The effect of different resistance and assistance loads on 30-m sprint kinematics.

Resisted sprint and assisted sprint are the two main types of training methods used by athletes in sprint training, so optimizing resisted sprint training and assisted sprint training process is beneficial for improving athletes' sprint performance. Kinematics is the most intuitive parameter that reflects the quality of training during running process, and it is particularly important to analyze the gait of athletes during resisted and assisted sprint process. Therefore, this paper investigates the effects of resisted and assisted sprint on the sprint kinematics of sprinters in the first 30 meters to demonstrate the targeted effects of resisted and assisted sprint training. The experimental results show that compared to the unloaded running, male collegiate sprinters increase their total step count, decrease their step length, increase their step time, increase their contact time, whereas have almost no change in the flight time when performing the 30-m resisted sprint. Male collegiate sprinters decrease their total step count, increase their step length, increase their step time, decrease their contact time and increase their flight time, when performing the 30-m assisted sprint. In addition, it is found that resisted sprint training is beneficial for improving the athletes' power and explosiveness during the acceleration phase, thereby improving acceleration ability. However, prolonged and frequent resisted sprint training may reduce the step length and step frequency of athletes. Assisted sprint training is beneficial for shortening the contact time of athletes, improving their step length and flight time, and enabling them to overspeed, thereby increasing their maximum speed ability.

Validity and test-retest reliability of a resistance training device for Smith machine back squat exercise.

This study evaluated the validity and test-retest reliability of a resistance training device Jueying (Beijing, China) for Smith machine back squat exercise. Twelve male participants completed two test sessions with an interval of one week. In each test session, participants completed 30%, 45%, 60%, and 75% of 1RM back squats on a Smith machine equipped with Jueying and a linear position transducer GymAware (Canberra, Australia), which measured the velocity and power during the movement simultaneously. Results showed that Jueying was both valid (Pearson correlation coefficient [r] = 0.896-0.999, effect size [ES] = 0.004-0.192) when compared with GymAware and consistent between two tests in terms of reliability (intraclass correlation coefficient [ICC] = 0.79-0.95) to assess speed and power within all exercises. The device could be applied to provide athletes and coaches with effective and reliable data in actual application.

Effect of performance determinants on nhl final goal difference / Impacto de los determinantes de desempeño en la diferencia final de goles en la nhl / Efeito dos determinantes de desempenho na diferença final de gols da nhl

ABSTRACT Introduction: In ice hockey games, the team's performance is influenced by many contextual factors, and understanding playing styles allows to reveal how key performance indicators vary under different situations. Objective: This research aims to explore the playing styles of elite ice-hockey teams and to identify key performance aspects under different final goal difference situations. Methods: This article analyzed compared the match performance of 31 National Hockey League teams during 1271 matches considering their playing styles and final goal difference. Results: The principal component analysis obtained 8 performance components describing the technical-tactical styles of the teams. The subsequent analysis found that there was significant difference between three match outcomes in unfavorable state, major penalties, puck possession maintaining ability, shot defending ability, aggressive performance (p<0.001; = 0.007-0.273). Conclusions: Higher-ranked teams winning the unbalanced games showed better performance in shot defending ability and aggressive performance. Lower-ranked teams losing in unbalanced games kept less possession of the puck and were more likely to be shorthanded (p<0.05, ES=0.131-1.410). The study demonstrates how playing styles can be used to contextualize key determinants from ice hockey games. Level of evidence I; Therapeutic Studies Investigating the Results of Treatment.

RESUMEN Introducción: En los juegos de hockey sobre hielo, el rendimiento del equipo está influenciado por varios factores contextuales, y comprender los estilos de juego permite revelar cómo varían los indicadores clave de rendimiento en diferentes situaciones. Objetivo: Esta investigación tiene como objetivo explorar los estilos de juego de los equipos de hockey sobre hielo de élite e identificar aspectos clave del rendimiento en diferentes situaciones de diferencia de gol final. Métodos: El rendimiento del partido de 31 equipos de la Liga Nacional de Hockey durante 1271 partidos fue analizado y comparado, considerando el estilo de juego y la diferencia de gol final. Resultados: El análisis de componentes principales obtuvo 8 componentes de rendimiento que describen los estilos técnico-tácticos de los equipos. El análisis posterior encontró que hubo una diferencia significativa entre tres resultados de partido en estado desfavorable, penalizaciones principales, habilidad para mantener la posesión del disco, habilidad para defender el tiro, desempeño agresivo (p<0,001; = 0,007-0,273). Conclusión: Los equipos de clasificación más alta que ganaron los juegos desequilibrados mostraron un mejor rendimiento en la capacidad de defensa de disparos y en el rendimiento agresivo. Los equipos de clasificación más baja que perdieron en juegos desequilibrados mantuvieron menos posesión del disco y tenían más probabilidades de estar en desventaja numérica (p<0,05, ES=0,131-1,410). El estudio demuestra cómo los estilos de juego pueden utilizarse para contextualizar los determinantes clave de los juegos de hockey sobre hielo. Nivel de Evidencia I; Estudios Terapéuticos que Investigan los Resultados del Tratamiento.

