Influence of recovery intensity on time spent at maximal oxygen uptake during an intermittent session in young, endurance-trained athletes

In this study, we examined the effects of three recovery intensities on time spent at a high percentage of maximal oxygen uptake (t90[Vdot]O(2max)) during a short intermittent session. Eight endurance-trained male adolescents (16 +/- 1 years) performed four field tests until exhaustion: a graded test to determine maximal oxygen uptake ([Vdot]O(2max); 57.4 +/- 6.1 ml x min(-1) . kg(-1)) and maximal aerobic velocity (17.9 +/- 0.4 km x h(-1)), and three intermittent exercises consisting of repeat 30-s runs at 105% of maximal aerobic velocity alternating with 30 s active recovery at 50% (IE(50)), 67% (IE(67)), and 84% (IE(84)) of maximal aerobic velocity. In absolute values, mean t90[Vdot]O(2max) was not significantly different between IE(50) and IE(67), but both values were significantly longer compared with IE(84). When expressed in relative values (as a percentage of time to exhaustion), mean t90[Vdot]O(2max) was significantly higher during IE(67) than during IE(50). Our results show that both 50% and 67% of maximal aerobic velocity of active recovery induced extensive solicitation of the cardiorespiratory system. Our results suggest that the choice of recovery intensity depends on the exercise objective.     

A microfluidic-based neurotoxin concentration gradient for the generation of an in vitro model of Parkinson's disease

In this study, we developed a miniaturized microfluidic-based high-throughput cell toxicity assay to create an in vitro model of Parkinson's disease (PD). In particular, we generated concentration gradients of 6-hydroxydopamine (6-OHDA) to trigger a process of neuronal apoptosis in pheochromocytoma PC12 neuronal cell line. PC12 cells were cultured in a microfluidic channel, and a concentration gradient of 6-OHDA was generated in the channel by using a back and forth movement of the fluid flow. Cellular apoptosis was then analyzed along the channel. The results indicate that at low concentrations of 6-OHDA along the gradient (i.e., approximately less than 260 μM), the neuronal death in the channel was mainly induced by apoptosis, while at higher concentrations, 6-OHDA induced neuronal death mainly through necrosis. Thus, this concentration appears to be useful for creating an in vitro model of PD by inducing the highest level of apoptosis in PC12 cells. As microfluidic systems are advantageous in a range of properties such as throughput and lower use of reagents, they may provide a useful approach for generating in vitro models of disease for drug discovery applications.     

Collaborative problem-solving with a computer: How can an interactive learning environment be designed?

This study was designed to evaluate the effects of a «familiar» learning situation on the strategies used by students in a computer mediated interactive environment. We examine the strategies used by 14–15 year-old students in solving physics problems according to whether the technical situation was presented using a canonical version of an electric circuit (rules currently used in class) or a non-canonical version. Students worked either in pairs or individually with a computer. The results show that the dyads only performed better than individuals in the non-canonical version to the problem. The results are discussed in a perspective which offers a renewed approach of student-computer interaction.     

Teaching Stress Management in Physical Education: A Quasi-Experimental Study with Vocational Students

The aim was to develop, implement, and evaluate a physical education-based coping training program for vocational students. Two vocational schools participated in the quasi-experimental pilot study (EPHECT I). One school received the intervention (intervention group: n?=?434), while the other school maintained regular physical education classes (control group: n?=?430). Repeated measures ANCOVAs were used to examine the effects on coping and perceived stress. Additionally, effects were compared among students who reported low versus elevated life satisfaction. Finally, the implementation rate was considered as a moderating factor. Overall, no significant time by group effects were found between the intervention group and the control group. However, a reduction in maladaptive coping occurred among students of the intervention group who reported low life satisfaction. The implementation rate did not moderate the findings. Despite a relatively low implementation rate, the intervention program reduced maladaptive coping strategies in adolescents with low life satisfaction. Program monitoring needs to be increased in future research.     

Spike jump biomechanics in male versus female elite volleyball players

ABSTRACT

There are well-known biological differences between women and men, especially in technical-coordinative variations that contribute to sex differences in performance of complex movements like the most important offensive action in volleyball, the spike jump. The aim of this study was to investigate sex-dependent performance and biomechanical characteristics in the volleyball spike jump. Thirty female and male sub-elite volleyball players were analysed while striking a stationary ball with maximal spike jump height. Twelve MX13 Vicon cameras with a cluster marker set, two AMTI force plates, surface EMG, and a Full-Body 3D model in Visual3D were used. Main findings include sex differences (P< .05) in jump height (pη² = .73), approach [speed (pη² = .61), step length], transition strategy [plant angle, neuromuscular activation (pη² = .91), horizontal force maxima and impulses], acceleration distances [centre of mass displacement (pη² = .21), minimal knee and hip angles], use of torso and arms [incline, angular velocity (pη² = .23)]. Correlations support that the results cannot be explained fully by strength and power differences between sexes but represent the product of technical-coordinative variations. Their relevance is acknowledged for both sexes and numerous performance determinants displayed sex differences. The integration of such attributes into sex-specific training seems promising but its effect requires further investigation.     

