The upper limit of physiologic cardiac hypertrophy in highly trained elite athletes

Comparison of athletes with life-threatening ventricular arrhythmias with two groups of healthy athletes and a group of normal control subjects

Sudden cardiac death in well-trained athletes is most often superimposed on the presence of structural heart disease. However, some athletes die suddenly in the absence of overt heart disease. To improve identification of athletes at high risk for ventricular tachycardia (VT), ventricular repolarization, the signal-averaged electrocardiogram (ECG), and the echocardiogram from 13 male athletes with symptomatic VT and without evidence of manifest cardiac disease were compared with data obtained in 3 matched control groups (15 apparently healthy professional road cyclists, 10 professional basketball players, and 15 normal control subjects without any sports activity). All patients had apparently normal QRS duration on the routine ECG, and none were taking antiarrhythmic drugs. Echocardiography and signal-averaged electrocardiography were useful in distinguishing the group of athletes with tachyarrhythmias from the group of normal nonsporting controls, but not from both groups of normal athletes. The QT interval (V4) and the QT interval corrected with the cubic root were shorter for the nonsporting controls. Three parameters for QT dispersion showed significant differences (p < 0.003) between athletes with disease and all other groups. It is concluded that although significant differences were detected between normal subjects and the 3 groups of athletes by routine ECG, the signal-averaged ECG, and echocardiography, only an increased QT dispersion from the 12-lead ECG was helpful in distinguishing athletes with VT from other athletes.

Morphology of the "athlete's heart" assessed by echocardiography in 947 elite athletes representing 27 sports

In the present study, we used echocardiography to investigate the morphologic adaptations of the heart to athletic training in 947 elite athletes representing 27 sports who achieved national or international levels of competition. Cardiac morphology was compared for these sports, using multivariate statistical models. Left ventricular (LV) diastolic cavity dimension above normal (> 54 mm, ranging up to 66 mm) was identified in 362 (38%) of the 947 athletes. LV wall thickness above normal (> 12 mm, ranging up to 16 mm) was identified in only 16 (1.7%) of the athletes. Athletes training in the sports examined showed considerable differences with regard to cardiac dimensions. Endurance cyclists, rowers, and swimmers had the largest LV diastolic cavity dimensions and wall thickness. Athletes training in sports such as track sprinting, field weight events, and diving were at the lower end of the spectrum of cardiac adaptations to athletic training. Athletes training in sports associated with larger LV diastolic cavity dimensions also had higher values for wall thickness. Athletes training in isometric sports, such as weightlifting and wrestling, had high values for wall thickness relative to cavity dimension, but their absolute wall thickness remained within normal limits. Analysis of gender-related differences in cardiac dimensions showed that female athletes had smaller LV diastolic cavity dimension (average 2 mm) and smaller wall thickness (average 0.9 mm) than males of the same age and body size who were training in the same sport.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of myocarditis in athletes with minor arrhythmias and/or echocardiographic abnormalities

We report the clinical and instrumental data, including the endomyocardial biopsy findings, of six young athletes presenting with minor arrhythmias and/or echocardiographic abnormalities. In one of them, a left ventricular dilation with moderate depression of the systolic function had been attributed to an athlete's heart. A diagnosis of arrhythmogenic right ventricular dysplasia had been made in three others, one with right ventricular dilation and apical hypokinesia, and two with ventricular arrhythmias with QRS morphology of left bundle branch block. A myocarditis could be unequivocally established in four athletes (two with and two without fibrosis). In the remaining two, with a clinical history strongly suggesting a previously acute myocarditis, the endomyocardial biopsy specimen revealed a nonspecific fibrosis compatible but not definitely pathognomonic of a healed myocarditis. Our report suggests that a myocarditis may be a cause of minor rhythm disturbances and/or echocardiographic abnormalities in athletes. A prevalent localization of the inflammatory process in the right ventricle with or without the occurrence of ventricular arrhythmias with left bundle branch block morphology can mimic an arrhythmogenic right ventricular dysplasia. An early diagnosis of myocarditis in athletes is useful to avoid the risk of fatal arrhythmias, also considering that rest still keeps on being one of the most effective strategies in myocarditis management.

