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Biomedical subjects

A Viru

Publications and source records attributed to A Viru.

At least 55 records · Page 3Linked to original sources
PubMed1990

The effect of a single-circuit weight-training session on the blood biochemistry of untrained university students.

The metabolic and hormonal responses to an intensive single-circuit weight-training session were studied in 15 untrained male students. The training programme consisted of ten exercises, employing all the large groups of muscles. Students performed three circuits using a work-to-rest ratio of 30 s:30 s at 70% of one-repetition maximum. The whole programme lasted 30 min. Blood samples were obtained from the anticubital vein 30 min before exercise, immediately after exercise finished and after 1-h, 6-h, and 24-h periods of recovery. The training session produced significant increases in the plasma adrenocorticotropic hormone, cortisol, aldosterone, testosterone, progesterone and somatotropin concentrations. The plasma level of insulin and C-peptide remained unchanged. The strength exercises caused elevated ratios of cortisol:testosterone and cortisol:insulin, indicating a prevalence of stimulation of catabolic processes as well as of mobilization of energy reserves but during the recovery period the reverse of this was observed. Immediately after exercise the mean lactate concentration was 7.19 mmol.l-1, SD 0.56, the glucose concentration increased significantly during exercise and decreased rapidly during recovery. The high density lipoprotein-cholesterol increased in 1-h period of recovery compared with the initial level. The concentration of total cholesterol, low density lipoprotein-cholesterol and triglyceride, did not change. Packed cell volume did not change during exercise or recovery.

Adrenocorticotropic Hormone↗
PubMed1990

Changes of beta-endorphin level in blood during prolonged exercise.

In 49 healthy subjects during 2 h exercise on bicycle ergometer four variants of changes of beta-endorphin level were observed: 1. an increase during first 30 min followed by a decreased below initial values; 2. biphasic increase (peak values at the 30th and 120th min); 3. increase only during the 2nd h of exercise; 4. decrease during the whole period of exercise. For trained subjects the most common was the biphasic increase, for untrained ones--the overall decrease.

Adrenocorticotropic Hormone↗
PubMed1989

Renal urea clearance in normal and adrenalectomized rats after exercise.

In groups of male Wistar rats, blood level, urinary excretion of urea, and renal urea clearance were determined in resting conditions or during 48-60 h after swimming for 30 min with an additional load of 10% of body weight as well as after swimming for 3 or 10 h without additional load. Both types of swimming exercise caused a significant increase in the blood level, urinary excretion, and renal clearance of urea. After 10-h swimming, the increase of renal urea clearance was observed only from the second period (0-12 h) of urine collection. In this type of exercise, an elevation of blood level of corticosterone was obtained after 6-h restitution. The increased urinary excretion and renal urea clearance persisted for a longer time than was necessary for the normalization of the blood level. A significant rise in blood urea level and a drop in renal urea clearance occurred after adrenalectomy. In adrenalectomized rats, increased urea excretion and renal clearance were observed 12-24 h after 3-h swimming, but the level of renal clearance obtained in sedentary normal rats was not achieved. The blood level of urea did not increase. This suggested that the glucocorticoids play a role both in urea formation during exercise and in its elevated renal clearance after exercise.

Adrenalectomy↗
PubMed1989

Biochemical changes in blood during the long and short triathlon competition.

The purpose of the study was to compare the effects of long (3.8 km swimming, 180 km biking, 42.2 km running, n = 7) and short (1.5 km swimming, 42 km biking, 14 km running, n = 14) triathlons on blood hormones, metabolites and substrates. Both variants of triathlon caused a significant rise in cortisol, somatotropin and aldosterone levels, the insulin and C-peptide levels decreased. The progesterone level increased considerably only after long triathlon. The testosterone level did not change essentially. The level of plasma glucose, total cholesterol, HDL, LDL did not change substantially during the both competitions. FFA concentration increased significantly and triglycerides concentration decreased only during the prolonged variant.

Adult↗
PubMed1985

Involvement of protein synthesis in the action of glucocorticoids on the working capacity of adrenalectomized rats.

The administration of cortisol for 3 or 5 days increased the maximal duration of swimming under additional load, equal to 3% of body weight, in adrenalectomized but not in intact Wistar rats. The liver tryptophan oxygenase activity also increased. The blockade of RNA synthesis by actinomycin D excluded both results of cortisol administration. High doses of progesterone (25 or 75 mg/day) decreased the working capacity, rendering the action of cortisol on the working capacity of adrenalectomized rats insignificant. However, the antagonism between two hormones was not striking at the level of liver tryptophan oxygenase induction. The results suggest that the action of glucocorticoids on the working capacity is mediated by RNA and, further, by protein synthesis. The competition for glucocorticoid cytoplasmic receptors, to be found between glucocorticoids and a high level of progesterone, can disturb this mechanism. The synthesis of hepatic enzyme proteins is not responsible for the action of glucocorticoids on the working capacity.

Adrenal Glands↗
PubMed1982

The catabolic effect of glucocorticoids on different types of skeletal muscle fibres and its dependence upon muscle activity and interaction with anabolic steroids.

Myofibrillar protease activity was found to be elevated, and content of RNA and DNA reduced in m. quadriceps femoris, especially in the fast-twitch white fibers, after dexamethasone treatment. Moderate physical activity prevents, to some extent, the effect of synthetic glucocorticoids. Exhaustive exercise augments the myofibrillar protease activity in both types of muscle fibers. The fast-twitch white type of muscle fibers in exhausted rats are found to have an elevated anticatabolic activity after the treatment of rats with anabolic steroid. It appears that there exists a close correlation between myofibrillar protease activity and muscle weight in the fast-twitch white fibers in dexamethasone treated and exhausted rats.

Anabolic Agents↗
PubMed1982

Independence of physical working capacity from increased glucocorticoid level during short-term exercises.

To investigate the influence of glucocorticoid levels on the physical working capacity, 18 trained and 18 untrained male subjects were examined before and after a short-term graded exercise test. By administration of dexamethasone during 3 days prior to the test or by injecting 25 U of corticotropin 30 min pre-exercise, the blood cortisol response to exercise was altered. It was found that the physical working capacity, as evaluated by PWC170, maximal oxygen deficit, and maximal pedaling rate were not influenced by the glucocorticoid response to the test. It is suggested that the effects of metabolic processes induced by adrenocortical response to exercise are seen only after a lag period.

Adrenocorticotropic Hormone↗
PubMed1982

Peculiarities of adaptation to systematic muscular activity in adrenalectomized rats.

A 3 week training period in running restored the maximal swimming time of adrenalectomized rats to the level of intact untrained rats, but had no influence on the maximal running time and hepatic glycogen reserve. The cardiac hypertrophy and the augmentation of the Mg2+-activated ATPase activity of myocardium in adrenalectomized rats were more pronounced than in intact animals. It is concluded that the deficiency of adrenocortical hormones does not exclude all the adaptive alterations during training, although it makes the complete adaptation and normal increase of the working capacity impossible.

Actomyosin↗