The importance of ST elevation in V2-4 ECG leads in athletes.

BACKGROUND: Early repolarization in the anterior ECG leads (ERV2-4) is considered to be a sign of right ventricular (RV) remodeling, but its etiology and importance are unclear. METHODS: A total of 243 top-level endurance-trained athletes (ETA; 183 men and 60 women, weekly training hours: 15-20) and 120 leisure-time athletes (LTA; 71 men and 49 women, weekly training hours: 5-6) were investigated. The ERV2-4 sign was evaluated concerning type of sport, gender, transthoracic echocardiographic parameters, and ECG changes, which can indicate elevated RV systolic pressure [left atrium enlargement (LAE), right atrium enlargement (RAE), RV conduction defect (RVcd)]. RESULTS: Stroke volume and left ventricular mass were higher in ETAs vs. LTAs in both genders (p < 0.01). Prevalence of the ERV2-4 sign was significantly higher in men than in women [p = 0.000, odds ratio (OR) = 36.4] and in ETAs than in LTAs (p = 0.000). The highest ERV2-4 prevalence appeared in the most highly trained triathlonists and canoe and kayak paddlers (OR = 13.8 and 5.2, respectively). Within the ETA group, the post-exercise LAE, RAE, and RVcd changes developed more frequently in cases with than without ERV2-4 (LAE: men: p < 0.05, females: p < 0.005; RAE: men: p < 0.05, females: p < 0.005; RVcd: N.S.). These post-exercise appearing LAE, RAE, and RVcd are associated with the ERV2-4 sign (OR = 4.0, 3.7, and 3.8, respectively). CONCLUSIONS: According to these results, ERV2-4 develops mainly in male ETAs due to long-lasting and repeated endurance training. The ERV2-4 sign indicates RV's adaptation to maintain higher compensatory pulmonary pressure and flow during exercise but its danger regarding malignant arrhythmias is unclear.

Early diastolic septal movement in patients with myocarditis.

AIM: To evaluate early diastolic septal relaxation as a parameter in the diagnostic workup via cardiovascular magnetic resonance imaging (CMRI) in patients with myocarditis. MATERIALS AND METHODS: Early diastolic septal movement was evaluated (EDS) prospectively via frame-by-frame analysis in 255 consecutive patients with presenting signs of myocarditis and in 64 controls matched 4:1 for gender and age. ECG-triggered, T2-weighted, fast spin echo triple inversion recovery sequences and late gadolinium enhancement were obtained, as well as left ventricular (LV) function and dimensions in patients and controls. RESULTS: EDS was detected in 66.7% of the patients and 18.7% of the controls (p<0.001). Sensitivity was 69.4% and specificity 79.7%. Patients with EDS had a significant lower LV ejection fraction (LV-EF) of 61.1±0.6% and significant higher end-diastolic volume (EDV) of 158.5±2.7 ml than in patients without EDS (LV-EF 65.3±0.9%, p=0.0001; EDV 148.4±3.9 ml, p=0.04). A significant negative correlation was observed between LV-EF and EDS in patients, and a lower LV-EF correlated with a more frequent occurrence of EDS (r=-0.24, p=0.0001). Scar tissue was also more frequent in patients than controls (63.1% and 7.8%, p=0.007). CONCLUSIONS: EDS is a parameter obtained non-invasively by CMRI and is present in a high percentage of patients with myocarditis. Cardiac functional parameters are significantly altered in patients with EDS. EDS is a feasible parameter that can play an important role in the diagnosis of myocarditis.

Cardiovascular results of an individually controlled complex prevention.

UNLABELLED: Lifestyle modifications (increased level of physical activity, favourable nutrition, and stress management) are important factors in the prevention of and the therapy for cardiovascular (CV) diseases. OBJECTIVES: The effects of an individualized, half-year long exercise program on CV risk factors were investigated in 50 patients with moderately high CV risk factors. PATIENTS AND METHODS: 75 subjects participated in the study. After the eleventh week of regular training, members of Group A performed 55-65 minutes of exercise at 4-5 times a week, while patients in Group B took part in 45-55 minute training sessions at 2-3 times a week. Activities were monitored using POLAR devices and controlled by a cardiologist and an exercise training expert. Members of the control group (C)were also affected by risk factors, they, however, were not involved in any physical activity. RESULTS: A marked improvement was seen in performance level (62% in Group A, 38% in Group B). There was a decrease in the LDL cholesterol level (30% and 21%), total cholesterol (16% and 14%), triglyceride (23% in both groups), and an increase in the HDL-cholesterol level (53% and 26%). Body mass (BM) decreased in both groups (8.7% and 5%).In addition, a decrease was also seen in the resting heart rate (HR) (9.6% and 4.5%) and blood pressure (BP: systolic 8.5% and 5.5 %, diastolic 7% and 4.7%). CONCLUSIONS: In persons affected by CV risk factors, lifestyle modification with personal, HR controlled complex (cardio and resistance) aerobic training effectively decreased CV risk factors and strongly improved state of health and quality of life.