Surviving competitive athletics with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HC) is probably the most common cause of sudden cardiac death in youthful athletes, and this diagnosis has represented a contraindication to continued participation in competitive sports. Less well appreciated is the fact that within the clinical spectrum of HC are patients who, despite having this disease, have been able to undertake particularly intensive and often extraordinary levels of training for sports competition over many years without dying suddenly. Fourteen such patients (13 men and 1 woman, aged 30 to 66 years [mean 43]) form the present study group. HC was initially identified at 24 to 57 years of age (mean 34), usually under fortuitous circumstances. Patients most often competed in distance running (including the marathon, 7), but also in swimming, triathalon, basketball, and football. The duration of training ranged from 6 to 22 years (mean 15) and 5 continue to train and compete actively. The magnitude of training, competition, and achievement was considerable in most patients; 12 of the 14 performed either at the national, collegiate or professional level in their sport, completed numerous marathon and triathalon events, or sustained particularly rigorous training regimens of > or = 50 miles/week. Echocardiographic studies demonstrated a left ventricular wall thickness of 18 to 28 mm (mean 20) in most patients (12 of 14) having a relatively localized pattern of ventricular septal hypertrophy. It is possible for some patients with HC to tolerate particularly intense athletic training and competition for many years, and even maintain high levels of achievement without incurring symptoms and disease progression or dying suddenly.(ABSTRACT TRUNCATED AT 250 WORDS)

Appropriate strength training

Strength training stimulates predictable cardiovascular and neuromuscular responses. The cardiovascular responses result in nonpathologic concentric left ventricular hypertrophy with preservation of ejection fraction and no diastolic dysfunction. Resting heart rates and blood pressures in strength-trained individuals remain unchanged or decrease slightly. Strength gains occur from enhanced neuromuscular activation over the initial 8 weeks and from increased muscle fiber density and hypertrophy during subsequent weeks. Significant strength gains are possible in all populations, including children, women, and the elderly, when exposed to an adequate strength-training program. Strength training can also be a valuable adjunct in cardiac rehabilitation with the possible exception of patients with baseline abnormal left ventricular function.

Absence of left ventricular wall thickening in athletes engaged in intense power training

There is a widely held perception that power training increases left ventricular (LV) wall thickness. Consequently, in individual power-trained athletes, confusion may legitimately occur with regard to the differential diagnosis of athlete's heart and nonobstructive hypertrophic cardiomyopathy. To investigate the effects of systematic strength training on cardiac dimensions (particularly absolute LV wall thickness), 100 relatively young and highly conditioned athletes participating in weight and power lifting, wrestling, bobsledding and weight-throwing events for 3 to 24 years (mean 7) were studied by echocardiography. No athlete showed a maximal absolute LV wall thickness that exceeded the generally accepted upper limits of normal (i.e., 12 mm; range 8 to 12). When compared with 26 normal, sedentary control subjects of similar age and body surface area, maximal septal thickness was mildly but significantly greater in athletes (9.6 +/- 0.8 vs 9.0 +/- 0.5 mm; p < 0.001), as was the calculated LV mass index (96 +/- 12 vs 81 +/- 8 g/m2; p < 0.001); LV end-diastolic cavity dimension was similar in athletes and controls (55 +/- 4 and 54 +/- 3, respectively; p > 0.05). Consequently, echocardiographic data in this selected group of purely strength-trained athletes show that whereas this form of conditioning is associated with increased LV mass and a disproportionate increase in wall thickness in relation to cavity dimension, only modest alterations in absolute wall thickness occur (which do not exceed upper normal limits). Therefore, in highly conditioned, strength-trained, competitive athletes, the presence of substantial LV wall thickening (> 13 mm) should suggest alternative explanations, such as the diagnosis of pathologic hypertrophy (i.e., hypertrophic cardiomyopathy).

