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PubMed2006

The intensity level of physical exercise and the bone metabolism response.

This study investigated the short-term effects of the intensity level of physical exercise on bone metabolism and related hormones. The responses of calciotropic hormones and bone biochemical markers were evaluated in seven male cyclists (mean age 24.4 years, range 20-39) during two 50-min cycling tests performed 15% below (-VT) and 15% above (+VT) the ventilatory threshold. In each test, venous blood samples were drawn at rest, at the 30th and 50th min of exercise, and after 15 min of recovery. For both intensity levels, no significant variation in calcium, 25-hydroxyvitamin D, 1.25-dihydroxyvitamin D, or cortisol level was observed. Intact parathyroid hormone (iPTH) level increased significantly after the last minute of the test (41%, p < 0.05) and peaked during the recovery (80%, p < 0.05) only in response to exercise performed at +VT. Serum phosphorus concentration rose during both tests, while albumin levels increased only at +VT. Concerning bone cell activity, osteocalcin, and type I-C telopeptide breakdown products transiently increased only in response to exercise performed at +VT (11% and 16.8%, respectively; p < 0.05). Bone alkaline phosphatase increased similarly for both intensity levels after 30 min (12%, p < 0.05) and 50 min (12% for -VT vs. 14% for +VT, p < 0.05). All markers of bone turnover returned to initial values during the recovery. In conclusion, a no-impact but intense and sustained exercise performed at +VT transiently stimulated bone turnover and iPTH secretion, suggesting the existence of a bone stimulation threshold. In addition to the well known effect of mechanical constraints, both the duration and intensity of exercise may induce changes in bone turnover.

Adult↗
PubMed1975

[Dynamic observations of tolerance to physical exercise in patients with ischemic heart disease during drug therapy].

Proceeding from a dynamic observation of the tolerance of physical exercises in the process of drug therapy of 90 patients with ischaemic heart disease the author concludes that a certain dissociation exists between the subjective effect of the antianginal drugs and the results of bicycle tests in the evaluation of the efficacy of the treatment. While a subjective improvement was declared in 2/3 of the patients, the exercise test indices improved only in 1/3. The bicylce test before and after the therapeutic course seems to facilitate a more precise evaluation of the efficacy of the antianginal drugs.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

[Aspartate aminotransferase metabolism in muscles during physical exercise].

It is established that the concentration of cytosolic aspartate aminotransferase decreases the first day after intensive physical exercises due to the intensification of the degradation processes, the decrease in the synthesis rate and the enzyme entry into the blood vessel. The enzyme content is normalized by the 24th hour of rest and then the supercompensatory phase takes place: the enzyme biosynthesis increases and its degradation decreases to a greater extent.

Animals↗
PubMed1993

Physical exercise increases middle cerebral artery blood flow velocity.

The effect on the middle cerebral artery blood flow velocity (VMCA) of moderate and hard physical exercise on an ergometer cycle was examined in 10 healthy volunteers using transcranial Doppler sonography (TCD). During exercise, the heart rate increased by 136% and the systolic blood pressure by 37% (mean values). During initial moderate exercise, VMCA increased by 51%; in a following period of maximal physical work, VMCA decreased again by 20% in 9 of 10 volunteers although the heart rate continued to increase by 10% and the systolic blood pressure by 5% (mean values). Constriction of the MCA may explain the initial increase of VMCA, suggesting a role for large cerebral arteries in autoregulation. Our data indicate that the subsequent decrease of VMCA is caused by arteriolar constriction, a likely cause of which was hyperventilation during the excessive work period.

Adult↗
PubMed1983

Influence of physical exercise after long-lasting hypodynamia on the morphological parameters of muscle fibers.

The purpose of this research was morphometric ultrastructure evaluation of the fibers in muscles taking part in the flight of pigeons forced to exercise after a long period of hypodynamia. It was found that following physical exercise, after 12 and 18 months of mobility limitation, there appeared marked qualitative and quantitative changes: a diminution of the volume fraction and number of mitochondria, increase of smooth sarcoplasmic reticulum and sarcoplasm, and a significant decrease of the number of glycogen granules as compared with those after 18 months hypodynamia. The above described changes were more pronounced in the supracoracoideus than in the pectoralis muscle.

