Effects Of Chronic Exercise Research Articles

Exercise termination effects on food intake, plasma insulin, and adipose lipoprotein lipase activity in the Osborne-Mendel rat

Thirteen-week-old male, Osborne-Mendel rats were exercised for 6 weeks on a motorized treadmill. Exercise depressed weight gain and cumulative light cycle food intake while cumulative dark cycle and 24-hour total food intake were unaffected. Rats in sedentary and exercise groups were killed 24 hours after the last bout of exercise to assess the effects of chronic exercise and at 48, 60, 72, and 84 hours to determine the effects of exercise termination. Compared to sedentary controls, exercise decreased plasma insulin, epididymal and retroperitoneal depot weight and cell size, and retroperitoneal lipoprotein lipase (LPL) activity. Forty-eight hours after exercise, plasma insulin concentration increased to sedentary levels. By 60 hours, dark cycle food intake was increased above and adipose LPL activity was comparable to sedentary levels. At 84 hours postexercise termination, dark cycle food intake, plasma triglyceride, and epididymal LPL activity per depot and per cell were significantly greater than sedentary values. Exercise termination resulted in a preparatory response for rapid lipid deposition probably arising from increased food intake, plasma insulin, and enhanced LPL activity within 84 hours following termination of exercise.

Effects of chronic exercise on the coronary circulation in conscious rats with renovascular hypertension.

Since various studies suggest that chronic physical conditioning promotes myocardial vascularity, we investigated whether it could prevent the coronary reserve abnormalities of hypertensive cardiac hypertrophy. One week after operation, female Sprague-Dawley rats with two-kidney, one clip Goldblatt hypertension were either subjected to a moderate exercise program by swimming (n = 21) or kept sedentary (n = 16) for 9 weeks. Sedentary (n = 16) and exercised (n = 15) sham-operated rats served as controls. Maximal coronary blood flow and minimal coronary resistance, either per unit mass or for the entire left ventricle, an index of the functional cross-sectional area of the coronary resistance vessels, were determined in conscious, unrestrained rats by left atrial microsphere injection following maximal vasodilation with carbochrome (12 mg/kg). Following exercise, left ventricular mass was moderately (+5-10%) but significantly increased in normotensive rats, whereas left ventricular hypertrophy was significantly accentuated in the hypertensive rats. Minimal coronary resistance for the entire left ventricle was significantly decreased (-24%) in normotensive rats but did not change significantly in hypertensive rats. Minimal coronary resistance per unit mass (the coronary vasodilator reserve) tended to decrease in normotensive rats (-17%), whereas it tended to be further augmented in hypertensive rats (+13%). However, these differences were marginally significant and were not associated with any changes in maximal coronary blood flow per unit mass (the coronary flow reserve). Thus, in normal rats, exercise promoted myocardial arterial vascularity in parallel with the development of cardiac hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic exercise on regional substrate oxidation in aged rat hearts

Effect of chronic exercise on regional substrate oxidation in aged rat hearts

Effects of acute and chronic exercise on myocardial ultrastructure

Histological and ultrastructural evaluation of the heart reveals that structural alterations may be induced by both acute and chronic exposure to exhaustive exercise. Following an acute bout of exercise to the point of exhaustion, the normal heart does not appear hypoxic as assessed by mitochondrial morphology. However, small shifts in intracellular volume fractions as well as dilatation of transverse tubules and sarcoplasmic reticulum have been observed. The functional significance of these ultrastructural changes is not well understood, but could explain any alterations in contractility observed at this point in time. Following repeated exposure to strenuous dynamic exercise on a daily basis for an extended period of time (endurance training), the effects seem to be principally on the vasculature of the heart, with no alterations in composition of the myocardial cell. This is manifested by an increase in size of the major coronary arteries and a corresponding change in the number of capillaries. The chronic effects of exercise on coronary arterioles are unknown. The results of retrospective studies in humans and laboratory experiments with primates and lower mammals indicate that these training-induced structural alterations may play a protective role with respect to coronary heart disease. Most importantly, this role would appear to be both preventive and rehabilitative in nature.

