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Results for “Endurance exercise”

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At least 19 recordsLinked to original sources

PubMed1989

Effect of low dose nebulised morphine on exercise endurance in patients with chronic lung disease.

Low dose nebulised morphine may relieve dyspnoea through a direct effect on lung afferent nerves. To study this further 11 adult patients with advanced chronic lung disease (FEV1 range 0.4-1.41), whose exercise endurance was limited by dyspnoea, were entered into a double blind, randomised, crossover study in which low dose morphine or a placebo was inhaled. The effects were assessed by an endurance exercise test at 80% of maximum work load. One hour after a control endurance test patients inhaled 5 ml of morphine 1 mg/ml or isotonic saline for 12 minutes from a jet nebuliser. An endurance exercise test was repeated 15 minutes later and change in endurance time recorded. The two endurance tests were repeated on a separate day, before and after inhalation of the alternative solution. In all tests 100% oxygen was inhaled from a demand valve. The mean (SD) increase in endurance time was significantly greater after the subjects had inhaled morphine (64.6 (115) s, 35%) than after placebo (8.9 (55) s, 0.8%; p less than 0.01). The mean dose of morphine nebulised was 1.7 (0.66) mg, giving a mean inhaled dose of about 0.6 mg, on the assumption of 30% retention of the nebulised dose by each patient. No side effects were reported. Possibly small amounts of morphine delivered to the lungs act directly on lung afferent nerves to reduce dyspnoea.

Administration, Inhalation↗

PubMed1989

Cardiovascular risk factors and graded treadmill exercise endurance in healthy adults: The Framingham Offspring Study.

To help describe the association between exercise endurance and cardiovascular risk factor profiles, 2,606 young and middle-aged healthy adults in the Framingham Offspring Study were given submaximal treadmill tests. For both men and women, exercise endurance was inversely related to resting heart rate (p less than 0.001), body mass index (p less than 0.001), systolic blood pressure (p less than 0.001) and blood glucose (p less than 0.01), and positively related to high density lipoprotein (HDL) cholesterol (p less than 0.05). In men, cigarette smoking (p less than 0.05), high levels of total cholesterol (p less than 0.01) and very low density lipoprotein (VLDL) cholesterol (p less than 0.001) were also associated with poor exercise endurance. After adjusting for age, resting heart rate and body mass index, significant independent associations persisted for HDL cholesterol (p less than 0.05) in both sexes and for systolic blood pressure, VLDL cholesterol, blood glucose and cigarette smoking in men (p less than 0.05). Risk factors associated with overt cardiovascular disease in older individuals are also associated with poor exercise endurance in those who are younger and asymptomatic.

Adolescent↗

PubMedDate not supplied

Glycogenolytic effect of adrenaline in skeletal muscle of rats adapted to endurance exercise.

Rats were adapted to endurance exercise (swimming) for six weeks. During the training program each rat swum totally for 108 hours. It was found that the training applied reduced markedly glycogenolytic effect of adrenaline (0.1 mg/kg) in each of the examined type of muscle (the white, red and intermediate ones). The reduction of the glycogenolytic effect of adrenaline in the trained rats was less pronounced in the intermediate muscle than in the other two muscles. The hyperglycemic effect of adrenaline was also reduced in the trained group. It is concluded that the decreased reactivity of glycogenolytic system in skeletal muscles to adrenaline could be partly responsible for the slower rate of the intramuscular glycogen mobilization during exercise in the trained individuals.

Animals↗

PubMed1992

Reduction in LBNP tolerance following prolonged endurance exercise training.