Animals↗
PubMed1979

The role of physical exercise and training in the management of diabetes mellitus.

The effects of physical activity on blood glucose homeostasis in diabetes mellitus and the potential benefits of exercise in the treatment of diabetic patients, are reviewed. Mild physical exercise results in a fall of blood glucose levels in controlled diabetic patients; this acute effect of exercise might be used in particular to inhibit the rise of blood glucose seen in insulin-treated diabetics after food intake. In contrast, physical activity will further deteriorate the metabolic situation in decompensated diabetic patients by an increase in blood glucose and a rapid aggravation of ketosis. On the other hand exercise potentiates the blood glucose lowering effect of subcutaneously injected insulin; therefore precautions have to be taken in order to avoid hypoglycemia in insulin-dependent diabetics especially during and after more strenous exercise. In juvenile-type diabetes, physical activity can be used as an efficient therapeutic adjunct only in cooperative, well-instructed patients who are used to check their metabolic situation on a regular basis. Physical training increases the tissues' sensitivity towards (endogenous) insulin. Hence, in addition to the diet, training might represent the most appropriate treatment in maturity onset-type diabetic patients. However, direct evidence for an improvement of glucose tolerance in diabetic patients by physical training is still lacking. In order to formulate detailed, generally applicable recommendations on how to carry out a useful therapeutic program of physical exercise and/or training in diabetic patients, further clinical studies assessing the quantitative effects of physical activity on carbohydrate metabolism are needed.

Animals↗
PubMedDate not supplied

Glycogen resynthesis in the rat muscle and liver after physical exercise.

Glycogen resynthesis was studied in muscles and liver of Wistar rats after a single bout of physical exercise, which included 30 min of enforced swimming in water at 32 degrees C. The experiment was carried out on untrained rats which rested after the exercise from 30 min to 24 h, receiving food ad libitum. During the postexercise restitution a rise was observed in the glycogen content of both tissues. This rise was more rapid in the muscles than in the liver. During the first 9 hours of rest the muscle glycogen content reached 92.6% of the initial value, and after 24 hours it exceeded this value by 20%. On the other hand, the resynthesis of hepatic glycogen was 67% of the initial value after 9 hours, and after 24 hours the liver glycogen content reached only 76.5% of this value. It has been pointed out also that the restitution of glycogen in the muscles occurs in two steps of the intensive increase, while in the liver it is more steady.

Animals↗
PubMed1999

Comparison between continuous and intermittent physical exercise on aging rats: changes in patterns of spontaneous activity and connective tissue stability.

Life-long physical exercise increases the mean but not maximum life span of laboratory rodents. It further improves the performance in an open field setting, which suggests a delay of sensorimotor disturbances, and retards the aging increase of thermal stability of collagen. The purpose of the present study was to examine whether the amount or continuity of training is more important. We trained male Sprague-Dawley rats for 12 months from the age of 12 months in a treadmill: 1) continuously for 3 km/week (total distance covered: 144 km); 2) intermittently for 3 km/week for 8-week periods with 8-week resting periods in between (72 km), and 3) intermittently for 6 km/week for 8-week periods with 8-week resting periods in between (144 km). All training regimens prevented the increase in body weight seen in sedentary animals, although the intermittent training programs caused fluctuations with the training and resting periods. With respect to spontaneous movements in an open field setting, continuous training was most effective in counteracting age-related changes. Continuous training was also most effective for delaying age-related increase in thermal stability of collagen. We conclude that the continuity of training is more important than the amount and intensity of training.

Aging↗
PubMed2006

Effects of a controlled program of moderate physical exercise on insulin sensitivity in nonobese, nondiabetic subjects.

