Functional properties of athlete’s heart

Dr. Biol., Professor I.N. Medvedev1
PhD, Associate Professor E.S. Kachenkova2
1Russian State Social University, Moscow
2Institute of Natural Sciences and Sports Technologies (Moscow City University), Moscow

Corresponding author: ilmedv1@yandex.ru

Keywords: track and field athletics, myocardium, left ventricle, heart, hemodynamics, physical loads.

Background. The effects of the regular track-and-field sports training on the morphofunctional processes in the myocardium are currently of great interest, especially when it comes to the parameters of its contractile function - the stroke volume output and the degree of reduction in the anterior-posterior dimension of the left ventricle, which dynamics may help to accurately assess the functional capabilities of the left ventricle [5].

There is evidence that professional runners have an increased systolic discharge and a shortened anterior-posterior dimension of the left ventricle. It is also noted that beginner athletes have a smaller ejection fraction as opposed to untrained athletes [4].

Despite the physiological significance of the cardiac function, the mechanisms of heart adaptation to regular physical loads during the track-and-field training sports process remain understudied [2]. Further development of the targeted track-and-field sports training, as well as the methods to achieve high sports results, requires additional research aimed to assess the impact of regular track-and-field sports training on the central hemodynamics [8].

Objective of the study was to assess the hemodynamic status and left ventricle function in athletes trained on a regular basis.

Methods and structure of the study. Subject to the study were 22 male athletes (12 first-rank athletes and 10 Candidate Masters of Sport of Russia) aged 18-23 years. All the track-and-field athletes taken under observation were trained on a daily basis. The subjects’ total years in track-and-field athletics equaled 4. The Control Group (CG) was made of 32 apparently healthy volunteer university students aged 18-23 years, who were subjected to physical loads at the academic physical education classes only.

The subjects’ state was analyzed based on the heart ultrasound results recorded in their medical cards. The heart ultrasound was performed on the Ultrasound Echo Aloka SSD-80 (Japan). The left ventricular diastolic volume was calculated [6]. The myocardial mass was estimated by the standard method [3]. The ratio between the left ventricular hypertrophy and the degree of dilation of its cavity was quantified by calculating the values of the end-diastolic volume/ mass of the myocardium [3].

Results and discussion. The study found that the considered characteristics of the track-and-field athletes differed from those obtained in CG (see Table 1). The greatest differences between the study groups were associated with the morphological parameters of the left ventricle.

The left atrium size in the athletes exceeded that in the CG subjects by 4.9% only, thus, not reaching the level of significance of the differences. In the athletes, the anterior-posterior diameter of the left ventricle at diastole, tended to increase (by 4.1%) over that in the untrained individuals. A similar pattern was found in relation to the shortening of the size (4.2% higher in the athletes).

The thickness of the left ventricular posterior wall at diastole, was 15.5% higher in the track-and-field athletes than in the CG subjects (p<0.05). At the same time, the end-diastolic volume in the athletes tended to concede that in the CG subjects (by 9.3%). Moreover, the stroke volume output rates in both groups were comparable.

The myocardial mass rates were higher (by 17.9%) in the athletes, which indicated the development of cardiac hypertrophy under the influence of training loads. At the same time, these processes did not affect the ejection fraction rate, which was found to be comparable in both groups.

In the left ventricle posterior wall, the maximum relaxation rate was significantly higher in the track-and-field athletes engaged in long-term training (28.4%) than in the non-sporting individuals.

The ratio between the end-diastolic volume and the mass of the myocardium also significantly exceeded that in CG (by 30.0%), thus, indicating a higher level of sensitivity to regular aerobic loads.

The studies indicated the possibility of comparison of the left atrium size, left ventricular dimension, its cavity and volume. A similar state was detected in terms of the central hemodynamics and myocardial contraction (except for the maximum rate of relaxation the left ventricle in the posterior wall). At the same time, the ratio between the end-diastolic volume to the myocardial mass under the influence of the track-and-field sports training reduced significantly as a result of the growth of the myocardial mass (primarily, the left ventricular posterior wall). The decrease in the ratio between the end-diastolic volume and myocardial mass in the athletes to 0.70±0.08 indicates the predominance of the left ventricular hypertrophy over the dilation of the cavity of this part of the heart.

Table 1. Studied indicators in the testees

Indicators

Track-and-field athletes, M±m, n=22

Control Group, M±m, n=32

Left atrium size, cm/m2

1.91±0.04

1.82±0.06

Anterior-posterior dimension of the left ventricle at diastole, cm

5.33±0.10

5.12±0.07

Shortening of the anterior-posterior dimension of the left ventricle, %

34.27±0.93

32.87±0.86

Thickness of the left ventricular posterior wall at diastole, cm

1.19±0.08

1.03±0.05

р<0.05

End-diastolic volume, cm3/kg

1.81±0.11

1.98±0.07

Systolic discharge, cm3/kg

1.10±0.10

1.08±0.06

Myocardial mass, cm3/kg

2.57±0.17

2.18±0.12

р<0.05

Ejection fraction, %

61.65±1.34

60.21±0.80

Maximum velocity of left ventricular relaxation in the posterior wall, cm/s

13.1±1.27

10.2±0.58

р<0.05

Ratio between the end-diastolic volume and the myocardial mass, cm3/kg

0.70±0.08

0.91±0.07

р<0.01

Note: р – significance of intergroup differences.

It becomes apparent that the left ventricular hypertrophy is typical of track-and-field athletes, as evidenced by the increase in the thickness of its posterior wall and its mass, with the constant volume and size of its cavity, which are comparable to those in CG.

It is believed that the high myocardial relaxation velocity is common to regularly trained individuals [7]. The weight of evidence suggests that the maximum rate of the left ventricular relaxation in the posterior wall, as a value that indirectly characterizes the time of development of this process during the diastole [1]. During the current study, this indicator increased in all athletes. At the same time, there is a view that, during ultrasound [3], this indicator is very dynamic and is capable of changing even during a single study and may therefore not be considered very reliable.

Conclusions. Regular physical loads affect the hemodynamic status and heart contractile function of track-and-field athletes. Long-term track-and-field sports training is accompanied by the growth of the left ventricular mass with the absence of its dilation and preservation of the central hemodynamics and cardiac functionality. Under the influence of the long-term track-and-field sports training, there is a tendency to a functionally advantageous increase in the maximum velocity of relaxation of the left ventricular posterior wall.

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