Hemodynamic Consequences of Physical Training after Myocardial Infarction

The emperor's tailors: the failure of the medical weight loss paradigm and its causal role in the obesity of America

During the past century, the medical profession has developed a paradigm for the treatment of obesity, which prescribes specific exercise and dietary goals under the umbrella of 'lifestyle change'. It has three components, all of which evolved from origins that had nothing to do with weight control. First, it is individually prescriptive, that is weight loss is considered the responsibility of the individual as contrasted to a societal or group responsibility. Second, it recommends exercise aimed towards structured, or non-functional, activities with a variety of physiological endpoints. Last, dietary goals are defined by calories, exchanges, food groups and various nutritional components. Diets are usually grouped by these goals. This model is unique to America, it is not working and it has also played a causal role in the obesity it is attempting to eliminate. A new model must be developed, which contains an observationally based societal prescription and links activity with functional outcomes and diets, which are food rather than nutritionally based.

Exercise training following myocardial infarction improves myocardial perfusion assessed by thallium-201 scintigraphy

AIM

We assessed the effects of a 6-week exercise programme on the thallium-201 myocardial perfusion characteristics of patients following myocardial infarction.

METHODS

Twenty-five patients presenting with a first acute myocardial infarction were randomised into two groups: (i) those undergoing a supervised exercise training programme over 6 weeks (n=15) and (ii) a control group who did not attend the exercise programme (n=10). All underwent three sequential stress thallium myocardial perfusion scans at 10 days, 6 weeks and 3 months after infarction. The stress conditions were identical on each occasion. The images were analysed using a polar plot with a computer assisted algorithm comparing stress and redistribution data. Values for extent, severity and percentage redistribution of the thallium images were generated.

RESULTS

A total of 29 perfusion defects were identified, 18 in the exercise group and 11 in the control group. Over 3 months in the exercise group the mean extent of the stress image defect fell from 109+/-64 to 95+/-51 pixels (P<0.05) while in the control group there was an increase from 133+/-57 to 144+/-57 pixels (P=ns). Stress defect severity fell in the exercise group from 581+/-417 to 494+/-346 S.D. (P<0.05) but increased in the control group from 765+/-494 to 877+/-543 S.D. (P=ns). On redistribution imaging in the exercise group a significant decrease was observed in both extent (94+/-56 to 76+/-43 pixels (P<0.05)) and severity (541+/-387 to 438+/-291 S.D. (P<0.05)) of the defects. However in the control group no significant change was observed for extent (125+/-54 to 125+/-52 pixels) or severity (745+/-485 to 820+/-503 S.D.) of the redistribution defects (P=ns). Reversibility of the defects increased slightly in both the exercise group (from 14.6+/-17 to 17.5+/-20%) and the control group (5.2+/-5 to 9.6+10%) (P=ns).

CONCLUSION

Following myocardial infarction a 6-week exercise programme improves myocardial perfusion characteristics. An exercise programme should be integrated into cardiac rehabilitation protocols for patients after infarction.

Cardiac rehabilitation: are the potential benefits being realized?

Cardiac rehabilitation or exercise training programmes are provided by many hospitals. This article discusses the evidence supporting the implementation of such facilities and reviews the reality of services in the UK.

Improved exercise tolerance by cardiac rehabilitation after myocardial infarction in the elderly: results of a preliminary, controlled study

Elderly patients are commonly excluded from cardiac rehabilitation after myocardial infarction (MI). The present controlled, non-randomized trial was undertaken as a preliminary study to compare some effects of cardiac rehabilitation between patients younger and older than 65 years without contraindications to physical exercise. Baseline total work capacity (TWC) was assessed by a maximal ergometric stress testing 4 weeks after MI. Patients were then prospectively enrolled into an 8-week ambulatory rehabilitation program (R-group: age < or = 65 N = 16; age > 65 N = 16). Those who refused or who could not participate in the program because of logistic difficulties served as controls (NR-group: age < or = 65 N = 16; age > 65 N = 14). In spite of non-randomized allocation, clinical characteristics did not differ between either treatment groups or age groups. TWC was re-assessed at 8 weeks from baseline evaluation in all patients. The number of completed training sessions in the R-group, and the proportion of sessions which were suspended for physiological or pathological (adverse events during exercise) causes were similar under and over 65 years. TWC increased (p < 0.001) in the R-group, the improvement being similar in the two age cohorts (< or = 65: +55% vs > 65: +65%, NS). A spontaneous enhancement of TWC (+37%, p < 0.001) occurred among younger controls as well. Only older controls did not improve their TWC; moreover, their +16% change was significantly (p < 0.05) less than the +65% increase obtained by the R-group of the same age.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of daily high-intensity exercise on myocardial perfusion in angina pectoris