Relationship between the heart rate and E/A ratio in athletic and non-athletic males.

UNLABELLED: To clarify whether the higher E/A quotient of male athletes is a favourable change in the intrinsic relaxation properties of the left ventricle. METHODS: Peak early (E) and atrial blood flow velocities (A) were assessed by Doppler echocardiography at rest in 1237 males (939 athletes) in Hungary. Data were collected between 1993 ­ 2009. Relationship between E/A and resting heart rate (HR), was determined by linear regression analysis. RESULTS: The E/A decreased with age, the rate of decrease was slower in the physically trained subjects, except in children. In children, adolescent-young and young adult subjects E/A against HR equations of the athletic and nonathletic groups were similar, differences between the means were only due to the differences of the HR. In the 31 ­ 44 yr old males, the intercepts of the athletes' regression lines were higher. The oldest (>44 yr) active subjects showed a significant regression while sedentary males did not. CONCLUSIONS: The HR-independent beneficial effect of regular physical training on the diastolic function manifests itself at the older ages. The impact of resting HR should always be taken into consideration when assessing intergroup differences in the E/A ratio, especially when studying the effect of exercise training upon cardiac function.

Echocardiographic and spiroergometric data of elite Hungarian female water polo players.

In the authors' earlier study the relative aerobic power of Hungarian top-level male water polo players was found to be smaller than that of other top-level athletes, while their echocardiographic parameters proved to be the most characteristic of the athlete's heart. In the present investigation echocardiographic and spiroergometric data of female top-level water polo players were compared to those of other female elite athletes and of healthy, non-athletic subjects. Relative aerobic power in the water polo players was lower than in endurance athletes. Mean resting heart rates were the slowest in the water polo players and endurance athletes. Morphologic indicators of the heart (body size related left ventricular wall thickness and muscle mass) were the highest in the water polo players, endurance and power athletes. In respect of diastolic functions (diastolic early and late peak transmitral flow velocities) no difference was seen between the respective groups.These results indicate that, similarly to the males, top-level water polo training is associated with the dimensional parameters of the heart rather than with relative aerobic power. For checking the physical condition of female water polo players spiroergometric tests seem to be less appropriate than swim-tests with heart rate recovery studies such as the ones used in the males.

Echocardiographic parameters in athlete and nonathlete offspring of hypertensive parents.

BACKGROUND: According to several reports, some cardiovascular signs of hypertension (left ventricular [LV] hypertrophy, impaired diastolic filling) can be found in the normotensive offspring of hypertensive parents. It is also well known that regular physical exercise decreases the risk of hypertension. AIM: The aim of the present study is to determine whether or not regular physical training influences these early hypertensive traits in the offspring of hypertensive parents. METHODS: Echocardiographic data of 215 (144 males, 71 females) 22- to 35-year-old nonathlete and athlete offspring of hypertensive (positive family history, FH+) and normotensive parents (negative family history, FH-) were compared in a cross-sectional design. RESULTS: In the nonathlete FH+ males and females, LV dimensions were not larger than in the FH- subjects. The E/A quotient was lower in the FH+ subjects in both genders. Absolute and heart rate adjusted isovolumetric relaxation times were slightly longer in the FH+ men than in their FH- peers. No differences were seen between athlete FH- and FH+ subjects. CONCLUSION: Regular physical exercise decreases the incidence of the adverse cardiac signs, which can be associated with hypertension in the normotensive offspring of hypertensive parents.

Echocardiographic characteristics in adolescent junior male athletes of different sport events.