Cardiac anatomy and diastolic filling in professional road cyclists

In the literature two divergent types of exercise-induced cardiac hypertrophy have been described: isotonic exercise induced eccentric hypertrophy with proportional increase in end-diastolic left ventricular dimension and wall thickness and isometric exercise induced concentric hypertrophy with normal end-diastolic left ventricular dimension but increased wall thickness. Using echocardiography, cardiac anatomy and diastolic filling were studied in 26 professional road cyclists. Compared to 21 control subjects, matched according to age, sex and morphometry the athletes had significantly larger left atrial dimension [41.3 (SD 4.8) vs 36.6 (SD 4.5) mm], left ventricular dimension [56.0 (SD 3.8) vs 53.2 (SD 4.7) mm], end-diastolic septum thickness [11.1 (SD 2.5) vs 8.4 (SD 1.9) mm], end-diastolic posterior wall thickness [11.6 (SD 2.2) vs 8.4 (SD 1.5) mm] and left ventricular mass index [170.4 (SD 40.6) vs 107.0 (SD 27.7) g.m-2]. We concluded that the hypertrophy in the road cyclists was of the mixed type (concentric-eccentric) with an increase in the internal dimension of the left ventricle and an even larger increase in the thickness of the ventricular walls. Diastolic filling however was similar in the athletes and control subjects. No correlations were found between the left ventricular mass index and diastolic filling parameters. We concluded therefore that professional road cycling causes mixed cardiac hypertrophy without diastolic filling abnormalities and can therefore be considered benign.

A computer package for the multivariate nonparametric rank test in completely randomized experimental designs

When research data are measured on at least an ordinal scale and the assumptions required in the theory underlying parametric statistical methods are in question, nonparameteric procedures based on the ranks provide a sound approach to statistical analysis. Biomedical investigations, especially clinical trials, typically involve multivariate response and therefore multivariate statistical methods are called for in the interpretation of results. We discuss applications of the nonparametric multivariate rank test for completely randomized designs. Large sample theory can be used to support these statistical methods for assessing group differences in location. In small samples, randomization tests provide a basis for inferences. The execution of the procedure is facilitated by a computer program developed by the authors.

Pitfalls in the echo-Doppler diagnosis of hypertrophic cardiomyopathy

While Doppler echocardiography has become the gold standard for the diagnosis of hypertrophic cardiomyopathy, there are many pitfalls in its use. Some of these pitfalls are technical in nature resulting from inadequate image quality, incorrect transducer angulation, and improper equipment settings. Other pitfalls relate to the diversity and heterogeneity in defining hypertrophic cardiomyopathy and to the host of disorders that may mimic it by echocardiography. The pattern and extent of ventricular hypertrophy, systolic anterior motion of the mitral valve, and Doppler determination of left ventricular outflow tract obstruction, diastolic dysfunction, and mitral regurgitation are discussed, as are wall-motion abnormalities and myocardial echo reflectivity. While these echocardiographic features of hypertrophic cardiomyopathy are nonspecific when seen in isolation, their combined presence in the appropriate clinical setting makes the diagnosis likely.

Reduction in left ventricular wall thickness after deconditioning in highly trained Olympic athletes

BACKGROUND

Clinical distinction between athlete's heart and hypertrophic cardiomyopathy in a trained athlete is often difficult. In an effort to identify variables that may aid in this differential diagnosis, the effects of deconditioning on left ventricular wall thickness were assessed in six highly trained elite athletes who had competed in rowing or canoeing at the 1988 Seoul Olympic Games. Each of these athletes showed substantial ventricular septal thickening associated with training (13-15 mm) which resembled that of hypertrophic cardiomyopathy.

METHODS

The athletes voluntarily reduced their training substantially for 6-34 weeks (mean 13) after the Olympic competition. Echocardiography was performed at peak training and also after deconditioning, and cardiac dimensions were assessed blindly.

RESULTS

Maximum ventricular septal thickness was 13.8 (0.9) mm in the trained state and 10.5 (0.5) in the deconditioned state (p < 0.005) (change 15-33%).

CONCLUSIONS

The finding that deconditioning may be associated with a considerable reduction in ventricular septal thickness in elite athletes over short periods strongly suggests that these athletes had a physiological form of left ventricular hypertrophy induced by training. Such a reduction in wall thickness with deconditioning may help to distinguish between the physiological hypertrophy of athlete's heart and primary pathological hypertrophy (for example, hypertrophic cardiomyopathy) in selected athletes with increased left ventricular wall thickness.

