Authors:Imre Juhász, I. Györe, Zs Csende, L. Rácz and J. Tihanyi
The objective of this study was to determine whether creatine supplementation (CrS) could improve mechanical power output, and swimming performance in highly trained junior competitive fin swimmers. Sixteen male fin swimmers (age:15.9±1.6 years) were randomly and evenly assigned to either a creatine (CR, 4×5 g/day creatine monohydrate for 5 days) or placebo group (P, same dose of a dextrose-ascorbic acid placebo) in a double-blind research. Before and after CrS the average power output was determined by a Bosco-test and the swimming time was measured in two maximal 100 m fin swims. After five days of CrS the average power of one minute continuous rebound jumps increased by 20.2%. The lactate concentration was significantly less after 5 minutes restitution at the second measurement in both groups. The swimming time was significantly reduced in both first (pre: 50.69±1.41 s; post: 48.86±1.34 s) and second (pre: 50.39±1.38 s; post: 48.53±1.35 s) sessions of swimming in CR group, but remained almost unchanged in the P group.The results of this study indicate that five day Cr supplementation enhances the dynamic strength and may increase anaerobic metabolism in the lower extremity muscles, and improves performance in consecutive maximal swims in highly trained adolescent fin swimmers.
Authors:Márk Váczi, A. Costa, L. Rácz and J. Tihanyi
This study compared two training regimens in which knee extensor exercises were performed at different range of motion.
Sixteen males performed bouts of 90 maximal isokinetic eccentric contractions over 6 consecutive days (B1-B6) at either small (n=8) or large (n=8) range of motion. Average of peak torque (Mp) of each of the 90 contraction trials were calculated, plasma creatine kinase (CK) and lactate dehydrogenase (LDH) activities were measured before, 24 h, 48 h and 6 d after B1. Muscle soreness was evaluated every day during the experiment.
At B3 Mp reduced more in group L than in group S. From B1 to B6 group S increased Mp, while in group L Mp did not return to the baseline level. In both groups CK activity elevated 24 h following B1. CK activity was significantly higher in group L 6d after B1. In group L muscle soreness was higher at 48 h, 72 h, 4 d and 5 d after B1.
High-intensity, consecutive eccentric knee extensor exercise training at large range of motion may induce greater development of muscle damage and force deficit, than training at small range of motion. Training at small range of motion may induce early adaptation in voluntary torque production.
Authors:G. Gyulai, L. Rácz, R. Di Giminiani and József Tihanyi
The acute residual effect of whole body vibration (WBV) on upper extremity muscles and testosterone secretion was studied. Eight highly (G1), nine moderately trained gymnasts (G2) and seven physically active persons (CG) were recruited for the investigation. The intervention occurred in push-up position with the elbow flexed at 90°. G1 and G2 received 30 s, 30 Hz and 6 mm amplitude vibration repeated five times. Subjects were tested before and after one and ten minutes intervention in push-up movement. Contact time (Tc), fly time (Tf), TF/Tc ratio and impulse was measured from the ground reaction force-time curves recorded during self-selected (SSRM) and full range of motion (FRM). Testosterone level in urine was also determined. Tf increased significantly in SSRM for G1 and decreased in SSRM and FRM for G2. Tf/Tc ratio in FRM and impulse in SSRM increased significantly for G1 only. No significant alteration in testosterone level was observed. We concluded that WBV is a reasonable training modality for influencing dynamic work of upper extremity muscle, but the reaction to WBV is training and individual dependent. It seems that WBV do not influence dynamic work through increased testosterone secretion because of the relatively low mass of the involved muscles.
Authors:L. Rácz, A. Bumbálová, M. Harangozó, J. Tölgyessy and O. Tomeček
Cesium and selenium intake of cultivated mushrooms (Agaricus bisporus), with these elements previously added to the culture medium, has been examined from the viewpoint of health- and environmental protection. The process of measuring has been carried out by the radionuclide X-ray fluorescence technique. Treattments of the elementary substance with Se salt appears to influence the Se content of the mushrooms to a significant extent. Cs intake is of considerable importance, as this element is accumulated by mushrooms.