The purpose of this study was to examine the effects of different sport activities on cardiac adaptation. Echocardiographic data of 137 athletes and 21 non-athletes were measured and compared in two age groups 15-16 and 17-18 years of age. Athletes belonged into three groups according to their sports activity (endurance events, power athletes, ball game players). The observed variables were related to body size by indices in which the exponents of the numerator and the denominator were matched. Left ventricular hypertrophy was manifest in all athletic groups. Power athletes had the largest mean left ventricular wall thickness (LVWTd) in both age groups. In the older age group differences between the athletic groups were smaller, but the endurance and power athletes had significantly higher wall thickness. Left ventricular internal diameter (LVIDd) was the largest in the endurance athletes, while mean relative muscle mass (LVMM) was the largest in the power athletes. LVMM of the older endurance athletes was significantly larger. Muscular quotient (MQ) was the highest in the endurance athletes; in the 17-18-year group there was no inter-event difference. Bradycardia was most manifest in the endurance athletes and ball game players, power athletes had higher resting heart rates than non-athletic subjects. It can be inferred that endurance training induces firstly an enlargement of the left ventricle what is then followed by an increase of muscle mass. In the studied functional and regulatory parameters no difference was found between the athletic and non-athletic groups.

Morphological and functional differences in cardiac parameters between power and endurance athletes: a magnetic resonance imaging study.

The present study compared morphological and functional parameters of the left ventricle by magnetic resonance imaging (MRI) in competitive athletes engaged in endurance and power activities and sedentary control subjects. Twenty male subjects, 7 endurance-trained athletes (ETA) (age 23.8+/-3.5 yr), 7 strength-trained athletes (STA) (age 22.8+/-4.0 yr), and 6 sedentary controls (age 24.1+/-2.2 yr) were studied by MRI. In the ETA group body size related left ventricular mass (rel.LVM) was significantly higher than that in the STA group (71.0+/-9.2 vs 57.4+/-15.7 g/m3). The difference between their size related left ventricular wall thickness (rel.LVWT) values (9.37+/-1.0 vs 8.37+/-1.8 mm/m) was near to the level of significance (p=0.057). Relative left ventricular internal diameter (rel.LVID) was significantly higher in the ETA group compared to the STA group (42.3+/-1.0 vs 40.1+/-2.5 mm/m, p<0.05). The muscular quotient (MQ=LVWT/LVID) of the ETA group was not significantly higher compared to the strength athletes. Relative left ventricular end-diastolic volume (LVEDV) was also higher in the ETA group than in the STA group (69.5+/-6.7 vs 59.9+/-8.2 ml/m3, p<0.05) and the controls (53.6+/-3.7, p<0.001). Significantly higher relative stroke volume (SV) was measured in the ETA group compared to the STA group and the controls (41.0+/-5.7; 32.6+/-6.9; 32.0+/-3.2 ml/m3). According to the present data, the strongest impact on LV cavity size and wall thickness is caused by long-term high intensity endurance training. Intense strength training does not necessarily induce wall thickening.

Cardiac hypertrophy and diastolic function in physically well trained and in obese men.

OBJECTIVE: The aim of the present study was to compare cardiac hypertrophy and diastolic function in extremely obese male patients and physically active adult male subjects of similar age (means 43.0-43.4 y). DESIGN: Data of male patients referred to our hospital ward in order to reduce their body weight (BW) were compared with those of physically active and nonactive healthy males. SUBJECTS: The groups contained 21-24 male subjects, very active and moderately active subjects taking part in regular competitive or leisure time physical activity were in the two athletic groups, severely overweight patients constituted the obese group and healthy persons served as controls. MEASUREMENTS: Two-dimensionally guided M-mode and Doppler recordings. RESULTS: In comparison with the controls, obese patients had larger left atrial systolic and left ventricular (LV) diastolic internal diameters, LV diastolic wall thickness and muscle mass. Of the body size-related indices, only the left atrial systolic diameter index was significantly higher. LV systolic and diastolic functions were impaired as indicated by a decreased ejection fraction (EF), higher heart rate (HR), decreased E/A quotient and increased isovolumetric relaxation time. In the physically very active subjects, a thicker LV diastolic wall was seen without LV dilatation. Body size-related wall thickness and muscle mass were significantly higher than in the controls. EF and HR did not differ from those of the controls. CONCLUSION: The most useful help to distinguish between physiological and pathological left ventricular hypertrophy can be to investigate diastolic functions. The most salient difference appeared in diastolic function, because E/A quotient was higher in the very active subjects than in the controls and it was the lowest in the obese persons.

