Execution time, kinetics, and kinematics of the mae-geri kick: comparison of national and international standard karate athletes

Little is known of the performance characteristics of the shotokan karate mae-geri kick. The aim of this study was to compare the execution time, the lower limb kinetics and kinematics, and their respective repeatability in the mae-geri kick of karate athletes of two different standards. Seventeen adult black belt karate competitors (9 national and 8 international athletes) performed six kicks with their dominant lower limb on a striking surface, combining maximum force impact and velocity. Execution time of movement and lower limb kinematics were recorded with a high-speed camera. Maximum force at impact and the forces exerted on the ground were measured using three force plates. The duration of the kick was significantly shorter for international than for national standard athletes. However, no significant difference in the maximum impact force of the kick was observed between the two groups. In addition, significant kinematic differences were observed between the groups, with two angles of motion and one velocity peak occurring sooner in the kick movement for the international athletes, specifically for the knee joint. International athletes also performed the kick with a significantly higher repeatability for duration and kinematics, specifically during the pre-loading phase that precedes the attack phase. We conclude that the duration of the kick and repeatability of lower limb kinematics could be useful in selecting top-level karate athletes and monitoring their training status.     

Predicting the throwing velocity of the ball in handball with anthropometric variables and isotonic tests

The aims of this study were to (1) investigate the influence of general anthropometric variables, handball-specific anthropometric variables, and upper-limb power and strength on ball-throwing velocity in a standing position (ν(ball)), and (2) predict this velocity using multiple regression methods. Forty-two skilled male handball players (age 21.0?±?3.0 years; height?=?1.81?±?0.07?m; body mass?=?78.3?±?11.3?kg) participated in the study. We measured general anthropometric variables (height, body mass, lean mass, body mass index) and handball-specific anthropometric parameters (hand size, arm span). Upper-limb dynamic strength was assessed using a medicine ball (2?kg) throwing test, and power using a one-repetition maximum bench-press test. All the variables studied were correlated with ball velocity. Medicine ball throwing performance was the best predictor (r?=?0.80). General anthropometric variables were better predictors (r?=?0.55-0.70) than handball-specific anthropometric variables (r?=?0.35-0.51). The best multiple regression model accounted for 74% of the total variance and included body mass, medicine ball throwing performance, and power output in the 20-kg bench press. The equation formulated could help trainers, athletes, and professionals detect future talent and test athletes' current fitness.     

Faster V̇O2 kinetics after priming exercises of different duration but same fatigue

This study compared the responses of two priming exercises of similar fatigue on the adjustment of the oxygen uptake time constant (τV?O₂) in cycling. Ten healthy young adults (25 ± 3 yr) performed: three step transitions from a 20-W baseline to the power output (PO) below the gas exchange threshold (MOD, MOD_PRE); a 3-min bout (P_3MIN) at 90% of peak PO (PO_peak), followed by MOD (MOD_3MIN); and a 6-min bout (P_6MIN) at 80% of PO_peak, followed by MOD (MOD_6MIN). The O₂ supply-to-O₂ demand ([HHb]/V?O₂) ratio was calculated for MOD_PRE, MOD_3MIN, and MOD_6MIN. Neuromuscular fatigue was measured isometrically pre- and post-priming exercise. Reductions in maximal voluntary contraction (?29 ± 6 vs ?34 ± 7%) and high-frequency doublet amplitude (?48 ± 13 vs ?43 ± 11%) were not significantly different between P_3MIN vs P_6MIN, suggesting similar fatigue. τV?O₂ for MOD_3MIN and MOD_6MIN were similar, being ~25% smaller than MOD_PRE. The [HHb]/V?O₂ ratio was significantly greater in MOD_PRE (1.13 ± 0.12) compared to MOD_3MIN (1.02 ± 0.04) and MOD_6MIN (1.02 ± 0.04). This study showed that priming exercise of shorter duration and higher intensity, was sufficient to accelerate V?O₂ kinetics similarly to that observed subsequent to P_6MIN when the muscle fatigue was similar.     

Interdisciplinary Research: A Promising Approach to Investigate Elite Performance in Sports

While the call for interdisciplinary studies has been loud and clear over the last decade or so, the number of interdisciplinary publications in sport sciences is rather limited. One of the reasons for this scarcity is the complexity of the research process itself. Still, the combination and integration of information from different scientific disciplines seems to be important to better explain how elite performance comes about. In this article, we focus on this issue and discuss the advantages of interdisciplinary research for understanding how elite athletes are able to achieve such high-proficiency levels. The first section provides an overview of the studies that investigated elite performance in sports. In the second section, we focus on the issue of interdisciplinarity and illustrate how the ecological–dynamical approach and the concept of dimensional reduction can be used to explain how elite performers cope with the complex nature of sport skills. In the last section, we present a research outline and some practical considerations that can be helpful for researchers who aim to study sport skills from an interdisciplinary perspective.     

Classroom and School Predictors of Civic Engagement Among Black and Latino Middle School Youth

This study used short‐term longitudinal data to examine the contributions of democratic teaching practices (e.g., the Developmental Designs approach) and equitable school climate to civic engagement attitudes, beliefs, and behaviors among 515 Black and Latino middle school students (47.9% male). Concurrent experiences of democratic homeroom and classroom practices, and equitable school climate were associated with higher scores on each civic engagement component. The relation between classroom practices and civic attitudes was more robust when school climate was seen as more equitable. Longitudinally, homeroom practices and equitable school climate predicted higher civic attitudes 1 year later. Discussion focuses on civic attitudes and future research on school experiences that support civic engagement among youth of color.