Authors:C. L. Frank, Szabina J. Czirok, Csilla Vincze, G. Rácz, Á. Szél and B. Vígh
In earlier works we have found that in the mammalian pineal organ, a part of autonomic nerves - generally thought to mediate light information from the retina - form vasomotor endings on smooth muscle cells of vessels. We supposed that they serve the vascular support for circadian and circannual periodic changes in the metabolic activity of the pineal tissue. In the present work, we investigated whether peripheral nerves present in the photoreceptive pineal organs of submammalians form similar terminals on microvessels. In the cyclostome, fish, amphibian, reptile and bird species investigated, autonomic nerves accompany vessels entering the arachnoidal capsule and interfollicular meningeal septa of the pineal organ. The autonomic nerves do not enter the pineal tissue proper but remain in the perivasal meningeal septa isolated by basal lamina. They are composed of unmyelinated and myelinated fibers and form terminals around arterioles, veins and capillaries. The terminals contain synaptic and granular vesicles. Comparing various vertebrates, more perivasal terminals were found in reptiles and birds than in the cyclostome, fish and amphibian pineal organs. Earlier, autonomic nerves of the pineal organs were predominantly investigated in connection with the innervation of pineal tissue. The perivasal terminals found in various submammalians show that a part of the pineal autonomic fibers are vasomotoric in nature, but the vasosensor function of some fibers cannot be excluded. We suppose that the vasomotor regulation of the pineal microvessels in the photosensory submamalian pineal - like in mammals - may serve the vascular support for circadian and circannual periodic changes in the metabolic activity of the pineal tissue. The higher number of perivasal terminals in reptiles and birds may correspond to the higher metabolic activity of the tissues in more differentiated species.
Authors:Z. Hegyi, T. Spitkó, C. Szőke, F. Rácz, T. Berzy, J. Pintér and L. Marton
The adaptability of twelve single cross maize hybrids was investigated at five different locations in Hungary over a three-year period. The characters examined were individual plant production (total mass of the ears on a single plant), thousand kernel mass, number of kernel rows, ear length, number of kernels per row, shelling % and the assimilating leaf area above the main ear.Among these yield components, the individual plant production, the ear length, the number of kernels per row and the grain-cob ratio (shelling %) were influenced to the greatest extent by the year, followed by the variety and the location. The greatest average yield was achieved by the tested hybrids at all five locations in 1997 (263 g/plant). The average yields in 1998 and 1999 were significantly lower (221 and 203 g/plant, respectively). The outstanding yields achieved in 1997 could be attributed to the favourable ecological conditions, which led to the development of secondary ears in Keszthely and Sopronhorpács. At the other three locations there was only one ear per plant, but these ears were longer than in the following years. The greatest year effect was recorded in Sopronhorpács, where the individual plant production amounted to 305 g/plant in 1997 and 238 g/plant in the worst year, 1999. In Gyöngyös conditions were very dry in all three years, so the year effect was least pronounced at this location (grand mean of 195 g/plant in 1997 and 201 g/plant in 1999). Stability analysis was carried out using the coefficient of variance for individual plant production. Hybrids Mv 3, Mv 5, Mv 9 and Mv 12 were found to have the best adaptability. The shelling % was not significantly influenced by the location; the grain-cob ratio is relatively stable for maize hybrids. A correlation was found between the individual plant production and the leaf area above the main ear (R
=0.66). Hybrids with the largest leaf area above the main ear also had the greatest ear mass.
Authors:A. Costa, Z. Orosz, P. Apor, N. Csaba, S. Siamilis, Z. Csende, L. Racz and J. Tihanyi
In animal models, unaccustomed eccentric exercise (EE) has been widely related to muscle fiber membrane (sarcolemma) damage. On the contrary, studies in humans reported that sarcolemma was not susceptible to damage following a single bout of EE. We hypothesized that the single bout of EE used by those studies was not sufficient to induce sarcolemma damage, in humans. In this study we examined muscle biopsies from untrained males who either performed six sets of 15 reps of maximum voluntary eccentric contractions (n=9), for six consecutive days, or served as control-group (n=6). Blood and biopsy samples were obtained one week prior to exercise, immediately after bout 3, and 24h after the last training session. In addition to standard haematoxylin-eosin staining, all biopsies were stained immunohistochemically using antibodies specific for fibronectin and desmin antigens. In the exercise-group, no biopsies taken at pre-exercise or post-exercise level showed evidence of sarcolemma damage as stained by anti-fibronectin antibody in eight of nine subjects. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities increased significantly throughout the study despite the lack of sarcolemma damage.We suggest that in humans, repeated bouts of EE do not cause gross sarcolemma damage in the mid-belly of Vastus Lateralis.
Authors:P. Koska, É. Dojcsák Kiss-Tóth, A. Juhász Szalai, G. Kovács, L. Barkai, O. Rácz and Bertalan Fodor
An important obstacle to achieve optimal glycaemic control in diabetics on intensive insulin therapy is the frequent occurrence of insulin induced hypoglycaemic events. In healthy subjects and in diabetics without autonomic neuropathy hypoglycaemia activates the sympathetic nervous system, resulting in epinephrine and glucagon release. Both hormones increase hepatic glucose production and this counterregulatory response is of key importance of glucose homeostasis. Recent research shed light on the fact that antecedent hypoglycaemic episodes play pivotal role in hypoglycaemia associated autonomic failure (HAAF). In this condition the sympatho-adrenal response to decreased blood glucose level is blunted. The existence of HAAF clearly indicates that the nervous system contributes to glucose homeostasis in a substantial manner. This review outlines the mechanisms of both peripheral and central neuronal glucose sensing and of neural pathways involved in the counterregulatory response.