Super-marathon race increases serum and urinary nitrotyrosine and carbonyl levels.

BACKGROUND: In normal conditions, proteins are not present in the urine, however, exercise of long duration could result in proteinurea. Increased levels of reactive oxygen and nitrogen species (RONS) are formed during exhaustive physical exercise and causes alterations to cellular proteins. MATERIALS: In the present study serum and urinary nitrotyrosine and protein carbonyl levels were measured before and after each run of a 4-day super-marathon race. RESULT: Serum nitrotyrosine and protein carbonyl levels increased after the first (93 km) day running and reached a plateau on the second (120 km), third (56 km) and forth (59 km) days of the competition. A significant correlation was found between urinary and serum protein carbonyl and nitrotyrosine levels (r=0.78, r=0.71, respectively). A large percentage of urinary proteins were carbonylated and nitrated. Therefore, it appears that clearance of oxidized proteins in certain conditions occurs not only by the proteolytic pathways but also by filtration and urination. CONCLUSION: Data reveals that exhaustive aerobic exercise causes oxidative stress and increases the nitration and carbonylation of serum proteins. The presence of carbonyl and nitrotyrosine in proteins of the urine might reflect oxidative stress and could serve as a noninvasive diagnostic tool for exercise physiology.

Echocardiographic characteristics of male athletes of different age.

Two dimensionally guided M mode and Doppler echocardiographic data for 578 male subjects (106 non-athletic and 472 athletes) were analysed from two aspects: (a) in the young adult category (19--30 years of age), competitors in different groups of sports were studied; (b) in the different age groups (children, 10--14 years; adolescent juniors, 15--18 years; young adults, 19--30 years; adults, 31--44 years; older adults 45--60 years), data for athletes and non-athletes were compared. Morphological variables were related to body size by indices in which the exponents of the numerator and denominator were matched. Morphological signs of athletic heart were most consistently evident in the left ventricular muscle mass: in the young adult group, the highest values were seen in the endurance athletes, followed by the ball game players, sprinters/jumpers, and power athletes. A thicker muscular wall was the main reason for this hypertrophy. Internal diameter was only increased in the endurance athletes, and this increase was more evident in the younger groups. The E/A quotient (ratio of peak velocity during early and late diastole) indicated more effective diastolic function in the endurance athletes. The values for E/A quotient also suggested that regular physical activity at an older age may protect against age dependent impairment of diastolic function.

Echocardiographic changes in the development of the athlete' s heart in 9 to 20-year-old male subjects.

The purpose of this cross-sectional investigation was to estimate the age at which specific traits of the "athlete's heart" first appear and how they evolve from the beginning of regular physical training until young adulthood in healthy active males. Male athletes (n=389) and non-athletes (n=55) aged between 9 and 20 years were examined by two-dimensionally guided M-mode and Doppler echocardiography. Intragroup differences were examined by t-tests for independent samples between age groups of two years each. Morphologic variables were related to body size by using ratio indices in which the power terms of numerator and denominator were matched. Relative left ventricular muscle mass (LVMM) was significantly larger in the athletic males at age of 11-12, and this significant difference was maintained with advancing age. Most of this increase of LVMM could be attributed to the increase in wall thickness that became significantly manifest first in the 13- to 14-year-old athletic subjects but was demonstrable in all the other groups. A significantly larger left ventricular internal diameter was only found in the age-group of 15-16. Fractional shortening percentage (FS%) did not show any change, while resting heart rate was decreased in our athletic groups.

The effect of moderate weight loss on echocardiographic parameters in obese female patients.

Based on the data collected by KNOLL Hungary Ltd. in Hungary in 1999, 37% of the adult population is overweight while 23% is obese. Inappropriate diet containing excess calories and physical inactivity are responsible for these statistical values. In their former studies, the authors investigated the effects of different stages of obesity on the cardiovascular system, and have verified that even moderate obesity elicits pathological geometric and functional changes in the heart. In the present study, effect of a half-year-long life-style modification program on the morphologic and functional characteristics of the heart was investigated in twenty-one obese women. Life-style modification contained a diet with reduced energy uptake (1000-1300 Cal/day) and a regular physical training of minimum 3-4 hours weekly. By the end of the sixth month the weight loss was 5.1 kg (5.9%) on an average. There was a marked reduction in cardiac dimensions measured by echocardiography, with a very slight, non-significant decrease in left ventricular internal diameter, and a marked, significant reduction in the left ventricular wall thickness. Decrease of the left ventricular muscle mass exceeded the decrease of body weight. A marked elevation was found in the E/A quotient that reflected a definite improvement in diastolic function. Results indicate that physical training programs have a favourable effect on the echocardiographic parameters, therefore the process is reversible even without a pharmacological intervention.