Physiological and biomechanical aspects of rowing. Implications for training

The drag force on a racing shell increases with the square of velocity corresponding to a 3.2 power increase in energy expenditure. However, the metabolic cost increases with only an approximately 2.4 power function of shell velocity. During international races the metabolic cost corresponds to an oxygen uptake of 6.7 to 7.0 L/min over 6.5 min. The relative anaerobic contribution to 6.5 min of 'all-out' rowing has not been determined but is estimated to range from 21 to 30%. Because of the large muscle mass involved in rowing, blood variables reach extreme values: adrenaline 19 nmol/L; noradrenaline 74 nmol/L; pH 7.1; and bicarbonate 9.8 mmol/L. Because of the static component of the rowing stroke at the catch, blood pressure increases to near 200mm Hg, and the heart of oarsmen has adapted to this load by increasing wall thickness and internal diameters. The maximal oxygen uptake of oarsmen may reach 6.6 L/min and ventilation 243 L/min. Arterial oxygen tension decreases by 20mm Hg during 'all-out' rowing corresponding to a decrease in pulmonary diffusion capacity. A force of approximately 800 to 900N is developed on the oar. Force generation during rowing is relatively slow, 0.3 to 0.4 sec. Oarsmen are strongest in low velocity movement with 70 to 75% slow twitch fibres in skeletal muscle. Data indicate that rowing technique and training may improve explaining why results become approximately 0.7 sec faster per year.

Usefulness of Doppler echocardiographic assessment of diastolic filling in distinguishing "athlete's heart" from hypertrophic cardiomyopathy

OBJECTIVE

In some athletes with a substantial increase in left ventricular wall thickness, it may be difficult to distinguish with certainty physiological hypertrophy due to athletic training from hypertrophic cardiomyopathy. The purpose of the present investigation was to determine whether assessment of left ventricular filling could differentiate between these two conditions.

DESIGN

Doppler echocardiography was used to obtain transmitral flow velocity waveforms from which indices of left ventricular diastolic filling were measured. Normal values were from 35 previously studied control subjects.

SETTING

Athletes were selected mostly from the Institute of Sports Science (Rome, Italy), and patients with hypertrophic cardiomyopathy were studied at the National Institutes of Health (Bethesda, Maryland).

PARTICIPANTS

The athlete group comprised 16 young competitive athletes with an increase in left ventricular wall thickness (range 13-16 mm; mean 14). For comparison, 12 symptom free patients with non-obstructive hypertrophic cardiomyopathy were selected because their ages and degree of hypertrophy were similar to those of the athletes.

RESULTS

In the athlete group, values for deceleration of flow velocity in early diastole, peak early and late diastolic flow velocities, and their ratio were not significantly different from those obtained in untrained normal subjects; furthermore, Doppler diastolic indices were normal in each of the 16 athletes. Conversely, in patients with hypertrophic cardiomyopathy, mean values for Doppler diastolic indices were significantly different from both normal subjects and athletics (p = 0.01 to 0.003), and one or more indices were abnormal in 10 (83%) of the 12 patients.

CONCLUSIONS

Doppler echocardiographic indices of left ventricular filling may aid in distinguishing between pronounced physiological hypertrophy due to athletic training and pathological hypertrophy associated with hypertrophic cardiomyopathy.

How to Recognize 'Athlete's Heart'

In brief Chronic endurance exercise inbrief duces various cardiac adapta- JHHHM tions, including an enlarged left ventricular cavity and an appropriate increase in wall thickness (eccentric hypertrophy), greater ability to increase stroke volume during exercise, and bradycardia at rest. Strength athletes have thicker left ventricular walls with no increase in cavity size (concentric hypertrophy). In the past, chest x-rays and ECG have suggested some of these changes, however, echocardiograms have clearly established the syndrome of the athlete's heart. In addition, these adaptations seldom exceed the range of normal variation seen in the general population. Understanding these alterations helps distinguish healthy adaptations to exercise from signs of disease.

Effects of triiodothyronine in spontaneously hypertensive rats. Studies on cardiac metabolism, function, and heart weight

We have studied the effects of triiodothyronine (T3) on heart function, on the myocardial oxidative pentose phosphate pathway, and on heart weight in spontaneously hypertensive (SHR) rats. Another aim was to examine whether these T3-effects may be reversible. T3 was administered daily (0.2 mg/kg s.c.) for 14 days. Compared to the untreated SHR controls, T3 induced an increase in heart rate (beats/min) from 357 +/- 10 (n = 17) to 553 +/- 10 (n = 17), in the pressure-rate-product (mm Hg/min) from 78 400 +/- 4500 (n = 15) to 113 700 +/- 4800 (n = 15), and in the heart weight/body weight ratio (mg/g) from 4.2 +/- 0.2 (n = 20) to 5.8 +/- 0.2 (n = 19). The activity of myocardial glucose-6-phosphate dehydrogenase, the first and rate-limiting enzyme of the oxidative pentose phosphate pathway (units/g protein), was elevated from 4.2 +/- 0.2 (n = 9) to 7.0 +/- 0.6 (n = 9) after 14 days of T3-treatment, while the activity of 6-phosphogluconate dehydrogenase, one of the following enzymes in the pathway, was not altered appreciably. These changes returned to the respective control values when T3-treatment was discontinued for 14 days. Our results demonstrate that T3 had a positive chronotropic effect and induced an additional heart enlargement in an animal model with already established cardiac hyperfunction and hypertrophy. The effects on heart function and weight, which were fully reversible, were not as pronounced as in normal Sprague-Dawley rats.