Eight young men underwent an 8-month endurance exercise training program. Prior to and following the training program, the subjects' maximal oxygen uptake (VO2max), total blood volume (TBV) and plasma volume (PV), tolerance to lower body negative pressure (LBNP) assessed by the cumulative stress index (CSI) to presyncope, and their hemodynamic responses to 0 to -45 torr LBNP was determined. Hemodynamic measures included rebreathe carbon dioxide cardiac output (Qc), heart rate (HR), directly measured arterial blood pressures (ABP), and strain gauge determination of forearm blood flow (FBF) and leg volume changes (delta LgV). Calculated values of stroke volume (SV), forearm, vascular resistance (FVR), and peripheral vascular resistance (PVR) were made. Following training, each subject had an increased VO2max (mean = +27.4%, P < 0.001), TBV (mean = +15.8%, P < 0.02), and PV (mean = +16.5%, P < 0.02) and each subject had a decreased tolerance to LBNP (mean CSI = -24%, P < 0.001). Stepwise linear regression identified that the major factors to significantly predict the decreased CSI pre- to post-training were a reduced response of PVR to LBNP from -15 to -45 torr (Model R2 = 0.853), the delta TBV (model R2 = 0.981), and the greater post-training reduction in SBP to LBNP of 0 to -45 torr (model R2 = 1.0). These data suggest that physiologic adaptations associated with the increased VO2max and TBV resulting from a prolonged endurance exercise training program can alter the reflex control of vasomotion and cardiac output during LBNP and reduce the LBNP tolerance.

Adult↗

PubMed1992

Muscle carnitine after strenuous endurance exercise.

The effect of very long endurance exercise on muscle carnitine was studied. Eighteen cross-country skiers took part in a race in the Alps (average inspired partial pressure of O2 100-110 Torr) that lasted on average 13 h 26 min. Carnitine intake, evaluated for 2 wk before the event, was 50 +/- 4 (SE) mg/day. Muscle (vastus lateralis) total carnitine concentration, measured twice with a 2-yr interval on eight rested subjects, did not change with time (17 vs. 16 mumol/g dry wt, NS) but showed consistent interindividual differences (range 12-22, P = 0.001) with no correlation with intake. After exercise, total muscle carnitine was unaltered (from 17.9 +/- 1.0 at rest to 18.3 +/- 0.8 mumol/g dry wt postexercise in the 15 subjects who completed the race, NS), but muscle free carnitine decreased 20% (from 14.9 +/- 0.8 mumol/g, P = 0.01) and short-chain acylcarnitine increased 108% (from 3.5 +/- 0.4 mumol/g, P = 0.01). These results suggest that carnitine deficiency will probably not result from strenuous aerobic exercise in trained subjects who consume a moderate amount of carnitine in their food.

Adult↗

PubMed1992

Hormonal and plasma volume alterations following endurance exercise. A brief review.

Plasma volume expansion usually occurs with acute endurance exercise and endurance training both in humans and in animals. In most cases, the increase in plasma volume is associated with lower haematocrit without red cell mass change or an actual reduction in red cell mass, causing relative or true anaemia, respectively. The combination of exercise and heat acclimation (which produces also hypervolaemia, but at a lesser degree than exercise) enhances hypervolaemia induced by exercise training alone. The onset of the phenomenon is extremely rapid: hypervolaemia is observed within minutes or hours of the cessation of exercise. However, 2 days are necessary to reach peak plasma volume expansion after a marathon run or longer race. The magnitude of this natural expansion ranges from 9 to 25%, corresponding to an additional 300 to 700 ml of plasma. The magnitude of this alteration depends on preceding exercise: ambient conditions, intensity and duration of exercise, body posture and frequency of the exercise bouts. The larger the reduction in plasma volume during exercise, the greater the subsequent hypervolaemia. The hydration status of the subjects before and during exercise might modify also plasma volume changes: sufficient fluid ingestion can lead to plasma volume expansion even during prolonged exercise. Fluid-regulating hormones (aldosterone, arginine vasopressin and atrial natriuretic factor) in conjunction with an elevation in plasma protein content promote hypervolaemia. However, the role and the mechanism of the increase in protein mass remain unclear and the hormonal role in the induction of chronic hypervolaemia is still an open question. Hypervolaemia can improve performance by inducing better muscle perfusion, and by increasing stroke volume and maximal cardiac output. By increasing skin blood flow, plasma volume expansion also enhances thermoregulatory responses to exercise. This leads to the important concept of optimal plasma volume and haematocrit, and performance.

Adaptation, Physiological↗

PubMed1988

Effect of calcium channel blockade and beta-adrenoceptor blockade on short graded and single-level endurance exercises in normal men.