Effects of chronic exercise on biochemical and functional properties of the heart

This paper summarizes the effects of physical conditioning on the intrinsic biochemical and functional properties of the heart. The majority of studies reported to date have focused on the rat as an exercise model. Two general methods of training have been utilized: endurance running and swimming. Results collectively suggest that swimming enhances both intrinsic biochemical and functional properties of the rodent contractile system. The mechanism for inducing these adaptations remains unknown, but it could be due to the hypoxic environment of swimming. In contrast, endurance running programs involving rodents (as well as other species) suggest relatively little change in the biochemical and functional properties of the contractile system. Initial findings indicate that adaptation in calcium availability to the contractile system may be occurring to enhance cardiac performance in response to training. However, this adaptation, along with the possibility of contractile protein phosphorylation, needs to be examined in greater detail before definitive conclusions on cardiac adaptation can be reached.

Effect of chronic exercise on glycolysis measured regionally in isolated perfused rat hearts

Effect of chronic exercise on glycolysis measured regionally in isolated perfused rat hearts

Effects of chronic exercise during aging on muscle and end-plate morphology in rats.

Terminal sprouting, myofiber atrophy, and fiber type changes were studied in soleus and distal gastrocnemius muscles of 21- and 26-mo-old rats and in rats who performed treadmill running from 21 to 26 mo. End-plate structure and muscle fiber types were demonstrated by staining for acetylcholinesterase and myosin ATPase activity. Terminal sprouting was expressed as the percentage of end plates with growth configurations. Fiber atrophy was assessed as percentage of small-diameter fibers. In all three groups, the percentage of small-diameter fibers was significantly smaller and the percentage of growth configurations significantly larger in the soleus than in the gastrocnemius. The exercised-soleus group had a significantly higher percentage of growth configurations than the 26-mo controls, which had a higher percentage than the 21-mo controls. Percentages among gastrocnemius groups were not different. Fiber type was similar among gastrocnemius groups. However, the exercised-soleus had significantly more slow-twitch fibers than the controls. These data suggest that the soleus responds differently to chronic exercise during aging than does the gastrocnemius.

Cigarette smoking, physical activity, and alcohol consumption: Relationship to blood lipids and lipoproteins in premenopausal females

A total of 164 premenopausal female subjects were randomly selected for evaluation from a much larger pool of volunteers. The relationships between blood lipid and lipoprotein levels as dependent variables and cigarette smoking, physical activity, and alcohol consumption were determined from partial regression coefficients. A lower HDL-C level (10.1 mg/dL) was seen in smokers v nonsmokers. For each ounce of alcohol consumed, HDL-C level was higher by 2.8 mg/dL, and greater physical activity was associated with a higher HDL-C level of 8.6 mg/dL. An analysis of covariance with covariance adjustments for age and body fat revealed that smokers who regularly exercise or consume alcohol had significantly lower HDL-C levels than nonsmokers with similar habits. Subjects who both exercise and consume alcohol demonstrated higher HDL-C levels than those who indulge in one or the other separately. Results suggest that cigarette smoking may attenuate the effects of chronic exercise or alcohol consumption, or of both, to raise HDL-C levels. Also, chronic exercise and alcohol consumption may exert an additive effect, raising HDL-C level.

Exercise and Diabetes

Prescribed exercise can be a useful adjunct to diet and insulin therapy in the diabetic child. The acute and chronic effects of exercise in diabetic patients are reviewed. The physician can determine the appropriate exercise prescription and training method for a particular patient from information outlined in this article. Guidelines for participation in sports activities are also provided.

Effect of prolonged exercise on serum lipids and lipoproteins

It has been shown that physical exercise lowers serum triglyceride levels and may increase high density lipoprotein-cholesterol levels. Understanding of the mechanisms responsible for these beneficial adaptations is still incomplete. Twenty-six men, who played soccer continuously for 64 hours to establish a world's record, were monitored for acute changes in lipid metabolism. Food intake was determined before and during the exercise period. Blood specimens were taken before and repeatedly during the match for the measurement of triglycerides (TG), total cholesterol (CH), glycerol, apolipoprotein A-I (apoA-I), and cholesterol in various lipoprotein fractions (quantitative lipoprotein electrophoresis). During exercise TG levels decreased from 116 ± 26 to 66 ± 13 mg/dL and CH from 180 ± 22 to 135 ± 25 mg/dL. Both TG and glycerol showed an initial increase followed by a continuous decrease. Alpha-CH increased by 19% whereas beta-CH and pre-beta-CH decreased markedly (39% and 78%, respectively). In contrast to alpha-CH, apo A-1 fell only slightly by 10%. These results indicate that the effect of chronic exercise on lipids and lipoproteins can be mimicked by acute prolonged exercise. Similar mechanisms may be involved in these adaptations. Moreover, the extreme length of physical exertion substantially lowered CH.