Forty male patients with chronic stable angina pectoris and no prior myocardial infarction were studied by planar thallium scintigraphy with use of circumferential profile analysis. Ischemic defects were assessed by measuring degrees of circumference involved and area of defect. Data were collected for 3 vascular regions in each of 3 views (anterior, 45 degrees and 65 degrees left anterior oblique projection). Patients were then randomized to exercise and control groups, the former training for a period of 1 year using the Canadian Airforce plan for physical fitness. After 1 year, both groups were restudied. Exercise training produced a 34% reduction in degrees of ischemia overall (p less than 0.02), the most significant change being seen on the anterior view (72 degrees +/- 59 degrees before vs 30 degrees +/- 35 degrees after training). Regional analysis showed markedly improved perfusion anterolaterally and apically on the anterior view and anteroseptally on the 65 degrees left anterior oblique view. These improvements support the hypothesis that exercise training improves myocardial perfusion by enhanced collateral function.

Antianginal efficacy of exercise training: a comparison with beta blockade

Forty men with chronic stable angina and no prior myocardial infarction were studied. Exercise tolerance testing was carried out off treatment and after beta blockade. beta Blockers were stopped and the patients were randomised to a control group and a study group of patients who undertook a one year high intensity training programme. The groups were then restudied. Submaximum heart rate was reduced by 13 beats per minute by training and by 23 beats per minute by atenolol. Training increased the maximum heart rate by 10 beats per minute and atenolol reduced it by 29 beats per minute. The double produce ST threshold was increased from 183 to 205 by training but reduced to 143 by atenolol. Maximum ST depression was similarly reduced by both training and atenolol. As a result of the effects on maximum heart rate, training produced a greater improvement in exercise tolerance than atenolol with a treadmill time increased from 741 seconds to 1272 seconds with training compared with 974 seconds with atenolol. Other variables were similarly affected. Thus the antianginal efficacy of exercise training is as good as that achieved by beta blockade and represents an alternative to such treatment.

Exercise training in patients with severe left ventricular dysfunction. Hemodynamic and metabolic effects

We studied the effects of exercise training in patients with chronic heart failure attributed to left ventricular dysfunction (ejection fraction, 24 +/- 10%). Twelve ambulatory patients with stable symptoms underwent 4-6 months of conditioning by exercising 4.1 +/- 0.6 hr/wk at a heart rate corresponding to 75% of peak oxygen consumption. Before and after training, patients underwent maximal bicycle exercise testing with direct measurement of central hemodynamic, leg blood flow, and metabolic responses. Exercise training resulted in a decrease in heart rate at rest and submaximal exercise and a 23% increase in peak oxygen consumption from 16.8 +/- 3.8 to 20.6 +/- 4.7 ml/kg/min (p less than 0.01). Heart rate, arterial lactate, and respiratory exchange ratio were unchanged at peak exercise after training. Maximal cardiac output tended to increase from 8.9 +/- 2.7 to 9.9 +/- 3.2 1/min and contributed to improved peak oxygen consumption in some patients, although this change did not reach statistical significance (p = 0.13). Rest and exercise measurements of left ventricular ejection fraction, left ventricular end-diastolic volume, and left ventricular end-systolic volume were unchanged. Right atrial, pulmonary arterial, pulmonary capillary wedge, and systemic arterial pressures were not different after training. Training induced several important peripheral adaptations that contributed to improved exercise performance. At peak exercise, systemic arteriovenous oxygen difference increased from 13.1 +/- 1.4 to 14.6 +/- 2.3 ml/dl (p less than 0.05). This increase was associated with an increase in peak-exercise leg blood flow from 2.5 +/- 0.7 to 3.0 +/- 0.8 l/min (p less than 0.01) and an increase in leg arteriovenous oxygen difference from 14.5 +/- 1.3 to 16.1 +/- 1.9 ml/dl (p = 0.07). Arterial and femoral venous lactate levels were markedly reduced during submaximal exercise after training, even though cardiac output and leg blood flow were unchanged at these workloads. Thus, ambulatory patients with chronic heart failure can achieve a significant training effect from long-term exercise. Peripheral adaptations, including an increase in peak blood flow to the exercising leg, played an important role in improving exercise tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)