Continuous measurement of left ventricular performance during and after maximal isometric deadlift exercise

BACKGROUND

Isometric exercise produces a reflex increase in arterial blood pressure that is proportional to the intensity and mass of muscle used during contraction. Little is known about the transient effects of heavy weight lifting on left ventricular performance. In this study, we measured continuous changes in left ventricular performance during maximal large-muscle isometric exercise using the standing deadlift position.

METHODS AND RESULTS

Ten healthy young men performed serial deadlifts at 50% of maximal voluntary effort for 90 seconds and 100% of maximal effort for 30 seconds. Echocardiographic imaging (apical four-chamber view), arterial blood pressure (brachial artery catheter), and electrocardiographic monitoring were recorded throughout the deadlift and for 30 seconds of recovery. Aortic flow velocity was also monitored during a separate series of deadlifts. During 100% maximal deadlift, mean arterial pressure increased from 108 +/- 4 to 164 +/- 6 mm Hg. Left ventricular ejection fraction declined initially (from 57 +/- 2% to 49 +/- 3%) at 15 seconds into the lift and recovered (56 +/- 1%) due to significant increases in end-diastolic volume (104 +/- 11 ml to 132 +/- 16 ml) by the end of the lift. The peak systolic pressure/end-systolic volume ratio did not change during the deadlift. After cessation of the deadlift, mean arterial pressure declined precipitously (to 88 +/- 4 mm Hg) within 5 seconds and gradually returned to baseline after 30 seconds. Left ventricular performance indexes all increased significantly during the recovery phase (ejection fraction to 68 +/- 3%, peak systolic pressure/end-systolic volume ratio to 5.9 +/- 0.9). Findings were qualitatively similar for the 50% deadlift.

CONCLUSIONS

During an intense isometric deadlift, left ventricular performance declines initially but is restored by the Frank-Starling mechanism. Upon release of the deadlift, increased left ventricular performance develops in conjunction with a rapid decrease in arterial pressure. The combined effects of increased wall stress during the lift phase and enhanced contractility during the release phase probably contribute to left ventricular hypertrophy associated with repetitive weight training.

Development and determinants of dynamic obstruction to left ventricular outflow in young patients with hypertrophic cardiomyopathy

BACKGROUND

To study the development of dynamic subaortic obstruction in young patients with hypertrophic cardiomyopathy (HCM), serial echocardiograms were retrospectively analyzed in a group of 26 consecutive children with this disease who showed no evidence of dynamic outflow obstruction at their initial evaluation (age, 11 +/- 3 years).

METHODS AND RESULTS

After a follow-up of 3-12 years (mean, 7 +/- 3 years), seven of the 26 patients (27%) developed echocardiographic evidence of subaortic obstruction, i.e., marked systolic anterior motion (SAM) of the mitral valve with mitral-septal apposition and increased left ventricular outflow tract systolic velocities (3.8 +/- 0.3 m/sec; range, 3.1-4.5). Patients who developed SAM had smaller transverse dimension of the left ventricular outflow tract and more anteriorly displaced mitral valve when initially evaluated than did patients without development of SAM (outflow tract dimension, 19.1 +/- 4 versus 24.6 +/- 4 mm; mitral valve position index, 1.07 +/- 0.2 versus 0.73 +/- 0.3; each p less than 0.02). In patients with development of SAM, the already reduced outflow tract dimension decreased further during follow-up, and the mitral valve became even more anteriorly displaced within the left ventricular cavity. These developmental alterations in outflow tract size were associated with increases in left ventricular wall thickness, particularly of the basal anterior septum (11.0 +/- 8 mm; 72 +/- 33%) compared with control patients with HCM who did not develop SAM (3.0 +/- 3 mm; 17 +/- 10%; p less than 0.05).