The effect of exercise on atherosclerosis in the coronary artery and abdominal aorta of mature female swine.

This study investigated the effects of chronic exercise on atherosclerosis in the aorta and coronary artery in mature female swine. Preceding and during the exercise training period these animals were fed high fat, (soybean or corn oil) cholesterol-free diets. Sixteen swine were paired according to breed, body weight, and diet. Eight swine were a non-exercise control group while the remaining eight were an experimental group and exercised 4 days per week for 4 months. The exercise training program initially consisted of running at 5.6 km·h−1, zero gradient, for 15 min with increments of 1 min of running time every 2 weeks.

Effect of exercise on collateral development in dogs with normal coronary arteries

To determine the effects of chronic exercise on the coronary collateral circulation of dogs with normal coronary arteries, 1-yr-old purebred beagles were divided into sedentary control and exercising groups. The latter were trained to run on a treadmill. A lower maximal heart rate during a standardized exercise test protocol after a 10- to 12-week training period and a higher gastrocnemius cytochrome oxidase activity in the runners attested to the presence of cardiovascular and skeletal muscle training effects. However, left ventricular weights, left ventricle/body weight ratios, myocardial myofibrillar and myosin ATPases, and hemodynamics were similar in sedentary and exercising dogs except for a significantly higher resting cardiac output in the runners. After occlusion of the left anterior descending coronary artery, both collateral conductance (retrograde flow/aortic pressure) and collateral flow measured with microspheres tended to be lower in the trained dogs, but differences were not significant. The endocardial/epicardial flow ratio in the ischemic area after coronary occlusion did not distinguish between exercisers and controls. Thus treadmill running in the dog with normal coronary arteries produced a training effect, but had no effect on coronary collateral vessels.

Effects of chronic exercise on the ultrastructure of the adrenocortical cells in the rat

Four groups of male rats were exercised for periods of 2, 4, 6, and 8 weeks with controls in each group. As a result of chronic exercise there was an increase in the width of the zona fasciculata of the adrenal cortex. Also, there was an increase in the number and size of the mitochondria, and an increase in the quantity of smooth endoplasmic reticulum, and during the first 4 weeks of exercise an increase in the number of lipid droplets in the zona fasciculata. The close relationship between the smooth endoplasmic reticulum and the mitochondria, and the relationship between the smooth endoplasmic reticulum and the lipid droplets suggests a possible means for a transport mechanism for movement of precursors between these organelles.

Effects of chronic exercise on the kidneys at different ages

In order to determine the effects of chronic exercise on the kidneys at different ages, young, adult, and old rats swam 1 hour either daily or twice a week for 10 weeks and then were killed along with unexercised controls. The kidneys were removed and sections were prepared for histometric analysis including planimetric measurements on camera lucida drawings of renal components and line sampling. With both degrees of exercise young rats showed lower kidney weight, fewer glomeruli and less medullary tissue than unexercised controls. In the adult group no significant differences were noted between exercised and unexercised rats. In old rats both degrees of exercise resulted in a loss of kidney weight and medullary and cortical mass, and a decrease in size of glomeruli while total number of glomeruli remained unchanged. Thus the effects of chronic exercise on the kidneys varied with age. Retarded kidney development occurred in young animals; a loss of renal tissue in old animals; and no change in adult animals.

The effect of physical conditioning on cardiac response to acute exertion.

The effect of chronic exercise (training) and acute exertion on myocardial water and electrolyte metabolism, Na–K-ATPase activity, and morphology was studied in the male rat. Training increased the potassium content in myocardial cells, the effect depending on the duration of the training period. Potassium accumulation in the heart cells was not associated with the cardiac hypertrophy that developed relatively quickly and depended primarily on the intensity of work, rather than on the duration of the training period. The most regular effect of acute exertion on myocardial electrolyte content was potassium uptake by the heart. Chronic physical overload, depending on its severity, reduced or abolished the heart's ability to accumulate potassium during physical exertion. An attempt was made to evaluate the possible role of Na–K-ATPase in the mechanism of depression of potassium transport against its electrochemical gradient after chronic physical overload. In comparison with normal response of the heart, both morphological and biochemical changes were diminished in both the trained and, to a smaller extent, the overtrained heart during acute extreme exertion. It is concluded that potassium accumulation in myocardial cells is an essential adaptive reaction to physical exertion and the extent of potassium uptake depends on the functional state of the heart.

