Effects of external loading on power output in a squat jump on a force platform: A comparison between strength and power athletes and sedentary individuals

The aim of this study was to determine the effects of external loading on power output during a squat jump on a force platform in athletes specializing in strength and power events (6 elite weight-lifters and 16 volleyball players) and in 20 sedentary individuals. Instantaneous power was computed from time-force curves during vertical jumps with and without an external load (0, 5 or 10 kg worn in a special vest). The jumps were performed from a squat position, without lower limb counter-movement or an arm swing. Peak instantaneous power corresponded to the highest value of instantaneous power during jumping. Average power throughout the push phase of the jump was also calculated. A two‐way analysis of variance showed significant interactions between the load and group effects for peak instantaneous power ( P < 0.01) and average power ( P < 0.001). Peak instantaneous power decreased significantly in sedentary individuals when moderate external loads were added. The peak instantaneous power at 0 kg was greater than that at 5 and 10 kg in the sedentary individuals. In contrast, peak instantaneous power was independent of load in the strength and power athletes. Mean power at 0 kg was significantly lower than at 5 kg in the athletes; at 0 kg it was significantly higher than at 10 kg in the sedentary males and at 5 and 10 kg in the sedentary females. In all groups, the force corresponding to peak instantaneous power increased and the velocity corresponding to peak instantaneous power decreased with external loading. The present results suggest that the effects of external loading on peak instantaneous power are not significant in strength and power athletes provided that the loads do not prevent peak velocity from being higher than the velocity that is optimal for maximal power output.     

Effects of regular training at the same time of day on diurnal fluctuations in muscular performance

The aim of this study was to determine whether there is an effect of time of day on the adaptation to strength training at maximal effort. Fourteen participants took part in this experiment. Their peak anaerobic power (Wingate anaerobic test) and peak knee extension torque at six angular velocities (1.05, 2.10, 3.14, 4.19, 5.24 and 6.29 rad · s -1 ) were recorded in the morning (between 07:00 and 08:00 h) and in the evening (between 17:00 and 18:00 h) just before and 2 weeks after a 6 week course of regular training. Seven of them trained only in the morning and seven only in the evening. Multivariate analysis of variance revealed a significant group 2 pre-/post-training 2 time of day interaction effect for peak torque and peak anaerobic power. Before training, in both groups, peak torque and peak anaerobic power were significantly higher in the evening than in the morning. After training, there was no significant difference in peak torque and peak anaerobic power between the morning and the evening for the morning training group. In contrast, in the evening training group, peak torque and peak anaerobic power were higher in the evening than in the morning. As a result of training, both peak torque and peak anaerobic power increased from their initial values as expected. The morning training group improved their peak anaerobic power significantly in the morning and in the evening, the absolute increase being larger in the morning than in the evening. The evening training group did not improve their peak anaerobic power in the morning, whereas it improved significantly in the evening. Although peak torque was significantly improved by training in the morning and evening in both groups, the absolute increase was greater in the morning than in the evening in the morning training group, whereas the opposite was the case for the evening training group. These results suggest that training twice a week at a specific hour increases the peak torque and the peak anaerobic power specifically at this hour and demonstrates that there is a temporal specificity to strength training.     

A hybrid numerical method to develop America’s Cup yacht appendages

A method aimed at the development of an America’s Cup racing yacht bulb is developed and validated against experimental data. The method relies heavily on Reynolds Averaged Navier Stokes computational fluid dynamics (CFD) and also factors in gravitational and aerodynamics effects through the use of a Velocity Prediction Program. Initial extensive use of towing tank results is made to be able to validate the CFD solution and thus develop a solid ground for predictive work. Then, in order to narrow down the focus on bulb developments, decoupled hypotheses are made on the influence of the hull and free surface wave. The development of a detailed performance analysis chart of a known base bulb allows the use of a relatively small series of CFD simulations together with physical hypotheses to assess any given bulb performance relative to the known base. The discussion of the results on a specific development highlights the promises and limitations of the method; final full scale results are discussed and analysed as well.     

Enhancing teacher moral judgment in difficult political times: Swimming upstream

Teachers at eight elementary schools in a large metropolitan school district participated in a multi-year program of professional ethical dilemma discussions that took place at monthly school meetings over a two-year or three-year period and focused on real-life situations faced by elementary school teachers. Discussions were structured using the Four Component Model of Moral Judgment. The DIT-2 served as a measure of moral judgment. Results proved to be counterintuitive; teacher moral judgment did not improve over time. We discuss the implications of promoting moral and democratic sensibilities at a time when American classrooms are tightly controlled and teachers held accountable for student performance on high stakes tests.     

Assessment of answers to questions about a text and knowledge of cognitive processes

This study examines to what extent assessment of text comprehension involves knowledge of the properties of human cognition (theory of mind) and the social context of assessment. The subjects (N=332) were asked to read a text and then assess eight answers to questions about this text. The independent variables were the quality of the answers to requests for paraphrases, the quality of answers to direct questions about the meaning of the text, the order of the paragraphs in the text and the human vs. artificial source attributed to the answers. Results show that answers to requests for paraphrases were thought to be better when the source was artificial rather than human. Inversely, answers to direct questions about the meaning of the text were thought to be better when their source was human. The assessment of answers attributed to a human source were differentiated by a greater integration of contiguous assessments (contrast effect between contiguous assessments). This was noted more particularly for a person than for a machine, poor paraphrasing being followed by a better assessment of answers to questions about the meaning of the text. The assessment of human understanding of a text is hypothesised to be guided by an expectation of answer coherency and a wider and more structured knowledge than the assessment of artificial answers.