The effect of verapamil (240 mg) on exercise capacity was studied during a short graded and a single-level endurance exercise test in 12 normal volunteers; it was compared to the effects of atenolol (100 mg x day-1). Intake of verapamil, atenolol and placebo, administered according to a randomized, double-blind cross-over design, was started 3 days before the exercise tests. Compared to placebo, verapamil did not affect peak oxygen uptake in the graded test or exercise duration in the endurance test. Heart rate, systolic blood pressure, rating of perceived exertion and respiratory data at submaximal and peak exercise were unaffected in either test. On the other hand atenolol reduced maximal oxygen uptake by 5% (p less than 0.001) and endurance exercise duration by 17% (p less than 0.05). Besides marked decreases in heart rate and systolic blood pressure during the two types of exercise, atenolol also reduced oxygen uptake at submaximal exercise levels and it increased the rating of perceived exertion (p less than 0.05), the latter only during the endurance exercise test.

Adrenergic beta-Antagonists↗

PubMed1978

Time course of sympathoadrenal adaptation to endurance exercise training in man.

One possible reason for the lower exercise heart rate after endurance exercise training is that the sympathetic drive to the heart is reduced. We have studied the relationship between plasma catecholamines and heart rate during exercise in the course of a 7-wk training program. Six untrained subjects exercised vigorously (on bicycle ergometers and by running) 30--50 min/day for 7 wk. Prior to the beginning of training and at weekly intervals thereafter, participants were subjected to a 5-min strenuous bicycle ergometer test. In the test prior to training, plasma epinephrine increased to 0.5 ng/ml and norepinephrine increased to 3.0 ng/ml. The major proportion of the training-induced decrement in catecholamine response was reached at the end of the 3rd wk when epinephrine increased to 0.17 ng/ml and norepinephrine increased to 1.5 ng/ml in response to the same test. Heart rate during exercise continued to decrease even after the catecholamine response had plateaued, implying that the reduced sympathetic response is not solely responsible for the reduced exercise heart rate.

Adaptation, Physiological↗

PubMedDate not supplied

Standardization of a device to measure unsupported arm exercise endurance in chronic obstructive pulmonary disease.

The purpose of this study was to compare respiratory responses with moderate and slow rates of unsupported arm exercise (UAE) with a newly developed electromechanical device. Twenty-one patients with chronic obstructive pulmonary disease (COPD) were studied. Exercise endurance limits, metabolic, ventilatory and sensation outcomes were determined at rest prior to exercise and at end-exercise endurance limits. Increases from baseline rest for both exercise rates were observed in: oxygen uptake, carbon dioxide production, inspiratory flow, minute ventilation, respiratory rate, dyspnea, respiratory effort, and arm fatigue. Endurance limits were similar for both rates of UAE. These data provide standards against which UAE in COPD can be evaluated.

Aged↗

PubMed1990

Enhanced leg exercise endurance with a high-carbohydrate diet and dihydroxyacetone and pyruvate.

The effects of dietary supplementation of dihydroxyacetone and pyruvate (DHAP) on metabolic responses and endurance capacity during leg exercise were determined in eight untrained males (20-30 yr). During the 7 days before exercise, a high-carbohydrate diet was consumed (70% carbohydrate, 18% protein, 12% fat; 35 kcal/kg body weight). One hundred grams of either Polycose (placebo) or dihydroxyacetone and pyruvate (treatment, 3:1) were substituted for a portion of carbohydrate. Dietary conditions were randomized, and subjects consumed each diet separated by 7-14 days. After each diet, cycle ergometer exercise (70% of peak oxygen consumption) was performed to exhaustion. Biopsy of the vastus lateralis muscle was obtained before and after exercise. Blood samples were drawn through radial artery and femoral vein catheters at rest, after 30 min of exercise, and at exercise termination. Leg endurance was 66 +/- 4 and 79 +/- 2 min after placebo and DHAP, respectively (P less than 0.01). Muscle glycogen at rest and exhaustion did not differ between diets. Whole leg arteriovenous glucose difference was greater (P less than 0.05) for DHAP than for placebo at rest (0.36 +/- 0.05 vs. 0.19 +/- 0.07 mM) and after 30 min of exercise (1.06 +/- 0.14 vs. 0.65 +/- 0.10 mM) but did not differ at exhaustion. Plasma free fatty acids, glycerol, and beta-hydroxybutyrate were similar during rest and exercise for both diets. Estimated total glucose oxidation during exercise was 165 +/- 17 and 203 +/- 15 g after placebo and DHAP, respectively (P less than 0.05). It is concluded that feeding of DHAP for 7 days in conjunction with a high carbohydrate diet enhances leg exercise endurance capacity by increasing glucose extraction by muscle.