An approach to primary prevention from the aspect of applied physiology.

The main reason for our decreasing population number--a most remarkable indicator of the inadequacy of our health culture--is the high rate of overall mortality. In its background one finds a number of risk factors of high prevalence, such as hypertension disease, addiction pathology, reduced stress tolerance as well as physical and psychic inactivity. Patterns of life that are positive are scarce and as yet not attractive or efficient. The spirit of primary prevention is yet far from permeating medicine; the most the clinical side did realize has been a recognition of the population's need for regular medical screenings. A completely new approach that involves prevention programs embracing the whole of society, and an elaboration of new strategies are badly needed to achieve a desirable change in the present set of values. One of the already available remedies is to give full and science-based support to the positive life patterns in our culture, for instance by demonstrating how physiology can be applied to human life, by putting the latter within a broader scope, namely that of psychophysiology and social psychology. In this framework the elements to be discussed are such aspects of culture as dietary habits, physical exercise, and mental and sexual hygiene. Placing greater emphasis on sports and intense habitual physical exercise can promote a healthier lifestyle, above all in our youth.

The effect of detraining on echocardiographic parameters due to injury.

Regular exercise training modifies the morphological and functional properties as well as the autonomous regulation of the heart. Such changes constitute what is termed an athletic heart, and were found to be reversible so after a discontinuation of regular exercise cardiac parameters gradually return to the non-athletic values. As yet, however, it has not been fully settled 1) how long a period of detraining is necessary to elicit such reversion, and 2) whether the various characteristics of an athletic heart would move concurrently or the time course of their change is different. In order to get more insight, the echocardiographic correlates of these problems were studied in 22 female and 23 male physical education students forced by an injury to discontinue their exercise for some time. A sex and age matched group of non-athletic subjects and data published about a group of elite athletes served as contrast. The studied resting parameters were the wall thickness and internal diameter of the left ventricle, left ventricular relative muscle mass, relative stroke volume and cardiac output, and heart rate. It was inferred that--in respect of the echographical parameters--the time taken until the first signs of detraining depended on the athlete's previously attained level of conditioning, and that there was a definite order of sequence in that functional changes preceded morphological ones.

Characteristics influencing changes in aerobic performance of children aged 7-9.

Interpretation of the actual level of aerobic endurance in a growing child is difficult. Endurance capacity per se is influenced by a number of factors, e.g. by genetic endowment, developmental rate, body composition and habitual physical activity. The respective effects of these factors cannot be distinctly separated from one another, so their particular role is not clearly definable in the various age periods. The aim of our investigation was to define the actual level of aerobic endurance performance in children aged 7-9, and to analyse the relevant factors that may affect this kind of performance according to the different level of sport activities. Two primary school classes (N=42) were selected for the experiment. Both groups had physical education classes every day (five times a week). One group (AG, N=31) consisted of children taking part in regular sport courses at least twice a week (e.g. basket ball, karate, triathlon swimming and gymnastics), as well, the other group (NAG, N=11) served as comparison group. Aerobic performance was estimated by measuring cardiorespiratory response during a Jaeger treadmill run using a "vita maxima" (all-out) testing protocol. The subjects were measured in the Laboratory for Spiroergometry of the Hungarian University of Physical Education twice, in 1997 and 1998. Body composition was assessed by the Drinkwater-Ross [4] body mass fractionation technique. Robustness of the body was described by using the plastic index (PLX) of Conrad's growth type [2], morphological age (MORF AGE) was estimated by using the method of Mészáros and Mohácsi [5]. Exercise performance was studied in the laboratory by using a Jaeger 6000 LE model treadmill and a Jaeger mu-DATASPIR model gas analyser. The functional status of the subjects' cardiopulmonary system was estimated by spiroergometric parameters and total mechanical work (WORK). The AG group had a better endurance performance in 1998 than that of non-athletic group. A factor analytic study (principal component method) of the employed variables revealed that the higher level of endurance fitness in the athletic group was not only affected by growth in size, but also by an increased level of cardiorespiratory performance capacity.