Myocardial perfusion changes following 1 year of exercise training assessed by thallium-201 circumferential count profiles

The effect of exercise training on myocardial perfusion was assessed using initial and 1-year thallium-201 (Tl-201) exercise studies in 56 patients with stable coronary artery disease (CAD). Subjects had been randomized into a trained group participating in supervised exercise three times per week and a control group. Indices (non-dimensional units) based on computer-analyzed circumferential count profile from nine regions of the heart, assessed in three projections, were used to eliminate observer bias and more accurately quantitate Tl-201 distribution and 4-hour washout. There was serial improvement of the global distribution count profiles in 21 of 27 (77.8%) of the trained and in 9 of 29 (31.0%) of the control subjects (p less than 0.001). The mean interval change in global initial distribution over the year period was 5 +/- 13 (mean +/- SD) in the trained and -6 +/- 14 in the control groups (p less than 0.003). The mean initial distribution of the trained group had improvement in all nine regions (significant in three), while the control group showed mean improvement in only one of nine regions. Additionally, the trained group showed improvement in the mean washout in five of nine regions (significant in three), while no mean regional washout improvement occurred in the control group. Thus, in this group of patients with stable CAD, exercise training resulted in apparently improved cardiac perfusion evidenced by enhance Tl-201 uptake and washout.

Cardiac adaptations to training: relevance to angina pectoris

Exercise training has for many years been suggested as a useful adjunct to medical therapy for patients with ischaemic heart disease. While its popularity amongst the general public continues to grow, limitations in our ability to assess its effects on the heart have meant that, as cardiologists, our desire to encourage this popular upsurge in physical activity has been tempered by our inability to provide convincing evidence of its value to our patients. In particular the role of exercise in the rehabilitation of patients with angina pectoris is as yet unclear. This review addresses this question and states what has been proven to date and also the questions which remain to be answered. It also suggests some reasons why we have failed to provide answers so far, and ways in which new technology may be used in the future. Studies in animals, asymptomatic humans, and patients with ischaemic heart disease have demonstrated that training reduces the resting heart rate and double product of heart rate times blood pressure at any given level of exercise. This has the benefit of reducing myocardial oxygen consumption during exercise. There is also evidence that it increases end-diastolic volume and left ventricular wall thickness. Evidence for an increase in maximal myocardial oxygen consumption in angina is limited to one or two studies showing an improved maximum double product and to the occasional patient proven by echocardiography or nuclear studies to increase ejection fraction by training. Better selection of patients and use of new imaging techniques should provide further information in the near future.

Early exercise training in patients older than age 65 years compared with that in younger patients after acute myocardial infarction or coronary artery bypass grafting

To evaluate potential benefits that elderly cardiac patients might gain from early exercise programs, 361 such patients were studied: group I--60 patients aged 44 years or younger; group II--114 patients aged 45 to 54 years; group III--111 patients aged 55 to 64 years; and group IV--76 elderly patients aged 65 years or older. All patients participated in a 12-week exercise program within 6 weeks of acute myocardial infarction or coronary artery bypass grafting. All patients performed symptom-limited exercise tests before and after completion of the exercise program. Between tests, elderly patients manifested significant differences in body weight (76.9 to 75.2 kg), percent body fat (22.3 to 20.8 kg), heart rate at rest (77 to 68 beats/min), maximal heart rate (126 to 138 beats/min), maximal METs (5.3 to 8.1), submaximal average double product (17,305 to 14,071), and submaximal average rating of perceived exertion (12 to 10 [p less than 0.05]). Magnitudes of change were similar among groups, although the elderly patient group had a significantly lower absolute physical work capacity at testing after training than the other 3 groups (p less than 0.05). In the 25 elderly patients who received beta-blocking drugs, METs increased from 5.1 to 7.8 (p less than 0.05). In the remaining 51 elderly patients not receiving beta-blocking drugs, METs increased from 5.4 to 8.2 (p less than 0.05). The magnitude of increase in patients who received beta-blocking drugs was not significantly different from that in patients not receiving beta-blocking drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of beta-adrenergic blockade on the hemodynamic effects of physical training in patients with ischemic heart disease