OBJECTIVE: To study the effect of a moderate, aerobic physical exercise program on insulin resistance and its accompanying metabolic changes in a group of healthy, middle-age, nonobese subjects, without modifying oxygen consumption and body weight. DESIGN: The inclusion of subjects was carried out among volunteers from the health personnel of our center, who complied with the inclusion criteria. PARTICIPANTS: Twelve subjects (age 30-60 years, 5 females), nonsmokers, body mass index (BMI) <27 kg/m2 and fasting plasma glucose <6.1 mmol/L. INTERVENTIONS: Insulin resistance was assessed using the Bergmann minimal model modified with insulin, and basal and maximum metabolic rate were measured with standard methods. All subjects completed a 2-month program of aerobic exercise using the American College of Sports Medicine guidelines, consisting of aerobic exercise of moderate, regular, and continual intensity (3 times per week), with a duration of 45 to 50 minutes per session. RESULTS: Following controlled exercise, no significant differences in BMI, waist-hip ratio, blood pressure, lipids, free fatty acids, and leptin plasma values were observed. Plasma glucose and insulin values decreased significantly (-0.37 mmol/L and -16.5 pmol/L, respectively). Insulin sensitivity showed an increase of 2.1 x 10(-4) mU L(-1) min(-1) (P = 0.001). Basal and maximum metabolic rate showed no significant differences after the exercise program. CONCLUSIONS: Moderate aerobic exercise increases insulin sensitivity in nonobese, nondiabetic subjects in the absence of significant changes in weight, BMI, waist-hip ratio, lipid profile, and oxygen consumption.

Adult↗
PubMed2005

Changes of cerebral hemodynamics in hypertensives during physical exercise.

BACKGROUND AND PURPOSE: Previously, 30 untreated hypertensive patients were investigated by transcranial Doppler (TCD) monitoring during physical exercise, and changes of hemodynamic parameters were compared with those of age matched healthy subjects. After 3-year antihypertensive (AHT) treatment, these hypertensives were investigated again. The aim of this study was to compare the cerebral hemodynamic changes in the regularly treated and noncompliant (untreated) hypertensives during ergometer cycling. METHODS: Nineteen of 30 previously untreated hypertensive patients could be investigated again using the same method as before. Eleven were regularly treated (treated hypertensive [T-HT] group), and 8 did not take their AHT medications due to lack of compliance (noncompliant hypertensive [NC-HT] group). Blood pressure, heart rate, end-tidal CO2 (etCO2; Capnogard capnograph), and bilateral middle cerebral artery mean blood flow velocity (MV) were continuously monitored during ergometer cycling according to the World Health Organization protocol. Values of 2-minute loading were analyzed. RESULTS: Median loading time did not differ significantly between the T-HT and NC-HT groups. After 2 minutes of cycling in treated patients, the ratio of MV and etCO changes (DeltaMV/DeltaetCO2) showed similar values as before therapy (P = .38), whereas in noncompliant patients, a further worsening of the ratio of DeltaMV/DeltaetCO2 could be observed (P = .04). CONCLUSION: The decrease of arteriolar vasodilation (ie, the ratio of DeltaMV/DeltaetCO2) could be demonstrated in the NC-HT group after 3 years. TCD combined with ergometer cycling is a useful method for evaluation of cerebral hemodynamic changes after AHT therapy.

Adult↗
PubMed2003

Influence of training volume and acute physical exercise on the homocysteine levels in endurance-trained men: interactions with plasma folate and vitamin B12.