Adult↗

PubMed1992

Blood ammonia and lactate concentrations during endurance exercise of differing intensities.

The purpose of this study was to examine the changes of blood ammonia concentration ([NH3]b) during endurance exercise of differing intensities on the cycle ergometer and to compare [NH3]b to the changes observed in the simultaneously monitored blood lactate acid concentrations ([la-]b) measurements. A group of 16 endurance-trained athletes participated in the first part of the study and performed exercise of 30 min duration in a randomized order at intensities of 85%, 95%, 100% and 105% of their individual anaerobic threshold (Th(an,ind); E85-E105) which had been determined beforehand by a cycle exercise test with stepwise increments in intensity. In the second part, 18 average endurance-trained sports students underwent exhausting intensive endurance exercise (IEE) with an intensity of 95% of Th(an,ind). An extensive endurance exercise (EEE) of the same duration at 85% of the Th(an,ind) was carried out 2 days later. The [NH3]b increased constantly with increasingly duration of all exercise. However, [la-]b only increased during exercise with intensities above the Th(an,ind) (E105). The increase of [NH3]b was higher with higher exercise intensities. At IEE, [NH3]b was significantly higher from the 30th min than at EEE, whereas [la-]b increased from the 5th min. In conclusion, [la-]b responded more sensitively to the intensity of exercise than [NH3]b, but it is conceivable that in the future measurements of [NH3]b could be used to advise on the duration of endurance training. At present, however, the lack of experience and lack of appropriate values still hinders the systematic use of [NH3]b measurements in the physiological monitoring of sports training.

Adult↗

PubMed1992

Recovery from endurance exercise.

1) During training for and competition in endurance exercise athletes often significantly reduce both liver and muscle glycogen reserves. 2) Replenishment of muscle glycogen probably occurs preferentially over the replenishment of liver glycogen after exercise. 3) Muscle and liver glycogen can be replenished within 24 h after exercise provided adequate carbohydrate is consumed. 4) To replenish muscle glycogen within 24 h, 8-10 g carbohydrate.kg-1 body weight should be consumed. 5) To optimize muscle glycogen synthesis during the 4-6 h after exercise, carbohydrate must be consumed immediately after exercise and at frequent intervals thereafter. 6) While normal muscle and/or liver glycogen levels can be normalized 24 h after exercise, muscle function may or may not be fully recovered.

Dietary Carbohydrates↗

PubMed1989

Effect of endurance exercise on somatomedin-C/insulin-like growth factor I concentration in male and female runners.

By means of 3 endurance exercises, the effect of a several-hour intensive somatic stress on the changes of the Sm-C/IGF-I concentration was tested during, immediately after and on the day following the exercise. Exp. 1: Marathon with 17 male sportsmen in 2 groups with different glucose supply. Exp. 2: 45-km crosscountry run with 41 males. Exp. 3: Three 20-km runs with 8 young females at intervals of 3 months. In the marathon, no significant changes of the Sm-C/IGF-I concentration were found between the start, half distance and final values. The exogenous glucose supply (continuous or discontinuous) had also no effect. The tendency of a slight decrease of the Sm-C/IGF-I concentration by 0.14 U/ml (p greater than 0.05) was observed between start and finish in the 45 km crosscountry run lasting one hour longer. In the three 20-km runs, reproducible, slightly increased levels were measured at the end, whereas a decrease to the initial value or even below was detected on the following day (p greater than 0.05). The insignificant alterations of the Sm-C/IGF-I concentration measured in the 3 variants of races show that neither the hormonal changes stimulating the Sm-C/IGF-I synthesis (e.g. increase of GH and prolactin) nor inhibiting factors (energy deficiency) clearly dominate during strenuous exercises. The binding of carrier protein prevents great variations of the Sm-C/IGF-I level even under the condition of 3- to 4-hour extreme endurance exercises.