Beta-blocking agents are widely used in the treatment of patients with coronary artery disease. Their negative chronotropic and inotropic actions may alter the effects of physical training in cardiac rehabilitation programs. Therefore, resting and exercise cardiac output, stroke volume, heart rate, and arteriovenous oxygen content difference were measured before and after training in 15 male patients with coronary artery disease, who were treated with beta blockers, and in a control group of 14 patients not treated with beta-blocking agents. At the end of a 3-month training period, oxygen uptake at peak exercise increased similarly in the two groups, 37% and 34%, respectively; this was related to increases in stroke volume and heart rate, and therefore cardiac output, and to increases in arteriovenous oxygen content difference. The effects were similar whether or not the patients were treated with beta blockers. Also, at rest and submaximal exercise, beta blockade did not affect the training-induced changes of cardiac output, heart rate, and arteriovenous oxygen content difference. In both groups heart rate decreased with training while stroke volume and cardiac output increased significantly. In conclusion, beta blockade did not significantly alter the hemodynamic effects of training.

Nifedipine and the conditioning response

The effect of nifedipine (N) on conditioning was studied in 14 healthy sedentary men, aged 20 to 34 years. Subjects were ranked according to maximal oxygen consumption (VO2 max), paired, and 1 of each pair randomly assigned to take N, 20 mg, or placebo (C) 3 times daily. Exercise conditioning was 5 times/week for 6 weeks at greater than 85% of maximal heart rate for both groups. Adherence to exercise was 81% for the N and 82% for the C group. After training, the N group improved VO2 max from 41.4 +/- 1.4 to 51.6 +/- 2.0 ml/kg/min (p less than 0.05) and exercise time from 22 +/- 1 to 28 +/- 1 minutes (p less than 0.05). Heart rate (HR) at rest and the product of heart rate and systolic blood pressure both decreased (p less than 0.05): 70 +/- 6 to 55 +/- 4 beats/min; 9,300 +/- 900 to 6,800 +/- 700 beats/min X mm Hg. In the C group, VO2 max increased from 43.2 +/- 2.5 to 49.9 +/- 2.5 ml/kg/min (p less than 0.05); exercise duration improved from 24 +/- 2 to 29 +/- 2 minutes (p less than 0.05), and the rate-pressure product at rest decreased from 8,000 +/- 400 to 6,700 +/- 400 (p less than 0.05). Differences between N and C were not significant. Thus, N, unlike propranolol, does not inhibit the response to exercise conditioning.

Influence of a cardiac rehabilitation program on the cardiovascular, psychological, and social functioning of cardiac patients

Twenty-eight male cardiac patients who had either experienced myocardial infarction or undergone coronary bypass surgery were assigned to a treatment condition and participated in a 3-month, exercise-based Cardiac Rehabilitation Program, whereas 20 other cardiac patients were assigned to a routine-care condition and did not participate in the rehabilitation program. Cardiovascular, psychological, and psychosocial functioning were assessed before treatment or routine care was begun, after 3 months of treatment or routine care, and 4 months later. Results indicated that patients in the treatment condition evidenced reliably more efficient cardiovascular functioning (resting heart rate, resting diastolic blood pressure, treadmill exercise performance, exercise heart rate, exercise systolic blood pressure), better understanding of heart disease, better understanding of and reported compliance with treatment recommendations, more positive self-perceptions (health, body concept, self-concept, progress toward goals), and better psychosocial functioning (e.g., decreased employment-related stress, more active use and enjoyment of leisure time, more physical and sexual activity). Chronic patients benefited as much from the treatment as did acute patients, and the beneficial effects for all treated patients were evident not only just after rehabilitation, but also 4 months later. This investigation appears to be the first such test of effects of this type of treatment, and the results have wide generalizability and applicability.

