-induced cardiac remodeling is sometimes difficult to distinguish from certain cardiomyopathies or other pathological processes (heart disease). Therefore, the athlete may be at risk for continued training and competition.
What About the Right Ventricle?
Right ventricular remodeling occurs during endurance sport activity only. Dilation will be similar to that of the left ventricle cavity. Doctors refer to it as a balanced or harmonic dilation. The muscle of the right ventricle does not thicken due to physical exercise, it is rather an abnormal phenomenon.
Potential Causes of Arrhythmias
High-level athletes may suffer from palpitations and certain arrhythmias are more common in this group of people. This is the case for atrial fibrillation, a disturbance of the electricity at the atria level.
- Atrial Fibrillation
When this type of arrhythmia is present, it requires the same care that is given to other people with a similar problem in terms of its control and prevention of a stroke.
We can also elaborate on 2 other possible rhythm disorders:
- Ventricular Extrasystoles
Ventricular extrasystoles are another type of arrhythmia encountered in athletes. On the other hand, they are also frequently found in the general population and do not represent a risk in the vast majority of cases.
- Ventricular Tachycardia
A small subset of athletes will develop incessant ventricular extrasystoles, resulting in ventricular tachycardia.
Although still not a fully understood phenomenon, this arrhythmia can occur when the athlete develops a reorganization of the thickness of the cardiac muscle or the size of the ventricular cavity in an extreme and pathological way. This form of arrhythmia is dangerous for an athlete and may prevent him from taking part in competitions.
Discontinuation of high-level training allows the ventricular chambers and walls to return to their normal dimensions in the vast majority of cases.
There are no clearly confirmed long-term consequences yet, although more recent studies have shown minor scarring in some veteran athletes.
Products that May Be Harmful to the Heart
The situation will be different if, in addition to the effects of overtraining, there is myocardial damage caused by products that may be harmful to the heart muscle.
One of the causes of toxic cardiomyopathy is the use of doping substances that increase the athlete’s performance. The list is long and includes stimulants such as amphetamines and decongestants, anabolic steroids, and growth hormones to name but a few.
A Widespread Problem
Doping in sports remains an ongoing issue, and is not only used by the elite. These products are available everywhere and easily accessible to all. What is even more disturbing is that there are far fewer doping controls among amateur athletes than at the professional level.
A Difficult but Necessary Admission
Generally speaking, admitting such use to one's doctor is embarrassing. The role of the health care professional is to ensure the treatment and prevention of the patient's health problems. Withholding this information is pointless because the patient's blood test will reveal to the physician some of the effects of doping.
Toxic cardiomyopathies can cause permanent damage including the possibility of arrhythmia, threatening the life of the athlete.