Adolescent↗

PubMed1990

Effect of long-term diltiazem treatment on central haemodynamics and exercise endurance in essential hypertension.

The effects of long-term treatment with diltiazem on blood pressure, central haemodynamics and exercise endurance were studied in 16 men (mean age 52 years) with essential hypertension. Intra-arterial pressure and heart rate (HR) were monitored continuously. Cardiac output (CO) was measured by Cardiogreen at rest (supine and sitting) and during 50 W, 100 W and 150 W bicycle exercise. Haemodynamic measurements were repeated after continuous bicycling at 150 W for 20 min or until exhaustion. After 1 year on diltiazem (mean daily dose 278 mg) intra-arterial pressure was reduced (P less than 0.001) in all situations (at rest sitting from 183/108 mmHg to 157/92 mmHg (14%] due to reduction in total peripheral resistance. HR was reduced at rest (7%) and during exercise (10%). Stroke volume tended to increase while CO was unchanged. Exercise time at constant workload increased by 25%. After a peak level, intra-arterial pressure fell by 3% to 5% (P less than 0.05) due to a decrease in total peripheral resistance both before and during diltiazem treatment. Stroke volume and CO remained unchanged during endurance exercise while HR showed a small increase. Thus, there was no reduction in the overall cardiac pump function after long-term diltiazem treatment, and blood flow during exercise was maintained.

Body Weight↗

PubMed1992

Differential mobilization of leucocyte and lymphocyte subpopulations into the circulation during endurance exercise.

A total of 14 healthy subjects [means (SD): 27.6 (3.8) years; body mass 77.8 (6.6) kg; height 183 (6) cm] performed endurance exercise to exhaustion at 100% of the individual anaerobic threshold (Th(an)) on a cycle ergometer (mean workload 207 (55) W; lactate concentrations 3.4 (1.2) mmol.l-1; duration 83.8 (22.2) min, including 5 min at 50% of individual Th(an)). Leucocyte subpopulations were measured by flow cytometry and catecholamines by radioimmunological methods. Blood samples were taken before and several times during exercise. Values were corrected for plasma volume changes and analysed using ANOVA for repeated measures. During the first 10 min of exercise, of all cell subpopulations the natural killer cells (CD3-CD16/CD56+) increased the most (229%). Also CD3+CD16/CD56+ (84%), CD8+CD45RO- (69%) cells, eosinophils (36%) and monocytes (62%) increased rapidly during that time. CD3+, CD3+HLA-DR+, CD4+CD45RO+, CD4+CD45RO-, CD8+CD45RO+ and CD19+ cells either did not increase or increased only slightly during exercise. Adrenaline and noradrenaline increased nearly linearly by 36% and 77% respectively at 10 min exercise. The increase of natural killer cells and heart rates between rest and 10 min of exercise correlated significantly (r = 0.576, P = 0.031). We conclude that natural killer cells, cytotoxic, non-MHC-restricted T-cells, monocytes and eosinophils are mobilized rapidly during the first minutes of endurance exercise. Both catecholamines and increased blood flow are likely to contribute this effect.

Adult↗

PubMed1989

Beta-endorphin, catecholamines, and cortisol during exhaustive endurance exercise.

To assess changes of beta-endorphin during intense endurance exercise, ten nonspecifically trained volunteers (aged 25.7 +/- 2.9 years) were subjected to an exhaustive endurance test on a cycle ergometer at the work load of the individual anaerobic threshold (IAT) determined in a preparatory graded exercise test. Prior to, in 25-min intervals during, and repeatedly subsequent to exercise venous blood samples were drawn to measure the levels of beta-endorphin (beta-E), cortisol (C), adrenaline (A), and noradrenaline (NA). In addition, lactate, heart rate, and rate of perceived exertion were determined. The levels of beta-E remained unchanged during the first 50 min; between the 50th and 75th min beta-E increased by 82% (p less than 0.01). At the end of the exercise (mean exercise time: 89 min), a beta-E level three times the resting level was measured. The maximum exercise-induced increase of beta-E showed a positive correlation to endurance capacity (W.kg-1 of IAT): r = 0.74; p less than 0.05. C exhibited similar changes to beta-E, but the onset of increase was delayed if compared with beta-E; there was a close correlation between these two stress hormones (75th min of exercise: r = 0.91; p less than 0.001). The catecholamines A and NA increased linearly during exercise, without a correlation with the behavior of beta-E being established.