The interrelation between physical exercise and plasma levels of homocysteine (Hcy), vitamin B(12), and folic acid has not been examined. Therefore, we investigated the influence of extensive endurance training and acute intense exercise on plasma concentrations of total Hcy, vitamin B(12), and folic acid in 42 well-trained male triathletes. Examinations and blood sampling took place before and after a 30-day endurance training period as well as before and 1 and 24 h after a competitive exercise (sprint triathlon). Following the training period, no significant change in Hcy levels could be detected for the whole group. Subgroup analysis in quartiles of training volume revealed that - as compared with the lowest quartile (low-training group: 9.1 h training/week) - athletes in the highest training quartile (high-training group: 14.9 h training/week) exhibited a significant decrease in Hcy levels (from 12.7 +/- 2.3 to 11.7 +/- 2.4 micromol/l as compared with levels of 12.5 +/- 1.5 and 12.86 +/- 1.5 micromol/l in the low-training group; p < 0.05). The plasma folate levels were significantly higher in the high-training group at all points of examination (p < 0.05). 1 h and 24 h after competition, the Hcy concentration increased in all athletes independent of the previous training volume (24 h: 12.3 +/- 1.8 vs. 13.5 +/- 2.6 micromol/l; p < 0.001), although the increase was decisively stronger in the low-training group. 1 h after competition, the plasma folate concentration increased (7.03 +/- 2.1 vs. 8.33 +/- 2.1 ng/ml; p < 0.05) in all athletes. Multivariate analysis showed that the exercise-induced increase in the Hcy levels was dependent on baselines levels of folate and training volume, but not on the vitamin B(12) levels. In conclusion, although intense exercise acutely increased the Hcy levels, chronic endurance exercise was not associated with higher Hcy concentrations. Moreover, athletes with the highest training volume, exhibiting also the highest plasma folate levels, showed a decrease in Hcy levels following the training period as well as a much lower increase of the Hcy concentration after acute intense exercise. The combined effect of training and higher plasma folate levels to reduce Hcy should be investigated in future studies.

Adult↗
PubMed1996

Effect of physical exercise on adoptive experimental auto-immune encephalomyelitis in rats.

The aim of the study was to determine whether different programmes of exercise influence adoptive monophasic experimental auto-immune encephalomyelitis (adoptive EAE), a paralytic disease mediated by T-cells. Adoptive EAE was induced by the transfer of activated encephalitogenic T-lymphocytes into syngeneic recipients (Lewis rats, n = 85) and its development was followed by two independent observers. The results showed that 2 days of severe exercise (250 and 300 min) performed after the adoptive transfer of EAE slightly delayed the onset of the disease (P <0.008) and the day of its maximal severity (P <0.016) without affecting the overall severity of the disease. When this programme of exercise was performed before the cell transfer, it had no effect (P > 0.05). Two more moderate exercise programmes (5 x 120 min of running at constant speed or 5 x 60 min of running at variable speed, 5 consecutive days) performed between the adoptive transfer and the onset of the disease did not modify the development of the clinical signs of adoptive EAE (P >0.05). These results showed that severe exercise slightly influenced the effector phase of monophasic EAE and confirmed that physical exercise performed before the onset of experimental auto-immune diseases did not exacerbate the clinical signs.

Animals↗
PubMed1996

Neither physical exercise nor alpha 1- and beta-adrenergic blockade affect plasma endothelin concentrations.

Endothelins (ET) are recently discovered vasoconstrictor agents released from endothelial cells and have been the object of intense investigation by researchers. Many of the factors that seem to influence the release of ET are modified by prolonged exercise. The purpose of this study was to investigate the effect of physical exercise on ET plasma concentrations and the effect of alpha- and beta-blockade on ET concentrations at rest and during exercise. Fifteen young volunteers (age 20-35 years) performed an exercise test on a bicycle ergometer. The starting workload of 50 W was increased by 30 W every 3 min until maximal heart rate was achieved; after a 2 min recovery period at 50 W the test continued for 15 min at 60% maximal work load. Blood samples were taken for ET determination before and after the test. After 1 week, the test was repeated. In the 2 days before either the first or the second test, each volunteer randomly received carvedilol (C) (25 mg), an alpha 1-adrenoceptor and beta-adrenoceptor blocker. There was no significant difference in ET concentrations after exercise with or without C administration (1.24 +/- 0.66, 1.42 +/- 0.83, 1.66 +/- 1.15, 1.61 +/- 0.87 pg/mL), showing that prolonged aerobic exercise does not affect plasma ET levels. Moreover, in our healthy young volunteers, blockade of alpha- and beta-adrenoceptors had no effect on ET levels at rest and after exercise.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2005

Effects of physical exercise in patients with end stage renal failure, on dialysis and renal transplantation: current status and recommendations.

