[Effect of triathlon competition on the content of various hormones and the energy substrate of the blood]. / Vliianie zaniatii triatlonom na soderzhanie nekotorykh gormonov i na énergeticheskie substraty v krovi.

The effect of triathlon (3.8 km swimming, 180 km biking, 42 km running) and of its short variant (1.5 km swimming, 42 km biking, 14 km running) was studied in 7 and 14 well-trained men, respectively. The level of plasma glucose, total cholesterol, HDL, LDL did not change significantly during the competition. FFA concentration increased significantly (by 439 and 61%, respectively). Triglycerides concentration decreased during the prolonged variant. Both variants of triathlon caused a pronounced rise in the cortisol level and moderate increase in somatotropin and progesterone levels. Testosterone concentration increased during a short variant and decreased during a prolonged one. Insulin and C-peptide levels decreased. All those changes in hormones concentration are consistent with an increased lipolytic activity and, may be, with increased glycolytic activity (maintenance of the normal glucose concentration in blood). The rise in the aldosterone level reflects the homeostatic activity in maintaining electrolyte balance.

[Relation between changes in the blood levels of beta-endorphin and various hormones during physical exercise]. / Vzaimootnosheniia mezhdu izmeneniiami soderzhaniia beta-éndorfina i riada gormonov v krovi vo vremia myshechnoi raboty.

Dynamics of beta-endorphin, corticotropin, cortisol, somatotropin, insulin and triiodothyronine content were studied using bicycle ergometer in blood of 22 persons during 2 hrs exercises. After an initial increase the beta-endorphin content was subsequently decreased. At the same time, the decrease in the neuropeptide content was accompanied by repeated elevation within the second hr of the exercise, mainly in persons exhibiting high working capacity, while in other persons the hormone concentration decreased below the initial level at the end of the exercise. These alterations in the content of beta-endorphin correlated distinctly with dynamics of pituitary-adrenocortical hormones variation. In untrained persons the initial increase in beta-endorphin content was especially distinctly related to the elevation in somatotropin and to a decrease in insulin content in blood. Concentration of triiodothyronine in blood was altered independently of the alterations of other hormones.

[Recovery after prolonged muscular work]. / Protsess vosstanovleniia posle dlitel'noi myshechnoi raboty.

Increased protein, tyrosine and 3-methylhistidine content has been observed in the skeletal muscles of rats 2-24 h after a 10-hour swimming period. This was accompanied by a significant rise in 3-methylhistidine excretion during the second day of the recovery period. Such combination of alterations suggests simultaneous augmentation of both protein synthesis and decomposition in the muscles after active work. The start of the alterations coincides with post-exercise increase of blood corticosterone level (2-6 h after work) and with the achievement of glycogen supercompensation in the liver and muscles.

[Protein metabolism in the muscles after work]. / Belkovyi obmen v myshtsakh posle ikh raboty.

The 20-hr swimming increased the contants of protein, thyrosine and 3-methylhistidine (also per 1 g of protein) in skeletal muscle of rat within 2-24 hrs. A significant increase in 3-methylhistidine excretion followed this on the 2nd day of the recovery period. The revealed combination of changes suggests a simultaneous augmentation of both synthesis and disintegration of protein in muscles after their activity. Hence, the increased excretion of 3-methylhistidine during recovery period reflects an intensive renewal of the molecular content of proteins of actinomyosine complex. The 3-methylhistidine level in intestine increased only for a short time and seems not to contribute to the delayed increase in excretion of the amino acid.

[Interrelation between corticotropin and cortisol during static physical loading]. / Vzaimootnosheniia mezhdu kortikotropinom i kortizolom pri staticheskoi fizicheskoi nagruzke.

The time-course of changes in the blood corticotropin and cortisol concentration was studied in 9 dogs during standing with a load on the back. The pituitary-adrenocortical system was shown to be activated fairly rapidly. The initially occurring rise in corticotropin concentration was coupled with a more prolonged elevation of blood cortisol. In the absence of cortisol from the blood which was caused by long-term injection of chloditan, activation of corticotropic function proceeded more intensely whereas the reduction in corticotropin concentration after its initial increment was less demonstrable as compared to that seen in normal adrenal function.

[Adaptation of skeletal muscle and myocardium to increased motor activity in hypo- and athyroid rats]. / Adaptatsiia skeletnykh i serdechnoi myshts k povyshennoi dvigatel'noi aktivnosti u gipo- i atireoidnykh krys.

Changes in contractility and synthesis of protein were studied in different types of muscles of hypo- and athyroid ratts during adaptation to physical exercise. Intensity of the exercises used corresponded to metabolic power output of 70% VO2max. Thyroidectomy caused a significant decrease in Mg2+ activated actomyosin ATPase activity and in content of RNA in myocardium and in fast oxidative-glycogenolytic and glycogenolytic skeletal muscle fibers. Exercises, intensity of which corresponded to metabolic power output of 70% VO2max led to a more distinct decrease in Mg2+ activated actomyosin ATPase activity in fast glycogenolytic muscle fibers, but in fast oxidative-glycogenolytic fibers the enzymatic activity was increased up to the level comparable with that of intact animals. Rhysical working capacity of athyroid rats was lower by 40% as compared with intact trained animals. Hypothyroidism, induced by means of administration of KJ into previously trained rats, caused a decrease in physical working capacity by 25%.

[Role of the thyroid gland in skeletal muscle adaptation to increased motor activity]. / Rol' shchitovidnoi zhelezy pri adaptatsii skeletnykh myshts k povyshennoi dvigatel'noi aktivnosti.

Experiments in 16-week old male Wistar strain rats showed that deficiency of thyroid hormones caused a decrease of cytochrome aa3, RNA, myofibrillar and sarcoplasmic protein contents in m. quadriceps femoris, Mg2+ activated actomyosin ATPase activity and physical working capacity of untrained and trained animals also reduced. Physical activity the intensity of which corresponded to metabolic power output of 190%. Vo2max stimulated thyroid function, elicited a significant elevation of blood thyroxine level, oxidative potential and intensity of protein synthesis in m. quadriceps femoris, the character of these changes depending on the type of muscle fibers. The stimulation of thyroid function caused an elevation of muscle content of cytochrome aa3 and content of RNA, especially in the glycolytic fibers of hypothyroid rats.