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Biomedical subjects

G F Fletcher

Publications and source records attributed to G F Fletcher.

At least 19 recordsLinked to original sources
PubMed2001

Effect of exercise intensity and frequency on lipid levels in men with coronary heart disease: Training Level Comparison Trial.

The objective of the Training Level Comparison Trial was to determine whether a more intense exercise program versus a less intensive program has additional favorable effects on blood lipids in men with coronary heart disease (CHD) over a 12-month period. The study-a randomized, controlled trial conducted at 2 clinical centers-enrolled 185 patients with documented CHD. A simple randomization procedure led to unequal numbers of patients in the 2 interventions: 82 in the low-intensity and 103 in the high-intensity group. Target heart rate during exercise corresponded to 50% of maximum oxygen uptake (VO(2 max)) +/- 5 beats/min in the low-intensity group and 85% +/- 5 beats/min in the high-intensity group. The intensity of exercise made little difference on lipid improvements. However, the attendance rates for the 6- and 12-month periods (percentage of total exercise sessions attended) were significantly related to increased high-density lipoprotein (HDL) cholesterol (r(s) [Spearman rank correlation coefficient 0.20 to 0.26, p <0.05]), and decreases in the ratios of low-density lipoprotein (LDL)-to-HDL cholesterol (LDL:HDL, r(s) = -0.24 to -0.28, p < 0.01) and total-to-HDL cholesterol (total:HDL, r(s) = -0.25 to -0.29, p < 0.01) at 6 and 12 months. The relation of the attendance rate to LDL:HDL and total:HDL ratios remained significant in repeated-measures regression analysis. Exercise frequency may be more important than intensity in improving HDL cholesterol and LDL:HDL and total:HDL ratios in men with CHD.

Adult↗
PubMed1998

Current status of cardiac rehabilitation.

Cardiac rehabilitation is an important management strategy in patients with coronary artery disease. Substantial data from both mortality and morbidity studies support the benefits. Recent studies of patients with coronary artery disease have shown that exercise confers greater benefit in those who are also on a fat-controlled diet than in those who are not. In addition, high-intensity exercise has been found to improve left ventricular function in men with coronary artery disease. Individual home exercise programs, both with and without telephone monitoring, are prescribed by physicians and health care professionals for an increasing number of patients. Aggressive modification of coronary risk factors is also incorporated in the overall cardiac rehabilitation program, and the concept of greater total kilocalorie expenditure per week is emphasized.

Exercise↗
PubMed1998

Exercise and coronary artery disease prevention.

Physical exercise has become universally accepted as an important component in the primary prevention of coronary disease and in the management of subjects with established coronary artery disease. Exercise should be utilized appropriately for each individual's needs and done in concert with aggressive modification of other risk factors such as abnormal blood lipids, high blood pressure, obesity and cigarette smoking. Such as approach in the preventive management of coronary artery disease is rewarded by beneficial clinical outcomes and savings in health dollars.

Coronary Disease↗
PubMed1997

Exercise and its role in the prevention and rehabilitation of cardiovascular disease.

The purpose of this article is to review the beneficial effects of regular exercise in the primary and secondary prevention of coronary artery disease (CAD). Epidemiologic studies indicate that a physically inactive life-style is associated with twice the risk of developing CAD. The magnitude of risk is similar to that of other modifiable risk factors. Meta-analysis of studies of cardiac rehabilitation after myocardial infarction demonstrate that cardiac rehabilitation participants lower their risk of death by 20% to 25% compared to controls. Exercise training results in several beneficial physiological changes including an increase in exercise endurance, higher resting and exercise stroke volumes, lower resting and submaximal exercise heart rates, and increased capillary density and oxidative enzyme capacity in skeletal muscle. In patients with established CAD, exercise training improves symptoms of angina and congestive heart failure and attenuates the severity of exercise-induced ischemia. Regular exercise can favorably modify other risk factors, but the benefits are modest. Reductions in systolic and diastolic blood pressure readings average 6 to 9 mm Hg; decreases in total and low-density lipoprotein (LDL) cholesterol approximate 5 to 10 mg/dL; and increases in high-density lipoprotein (HDL) cholesterol approximate 2 mg/dL. Exercise training as a sole intervention does not appear to enhance smoking cessation. Regular exercise does improve psychosocial well-being. Most studies of physical activity have enrolled predominantly middle-aged men; however, available evidence suggests similar cardiovascular benefits for women, the elderly, and children and youth. Physical activity levels decrease substantially during the school-age-adolescent transition in both males and females. More than half of the adult population is sedentary or inactive. Collectively, accumulated data suggest the need for both individualized/high-risk and population-based approaches to increasing physical activity across the life span.