Effect of prolonged intense endurance training on systolic time intervals in patients with coronary artery disease

We studied the effect of exercise training (ET) on systolic time intervals (STI) in 13 patients with coronary artery disease (CAD). All patients trained for at least 10 months. They exercised three times/week at 50% to 70% of maximal oxygen uptake (VO2max) for the initial 3 months and at least four times/week for approximately 50 minutes at 70% to 90% of VO2max thereafter. A significant training effect was documented by an increase in VO2max from 26.0 +/- 4.3 to 37.2 +/- 5.8 ml/kg/min (p less than 0.01), a lower heart rate (HR) at rest, and a lower blood pressure and HR during submaximal work. The indices of total electromechanical systole (QS2I) and left ventricular ejection time (LVETI) did not change. However, pre-ejection period index (PEPI) decreased from 137 +/- 9 msec to 129 +/- 9 msec (p less than 0.01). PEP/LVET decreased from 0.373 +/- 0.028 to 0.342 +/- 0.032 (p less than 0.01). Left ventricular end-diastolic dimension and posterior wall thickness, measured echocardiographically, were increased after training. We conclude that exercise training may improve myocardial performance in some patients with CAD.

Effect of 12 months of intense exercise training on stroke volume in patients with coronary artery disease

The purpose of this study was to determine whether 12 months of intense endurance exercise training can induce an increase in left ventricular stroke volume and in stroke work during exercise in patients with coronary artery disease. Eleven male patients were studied. With training, mean maximal oxygen uptake capacity (Vo2max) increased 39%, from 1.85 +/- 0.36 to 2.57 +/- 0.43 l/min. Stroke volume during upright exercise that required 35-65% of Vo2max was 18% higher after training. At the same percentage of Vo2max, mean blood pressure was the same before and after training; as a result, left ventricular stroke work (mean blood pressure X stroke volume) increased 18% (p less than 0.01). These findings suggest that in patients with coronary artery disease, prolonged, intense training induces an increase in stroke volume, and this is a result of cardiac rather than peripheral adaptations.

Exercise responses before and after physical conditioning in patients with severely depressed left ventricular function

The ability of patients with severely impaired left ventricle function to perform short-term exercise and to participate in a cardiac rehabilitation program and attain physical training effects was evaluated. Treadmill exercise tests were performed before and after physical conditioning in 10 patients with a prior myocardial infarction and a left ventricular ejection fraction at rest of less than 27 percent (range 13 to 26) determined by radionuclide angiography. All patients participated in a supervised exercise program with a follow-up period of 4 to 37 (mean 12.7) months. Baseline exercise capacity showed marked variability, ranging from 4.5 to 9.4 (mean 7.0 +/- 1.9) METS, and improved to 5.5 to 14 (mean 8.5 +/- 2.9) METS after conditioning (p = 0.05). The oxygen pulse (maximal oxygen uptake/maximal heart rate) before and after conditioning was used to assess a training effect and increased significantly from 12.8 +/- 2.0 to 15.7 +/- 3.2 ml/beta (p less than 0.01). There was no exercise-related morbidity or mortality, although two patients died during the study period. It is concluded that selected patients with severely imparied left ventricular function can safely participate in a conditioning program and achieve cardiovascular training effects.

Serumlipoprotein cholesterol in sedentary and trained male patients with coronary heart disease

To demonstrate the influence of exercise training on the lipoprotein cholesterol fractions (high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) cholesterol) in patients with coronary heart disease (CHD), 65 male patients were examined for cardiovascular function and lipid metabolism, before starting or after having participated in a coronary training group for more than one year. There were notable improvements not only in the physical performance data of the trained patients in reference to the tested maximal performance capacity per body weight (MPC/W) as well as the calculated heart volume performance ratio (HVPR) (MPC/W, + 26.0%; HVPR, -18.0%), but also in the lipoprotein cholesterol values and the calculated risk quotient of HDL and total cholesterol (HDL cholesterol, +5.1 mg/dl; LDL cholesterol, -23.3 mg/dl; VLDL cholesterol, -12.5 mg/dl; HDL/total cholesterol, +0.038). The results indicate the positive effect of physical training on lipoprotein cholesterol concentrations, and also in CHD patients in coronary training groups.

