Correlations between serum and salivary hormonal concentrations in response to resistance exercise     

Eduardo Cadore  Francisco Lhullier  Michel Brentano  Eduardo Silva  Melissa Ambrosini  Rafael Spinelli 《Journal of sports sciences》2013,31(10):1067-1072

Abstract

The aim of present study was to examine the relationships between serum and salivary values of free testosterone, dehydroepiandrosterone, and cortisol before and after a session of resistance exercise. Twenty-eight healthy men (mean age 40 years, s = 4) participated in the present study. Serum and salivary samples were collected at rest and after a multiple-sets resistance exercise protocol, of approximately 25 minutes duration. Concentrations of free testosterone, dehydroepiandrosterone, and cortisol were measured using radioimmunoassay kits. No significant correlation was observed between serum free testosterone and salivary testosterone (r = 0.22 to 0.26, P > 0.05). Serum cortisol was significantly correlated with salivary cortisol before (r = 0.52, P = 0.005) and after (r = 0.62, P = 0.001) the exercise protocol. Serum and salivary concentrations of dehydroepiandrosterone were significantly correlated before (r = 0.68, P < 0.001) and after (r = 0.7, P < 0.001) exercise. The results of the present study suggest that even under exercise conditions, the salivary values of cortisol and dehydroepiandrosterone can reflect the behaviour of these hormones in blood. However, further studies are necessary to verify if salivary testosterone reflects the behaviour of serum free testosterone during resistance exercise.  相似文献   

Protection against muscle damage in competitive sports players: the effect of the immunomodulator AM3     

Alfredo Córdova  J Francisco Martin  Eduardo Reyes  Melchor Alvarez-Mon 《Journal of sports sciences》2013,31(9):827-833

Strenuous physical exercise of the limb muscles commonly results in damage, especially when that exercise is intense, prolonged and includes eccentric contractions. Many factors contribute to exercise-induced muscle injury and the mechanism is likely to differ with the type of exercise. Competitive sports players are highly susceptible to this type of injury. AM3 is an orally administered immunomodulator that reduces the synthesis of proinflammatory cytokines and normalizes defective cellular immune fractions. The ability of AM3 to prevent chronic muscle injury following strenuous exercise characterized by eccentric muscle contraction was evaluated in a double-blind and randomized pilot study. Fourteen professional male volleyball players from the First Division of the Spanish Volleyball League volunteered to take part. The participants were randomized to receive either placebo (n?=?7) or AM3 (n?=?7). The physical characteristics (mean±s) of the placebo group were as follows: age 25.7±2.1 years, body mass 87.2±4.1?kg, height 1.89±0.07?m, maximal oxygen uptake 65.3±4.2?ml?·?kg^?1?·?min^?1. Those of the AM3 group were as follows: age 26.1±1.9 years, body mass 85.8±6.1?kg, height 1.91±0.07?m, maximal oxygen uptake 64.6±4.5?ml?·?kg^?1?·?min^?1. All participants were evaluated for biochemical indices of muscle damage, including concentrations of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatine kinase (CK) and its MB fraction (CK-MB), myoglobin, lactate dehydrogenase, urea, creatinine and γ-glutamyltranspeptidase, both before and 30 days after treatment (over the peak of the competitive season). In the placebo group, competitive exercise (i.e. volleyball) was accompanied by significant increases in creatine kinase (494±51 to 560±53?IU?·?l^?1, P?<?0.05) and myoglobin (76.8±2.9 to 83.9±3.1?μg?·?l^?1, P?<?0.05); aspartate aminotransferase (30.8±3.0 to 31.1±2.9?IU?·?l^?1) and lactate dehydrogenase (380±31 to 376±29?IU?·?l^?1) were relatively unchanged after the 30 days maximum effort. AM3 not only inhibited these changes, it led to a decrease from baseline serum concentrations of creatine kinase (503±49 to 316±37?IU?·?l^?1, P?<?0.05) and myoglobin (80.1±3.2 to 44.1±2.6?IU?·?l^?1, P?<?0.05), as well as aspartate aminotransferase (31.1±3.3 to 26.1±2.7?IU?·?l^?1, P?<?0.05) and lactate dehydrogenase (368±34 to 310±3?IU?·?l^?1, P?<?0.05). The concentration of CK-MB was also significantly decreased from baseline with AM3 treatment (11.6±1.2 to 5.0±0.7?IU?·?l^?1, P?<?0.05), but not with placebo (11.4±1.1 to 10.8±1.4?IU?·?l^?1). In conclusion, the use of immunomodulators, such as AM3, by elite sportspersons during competition significantly reduces serum concentrations of proteins associated with muscle damage.  相似文献   

Magnesium status and the physical performance of volleyball players: effects of magnesium supplementation     

Luciana Setaro  Paulo Roberto Santos-Silva  Eduardo Yoshio Nakano  Cristiane Hermes Sales  Newton Nunes  Júlia Maria Greve 《Journal of sports sciences》2013,31(5):438-445

