Influence of a stressing constraint on stiffness and damping functions of a ski simulator's platform motion

The aim of this study was to assess the effect of stress on a previously acquired motor coordination. Following a longitudinal learning experiment, four participants performed oscillations on a ski simulator, either in normal or stressful conditions. The results showed that the amplitude of the oscillations decreased under stress, but no significant effect was seen regarding coordination, suggesting the strong resistance to stress of overlearned behaviour. Nevertheless, for one participant, a transient regression towards a former stage of learning was observed. This result was consistent with the regression hypothesis formulated by Fuchs (1962).     

Energy turnover during 24 hours and 6 days of adventure racing

Abstract

Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake ([Vdot]O₂) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and [Vdot]O₂ were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 ± 2,390 kcal (750 ± 100 kcal · h^?1) and 80,000 ± 18,000 kcal (500 ± 100 kcal · h^?1) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 ± 1,160 kcal, resulting in an energy deficit of 9,590 ± 770 kcal. Body mass decreased in Study 1 (?2.3 ± 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (?2.3 ± 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift.     

One- or Two-Legged Standing

To highlight the capacity of one- and two-legged standing protocols when assessing postural behavior induced by a rigid ankle orthosis, 14 healthy individuals stood upright barefoot and wore either an elastic stocking on the preferred leg or a rigid orthosis with or without additional taping in one- or two-legged (TL) conditions. Traditional center-of-pressure (CP) measures were evaluated for the total two-feet resultant CP and under the feet (plantar CP). Focusing on the plantar CP displacements under the leg fitted with the various orthoses demonstrated particular postural behaviors for traditional parameters with main effects along the mediolateral axis. Only the TL protocol showed the limiting effects of the rigid shells on the inversion-eversion movements in healthy individuals.     

Impact of Background Music on Medical Student Anxiety and Performance During Anatomical Dissections: A Cluster Randomized Interventional Trial

Anatomical dissection on cadavers can be a source of anxiety for medical students. Studies in other stressful settings have shown a reduction in anxiety when there is background music. The objective of this study was to determine if music can have an impact on student anxiety, student satisfaction, and student performance in dissection room. This cluster randomized interventional trial included 187 second-year medical students. The intervention was standardized background music, selected based on the literature, with a tempo of between 60 and 80 bpm. Six balanced clusters were randomized (1:1) to music or no music during dissection sessions. The main assessment criterion was a validated self-evaluation scale score for anxiety, the State Trait Anxiety Inventory. Student satisfaction was measured using a visual analog scale and dissection performance was evaluated by an examination. The outcomes were analyzed with mixed models adjusted on group effect, chronic anxiety, and confounding factors. A significant (58%) relative decrease in acute anxiety, odds ratio 0.423 [0.160; 0.710] was found for the music intervention group. Music also had a positive impact on performance with students in the intervention group attaining higher grades than those in the control group (0.42/10 higher, P = 0.0016). The study also showed a nonsignificant increase in satisfaction with 0.37 extra points (P = 0.137) in the intervention group. Background music had a significant impact on anxiety in the dissection room and on technical and theoretical performance in the subsequent anatomy examination. This music intervention could be extended to other stressful work environments.     

How failure experience combined with high teacher self-aspect importance puts self-efficacy at risk among student teachers

European Journal of Psychology of Education - The present study focuses on how elementary-level student teachers reacted to difficulties during their first internship experience. More specifically,...     

The effects of required amplitude and practice on frequency stability and efficiency in a cyclical task

From an ecological point of view, motor learning emerges from the interplay of constraints on action, which shape behaviour towards the optimal solution, and practice, conceived as an active exploration of the work-space, to search this optimal solution. In the experiment reported here, we studied this interplay for a cyclical task performed on a ski-simulator. Our aim was to assess the respective effects of amplitude and practice on frequency variability and efficiency. On the basis of previous empirical findings, amplitude was expected, beyond a critical value, to constrain and stabilize the frequency of the movement. Three groups of participants practised during four sessions at three different amplitudes (15, 22.5 and 30 cm). The results showed that participants moving at large amplitude displayed more stable and more consistent frequencies. Nevertheless, there was no interaction effect between target amplitude and practice. On the other hand, movement economy and harmonicity increased with practice, but were not affected by amplitude. Finally, the results of transfer tests showed that the effects of large amplitude on frequency variability were not resistant to a subsequent decrease in target amplitude. These results suggest that constraints and practice act independently on motor behaviour, and that a high constraint could be detrimental to the development of effective search strategies.     

Social insertions and representations of oneself and young people: Apprentices and high school students

What does the category or the term “young people” evoke for teenagers who identify themselves in terms of their social group memberships? On the basis of two studies we were able to demonstrate that whereas for apprentices (positioned between school and the world of work) youth is defined in terms of various activities — one is young by virtue of what one is doing, for those pursuing studies in senior high school (the “lycéens”), one is young by virtue of how one thinks. In addition, while apprentices tend to value the group, high school students value the individual above all else.     

Do subjective assessments of running patterns reflect objective parameters?

Running patterns are often categorized into subgroups according to common features before data analysis and interpretation. The Volodalen^® method is a simple field-based tool used to classify runners into aerial or terrestrial using a 5-item subjective rating scale. We aimed to validate the Volodalen^® method by quantifying the relationship between its subjective scores and 3D biomechanical measures. Fifty-four runners ran 30?s on a treadmill at 10, 12, 14, 16, and 18?km?h^?1 while their kinematics were assessed subjectively using the Volodalen^® method and objectively using 3D motion capture. For each runner and speed, two researchers scored the five Volodalen^® items on a 1-to-5 scale, which addressed vertical oscillation, upper-body motion, pelvis and foot position at ground contact, and footstrike pattern. Seven 3D biomechanical parameters reflecting the subjective items were also collected and correlated to the subjective scores. Twenty-eight runners were classified as aerial and 26 as terrestrial. Runner classification did not change with speed, but the relative contribution of the biomechanical parameters to the subjective classification was speed dependent. The magnitude of correlations between subjective and objective measures ranged from trivial to very large. Five of the seven objective parameters significantly differed between aerial and terrestrial runners, and these parameters demonstrated the strongest correlations to the subjective scores. Our results support the validity of the Volodalen^® method, whereby the visual appreciation of running gait reflected quantifiable objective parameters. Two minor modifications to the method are proposed to simplify its use and improve agreement between subjective and objective measures.