Effects of exercise training on left ventricular performance and myocardial perfusion in patients with coronary artery disease

To determine the effects of exercise training on left ventricular performance and myocardial perfusion in coronary artery disease, rest and exercise radionuclide angiocardiography and thallium-201 scintigraphy were performed before and after 12 weeks of training in 16 coronary patients. After training, 15 of the 16 patients had improved exercise tolerance; total treadmill exercise duration increased from (mean +/- standard error of the mean) 491 +/- 37 to 602 +/- 31 seconds (p less than 0.01), and the estimated rate of oxygen consumption (VO2 max) increased from 29.4 +/- 1.4 to 33.8 +/- 1.2 ml/kg per min (p less than 0.001). Resting left ventricular ejection fraction increased from 52 +/- 4 to 57 +/- 4 percent (p less than 0.02); no change occurred in left ventricular functional reserve assessed by ejection fraction and regional wall motion response to exercise at the same rate-pressure product before and after training. Myocardial perfusion at equivalent pre- and post-training cardiac work loads during exercise and on redistribution was unchanged by training. It is concluded that in patients with coronary heart disease, physical training increases exercise tolerance, and results in minimal improvement in resting left ventricular systolic performance. Functional reserve of both left ventricular systolic performance and the coronary circulation appears to be unchanged by exercise training. These data suggest that the beneficial effects of training for 12 weeks in patients with coronary artery disease predominantly result from factors other than improvement in left ventricular pump performance or perfusion.

Effects of physical training on myocardial ischaemia in patients with coronary artery disease

The effects of a simple physical training programme were investigated in a prospective and randomised trial in patients with stable angina pectoris using a modified exercise test. Twenty-four patients with ischaemic heart disease and an ischaemic response to conventional exercise electrocardiography were randomised into two groups: 12 patients took part in a training programme and 12 patients were allocated to a control group (no training). Exercise testing was performed sequentially at entry to the study and six months afterwards. At both studies we determined the heart rate at the same level of ischaemic ST segment depression (HR/ST threshold), the duration of the test, and relation of heart rate to the exercise load. The HR/ST threshold increased only in patients who underwent the exercise programme, suggesting indirectly that training resulted in the ability to do more work and attain a higher degree of myocardial oxygen consumption at the same level of myocardial ischaemia. In addition, training led to an increase in the duration of the test and to a reduction in heart rate at any level of submaximal exercise load. It is concluded that physical training in anginal patients results in an enhancement of myocardial oxygen availability.

Exercise can promote coronary collateral development without improving perfusion of ischemic myocardium

We studied the effect of exercise training on the coronary collaterals that developed in response to gradual coronary occlusion in dogs. After their proximal left circumflex coronary artery occlusion, 33 dogs were randomly assigned to exercise or sedentary groups. Coronary collateral function was evaluted 5 weeks or 8 weeks later. The exercised dogs developed better epicardial collateral connections to the occluded left circumflex as judged by higher retrograde blood flow from the distal left circumflex and lower pressure drop across the collaterals. No difference in collaterals was apparent angiographically. Microsphere data indicated that exercise dogs were not better protected against tachycardia provoked subendocardial ischenia in the myocardium supplied by the collaterals.

Long-term effects of physical training on coronary patients with impaired ventricular function

Eighteen patients with coronary heart disease and an ejection fraction of 0.40 or less were entered into an individualized exercise training program. Maximal symptom-limited exercise stress test and cardiac catheterization studies were performed initially and 12--42 months (average 18.5 months) after exercise training. At the time of the follow-up study, the mean functional aerobic impairment (FAI) improved from 32.1 to 23.4% (p less than or equal to 0.01); resting and submaximal heart rates were significantly lower (p less than 0.01 and 0.05, respectively). There was no significant change in the pulmonary artery or left ventricular end-diastolic pressure, cardiac index, stroke index, left ventricular end-diastolic volume or ejection fraction. Exercise training, therefore, can be beneficial even for patients with impaired ventricular function. Increase in physical work capacity was not correlated with improvement of ventricular function; on the other hand, exercise training did not cause deterioration of ventricular function.