CONCLUSIONS

Development of subaortic obstruction in young patients with HCM results from a process of dynamic remodeling of left ventricular geometry over several years and is characterized by progressive narrowing of the outflow tract with anterior displacement of the mitral valve and disproportionate thickening of the basal anterior ventricular septum.

Hypertension in Children and Adolescents

In brief For hypertensive children and adolescents who participate in sports, hygienic interventions may already be adequate-or may be unachievable. Yet, the decision to initiate pharmacotherapy is difficult. Physicians must weigh factors such as the presence of end-organ damage or a family history of early hypertensive complications with possible adverse effects of antihypertensive drugs, including depressant effects on the heart and reduced exercise tolerance. The authors favor long-lasting ACE inhibitors or calcium channel blockers, which usually do not alter heart rate and are relatively free of side effects.

Exercise and the heart. Good, benign, or evil?

The risks and benefits of regular aerobic exercise have been studied extensively. Because of the potential risks, we believe that sedentary persons over age 40 who have cardiac risk factors, as well as patients with coronary artery disease (CAD), should have a complete physical examination and probably an exercise electrocardiogram before starting a vigorous exercise program. In general, however, regular exercise has proven to be extra-ordinarily safe and the theoretical and proven benefits appear to greatly outweigh the risks in most people, including those with CAD, those with severe left ventricular dysfunction, and the elderly.

The frequency of familial dilated cardiomyopathy in a series of patients with idiopathic dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy is characterized by an increase in ventricular size and impairment of ventricular function. Most cases are believed to be sporadic, and familial dilated cardiomyopathy is usually considered to be a rare and distinct disorder. We studied the proportion of cases of idiopathic dilated cardiomyopathy that were familial in a large sequential series of patients whose first-degree relatives were investigated regardless of whether these relatives had cardiac symptoms.

METHODS

We studied relatives of 59 index patients with idiopathic dilated cardiomyopathy of obtaining a family history and performing a physical examination, electrocardiography, and two-dimensional, M-mode, and Doppler echocardiography. A total of 315 relatives were examined.

RESULTS

Eighteen relatives from 12 families were shown to have dilated cardiomyopathy. Thus, 12 of the 59 index patients (20.3 percent) had familial disease. There was no difference in age, sex, severity of disease, exposure to selected environmental factors, or electrocardiographic or echocardiographic features between the index patients with familial disease and those with nonfamilial disease. A noteworthy finding was that 22 of 240 healthy relatives (9.2 percent) with normal ejection fractions had increased left ventricular diameters during systole or diastole (or both), as compared with 2 of 112 healthy control subjects (1.8 percent) who were studied separately.

CONCLUSIONS

Dilated cardiomyopathy was found to be familial in at least one in five of the patients in this study, a considerably higher percentage than in previous reports. This finding has important implications for family screening and provides direction for further investigation into the causes and natural history of dilated cardiomyopathy.

Reversal of adaptive left ventricular atrophy following electrically-stimulated exercise training in human tetraplegics

Left ventricular (LV) myocardial atrophy and diminished cardiac function have been shown to accompany chronic human tetraplegia. These changes are attributable both to physical immobilisation and abnormal autonomic circulatory regulation imposed by a spinal cord injury (SCI). To test whether exercise training increases LV mass following chronic SCI, 8 neurologically complete quadriplegic males at 2 SCI rehabilitation and research centres underwent one month of electrically-stimulated quadriceps strengthening followed by 6 months of electrically-stimulated cycling exercise. Resting M-mode and 2-D echocardiograms were measured before and after exercise training to quantify the interventricular septal and posterior wall thicknesses at end-diastole (IVSTED and PWTED, respectively), and the LV internal dimension at end-diastole (LVIDED). LV mass was computed from these measurements using standard cube function geometry. Results showed a 6.5% increase in LVIDED following exercise training (p less than 0.02), with increases in IVSTED and PWTED of 17.8 (p less than 0.002) and 20.3% (p less than 0.01), respectively. Computed LV mass increased by 35% following exercise training (p = 0.002). These data indicate that myocardial atrophy is reversed in tetraplegics following electrically-stimulated exercise training, and that the changes in cardiac architecture are likely to be the result of both pressure and volume challenge to the heart imposed by exercise.