ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08925.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08926.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08927.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.Three classical problems in the field of man's adaptive response to exercise are reviewed. A case is made for the pump capacity of the heart limiting maximal oxygen uptake in man. This conclusion is based on findings that the capacity of skeletal muscle of man markedly surpasses that of the heart supplying it with a flow and thereby oxygen. It is suggested that only one third of the muscle mass of man can fully tax the capacity of the heart and consume the oxygen delivered by the heart. If a larger muscle mass is intensely engaged in the exercise, vasoconstriction must occur in the arterioles of the exercising limbs to avoid a reduction in blood pressure Evidence is presented that a decrease in heart rate at submaximal exercise‐observed after a period of physical conditioning, is caused by an altered autonomic chronotropic activity to heart, which most likely is due to a less potent feed back reflex from exercising muscles. The enlarged stroke volume is secondary to a larger diastolic filling, which via a Frank‐Starling mechanism results in an elevation in the stroke volume. Last, it is argued that the altered metabolic response to exercise after physical conditioning, i.e. the larger lipid oxidation and reduced lactate production, results from local regulatory mechanisms rather than from changes in supply of oxygen, substrates, or hormones. Further, the muscle metabolic response to exercise is thought to play a major role in modulating systemic cardiovascular regulation in exerc

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08928.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.There is a very high probability that lipoprotein metabolism plays a central role in the etiology of coronary heart disease. In sedentary persons one way to favorably alter lipoprotein metabolism and possibly delay the progression of coronary atherosclerosis is by an increase in their habitual physical activity. More physically active persons tend to have lower plasma triglycerides and very low density lipoprotein concentrations, and a greater high‐density lipoprotein mass due to higher concentrations of the subfraction HDL2and apoprotein A‐I. Plasma low‐density lipoprotein concentrations usually are not significantly reduced by exercise unless accompanied by weight loss, but there may be important changes in the distribution among the low‐density subfractions. These exercise effects are most likely mediated by alterations in the activity of enzymes involved in the synthesis, transport and catabolism of the various lipoproteins including lipoprotein lipase, hepatic lipase and lecithin: cholesterol acyltransferase. In healthy persons as well as in patients with ischemic heart disease, diabetes and renal failure, an increase in moderate‐intensity, endurance‐type activity requiring an expenditure of approximately 4 MJ (1 000 kcal) per week usually produce favorable lipoprotein changes. Above this level a dose‐response relationship exists, with greater changes occurring up to energy expenditures of 19 MJ (4500 k

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08929.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.With advancing adult aging an increase in vascular stiffness, an increase in systolic, pulse and mean arterial pressure, modest left ventricular hypertrophy, and a moderate decline in early diastolic filling rate have uniformly been observed. In some individuals these changes are not associated with enhanced systemic resistance if arterial pressure remains within the normotensive range. End‐systolic volume, stroke volume, ejection fraction, velocity of ejection, and cardiac output are preserved in these elderly subjects. In other individuals both aortic impedance and peripheral vascular resistance are increased with age and modest declines in resting stroke volume and cardiac output have been observed. During maximal exercise a diminished heart rate and a diminished reduction of end‐systolic volume occur in elderly subjects. In some, an enhanced end‐diastolic volume prevents a reduction in or enhances stroke volume (Starling mechanism); this adaptation bears a striking resemblance to that observed during exercise when the beta‐adrenergic system is pharmacologically inhibited. In other elderly subjects, stroke volume during exercise does not increase to the extent that it does in younger subjects. Even in these subjects in whom peak cardiac output during exercise declines, however, it is not entirely clear that the central circulation limits peak oxygen consumption (VO2). The non‐uniformity of results of studies that have investigated the effect of aging on cardiac function and vascular resistance suggests that variables that impact on cardiovascular function other than agingper se, i.e. life style variables, e.g. nutrition, smoking, physical conditioning status, or the prevalence of occult coronary disease, differed among the various subject

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08930.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08931.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.With aging, glucose tolerance (GT) declines, plasma insulin concentration increases, and sensitivity to the action of insulin declines. Evidence is accumulating that this decline in glucose tolerance and insulin sensitivity can be prevented by regularly performed vigorous exercise. Preliminary results are presented in this paper showing that prolonged, strenuous and frequent exercise can also completely normalize GT by decreasing resistance to insulin in some patients with mild non insulin dependent diabetes mellitus (NIDDM) and in some individuals with impaired glucose tolerance (IGT). Exercise appears to be effective in normalizing GT only in patients who still have an adequate capacity to secrete insulin, and in whom insulin resistance is the major cause for abnormal GT. The amount of exercise required to normalize GT in such patients appears to be in the range of 25 to 35 km per week of running, or a comparable amount of another form of exercise, performed on a regular basis.

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08932.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.The changes in fitness and body composition which accompany physical training in people of normal weight would be very valuable in the treatment of obesity. However, one of the most marked disabilities arising from obesity is a reduced exercise tolerance, so severely obese patients are unable to perform the exercise which would bring these benefits. It has been suggested that exercise may confer benefits on the obese person by reducing voluntary food intake, or by causing a prolonged elevation of metabolic rate. There is no good evidence for these claims. Obesity is best treated by a combination of dietary restriction and exercise: the more severe the obesity the more important the diet component of treatment, but exercise becomes more important with the management of mild obesity or the prevention of obesity.

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08933.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.Exercise‐training at environmental temperatures outside the thermal neutral zone, causes thermoregulatory adaptive reactions. In the heat, sweat efficiency is enhanced thus reducing the incidence of hyperthermia while in the cold discomfort and danger of frostbite are minimized by an improved cutaneous circulation specially in the extremities. Over long periods of time exercise does not affect thermogenesis except when refeeding. It is suggested that the reduced postprandial heat production reported in exercise‐trained subjects is related to changes in nutrient metabolism which in turn could be related to insulin and norepinephrine modified acti

ISSN:0001-6101    

DOI:10.1111/j.0954-6820.1986.tb08934.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY