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PubMed2001

[Physical exercise and insulin sensitivity].

Physical exercise is known to be essential in the treatment of type 2 diabetes. An increased glucose uptake is evidenced during acute muscular exercise, over the post-exercise period, and following physical training. In this paper, we review metabolic and molecular aspects of physical exercise. We emphasize on the non-insulin dependent glucose transport induced by muscular contraction, which involves AMP-activated protein kinase. The discovery of this pathway is likely to open new therapeutic targets for type 2 diabetes.

Biological Transport↗
PubMedDate not supplied

Metabolic changes in man under hypokinesia and physical exercise.

It was theorized that physical exercise may be used to prevent the development of metabolic changes in man under hypokinesia (diminished muscular activity). In this investigation we assessed the efficacy of physical exercise in attenuating metabolic disturbances in twelve physically healthy men aged 19 to 23 years under 100 days of hypokinesia and 15 days of a readaptation period. The subjects were divided into an experimental and a control group with six men each. The experimental group was subjected to combined hypokinesia and physical exercise and the control group to pure hypokinesia (that is, without the use of any preventive measures). The actual experimental period was preceded by a period to establish baseline values. Both groups of men were on a diet that consisted of about 2700 kcal/day. For the simulation of the hypokinetic effect the men were kept under a liberal bed rest regimen. During the background period, hypokinetic period, and readaption period, several biochemical parameters were measured. Energy requirements were found to be suppressed, protein metabolism impaired, loss of nitrogenous products increased, fluid and electrolyte excretion accelerated, vitamin elimination was enhanced, corticosteroid blood concentration decreased, and hemoglobin and cell counts increased. It was concluded that hypokinesia caused marked debilitating metabolic changes in man. Physical exercise failed to counteract effectively the development of adverse reactions in the examined parameters under hypokinesia.

Adaptation, Physiological↗
PubMed1991

Increased insulin-stimulated glucose uptake by exercised human muscles one day after prolonged physical exercise.

We evaluated whether the increased peripheral insulin sensitivity often reported after physical exercise is generalized or limited to the active musculature. Substrate exchange in leg (previously active) and forearm (previously inactive) were measured by catheterization technique basally and during a hyperinsulinaemic euglycaemic clamp (2 mU insulin kg-1 BW min-1) in nine healthy men before and 1 day after 3-h exercise (50% VO2max). One day after exercise basal glucose uptake was unchanged in the leg, while it was decreased in the forearm (-61%, P less than 0.01) compared with the pre-exercise condition. Glucose uptake during hyperinsulinaemia was increased in the leg (+31%, P less than 0.05), but not in the forearm. Basal lactate release by the leg was increased by the exercise, while lactate release by the forearm was decreased, significantly only during the clamp. These results indicate that local and not systemic factors are responsible for the changes in insulin sensitivity observed in the recovery from physical exercise.

Adult↗
PubMed2004

Five months of physical exercise in hemodialysis patients: effects on aerobic capacity, physical function and self-rated health.

BACKGROUND: The number of chronic renal failure patients treated by hemodialysis (HD) is continuously increasing. Most patients have reduced physical capacity and have a high risk of cardiac and vascular diseases. The aim of this study was to determine the effects of 5 months physical exercise of HD patients' physical capacity, self-rated health and risk factors for cardiovascular disease. METHODS: 33 HD patients were included in the study. INCLUSION CRITERIA: HD for more than 3 months, age >18 years. EXCLUSION CRITERIA: Diabetes mellitus, symptomatic cardiovascular disease, musculoskeletal limitations, severe peripheral polyneuropathy, inability to speak Danish or English, dementia or other mental disorders. The patients were randomly assigned to an exercise group (EG, n = 22) or a control group (CG, n = 11). Prior to randomization, baseline testing was performed. The effects were measured by aerobic capacity, '2-min stair climbing', 'squat test', self-rated health (SF36), blood pressure and lipids. All tests were carried out by blinded testers. The intervention consisted of 1 h of physical exercise twice a week for 5 months. RESULTS: 20 patients completed the intervention. Attendance was 74% of all sessions. There were no dropouts caused by complications related to the intervention. The EG had a significant increase in aerobic capacity, 'squat test' and Physical Function and Physical Component Scale (SF36). No significant changes were observed in any of the parameters in the CG. CONCLUSION: Physical exercise twice a week for 5 months increases physical function and aerobic capacity in HD patients. An exercise program with only two exercise sessions per week seems easy to implement in clinical practice with high attendance among participants. Further investigation is needed to determine the effects on blood pressure and lipids. There were no medical complications related to the exercise program.

Activities of Daily Living↗
PubMed2000

Serum isoforms of bone alkaline phosphatase increase during physical exercise in women.

Physical activity is an important factor for maintaining and probably increasing bone mass in humans. However, the mechanism by which this takes place is not completely understood. The purpose of this study was to examine the influence of physical exercise on serum alkaline phosphatase (ALP) and in particular, the bone isoforms of ALP. Six ALP isoforms were quantified by high-performance liquid chromatography: three bone (B/I, B1, and B2), and three liver ALP isoforms. In addition, serum calcium, parathyroid hormone (PTH), and other markers of bone formation and degradation, as measured by osteocalcin and cross-linked carboxyterminal telopeptide of type I collagen (ICTP), were analyzed. The study groups comprised 15 women, 8 postmenopausal (range 51-62 years) and 7 near age of peak bone mass (range 21-27 years). When the postmenopausal women exercised on an ergometer cycle until exhaustion we found significant increases in serum of bone ALP isoforms B1 and B2, and phosphate, even considering the hemoconcentration that occurred during the exercise. When the young women jogged in a moderate tempo for 40-40 minutes the levels of serum B2 and PTH increased. All changes turned towards baseline within 20 minutes after exercise. In conclusion, exercise increased serum ALP bone isoforms B1 and B2, and their responses were differentiated. As B1 and B2 are known to represent specific bone compartments, cortical and trabecular bone, the present findings may indicate different effects on bone of weight- and nonweight-bearing exercise.

Adult↗
PubMedDate not supplied

[Physical exercise and vascular endothelium].

Physical exercise has positive effects at patients with atherosclerotic cardiovascular diseases. These benefits are explained not only by the action upon the cardiovascular risk factors, but also by the improvement of the endothelial dysfunction. Physical exercise has vasodilator, antiplatelet, antioxidative, antiadhesive, antiproliferative and antiapoptotic effects upon the vascular endothelium. It improves the endothelium-mediated vasodilation in coronarian and peripheral beds in coronary heart disease, arterial hypertension, heart failure, diabetes mellitus, and also at sedentary and smokers, thus exerting a vasculoprotective action against atherosclerotic disease.

Arteriosclerosis↗
PubMed1988

Effects of physical exercise for elderly patients with physical impairments.

Exercise is known to preserve many physiological responses in the healthy elderly, yet those with physical impairments are often discouraged from exercising. The authors studied the effects of a closely supervised exercise program designed specifically for elders with health problems and functional limitations. Tests, selected for their relevance to clinical patient management, included the Self Evaluation of Life Function questionnaire, treadmill performance, and tests of autonomic nervous system and neuromotor functions. Ambulatory volunteers, aged 64 to 83 years, with noncardiac health problems, were randomly assigned to a control group (CG; n = 17) or a 16-week exercise group (EG; 3 hr/wk, n = 18). Nine of the control and 13 of the exercise subjects completed the study. All EG dropouts were due to illness. EG attendance averaged 87%, and subjects trained at a heart rate (HR) of 103 +/- 5 beats/min (SD) (98% of prescription HR). Though EG test responses showed a tendency to improve, none reached statistical significance. This result was affected by the small number completing the study and the variability inherent in such a sample. Though these impaired elderly subjects enthusiastically and safely participated with high attendance and at an exercise intensity adequate to expect benefit, measurable training effects were not demonstrated.

Aged↗
PubMed1998

Reduction of 8-hydroxyguanine in human leukocyte DNA by physical exercise.

We investigated the effect of physical exercise on the level of 8-hydroxyguanine (8-OH-Gua), a form of oxidative DNA damage, and its repair activity in human peripheral leukocytes. Whole blood samples were collected by venipuncture from 21 healthy male volunteers (10 trained athletes and 13 untrained men), aged 19-50 years, both before and after physical exercise. Trained athletes showed a lower level of 8-OH-Gua (2.4+/-0.5/10(6) Gua, p = 0.0032) before exercise when compared to that of untrained men (6.2+/-3.5). The mean levels of 8-OH-Gua of untrained subjects decreased significantly (p = 0.0057) from 6.2+/-3.5/10(6) Gua (mean+/-SD/10(6) Gua) to 3.3+/-1.4/10(6) Gua after physical exercise. On the other hand, the mean levels of repair activity of untrained subjects significantly increased after exercise (p = 0.0093) from 0.037+/-0.024 (mean DNA cleavage ratio+/-SD) to 0.056+/-0.036. In the trained athletes 8-OH-Gua level and its repair activity were not changed before and after the exercise. We also observed inter-individual differences in 8-OH-Gua levels and its repair activities. These results suggest that physical exercise causes both rapid and long-range reduction of oxidative DNA damage in human leukocytes, with individually different efficiencies.

Adult↗
PubMed1997

Potentiation of acetaminophen hepatotoxicity by acute physical exercise in rats.

Effects of acute physical exercise on the acetaminophen-induced hepatotoxicity were examined in adult female rats. Rats were forced to move at a speed of 10 m/min for 2 hr in a rotating cage. Immediately following the exercise bout rats were treated with acetaminophen (APAP; 700 mg/kg, i.p.). The physical exercise enhanced the hepatotoxicity of APAP as shown by increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities measured 24 hr following the treatment. A significant decrease in hepatic glutathione (GSH) was observed in the rats forced to exercise suggesting that the enhancement of APAP hepatotoxicity was associated with the depression of this endogenous tripeptide. The role of adrenergic stimulation in the exercise-induced hepatic GSH depression was examined by pretreating the animals with a receptor specific adrenergic antagonist, such as prazosin HCl (15 mg/kg, i.p.), propranolol HCl (15 mg/kg, i.p.), and yohimbine HCl (15 mg/kg, i.p.) 15 min prior to the exercise bout, but neither of the antagonists prevented the GSH depression. Administration of alpha-tocopherol acetate (450 mg/kg/day for 3 days and 150 mg/kg on day 4, i.p.) did not affect the exercise-induced GSH depression or lipid peroxidation in liver homogenates as determined by increases in malondialdehyde formation. These results suggest that neither adrenergic stimulation nor oxidative stress plays a significant role in the enhancement of APAP hepatotoxicity and hepatic GSH depression induced by acute physical exercise.

Acetaminophen↗
PubMed1993

High intensity physical exercise induced effects on plasma levels of copper and zinc.

Physical exercise leads to many metabolic, cardiovascular, and muscular changes in the body. The trace elements (TE) zinc and copper are directly involved, as enzymatic cofactors, in many of these processes, especially those related to nutrients metabolism, oxygen transport, and formation of usable energy. The effects of high-intensity physical exercise on plasma levels of CU2+ and Zn2+ in 19 subjects are investigated (9 males and 10 females). Plasma copper concentration decreases, and plasma zinc concentration increases, after exercise, in both sexes. After 30 min recovery, both TE concentration values shifts toward rest values in both sexes. These results only partially agree with literature data, probably because we used the treadmill exercise, which makes many muscles work, whereas other authors made their subjects perform a cycloergometer exercise. Physical exercise causes a marked redistribution of TE (copper and zinc) between body stores, bloodstream, and tissues. The condition of high metabolism may lead to a deficiency of TE, requiring supplementation in order to maintain high level performance.

Adult↗
PubMed2003

Acute exposure to moderate high altitude decreases growth hormone response to physical exercise in untrained subjects.

AIM: Physical exercise in recreational mountain sports is frequently performed without acclimatization to hypoxic conditions. Hypoxia may modify the hormonal and metabolic adaptive response to exercise depending on the type of exercise and on the physical fitness of the subject. This study aims at investigating the growth hormone (GH) response to submaximal exercise after acute exposure to moderate high altitude. METHODS: Ten trained (T) and 10 untrained (UT) male volunteers (mean age 23.8+/-3.2 y) underwent, in random order, 2 submaximal exercise (ergocycle) tests of the same absolute intensity. One test was performed at their habitual living altitude (690 m above sea level); the other, after acute exposure to 2325 m above sea level. Plasma levels of GH, Insulin-like growth factor-1 (IGF-1) and lactate were measured before and immediately after the exercise tests. RESULTS: Plasma GH levels increased after exercise (p<0.05) in both experimental conditions, and for both T and UT subjects. Hypoxia decreased the GH-IGF-1 response to exercise in the UT group. By contrast, the GH-IGF-1 response to exercise was not modified in the T group. The increase in plasma lactate levels induced by exercise was much higher in the UT than in the T group, and it was not affected by hypoxia. CONCLUSION: Acute exposure to hypoxia blunts the GH response to submaximal physical exercise in untrained individuals.

