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

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 gamma-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 microg.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.     

The perception of workload and task complexity and its influence on students’ approaches to learning: a study in higher education

Researchers have tried to induce a deeper approach to learning by means of student-centred learning environments. Findings did not always confirm the positive hypotheses. This has given rise to the question as to what the discouraging or encouraging factors are for inducing a deep approach to learning. The aim of this research study is to determine whether perceived workload and task complexity are discouraging or encouraging factors. In addition, these relationships will be investigated under different induced conditions which offer the potential to deepen our understanding of the nature of the investigated relationships. Participants were 128 second year Bachelor level students in educational sciences. After an introduction with the theory, students were given four tasks with various workloads and task complexities after which they filled out questionnaires on learning approaches, perceived workload and perceived task complexity. For every task, correlations and multiple stepwise regressions were calculated. The information from the interviews was used to support and illustrate the results of quantitative analyses. In general, results show no significant relationship between perceived workload and students’ approaches to learning. For perceived task complexity, it was found that a perceived lack of information is a discouraging factor for inducing a deep learning approach. A lack of information consistently increases students’ surface approaches to learning regardless of the induced workload and task complexity.     

Decentralized neural identification and control for uncertain nonlinear systems: Application to planar robot

This paper presents a discrete-time decentralized neural identification and control for large-scale uncertain nonlinear systems, which is developed using recurrent high order neural networks (RHONN); the neural network learning algorithm uses an extended Kalman filter (EKF). The discrete-time control law proposed is based on block control and sliding mode techniques. The control algorithm is first simulated, and then implemented in real time for a two degree of freedom (DOF) planar robot.     

Influence of force-vector and force application plyometric training in young elite basketball players

Plyometric training composed by unilateral exercises with horizontal jumping direction seems to be an effective way to improve physical performance in athletes. The present study aimed to compare the influence of a combined jumping direction and force application (horizontal-unilateral vs. vertical-bilateral) plyometric training on linear sprinting, jumping, change of direction (COD) and dynamic balance in young elite basketball players. Twenty young (U-13 to U-14) male basketball players (age: 13.2?±?0.7 years, body mass: 59.5?±?12.7?kg, height: 172.9?±?7.9?cm) were randomly assigned either to a unilateral-horizontal (UH, n?=?10) or bilateral-vertical (BV, n?=?10) plyometric group, twice a week for 6-wk. Both groups performed between 60 and 100 jumps/session. UH executed all jumps unilaterally with horizontal direction, while jumps in the BV were bilaterally with vertical direction. Performance was assessed by a linear sprinting test, vertical and horizontal jumping tests, COD tests (V-cut and 5+5?m with a 180°COD test), an ankle dorsiflexion test and dynamic balance tests (anterior and postero-lateral directions). Within-group differences showed substantial improvements (Effect size (ES):0.31–1.01) in unilateral vertical and horizontal jumping, V-cut test and postero-lateral direction with right leg after both training interventions. Furthermore, UH group also substantially improved (ES:0.33–0.78) all sprinting times and postero-lateral direction with left leg, while BV enhanced anterior direction with left leg (ES:0.25). Between-group analyses showed substantially greater improvements (ES:0.33) in 10-m and V-cut test in UH than in BV. The likely beneficial effect (small ES) achieved in sprinting abilities suggests the combination of unilateral-horizontal jumps to improve such abilities.     

Bar velocities capable of optimising the muscle power in strength-power exercises

This study aimed at testing whether there are mean propulsive velocities (MPVs) capable of maximising the mean propulsive power (MPP) during the execution of bench press (BP), bench throw (BT), half squat (HS) and jump squat (JS). Additionally, we assessed the differences in MPP/MPV between ballistic and traditional exercises. Seventeen male rugby sevens players performed MPP tests in BP, BT, HS and JS and maximum isometric force (MIF) tests in HS and BP. The JS presented higher MPP (977.4 ± 156.2 W) than the HS (897.9 ± 157.7 W) (P < 0.05); the BP (743.4 ± 100.1 W) presented higher MPP than the BT (697.8 ± 70.4 W) (P < 0.05). Ballistic exercises presented higher optimum MPV (JS = 1.02 ± 0.07 m·s^?1; BT = 1.67 ± 0.15 m·s^?1) than traditional exercises (HS = 0.93 ± 0.08 m·s^?1; BP = 1.40 ± 0.13 m·s^?1) (P < 0.05). The optimum MPP in the JS, BT, HS and BP occurred at 28.2 ± 5.79, 23.3 ± 4.24, 32.4 ± 9.46 and 27.7 ± 5.33% of the MIF, respectively. The coefficient of variation (CV) of MPV at optimum MPP ranged from 7.4% to 9.7%, while the CV of %MIF ranged from 18.2% to 29.2%. The MPV is a more precise indicator of the optimum loads than the percentages of MIF due to its low inter-subject variability as expressed by CV. Therefore, MPV can be used to determine the optimum power load in the four investigated exercises.     

Performing in a multi-cultural context: The role of personality

Performance in situations where individuals from multiple countries are operating in a foreign culture is an underexplored domain of organizational behavior. We test hypothesized relationships between Big Five personality factors and dimensions of international performance using a sample of 232 international business students from 14 countries studying in Mexico. The results indicate differential relationships between personality factors and performance dimensions that emphasize interacting with host nationals and students from other countries, adjusting to a foreign environment, and maintaining a positive attitude in a foreign country. We discuss theoretical and practical implications for understanding and influencing performance in multi-cultural contexts.     

¿Podemos favorecer el aprendizaje autónomo del significado de palabras?

Se presenta aquí un programa de adquisición del vocabulario y desarrollo de la comprensión a partir de contextos naturales. El programa, que abandona otras rutinas tradicionales de enseñanza de vocabulario, trata de mejorar la capacidad de inferencia y comprensión textual de los alumnos para dotarles de mayor autonomía lectoescrita.     

Individual differences in working memory capacity and attention,and their relationship with students’ approaches to learning

Past research has shown that working memory capacity, attention and students’ approaches to learning are all important predictors for educational achievement. In this study the interrelations between these three variables are investigated. Participants were 128 university students. Results show a negative relationship between attention and deep approaches to learning: students with a lower level of attention seem to use more deep approaches to learning than students with higher levels of attention. It was also found that students with a high working memory capacity score lower on both the surface and deep approaches to learning than students with a low working memory capacity. A possible explanation is that these high capacity students might not need a consistent profound strategy to be successful because they are very good at acquiring, processing and integrating all types of new information before moving it to storage.