Beneficial effect of physical training on blood flow to myocardium perfused by chronic collaterals in the exercising dog

To determine the effect of physical training on collateral blood flow, we measured regional myocardial blood flow (MBF) by injecting 15 mu radioactive microspheres at rest and during exercise in 14 dogs with chronic coronary occlusive lesions. Seven dogs subsequently trained for 6 weeks while the other seven remained in kennels. Training effect was documented by decrease in heart rate during exercise that averaged 35 beats/min. MBF studies were repeated after 6 weeks. Myocardial samples were obtained from normally perfused zones (NZ) and from regions supplied via collaterals (collateral dependent zones or CZ). Initially, endocardial blood flow in CZ averaged 1.110 ml/min/g (83% of NZ, P less than 0.05) at rest and 1.36 ml/min/g (69% of NZ, P less than 0.05) during exercise, indicating relative underperfusion. Epicardial blood flow was equal in NZ and CZ. After 6 weeks MBF was not significantly changed in control animals. After training, however, MBF to underperfused endocardium of CZ during exercise was 39% greater than it had been prior to training. The epicardial portion of CZ (not exhibiting underperfusion) showed no change in MBF during exercise after training. Our data suggest that beneficial effects of training in coronary disease may include improvement in MBF to underperfused collateral-dependent portions of myocardium.

Alterations in ventricular mass and performance induced by exercise training in man evaluated by echocardiography

Few data are available regarding the effects of exercise training upon cardiac structure and performance in man. We evaluated the echograms of 24 normals before (PRE) and after (POST) 11 weeks of endurance exercise training. Conditioning consisted of a walk-jog-run protocol at 70% maximal heart rate for one hour four days per week. Training reduced heart rate and increased maximal duration and estimated oxygen consumption of treadmill exercise. Compared to PRE, the echogram in the POST training period revealed an increased left ventricular (LV) end-diastolic dimension (EdD), a decreased end-systolic dimension (EsD) and thus an increased stroke volume (EdD3-EsD3) and shortening fraction (EdD-EsD)/EdD). Cardiac output (CO) and peripheral vascular resistance (BP/CO X 80) were identical PRE and POST conditioning. Importantly, an increase in mean fiber shortening velocity was observed POST training as were increases in LV wall thickness, ECG voltage of S in V1 + R in V5, and LV mass. Thus endurance training was accompanied by increases in both LV dimension and mass as well as LV shortening fraction and contraction velocity as observed by echocardiogram.

A study of left ventricular function in coronary patients before and after physical training

Fifteen subjects recovering from a myocardial infarction or suffering from angina were given a maximum effort test on a bicycle ergometer and hemodynamic and angiographic investigations before and after a period of physical training. The training program consisted of three sessions of 60 to 75 min each week for two months. Maximum effort tests showed that physical capacity had increased by 17% (P less than 0.02) and that for the same amount of effort the heart rate had decreased by 13% and the blood pressure by 7% (P less than 0.01). Hemodynamic and angiographic investigations showed no significant changes after training in the left ventricular end-diastolic pressure, ventricular volume, ejection fraction, VCF, percentage of shortening and segmental contractility, in the total group, in those patients whose contractility was considerably impaired, or in those who had large dyskinetic areas or widespread akinesia. It is concluded that training had no direct influence on the myocardium, either beneficial or detrimental.

Comparison of active participants and dropouts in CAPRI cardiopulmonary rehabilitation programs

Of 547 men and 56 women enrolled up to April 1974 in Cardiopulmonary Research Institute (CAPRI) community programs for cardiopulmonary rehabilitatation, 84.5 percent had clinical manifestations of coronary heart disease. These medically supervised programs of physical training involved 30 to 60 minutes of graded levels of working, calisthenics and, if indicated, jogging for 3 mornings/week. Altogether 352 (58.4 percent) dropped out after an average of 8.6 months for men and 5.7 months for women. The remaining 230 men and 21 women remained active for 22 and 20 months, respectively. In retrospect, there were few minor differences between active participants and dropouts in physical characteristics, clinical diagnoses and responses to exercise testing on enrollment. Elapsed time to morbidity tended to be longer in active persons than in dropouts. Over one half of active men and about one third of dropouts were working. Of six early deaths, one occurred before training was instituted, and five within the first 2 weeks of training. Among men, the respective total mortality rates were 2.7 and 4.7/100 person-years for active participants and dropouts; among women, the rates were 0 and 3.8 respectively. Whereas 24 episodes of cardiac arrest occurred in 13 men, with three fatalities outside the training program, in 11 instances of exertional arrest during class training all defibrillations were successful. Without this benefit of medical supervision there would have been little difference in mortality experience.