Adult↗
PubMed1997

Cardiovascular evaluation of the athlete. Issues regarding performance, screening and sudden cardiac death.

Recent studies have reported ECG anomalies and a high prevalence of exercise-related arrhythmias among well trained, apparently healthy endurance athletes with superior levels of cardiorespiratory fitness. The occurrence of sudden and premature cardiac deaths in amateur and professional athletes, who appear to embody all of the virtues of health and fitness, ahs raised our consciousness regarding the underlying atherosclerotic or nonatherosclerotic causes, and the need for, and extent of, preparticipation screening in competitive athletes. It appears that strenuous physical activity may trigger acute cardiovascular events in some athletes. Coronary artery disease is the most frequent autopsy finding in those over the age of 35 years who die suddenly. In contrast, structural cardiovascular abnormalities, including hypertrophic cardiomyopathy and malformations of the coronary arteries, are the major cause of sudden death in younger athletes. This article reviews these issues, with specific reference to the assessment of cardiorespiratory fitness, legal and prohibited performance-altering medications, the pathophysiological basis of exertion-related untoward events, the athlete at risk, limitations of conventional screening programmes and contemporary recommendations to identify latent cardiovascular disease in athletic populations.

Anaerobic Threshold↗
PubMed1996

The antiatherosclerotic effect of exercise and development of an exercise prescription.

Atherosclerosis and its sequelae of MI, bypass surgery, and angioplasty can be affected positively in both the primary and secondary setting by the use of properly prescribed physical activity. Such activity in a higher weekly kilocalorie expenditure (usually involving greater intensity) seems to be effective in achieving regression of atherosclerosis and in improving LVEF. In general, any activity is better than none, but more energy expenditure seems associated with greater benefits. Regardless of these apparent beneficial effects of exercise, such benefits are much less apparent if modification of other coronary risk factors is not also achieved. These efforts must focus on cessation of smoking, control of abnormal blood lipids, and normalization of high blood pressure. With these less costly methods of controlling atherosclerosis, the future impact of this type of intervention will likely be of great importance as society adjusts to the cost constraints of managed (especially capitated) care in the near future.

Clinical Trials as Topic↗
PubMed1996

Adherence in the training levels comparison trial.

In the Training Levels Comparison Trial, 197 male coronary heart disease patients were randomized to low or high intensity training with target heart rates, which corresponded to 50% and 85% of the VO2max achieved on the previous exercise test, respectively. Patients were to exercise at their assigned intensity level at three 1-h long supervised sessions per week for 2 yr. This paper reports on two components of adherence: attendance at exercise sessions and achievement of heart rates in the target range. During the first year of training, the average percent of exercise sessions attended (mean +/- SE) for the low intensity group (64.0 +/- 2.5%) was significantly higher than for the high intensity group (55.5% +/- 2.7%). At the end of 1 yr of training, 54% and 37% of the low and high intensity patients, respectively, achieved heart rates within 5 beats.min-1 of their target heart rates. Although the low intensity program was preferable to achieve maximum attendance, attenders on the high intensity program achieved higher heart rates. These results suggest that to maximize the achieved heart rate, it would be optimal to motivate a cardiac rehabilitation patient to train at the high intensity level for a prolonged period of time.

Adult↗
PubMed1995

Efficacy of high-intensity exercise training on left ventricular ejection fraction in men with coronary artery disease (the Training Level Comparison Study).

The purpose of this study was to compare high- versus low-intensity exercise training on the change in echocardiographic left ventricular ejection fraction (LVEF) from rest to peak exercise. Sedentary men with coronary artery disease, aged 30 to 70 years, were randomized to dynamic exercise training of either low intensity, 50% of maximal oxygen consumption, n = 89; or high intensity, 85% of maximal oxygen consumption, n = 111. No other interventions were imposed and patients were evaluated at 6 months and 1 year. Both exercise groups significantly increased exercise capacity without adverse events, but the increase was greater (p = 0.02) in the high-intensity exercise group. The mean exercise test rest-peak LVEF in the high-intensity group rose from 6.20% at baseline to 6.54% in 6 months and to 6.73% at 12 months, while the low-intensity group showed no improvement at 6 months and a decrease at 12 months. Multivariate analyses revealed that treatment group (high versus low intensity) significantly contributed to the change in rest-peak LVEF. When the exercise groups were subdivided by initial baseline LVEF < or = 50% versus > 50%, those with the higher LVEF in the high-intensity group showed a greater (p = 0.05) increase in the rest-peak LVEF from baseline to 1 year. Over a 1-year period, exercise capacity improved in both exercise-intensity groups, but more so in the high-intensity group, with no adverse events. The high-intensity group, compared with the low-intensity, showed more improvement in the rest-peak LVEF, especially in those with a higher LVEF at baseline.

Adult↗