The effect of chronic exercise on reserpine-induced gastric ulceration in rats

The effect of chronic exercise on reserpine-induced gastric ulceration was studied in the rat. One group of male albino rats was exercised on a treadmill daily for eight weeks and then compared to a control group, not exercised but exposed to similar handling and environment. Another group swam in a tank daily for eight weeks and was compared to a control group, not exercised but exposed to similar handling and environment. The degree of ulceration of the glandular portion of the stomach produced by administration of reserpine was significantly lower in treadmill runners than in their controls, however, the degree of ulceration for the swimmers was not significantly different from that of their controls.

The effect of chronic exercise on the personality of middle-aged men by univariate and multivariate approaches.

The effect of chronic exercise on the personality of middle-aged men by univariate and multivariate approaches.

Effect of chronic exercise on adrenocortical function and structure in the rat

ARTICLESEffect of chronic exercise on adrenocortical function and structure in the ratR. J. Buuck, and G. D. TharpR. J. Buuck, and G. D. TharpPublished Online:01 Dec 1971https://doi.org/10.1152/jappl.1971.31.6.880MoreSectionsPDF (917 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByChanges in basal hypothalamo-pituitary-adrenal activity during exercise training are centrally mediatedEdward Park, Owen Chan, Qifu Li, Mike Kiraly, Stephen G. Matthews, Mladen Vranic, and Michael C. Riddell1 November 2005 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 289, No. 5Effect of physical activity on hippocampal high affinity choline uptake and muscarinic binding: a comparison between young and old F344 ratsBrain Research, Vol. 541, No. 1The rat as a model for physical fitness studiesComparative Biochemistry and Physiology Part A: Physiology, Vol. 66, No. 4Physical training in human hyperplastic obesity. IV. Effects on the hormonal statusMetabolism, Vol. 26, No. 3Effects of chronic exercise on the ultrastructure of the adrenocortical cells in the ratCell And Tissue Research, Vol. 168, No. 2 More from this issue > Volume 31Issue 6December 1971Pages 880-883 Copyright & PermissionsCopyright © 1971 the American Physiological Societyhttps://doi.org/10.1152/jappl.1971.31.6.880PubMed5123668History Published online 1 December 1971 Published in print 1 December 1971 Metrics

Influence of physical training, aortic constriction and exogenous anterior pituitary hormones on the heart weights of hypophysectomized rats.

Studies were conducted with hypophysectomized rats to determine the effects of chronic exercise (training), injections of exogenous hormones, aortic constrictions and combinations there of on the weight of the heart. In addition, the role of growth hormone on cardiac weight was reinvestigated. The hypophysectomized rats that were trained for 10 weeks or longer had significantly heavier heart weights than their nontrained counterparts. When daily injections of a single exogenous hormone of ACTH, GH, ICSH or TSH were made into trained and nontrained animals, there was no trained group that had significantly heavier heart weights than their control group. Rats having aortic constrictions or receiving DOCA injections also had significantly heavier heart weights than their controls. When various dosages of GH (0.2 mg to 6.0 mg) were injected daily for three weeks, no evidence was obtained that indicated that the presence of this hormone resulted in cardiac enlargement. It was concluded that under the experimental condition of this study, cardiac enlargement can occur in hypophysectomized rats when the work demands on the heart have been increased.

Reduction of serum uric acid in young men during physical training

The effects of eight weeks of chronic physical exercise (training) on serum sodium urate concentration were investigated. Thirty normal, healthy male college students, aged 18 to 29, comprised the sample. Ten students were extremely active (athletic group), 10 were moder ately active participants in a physical education class (training group) and 10 were relatively sedentary (control group). Serum sodium urate concentration and a physical fitness index (modified Harvard step test) were measured at the beginning, periodically during an eight week training period and after a four week “deconditioning” period. Pre-experimental correlation coefficients between serum uric acid levels and age, height, weight, body surface area, resting heart rate and fitness index were low (0.003 to 0.214) and not significant statistically. It was also found that chronic physical exercise lowered serum uric acid 0.3 to 3.2 mg/100 ml in 80 percent of the subjects in the athletic and training groups, particularly in those healthy persons with values of 7.0 to 8.5 mg/100 ml. The most important finding of this study was a significant ( P < 0.05) decrease in serum sodium urate concentration in the members of the athletic group, who underwent an extremely strenuous conditioning program compared to members of the other groups. Probable mediating physiologic mechanisms are discussed to explain this finding. Practical implications are also discussed in view of the association between serum uric acid, gout and coronary artery disease and the uncertain effect of chronic exercise (training) on serum sodium urate concentration.