Effect of physical conditioning on cardiovascular function. a ballistocardiographic study.
TL;DR: Five of the 5 men with initially abnormal ballistocardiograms had normal records at the end of the program, and significant increases occurred in mean I, J, GI, HI and IJ forces.
Abstract: Fifteen middle-aged men participated in a program of endurance exercise and running for six months. Changes in cardiovascular function were evaluated by using an air-supported ultralow-frequency ballistocardiograph. Significant increases occurred in mean I, J, GI, HI and IJ forces. Four of the 5 men with initially abnormal ballistocardiograms had normal records at the end of the program.
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TL;DR: This historical review describes the research on the regulation of glucose transport in skeletal muscle conducted in my laboratory and in collaboration with a number of colleagues in other laboratories, and the interactions between the effects of exercise and insulin.
Abstract: This historical review describes the research on the regulation of glucose transport in skeletal muscle conducted in my laboratory and in collaboration with a number of colleagues in other laborato...
138 citations
Cites background from "Effect of physical conditioning on ..."
...We found that exercise lowered serum triglycerides and improved heart function (70, 71, 118)....
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137 citations
TL;DR: The data support the thesis that in some patients increased physical activity after myocardial infarction is followed by beneficial hemodynamic effects on the heart and possibly by increased coronary blood flow.
Abstract: The hemodynamic effects of physical training, three periods weekly for 1 to 2 months, after myocardial infarction were assessed in seven patients by cardiac catheterization at rest and during exercise. The training was followed by reduction in exercise heart rate and tension-time index as determined from brachial artery pressures. Stroke volume during exercise was enhanced. No significant change occurred in the heart volume. Left ventricular function was improved, and a significant increase in the rate of rise of right ventricular pressure occurred. These were interpreted as indicating myocardial hypertrophy, which probably through reduced compliance also accounted for increased ventricular filling pressures. Lactate in arterial blood was reduced during exercise without any change in the arteriovenous oxygen difference. Small and not significant changes occurred in vital capacity, forced expiratory volume, fasting blood sugar, and serum lipids.
Concomitant with the hemodynamic changes exercise tolerance was improved. The data support the thesis that in some patients increased physical activity after myocardial infarction is followed by beneficial hemodynamic effects on the heart and possibly by increased coronary blood flow. The need for proper selection of patients and close medical supervision during training is illustrated and emphasized.
97 citations
TL;DR: It is believed that the evidence that increased physical activity might be beneficial is sufficient to justify further extensive studies and the proof of the preventive therapeutic value of activity programs must come from observations of significant numbers of the population at risk.
Abstract: 1. 1. A review of investigations on the relation of physical activity to cardiovascular health and disease has been undertaken, with a brief discussion of some mechanisms that might play a part. 2. 2. There is a suggestion that recent activity is more important than activity earlier in life; even a light or moderate amount of physical activity may have significance. Encouraging as this is, most studies are of occupational activity and might not have direct applicability to physical activity undertaken as preventive therapy. 3. 3. We believe that the evidence that increased physical activity might be beneficial is sufficient to justify further extensive studies. More information is needed concerning the mechanisms of the possible benefits. 4. 4. The proof of the preventive therapeutic value of activity programs must come from observations of significant numbers of the population at risk. We favor an experimental design with active intervention and randomization of subjects. There is much virtue in a study of men with high indexes of risk relative to coronary heart disease. 5. 5. There is a pressing need to enlist and train more personnel to undertake the numerous pilot studies that are needed and the larger, more definitive studies that should follow. 6. 6. Increased communication and joint planning among physicians, physical educators, physiologists and biometricians are needed.
91 citations
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Book•
01 Jan 1956
TL;DR: This is the revision of the classic text in the field, adding two new chapters and thoroughly updating all others as discussed by the authors, and the original structure is retained, and the book continues to serve as a combined text/reference.
Abstract: This is the revision of the classic text in the field, adding two new chapters and thoroughly updating all others. The original structure is retained, and the book continues to serve as a combined text/reference.
35,552 citations
1,554 citations
TL;DR: The present study provides a picture of coronary heart disease in one of its simpler forms, and may help in elucidating social connexions, as well as providing information on the pathological mechanisms of any differences with physical activity of work that were found.
Abstract: It has previously been shown that the drivers of London's double-decker buses are more likely to die suddenly from \"coronary thrombosis\" than the conductors, and that Government clerks suffer more often from rapidly fatal cardiac infarction than do postmen.43 On the basis of these and similar observations a hypothesis has been stated that nmen in physically active jobs have a lower incidence of coronary (ischaemic) heart disease in middle-age than men in physically inactive jobs. More important, the disease is not so severe in physically active workers, tending to present in them in relatively benign forms. It is a principle of epidemiological research of this type to seek evidence from as many, as various, and as independent sources as possible.40 The present report deals with the frequency, in relation to occupation, of ischaemic myocardial fibrosis in men dying from causes other than coronary heart disease itself. These myocardial scars are often evidence of early coronary heart disease and of less severe, or at any rate non-lethal, ischaemia. Thus the present study provides a picture of coronary heart disease in one of its simpler forms, and this may help in elucidating social connexions. At the same time another test of the hypothesis is made, using quite different data from the previous inquiries and upon quite another aspect of the condition. The inquiry it was hoped would provide some information on the pathological mechanisms of any differences with physical activity of work that were found; and in particular we sought to learn something about the relationships of occupation to coronary artery disease. In brief, Can the hearts of men be seen to vary with the kind of work they have done ? At what phases in the complex of coronary-myocardial disease as a whole can this particular \" cause \"-physical activity/inactivitybe seen to operate ? More generally the inquiry was intended to provide a statistical account of the coronary arteries of the middle-aged British male population, 1954-6.42
634 citations
TL;DR: The capabilities of the heart as a pump are investigated on the heart-lung preparation as used in this laboratory, where all the mechanical factors of the circulation are under strict control, to give an idea of the behaviour of this organ in the intact animal.
Abstract: THE working capacity of a pump is measured by its output. In the heart the output has to undergo large alterations with varying conditions of the body, and its measurement is therefore the most important quantitative determinat.ion connected with this organ. Most of the previous researches on this subject have been carried out on the whole animal, and in view of the difficulty of controlling the different factors involved under these circumstances it is not surprising that considerable discrepancies exist between the views of different workers as to the relative importance of the various factors involved. Thus whereas Zun tz m and his pupils describe great variations in the outpuit associated with exercise, and Krogh (2) has actually measured these variations in marl, Yandell Henderson (3), as a result of a number of careful experiinents, considers it impossible for the heart to more than double its output under any circumstances, though Krogh finds variations in the output of the left ventricle between 2 8 and 21 litres per minute. It seemed to us that the whole question might be put on a securer basis if investigated on the heart-lung preparation as used in this laboratory, where all the mechanical factors of the circulation are under strict control. The results obtained in this way should give us somie idea of the capabilities of the heart as a pump, which might serve to explain the behaviour of this organ in the intact animal. It has been shown lately by Mark walder (4) and one of us that, provided the venous inflow be maintained constant, the ouitput of the left ventricle is within wide limits irndependent of the arterial resistance, the small falling off in the output with rise of pressure, observed in previous experiments, being fully accounted for by the increased leakage from the aorta through the coronary system of vessels as the arterial pressure rises. Knowlton
541 citations
332 citations