Work-time profile,blood lactate concentration and rating of perceived exertion in the 1998 Greco-Roman wrestling World Championship     

Johnny Nilsson  Sandor Csergö  Lennart Gullstrand  Per Tveit  Per Egil Refsnes 《Journal of sports sciences》2013,31(11):939-945

The aim of this study was to examine work-time profiles, blood lactate concentrations and perceived exertion among Greco-Roman wrestlers in the 1998 World Championship. Forty-two senior wrestlers from nine nations were studied in 94 matches. Each match was recorded with a video camera (Panasonic AG 455, film rate: 25 Hz) and analysed for duration of work (wrestling) and rest (interrupt) periods. Blood lactate concentration was determined with an electrochemical device (Analox P-LM5) and a rating of perceived exertion scale (Borg) was used to estimate general exertion and exertion in the extremity and trunk muscles. The mean duration of the matches was 427 s (range 324-535 s), with mean durations of work and rest of 317 and 110 s, respectively. The mean periods of work and rest were 37.2 and 13.8 s, respectively. Mean blood lactate concentration was 14.8 mmol · l -1 (range 6.9-20.6). The difference in mean blood lactate concentration between the first- and final-round matches was not significant ( P > 0.05). Blood lactate concentration was significantly higher ( P ? 0.04) in matches of long duration than in those of short duration. The mean general rating of perceived exertion for all matches was 13.8 according to the scale used. Most of the wrestlers (53.3%) perceived exertion to be highest in the flexors of the forearm, followed by the deltoids (17.4%) and the biceps brachii muscles (12.0%). In addition to a relatively high rating of perceived exertion in the arm muscles, this indicates a high specific load on the flexor muscles of the forearm.  相似文献   

Loaded hip thrust-based PAP protocol effects on acceleration and sprint performance of handball players     

Antonio Dello Iacono  Johnny Padulo  Laurent D Seitz 《Journal of sports sciences》2018,36(11):1269-1276

This study aimed to investigate the acute effects of two barbell hip thrust-based (BHT) post-activation potentiation (PAP) protocols on subsequent sprint performance. Using a crossover design, eighteen handball athletes performed maximal 15-m sprints before and 15s, 4min and 8min after two experimental protocols consisting of BHT loaded with either 50% or 85% 1RM (50PAP and 85PAP, respectively), in order to profile the transient PAP effects. The resulting sprint performances were significantly impaired at 15s only after the 85PAP protocol, which induced likely and very likely greater decreases compared to the 50PAP. At 4min and 8min, significant improvements and very likely beneficial effects were observed in the 10m and 15m performances following both protocols. Significant differences were found when comparing the two PAPs over time; the results suggested very likely greater performance improvements in 10m following the 85PAP after 4min and 8min, and possible greater performance improvements in 15m after 4min. Positive correlations between BHT 1RMs values and the greatest individual PAP responses on sprint performance were found. This investigation showed that both moderate and intensive BHT exercises can induce a PAP response, but the effects may differ according to the recovery following the potentiating stimulus and the individual`s strength level.  相似文献   

Noun or verb? Adult readers’ sensitivity to spelling cues to grammatical category in word endings     

Nenagh Kemp  Jodi Nilsson  Joanne Arciuli 《Reading and writing》2009,22(6):661-685

The spelling of many disyllabic English word endings holds cues to their grammatical category, beyond obvious inflectional endings such as -ing for verbs. For example, some letter sequences are clearly associated with nouns (e.g., -oon) and others with verbs (e.g., -erge). This study extended recent research by Arciuli and Cupples (2006), and confirmed that skilled adult readers are sensitive to these orthographic cues. It was found that adults were more likely to treat pseudowords as nouns when they had noun-like endings than verb-like or control endings, and more likely to treat pseudowords as verbs when they had verb-like than noun-like endings. This sensitivity held across three tasks (sentence construction, sentence judgement, and pseudoword judgement), which required increasingly explicit awareness of the way that cues could allow grammatical categorisation. In some tasks sensitivity to verb-like endings was related to reading ability, although not to spelling ability or grammatical awareness. Implications for our understanding of language processing are discussed.  相似文献   

Popular Science Writing to Support Students’ Learning of Science and Scientific Literacy     

Susanne Pelger  Pernilla Nilsson 《Research in Science Education》2016,46(3):439-456

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The sensitivity of the alternative maximal accumulated oxygen deficit method to discriminate training status     

Alessandro M. Zagatto  Fabio Y. Nakamura  Fabio Milioni  Willian E. Miyagi  Rodrigo A. B. de Poli  Johnny Padulo 《Journal of sports sciences》2017,35(24):2453-2460