Abstract

The aim of this study was to test the hypothesis that magnesium supplementation influences the physical performance of volleyball players, as the efficacy of this approach remains questionable. Twenty-five professional male volleyball players were assigned randomly to experimental (350 mg Mg · d^–1, 4 weeks) and control groups (500 mg maltodextrin · d^–1, 4 weeks) maintaining inter-group homogeneity of urinary magnesium. Erythrocyte, plasma and urinary magnesium levels, plasma creatine kinase activity, lactate production, maximal oxygen uptake (VO₂ max) and plyometric (squat jump, countermovement jump, countermovement jump with arm swing) and isokinetic (peak torque, potency and total work) performances were evaluated before (T₀) and after (T₁) supplementation. Levels of erythrocyte and urinary magnesium and creatine kinase activity and VO₂ max remained within normal ranges in both groups. Plasma magnesium decreased significantly only within the experimental group. Significant decreases in lactate production and significant increases (of up to 3 cm) in countermovement jump and countermovement jump with arm swing values were detected in the experimental group following magnesium supplementation, but not in the control group at T₁. It is concluded that magnesium supplementation improved alactic anaerobic metabolism, even though the players were not magnesium-deficient.  相似文献   

Defending Constructivism in Science Education     

Gil-Pérez  Daniel  Guisasola  Jenaro  Moreno  Antonio  Cachapuz  Antonio  Pessoa De Carvalho  Anna M.  Martínez Torregrosa  Joaquín  Salinas  Julia  Valdés  Pablo  González  Eduardo  Gené Duch  Anna  Dumas-Carré  Andrée  Tricárico  Hugo  Gallego  Rómulo 《Science & Education》2002,11(6):557-571

After an impressive development throughout the last two decades, supported by a greatamount of research and innovation, science education seemed to be becoming a newscientific domain. This transformation of Science Education into a specific field of researchand knowledge is usually associated with the establishment of what has been called anemergent consensus about constructivist positions. However, some voices have begunto question these constructivist positions and therefore the idea of an advancementtowards a coherent body of knowledge in the field of science education. The goalof this work is to analyse some of the current criticisms of the so-called constructivistorientations and to study their implications for the development of science education asa coherent body of knowledge.  相似文献   

Curricular change and educational quality / Cambio de plan y calidad educativa     

Adán Robles-Fernández  Javier Suárez-Álvarez  Ignacio Blanco-Saldaña  Eduardo García-Cueto 《Cultura y Educación》2017,29(1):97-119

There is no doubt that the teaching change generated by the adaptation of the former study programme to the EHEA has led to significant shifts regarding teaching loads and the organization of subjects. This paper assesses the students’ perception of the subject, the teacher and the teaching organization according to the study programme followed. For this purpose, 226 students have been assessed who have all received teaching in the same subject, with the same teacher and with the same contents, with the only variant being their study plan. An instrument developed ad hoc was applied, which comprises 18 items and assesses the students’ perceptions of the content and the perceived organization of the teaching. On the one hand, the results show the instrument to be an adequate scale that assesses teaching and organizational aspects linked to study plans in a valid and reliable way. On the other hand, it reveals that students following the new plan show more negative perceptions of organizational quality and aspects related to learning content. Moreover, these students’ marks tend to be lower compared to those achieved by students following the former plan.  相似文献   

Near-peer teaching in an anatomy course with a low faculty-to-student ratio     

Durán CE  Bahena EN  Rodríguez Mde L  Baca GJ  Uresti AS  Elizondo-Omaña RE  López SG 《Anatomical sciences education》2012,5(3):171-176

Near-peer teaching is an educational format which utilizes tutors who are more advanced in a curriculum's content to supervise students' activities and to act as instructors in laboratory settings. This format is often used in anatomy laboratory courses. The goal of the present study is to describe the design and implementation of near-peer teaching in an anatomy course and to evaluate students' perceptions of the program. A total of 700 students were registered for this anatomy course which employed near-peer instructors. Of enrolled students, 558 (79.7%) agreed to participate in this study. In general, the practical section (e.g., the clinical hour, image-based anatomy session, and gross anatomy laboratory) of the course was viewed more favorably compared to the theory section (54.8%, n = 306), with dissection and prosection in the laboratory rated as the most valued experiences (34.9%, n = 195). Near-peer teaching is a viable option that satisfies the demands of modern curricula using small groups. This format stimulates learning within courses that have large numbers of students and low faculty-to-student ratios.  相似文献   

Predicting shifts in generalization gradients with perceptrons     

Wisniewski MG  Radell ML  Guillette LM  Sturdy CB  Mercado E 《Learning & behavior》2012,40(2):128-144

Perceptron models have been used extensively to model perceptual learning and the effects of discrimination training on generalization, as well as to explore natural classification mechanisms. Here, we assess the ability of existing models to account for the time course of generalization shifts that occur when individuals learn to distinguish sounds. A set of simulations demonstrates that commonly used single-layer and multilayer perceptron networks do not predict transitory shifts in generalization over the course of training but that such dynamics can be accounted for when the output functions of these networks are modified to mimic the properties of cortical tuning curves. The simulations further suggest that prudent selection of stimuli and training criteria can allow for more precise predictions of learning-related shifts in generalization gradients in behavioral experiments. In particular, the simulations predict that individuals will show maximal peak shift after different numbers of trials, that easier contrasts will lead to slower development of shifted peaks, and that whether generalization shifts persist or dissipate will depend on which stimulus dimensions individuals use to distinguish stimuli and how those dimensions are neurally encoded.  相似文献