There is increasing evidence about the benefits of regular physical activity in the chronically ill. Patients with chronic renal failure prior to and after renal transplant are one of the target groups in which increased controlled physical activity is highly recommended. Significant atrophy and increased non-contractile tissue are present in the muscle of predialytic and patients on hemodialysis, which is associated with poor physical performance and poor outcome of renal disease. Thus, interventions to increase physical activity or otherwise address atrophy may improve performance and quality of life in these patients. Other abnormalities in these patients, such as metabolic impairments, anemia, and hormonal changes, especially insulin resistance and lipid disorders, could be also modulated by certain therapeutic agents and physical activity. Increasing activity levels in this target group could be particularly important since it is well established that controlled physical exercise reduces the risk of cardiovascular disease in the general population. Patients who participate in regular physical activity following transplant will have higher health-related fitness and quality of life compared to those who remain inactive. The potential risk of physical activity can be reduced by medical evaluation, risk stratification, careful supervision, and education.

Exercise↗
PubMed1978

The influence of thoracic epidural analgesia on the circulation at rest and during physical exercise in man.

The effects of thoracic epidural analgesia (TEA) on the circulation at rest, during, and after physical exercise were investigated in 10 volunteers. At rest, TEA did not affect oxygen consumption (VO2) or cardiac output (Q), but heart rate (HR) was, increased by 7 beats/min, and stroke volume decreased correspondingly by 13 ml. Systolic arterial blood pressure was slightly reduced, but no other changes in systemic or pulmonary circulatory parameters were produced. TEA did not change VO2 during exercise, a 2.11/min reduction of Q being accompanied by a 4.2% increase of oxygen utilization coefficient. HR showed a relative reduction of about 10%. At moderate work loads during TEA, systemic arterial blood pressures were significantly lower than during control exercise. The resulting rate pressure product (RPP) was markedly reduced, while total peripheral resistance (TPR) remained unchanged. During recovery after the termination of exercise during TEA, VO2, Q, HR, RPP and TPR fell more rapidly towards values obtained at rest. From a clinical point of view the results support the safeness of TEA and also support its use in surgical patients with heart disease.

Adult↗
PubMed2002

Physical exercise or micronutrient supplementation for the wellbeing of the frail elderly? A randomised controlled trial.

OBJECTIVE: To examine the effects of 17 weeks of physical exercise and micronutrient supplementation on the psychological wellbeing of 139 independently living, frail, elderly subjects (inactive, body mass index < or =25 or experiencing weight loss). METHODS: Participants (mean (SD) age 78.5 (5.7)) were randomly assigned to: (a) comprehensive, moderate intensity, group exercise; (b) daily micronutrient enriched foods (25-100% recommended daily amount); (c) both; (d) neither. A social programme and identical regular foods were offered as attention control and placebo. RESULTS: At baseline, moderate to low but significant correlations were found between general wellbeing scores and physical fitness (r = 0.28), functional performance (r = 0.37), and blood concentrations of pyridoxine (r = 0.20), folate (r = 0.25), and vitamin D (r = 0.23) (all p values < or =0.02), but not with physical activity levels and other blood vitamin concentrations. General wellbeing score and self rated health were not responsive to 17 weeks of exercise or nutritional intervention. CONCLUSION: Psychological wellbeing in frail elderly people was not responsive to 17 weeks of intervention with exercise and/or micronutrient enriched foods. The moderate but significant correlations between wellbeing and physical fitness and several blood vitamin concentrations at baseline suggest that changes in wellbeing may occur after long term interventions.

Activities of Daily Living↗
PubMed1990

[Effect of regular physical exercises on cardiac resistance to ischemia].

The experiments were performed in rats to assess the effects of regular physical exercises (swimming and running) on cardiac responses to ischemia. The regular exercises aimed at increasing the glycolytic capacity of the muscle and causing no substantial cardiac hypertrophy were found to elevate cardiac resistance to ischemia. They also enhanced cardiac responses to catecholamines as manifested by higher activity of ATP-consuming and resynthesizing mechanisms. With these changes, ischemia caused a more rapid ATP drop in the myocardium and development of its contracture than in untrained animals.

Animals↗