Postponement in the completion of the final dissertation: an underexplored dimension of achievement in higher education

Research on academic achievement at a university has mainly focused on success and persistence among first year students. Very few studies have looked at delay or failure in the completion of a final dissertation. However, this phenomenon could affect a substantial proportion of students and has considerable costs. The purpose of the present study is to identify factors which predict postponement in the completion of the final dissertation. Several potential predictors (e.g., background, personality, social support, motivational beliefs, and engagement) were selected through an integrative review of the literature on achievement in higher education. A questionnaire assessing these variables was administered to 341 students a few months before the deadline for their final dissertation. Results indicate that perceived peer support, perceived relatives support, role conflict, and age have an independent and significant effect on whether or not the final dissertation is completed on time. In addition, self-efficacy and behavioral engagement appeared to be mediators of the relationship between the social support and the final dissertation completion.     

Evaluation of oxidative stress and antioxidant status of pregnant women suffering from malaria in Cameroon

Oxidative stress is thought to be involved in the pathophysiology of malaria, especially in pregnancy where natural resistance is markedly reduced. In the present study we investigated oxidative stress in 315 pregnant women out of which 159 had Plasmodium falciparum malaria and 154 controls. We evaluated the level of lipid peroxidation products (MDA level) in the plasma, the activity of erythrocyte antioxidant defense enzymes, superoxide dismutase (SOD, EC: 1.15.1.1) and catalase (Cat, EC: 1.11.1.6) as well as the ability to resist oxidative stress by the FRAP (Ferric Reducing Ability of Plasma) assay. Total erythrocyte protein levels were also examined. For the two groups of patients, several differences between the biochemical parameters tested were found. Median parasitaemia in women with malaria was 25,392 parasites/μl of blood (Range1200–82000), while in controls we had no parasites found in thin and thick smears. Levels of lipid peroxidation products (MDA) were significantly higher in patients with parasitemia than in healthy asymptomatic volunteers (mean: 0.844 ± 0.290 and 0.384 ± 0.129 respectively, p<0.001). This MDA level was higher in primigravidea and also correlates well with parasite density (p<0.001). Catalase activity in erythrocytes of women with malaria did not differ statistically from that of controls. In contrast, SOD activity of patients with malaria was found to be significantly higher than that of controls (mean: 0.7899 ± 0.2777 and 0.4263 ± 0.2629 respectively, p<0.05). FRAP values declined, from parasitemic patients (1.4619 ± 0.6565) compare to controls (2.4396 ± 0.8883, p<0.05), particularly in the first and third trimester of gestation (p<0.05 and p<0.01 respectively). Finally, total erythrocyte protein concentrations of women with malaria did not differ from that of the controls. Our results suggest an imbalance between oxidants and antioxidants in pregnant women suffering from malaria, a situation which could lead to severe damage for either the mother or the fetus. Therefore, further research should be done to assess the potential benefits of antioxidant supplementation for the pregnant women suffering from malaria.     

Effects of Aerobic Exercise on Cognitive Performance Among Young Adults in a Higher Education Setting

Purpose: Acute benefits of aerobic exercise on executive functioning have been reported frequently under laboratory conditions. However, to date, a beneficial effect on long-term memory has been less well supported and no data are available regarding nonlaboratory conditions in young adults. The aim of the current study was to investigate acute effects of aerobic exercise on cognitive functioning in a university classroom setting. Method: Using a cross-over design, 51 participants performed a bout of moderately intense running (RUN) and read an article while seated (CON). Afterwards, they completed free-recall tests, followed by a Flanker task and an n-back task. Results: Participants in the RUN condition compared with those in the CON condition showed shorter reaction time on the inhibition task, F(1, 50) = 5.59, p = .022, η² = .101, and recalled more words in the immediate- and delayed-recall tests, F(1, 50) = 8.40, p = .006, η² = .144. Conclusion: The present findings suggest that a moderately intense bout of aerobic exercise benefits verbal short-term and long-term memory as well as inhibitory control among students in a classroom setting.