RESUMO Introdução: Nos jogos de hóquei no gelo, o desempenho da equipe é influenciado por vários fatores contextuais, e entender os estilos de jogo permite revelar como os principais indicadores de desempenho variam em diferentes situações. Objetivo: Esta pesquisa tem como objetivo explorar os estilos de jogo das equipes de hóquei no gelo de elite e identificar aspectos-chave de desempenho em diferentes estilos de jogo e a diferença do resultado final. Métodos: O desempenho de partida de 31 equipes da National Hockey League durante 1271 partidas foi analisado e comparado, considerando o estilo de jogo e a diferença de gol final. Resultados: A análise de componentes principais retornou 8 componentes de desempenho, descrevendo os estilos técnico-táticos das equipes. A análise subsequente revelou que houve diferença significativa entre três resultados de jogo em estado desfavorável, penalidades principais, habilidade de manter a posse do disco, habilidade de defender o lance e desempenho agressivo (p<0,001; = 0,007-0,273). Conclusão: As equipes de classificação mais alta que venceram os jogos em desequilíbrio numérico de jogadores apresentaram melhor desempenho na habilidade de defender o lance e no desempenho agressivo. As equipes de classificação mais baixa, que perderam em jogos desequilibrados, mantiveram menos posse do disco e tiveram maior probabilidade de ficar com um jogador a menos (p <0,05, ES = 0,131-1,410). O estudo demonstra como os estilos de jogo podem ser usados para contextualizar os principais determinantes dos jogos de hóquei no gelo. Nível de Evidência I; Estudos Terapêuticos Investigação dos Resultados do Tratamento.

A new kinematic dataset of lower limbs action for balance testing.

Balance is a common performance but nevertheless an essential part of performance analysis investigations in ski. Many skier pay attention to the training of balance ability in training. Inertial Measurement Unit, as a kind of Multiplex-type human motion capture system, is widely used because of its humanized human-computer interaction design, low energy consumption and more freedom provided by the environment. The purpose of this research is to use sensor to establish a kinematics dataset of balance test tasks extracted from skis to help quantify skier' balance ability. Perception Neuron Studio motion capture device is used in present. The dataset contains a total of 20 participants' data (half male) of the motion and sensor data, which is collected at a 100 Hz sampling frequency. To our knowledge, this dataset is the only one that uses a BOSU ball in the balance test. We hope that this dataset will contribute to multiple fields of cross-technology integration in physical training and functional testing, including big-data analysis, sports equipment design and sports biomechanical analysis.

A Quantitative Assessment Grading Study of Balance Performance Based on Lower Limb Dataset.

Balance ability is one of the important factors in measuring human physical fitness and a common index for evaluating sports performance. Its quality directly affects the coordination ability of human movements and plays an important role in human productive activities. In the field of sports, balance ability is an important indicator of athletes' selection and training. How to objectively analyze balance performance becomes a problem for every non-professional sports enthusiast. Therefore, in this paper, we used a dataset of lower limb collected by inertial sensors to extract the feature parameters, then designed a RUS Boost classifier for unbalanced data whose basic classifier was SVM model to predict three classifications of balance degree, and, finally, evaluated the performance of the new classifier by comparing it with two basic classifiers (KNN, SVM). The result showed that the new classifier could be used to evaluate the balanced ability of lower limb, and performed higher than basic ones (RUS Boost: 72%; KNN: 60%; SVM: 44%). The results meant the established classification model could be used for and quantitative assessment of balance ability in initial screening and targeted training.

Sequence-related amplified polymorphism, an effective molecular approach for studying genetic variation in Fasciola spp. of human and animal health significance.

In the present study, a recently described molecular approach, namely sequence-related amplified polymorphism (SRAP), which preferentially amplifies ORFs, was evaluated for the studies of genetic variation among Fasciola hepatica, Fasciola gigantica and the "intermediate" Fasciola from different host species and geographical locations in mainland China. Five SRAP primer combinations were used to amplify 120 Fasciola samples after ten SRAP primer combinations were evaluated. The number of fragments amplified from Fasciola samples using each primer combination ranged from 12 to 20, with an average of 15 polymorphic bands per primer pair. Fifty-nine main polymorphic bands were observed, ranging in size from 100 to 2000 bp, and SRAP bands specific to F. hepatica or F. gigantica were observed. SRAP fragments common to F. hepatica and the "intermediate" Fasciola, or common to F. gigantica and the "intermediate" Fasciola were identified, excised and confirmed by PCR amplification of genomic DNA using primers designed based on sequences of these SRAP fragments. Based on SRAP profiles, unweighted pair-group method with arithmetic averages clustering algorithm categorized all of the examined representative Fasciola samples into three groups, representing the F. hepatica, the "intermediate" Fasciola, or the F. gigantica. These results demonstrated the usefulness of the SRAP technique for revealing genetic variability between F. hepatica, F. gigantica and the "intermediate" Fasciola, and also provided genomic evidence for the existence of the "intermediate" Fasciola between F. hepatica and F. gigantica. This technique provides an alternative and a useful tool for the genetic characterization and studies of genetic variability in parasites.