Gender differences in the echocardiographic characteristics of the athletic heart.

Differences between males and females in the effects of regular physical training on the heart were investigated by echocardiography in 579 male (nonathletes: 122, athletes: 457) and in 336 (nonathletes: 84, athletes: 252) female subjects of variable age. The age groups were: children (<15 yr.), adolescent-young (15-18 yr.), young adult (19-30 yr.), adult (31-45 yr.) and people elder than 45 yr older (45<). Hypertrophy characterised by relative left ventricular muscle mass (rel.LVMM) of the athletic heart was manifest also in the females, but in comparison with the males female values were much lower both in the unconditioned and in the conditioned groups. In people belonging to the oldest groups no differences were seen either between the males and females or between athletes and nonathletes. In comparing nonathletic subjects, females showed smaller left ventricular contractility as reflected by a higher LVET/QT ratio and an increased ability of diastolic relaxation as indicated by a higher E/A ratio. Physical training induced a more marked development when the initial level was lower, namely, in the contractility of the females, and in the compliance of the males. No intersex difference was seen in the modified regulation of the athletic heart, characterised by a lower resting heart rate and slower circumferential shortening velocity (VCF).

Doppler echocardiographic examinations in the assessment of the athletic heart.

Doppler echocardiography is a method with the help of which flow velocity and the duration of different intervals can be estimated. The ratio between early and late peak velocities (E/A) is linearly proportional to diastolic function, i.e. to ventricular compliance. Data of 179 athletes and of 42 nontrained young healthy men indicated that the E/A quotient was higher in athletes than in the sedentary controls (2.086 +/- 0.505 vs. 1.905 +/- 0.384) in young adult age, but of the different athletes it was the only group of endurance athletes that showed a significant increase. Regular physical training seems to protect against an age-dependent impairment of left ventricular compliance, as an increased E/A ratio can be observed at the age of 31-45 years (1.77 +/- 0.46 vs. 1.43 +/- 0.276) as well as in men above 45 years of age (1.61 +/- 0.36 vs. 1.24 +/- 0.36). Bradycardia of the athletic heart resulted in a significantly longer duration of the cardiac cycle in athletes than in non-athletes. Different phases of the cardiac cycle, however, were not equally modified. There were periods the absolute duration of which were slightly decreased, unchanged or slightly increased, but the relative ones are strongly decreased: such as isovolumetric contraction time (ICT), acceleration of the transaortic flow (AOAT), deceleration of the transaortic flow (AODT), acceleration period of the early diastolic filling (EACC), and deceleration period of the early diastolic filling (EDT). There were periods the absolute duration of which increased proportionally to the increase of the whole cardiac cycle, while relative duration was not changed: isovolumetric contraction time (IVRT) and the atrial systole (A). There was one period that showed the greatest variability in the different subjects and both its absolute and relative duration was definitely increased in the athletes: this was the EA period, i.e. the period from the end of early filling to the beginning of the atrial systole.

Resting echocardiographic parameters after cessation of regular endurance training.

Resting echocardiograms were examined in nonathletic healthy young men (controls, n = 16), in highly trained endurance athletes (n = 20), and in endurance athletes who stopped regular training (n = 40). The relative muscular wall thickness (Rel. MWTd), left ventricular internal diameters both in diastole and in systole (LVIDd, LVIDs), thus also the end-diastolic and end-systolic volumes (LVEDV, LVESV), and the stroke volume index (SVI) were greater in the endurance athletes still in training than in the nonathletes. The ejection fraction (EF), heart rate (HR), cardiac index (CI), and mean circumferential shortening velocity (Vcf) were significantly lower in the athletes. During the 60 days of detraining no change was seen in the Rel. MWTd, LVEDV, LVESV, and HR. The SVI became even greater; EF and Vcf rose up to the control level while CI exceeded it. The cardiovascular regulation is therefore assumed to undergo a peculiar shift during detraining in that a persisting cardiac enlargement and bradycardia is associated with a temporarily unstable autonomous control. This imbalance often leads to a hyperkinesis-like syndrome when an athlete stops endurance training abruptly.