The influence of shoe drop on the kinematics and kinetics of children tennis players     

Alexis Herbaut  Pascale Chavet  Maxime Roux  Nils Guéguen  Christophe Gillet  Franck Barbier 《European Journal of Sport Science》2016,16(8):1121-1129

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12?mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p?=?.004) and the ankle was less dorsiflexed at foot strike (p?=?.037). In D0 compared with D12, the peak impact force was reduced by 17% (p?=?.049), the ankle was less dorsiflexed at foot strike (p?=?.045) and the knee was more flexed at foot strike (p?=?.007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p?=?.658) or the peak ankle plantarflexor moment (p?=?.071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.  相似文献   

Europalia.China Concludes with Great Success     

Christophe Pourtois  Marcelle Rabinowicz 《中外文化交流(英文版)》2010,(4):4-9

<正>Europalia is a major international arts festival held every other year to celebrate one invited country's cultural heritage. Founded in 1969, this biennial festival is celebrated in  相似文献   

Beating the bounds: The Tour de France and national identity     

Christophe Campos 《国际体育史杂志》2013,30(2):149-174

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Augmenting performance feedback does not affect 4 km cycling time-trials in the heat     

Mark Waldron  Vincent Villerius  Aron Murphy 《Journal of sports sciences》2015,33(8):786-794

We compared the effects of (1) accurate and (2) surreptitiously augmented performance feedback on power output and physiological responses to a 4000 m time-trial in the heat. Nine cyclists completed a baseline (BaseL) 4000 m time-trial in ambient temperatures of 30°C, followed by two further 4000 m time-trials at the same temperature, randomly assigning the participants to an accurate (ACC; accurate feedback of baseline) or deceived (DEC; 2% increase above baseline) feedback group. The total power output (PO) and aerobic (P_aer) and anaerobic (P_an) contributions were determined at 0.4 km stages during the time-trials, alongside measurements of rectal (T_rec) and skin (T_skin) temperatures. There were no differences (P > 0.05) in any of the variables between BaseL, ACC and DEC, despite increases (P < 0.05) in T_rec and T_skin. Typical pacing profiles were demonstrated; however, there was no interaction (P > 0.05) between feedback condition and time-trial stage. Providing surreptitiously augmented performance feedback to well-trained cyclists did not alter their performance or physiological responses to a 4000 m time-trial in a hot environment. The assumed influence of augmented performance feedback was nullified in the heat, perhaps reflecting a central down-regulation of exercise intensity in response to an increased body temperature.  相似文献   

Shoe drop reduction influences the lower limb biomechanics of children tennis players during an open stance forehand: A longitudinal study     

Alexis Herbaut  Emilie Simoneau-Buessinger  Franck Barbier  Christophe Gillet  Maxime Roux  Nils Guéguen 《European Journal of Sport Science》2017,17(10):1261-1269

Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8?mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (?73%, p?=?.005) but increased peak ankle plantarflexors moment (+47%, p?=?.050) and peak ankle power absorption (+107%, p?=?.005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.  相似文献   

Some recent developments in textile processes     

Aron Hamburger 《Journal of The Franklin Institute》1898,145(6):453-466

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Bridge over troubled water: using implementation science to facilitate effective services in child welfare     

Mildon R  Shlonsky A 《Child abuse & neglect》2011,35(9):753-756

To maximize benefits to children and their families, effective practices need to be used competently in child welfare settings. Since the 1990s, researchers and policy makers have focused attention on empirically supported interventions (ESIs). Much less attention has been paid to what is needed to implement these in a range of real-world settings. Without proper implementation, which includes an evaluation strategy from feasibility to fidelity to on-going work on moderators and mediators of program effects, established effective programs can be rendered ineffective in practical application. The paper will touch on progress, to date, of implementation science, its application to child welfare programs and practices, and will highlight a set of practical strategies for implementing empirically supported interventions in child welfare.  相似文献   

Students and Europe     

Christophe Campos 《Higher Education Quarterly》1972,26(3):280-309

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Mobility of university staff in Europe     

Christophe Campos 《Higher Education Quarterly》1970,25(1):28-48

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General Growth Mixture Analysis of Adolescents' Developmental Trajectories of Anxiety: The Impact of Untested Invariance Assumptions on Substantive Interpretations     

Alexandre J. S. Morin  Christophe Maïano  Benjamin Nagengast  Herbert W. Marsh  Julien Morizot  Michel Janosz 《Structural equation modeling》2013,20(4):613-648

Substantively, this study investigates potential heterogeneity in the developmental trajectories of anxiety in adolescence. Methodologically, this study demonstrates the usefulness of general growth mixture analysis (GGMA) in addressing these issues and illustrates the impact of untested invariance assumptions on substantive interpretations. This study relied on data from the Montreal Adolescent Depression Development Project (MADDP), a 4-year follow-up of more than 1,000 adolescents who completed the Beck Anxiety Inventory each year. GGMA models relying on different invariance assumptions were empirically compared. Each of these models converged on a 5-class solution, but yielded different substantive results. The model with class-varying variance–covariance matrices was retained as providing a better fit to the data. These results showed that although elevated levels of anxiety might fluctuate over time, they clearly do not represent a transient phenomenon. This model was then validated in relation to multiple predictors (mostly related to school violence) and outcomes (grade-point average, school dropout, depression, loneliness, and drug-related problems).  相似文献