The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction     

Angus M. Hunter  Giuseppe De Vito  Claire Bolger  Hugh Mullany  Stuart D. R. Galloway 《Journal of sports sciences》2013,31(12):1261-1269

Abstract

The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; [Vdot]O_2max 62 ml · kg^?1 · min^?1, s = 8) ingested capsules containing either CaCO₃ (placebo) or NaHCO₃ (0.3 g · kg^?1 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO₃ were higher (P < 0.01) during the NaHCO₃ trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO₃ than with placebo (5.1 m · s^?1, s = 0.4 vs. 4.2 m · s^?1, s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling.  相似文献   

Reliability of a combined biomechanical and surface electromyographical analysis system during dynamic barbell squat exercise     

Raphael Brandon  Glyn Howatson  Angus Hunter 《Journal of sports sciences》2013,31(13):1389-1397

Abstract

An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39–0.0057 × knee angle (degress), with goodness-of-fit value, r ² = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods.  相似文献   

A study of user's acceptance on situational mashups in situational language teaching     

Angus F. M. Huang  Stephen J. H. Yang  Shu‐Sheng Liaw 《British journal of educational technology : journal of the Council for Educational Technology》2012,43(1):52-61

Situational awareness and mashups are two key factors influencing the success of situational language teaching. However, traditional situational language teaching cannot smoothly conduct relevant learning activities in changing learning context. This study developed a situational mashups system for detecting users' context and proposed a research model for evaluating users' acceptance on the situational mashups in situational language teaching. The proposed model consisted of users' individual experiences, situational learning theory and technology acceptance theory. The experimental results showed that users' experiences of using computer, Internet, mashups system and mashups‐based learning, as well as users' perceived enjoyment, perceived usefulness and perceived ease of use of situational mashups are all key factors affecting users' acceptance of situational mashups in situational language teaching.  相似文献   

Reviews     

Jan Visser  Muriel Visser  Ron Burnett 《TechTrends》2004,48(2):70-73

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Teacher Praise and Feedback and Students' Perceptions of the Classroom Environment   总被引：2，自引：0，他引：2  

Paul C. Burnett 《教育心理学》2002,22(1):5-16

The relationships between teacher praise and feedback, and students' perceptions of the classroom environment were investigated in six rural elementary schools (n = 747). The Teacher Feedback Scale and My Classroom Scale were developed as part of this study and used to collect the data. Structural equation modelling was used to test a hypothesised model. The results indicated that negative teacher feedback and effort feedback were both related to students' relationships with their teachers, while ability feedback was associated with perceptions of the classroom environment. Praise was not related to classroom environment or teacher-student relationships. Significant age and gender differences were found. Additionally, differences were found between students who were satisfied with their classroom and those who were dissatisfied. Satisfied students received more general praise, general ability feedback, effort feedback and less negative teacher feedback when compared to dissatisfied students.  相似文献   

Self-concept and self-esteem in elementary school children     

Paul C. Burnett 《Psychology in the schools》1994,31(2):164-171

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What do clients learn from counseling?     

Paul C. Burnett  Linda Van Dorssen 《International journal for the advancement of counseling》2000,22(3):241-254

Thirty-five clients who received counselingparticipated in this exploratory study by completinga letter to a friend that described in as much detailas possible what they had learned from counseling. Theparticipants' written responses were analyzed using acontent analysis approach. The analysis indicated thatthe data were best categorized in terms of three broadareas of learnings (Self, Relations with Others, andthe Process of Learning and Change). The Self taxonomywas found to consist of six hierarchical levels. TheRelations with Others taxonomy consisted of fivehierarchical levels, while the Process of Learning andChange taxonomy consisted of five hierarchical levels.The results suggested that these three taxonomiesoffer a promising and exciting way to view the impactof counseling within a learning framework. If thesetaxonomies are found to be stable in future researchand clients are easily classified using the taxonomiesthen this approach may have implications forcounseling. It may well be that to maximise thelearnings counselors could use specific strategies andtechniques to enhance their clients' learning in thethree areas.  相似文献   

Characteristics of the start in women's World Cup skeleton     

Bullock N  Martin DT  Ross A  Rosemond D  Holland T  Marino FE 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(3):351-360

This study characterizes key elements of the start in elite female World Cup skeleton athletes. The top 20 female competitors in three World Cup races were videotaped within a calibrated space to allow the following components of the start to be quantified: (1) acceleration (velocity at 15-m mark, time to 15-m mark), (2) capacity (time to load, total number of steps to load), and (3) load (velocity at 45-m mark). A correlation analysis was used to establish the relationship between the variables of interest and overall start time (15- to 65-m mark). Velocity at the 15-m mark accounted for 86% of the variance in overall start time at St. Moritz and 85% at Sigulda. A stepwise regression analysis revealed that approximately 89% of the variation in start time could be explained by velocity at the 15-m mark, time to load, and velocity at the 45-m mark. Of the variables analysed in this study, rapid acceleration to attain a high velocity at the 15-m mark was the most important component of a fast overall start time. The importance of the time to load and velocity at the 45-m mark vary according to the different track characteristics.  相似文献   

Simulations: Time to take another look!     

Angus Reynolds  Cheryl Samuels-Campbell 《Performance Improvement》1985,24(4):15-17

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