Adult↗

PubMed1991

Comparison of sympatho-adrenal activity during endurance exercise performed under high- and low-carbohydrate diet conditions.

Effects of varied carbohydrate (CHO) content in the diet on sympatho-adrenal activity to endurance exercise during which blood sugar was kept over a preexercise level were studied in five male physical education students. The CHO loading was used and consisted of a 7-day low CHO diet (30% CHO, 50% fat, 20% protein) followed by a 7-day high CHO diet (70% CHO, 20% fat, 10% protein). The results obtained from the present study were as follows: (1) plasma epinephrine (E) was almost the same between the low and the high CHO diets before and at 30 min of the exercise, while plasma norepinephrine (NE) level at 30 min of the exercise was significantly higher in the low (959 +/- 98 pg/ml) than in the high CHO diet (679 +/- 64 pg/ml) (p less than 0.05); (2) serum free fatty acid (FFA) level was significantly higher in the low than in the high CHO diet before (p less than 0.05) and at 30 min of the exercise (p less than 0.01); (3) a negative correlation was found between muscle glycogen and plasma NE (p less than 0.05). In all the subjects, increase in serum FFA accompanied by increase in plasma NE was detected in the low CHO diet. In conclusion, sympathetic activity to endurance exercise during which blood sugar was kept over a preexercise level was elevated more in the low than in the high CHO diet. It was suggested that the more elevated sympathetic nervous activity would have resulted from glycogen depletion in the working muscle due to the low CHO diet and would have increased FFA mobilization from the adipose tissue.

Adrenal Glands↗

PubMed1992

Immunoregulatory hormones, circulating leucocyte and lymphocyte subpopulations before and after endurance exercise of different intensities.

Sixteen subjects (male, age: 26.3 +/- 3.5 years, weight: 75.1 +/- 6.5 kg, maximal oxygen uptake: 53.6 +/- 6.7 ml.min-1.kg-1) performed endurance exercises at 100% (exhaustive), and 85% (limited) of the individual anaerobic threshold [IAT; workload (100% IAT): 3.00 +/- 0.50 W.kg-1, duration of both exercises: 87 +/- 21 min]. Before (b), immediately (0 p), 60 min (60 p), 120 min (120 p) and 24 hours (24 hp) after exercise, leucocyte subpopulations (flow cytometry) as well as epinephrine, norepinephrine, cortisol, beta-endorphin and ACTH were determined. At 0 p, 60 p and 120 p, granulocytes were significantly higher at 100% IAT than at 85% IAT, lymphocytes and monocytes did not differ. At 60 p and 120 p, granulocytes had highest, lymphocytes lowest values. CD8(+)- and CD16(+)-lymphocytes showed greater changes than CD3(+)-, CD4(+)-, CD19(+)-lymphocytes and were significantly higher at 100% IAT than at 85% IAT (0 p). Epinephrine and norepinephrine were significantly higher at 100% IAT than at 85% IAT. Cortisol, ACTH and beta-endorphin increased at 100% IAT, but not at 85% IAT (0 p). Significant correlations were calculated for cortisol (0 p) versus granulocytes (60 p, 120 p) at 100% IAT. Epinephrine did not correlate to increases of lymphocytes or lymphocyte subpopulations. In conclusion, increases of granulocytes, CD16(+)- and CD8(+)-lymphocytes are dependent on the intensity of endurance exercises and precise definition of the individual workload is important. The increase of granulocytes after exercise is partly due to increased levels of cortisol. Increased cell numbers of lymphocytes, especially CD16(+)-cells, did not correlate to increased levels of catecholamines.

Adrenocorticotropic Hormone↗