Adult↗
PubMed1996

[Treatment of moderate arterial hypertension with physical exercise].

OBJECTIVE: To compare the anti-hypertensive effect of physical exercise programs with that of usual therapeutic regimens. METHODS: Blood pressure measurements at rest and during exercise were compared in two groups of patients with moderately high blood pressure treated either medically or with physical exercise. Outcome was evaluated at 5 years. RESULTS: In the first group there were 28 patients who were given drug treatment (excepting beta blockers). In the second group, 53 patients performed regular physical exercises specifically prescribed. After 5 years, the analysis of variance confirmed that physical exercise had a real anti-hypertensive effect. CONCLUSION: Physical exercise can be an effective mean of treating moderately high blood pressure with a more prolonged effect than drug regimens.

Adult↗
PubMed1982

[Catecholamine excretion during physical exercise and mental performance].

The basal and exercise-induced heart rates, lactate levels, and the adrenaline and noradrenaline excretions in the urine were measured during different types of physical exercise and mental performance: during moderate physical exercise (Ia, n = 12), submaximal physical exercise (Ib, n = 24), during moderate mental performance (motorway driving, IIa and IIb, n = 25), higher-grade mental performance (driving car-simulator, III, n = 14), and during submaximal mental performance (car racing, IV, n = 48). The moderate physical exercise and moderate mental performance could not be differentiated from one another, or from the higher-grade mental performance using the above-mentioned parameters. Both the submaximal physical exercise and mental performance resulted in a comparable lactate acidosis, heart rate increase, and noradrenaline excretion; the excretion of adrenaline is, however, 3 times higher after submaximal mental performance, than after submaximal physical exercise. The ratio of adrenaline to noradrenaline excretion changed from approximately 1:4 (during physical exercise and moderate mental performance) to approximately 1:2 during submaximal mental performance. The excretion of adrenaline and the ratio of adrenaline to noradrenaline excretion can therefore be used to differentiate between higher-grade mental performance and physical exercise. These parameters can be easily measured without discomfort to the subjects.

Acidosis↗
PubMed1983

Type I diabetes and physical exercise.

Metabolic effects of physical exercise in type I diabetes are reviewed. Physical training leads to an increased insulin sensitivity but does not seem to influence the metabolic control. However, the metabolic control is of importance for the exercise results. Patients in a good control do not differ from normal individuals concerning working capacity, recovery after hypoglycemia and hormonal balance. Furthermore, abnormalities in the blood glucose homeostasis during exercise in type I diabetes are discussed as well as potential beneficial effects of physical training in the prevention of cardiovascular disease.

Blood Glucose↗
PubMed1998

Effects of propranolol on the hepatic hemodynamic response to physical exercise in patients with cirrhosis.

Physical exercise increases portal pressure (hepatic venous pressure gradient [HVPG]) in patients with cirrhosis. It is unknown if this deleterious effect is associated with changes in gastroesophageal collateral blood flow and if these can be prevented by propranolol administration. The aim of this study was to characterize the effects of propranolol on the splanchnic hemodynamic response to exercise in patients with cirrhosis. Twenty-three patients with cirrhosis and portal hypertension had hemodynamic measurements in baseline conditions, and during moderate cycling exercise (40 W) under double-blind propranolol or placebo administration. In patients receiving placebo, HVPG significantly increased during exercise (from 16.7 +/- 0.9 to 19.0 +/- 1.0 mm Hg; P < .01), hepatic blood flow (HBF) decreased (-18% +/- 4%; P < .01), while azygos blood flow (AzBF) was unchanged (4% +/- 12%; ns). In patients receiving propranolol, portal pressure did not increase during exercise, but decreased from 16.3 +/- 1.0 to 12.9 +/- 1.1 mm Hg (P < .01). The lack of increase in HVPG in response to exercise in patients receiving propranolol may be related to a more pronounced decrease in HBF, as compared with patients receiving placebo, and to a blunted increase in cardiac output (CO). Moderate physical exercise adversely influences the hepatic hemodynamics in patients with cirrhosis, causing a significant increase in portal pressure. This is effectively prevented by propranolol pretreatment.

Adrenergic beta-Antagonists↗