The purpose of the study was to investigate the sensitivity of an alternative maximal accumulated oxygen deficit (MAOD_ALT) method to discriminate the “anaerobic” capacity while comparing: least trained (LT) participants (n = 12), moderately trained (MT) participants (n = 12), endurance trained (ET) participants (n = 16), and rugby (RG) players (n = 11). Participants underwent a graded exercise test on a treadmill and a supramaximal effort for assessing MAOD_ALT. MAOD_ALT was calculated as the sum of oxygen equivalents from the phosphagen and glycolytic metabolic pathways. MAOD_ALT was significantly higher (P < 0.05) in RG (64.4 ± 12.1 mL · kg^?1) than in ET (56.8 ± 5.4 mL · kg^?1; effect size [ES] = 0.77; +13.5%), MT (53.8 ± 5.3 mL · kg^?1; ES = 1.08; +19.8%), and LT (49.9 ± 4.5 mL · kg^?1; ES = 1.50; +36.4%). In addition, the magnitude-based inference analysis revealed that MAOD_ALT was likely (LT vs. MT), very likely (MT vs. RG, and ET vs. RG) and most likely (LT vs. ET, and LT vs. RG) different between all groups, except for MT and ET, which presented an unclear difference. In conclusion, MAOD_ALT was sensitive enough to distinguish the “anaerobic” capacity in individuals with different training status, especially for RG players compared with LT participants and MT participants.  相似文献   

Reliability and validity of a new double poling ergometer for cross-country skiers   总被引：1，自引：0，他引：1  

Holmberg HC  Nilsson J 《Journal of sports sciences》2008,26(2):171-179

Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50-70% higher than that at the flywheel. There was a high test-retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W x kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.  相似文献   

Exploring the Development of Pre-Service Science Elementary Teachers’ Pedagogical Content Knowledge   总被引：1，自引：0，他引：1  

Pernilla Nilsson  John Loughran 《Journal of Science Teacher Education》2012,23(7):699-721

This paper explores how a group of pre-service elementary science student teachers came to understand the development of their Pedagogical Content Knowledge (PCK) over the course of a semester??s study in a science methods course. At the start of the semester, PCK was introduced to them as an academic construct and as a conceptual tool that they could use to plan for, and assess, the development of their professional knowledge and practice as beginning science teachers. All participants were provided with a tool known as a CoRe (Content Representation) and the manner in which they worked with the CoRe was such that it supported them in planning for and assessing their own learning about teaching elementary science through a focus on the development of their PCK. Through analysis of data derived from the application of a CoRe based methodology (modified and adapted for this study) to the teaching of the science topic of Air, participants?? reasons for, confidence in, and perceived meaningfulness of their learning about science teaching could be examined. In so doing, the nature of participants?? PCK development over time was made explicit. The results illustrate real possibilities for ways of enhancing student teachers?? ongoing professional learning in teacher preparation and offer a window into how the nature of PCK in pre-service education might be better understood and developed.  相似文献   

Skiing     

Johnny Nilsson  Vidar Jakobsen  Per Tveit  Olav Eikrehagen 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):227-236

The purpose of the investigation was to study the relationship between thrust phase duration, ground reaction force, velocity increase after pole thrust and pole angles versus pole length during double poling in roller skiing. Seven male regional elite cross‐country skiers volunteered as subjects for the study. The subjects performed a maximal double pole thrust on roller skis with each of the three different pole lengths: ‘short’, self‐selected (normal) and ‘long’. The short and long poles were 7.5 cm shorter and 7.5 cm longer than the self‐selected pole length. The subjects made seven maximal pole thrusts with each pole length, which were randomly selected during 21 trials. For each trial the subjects accelerated from a 1.2 m high downhill slope attaining a speed of 3.92 m.s^‐1 before making a maximal double pole thrust on a force plate placed at the bottom of the slope. The vertical (F_z), anterior‐posterior (F_y) and medio‐lateral (F_x) reaction forces of the left pole were measured by the force plate. The positions of the pole were recorded in 3‐D by an opto‐electronic system. Thrust phase duration, impulse, mean force, velocity increase after pole thrust and pole angles were calculated from the recorded data. Double poling with long poles produced a significantly larger propulsive anterior‐posterior reaction force impulse and velocity increase than normal (p < .05) and short poles (p < .05). This was in spite of a larger mean anterior‐posterior reaction force being produced with short poles. Thus, thrust phase duration was a primary factor in determining propulsive anterior‐posterior impulse. For the practitioner, the results can be useful in the selection of pole length when the aim is to increase thrust phase duration, anterior‐posterior force impulse and velocity.  相似文献   

A new device for measuring ski running surface force and pressure profiles     

Johnny Nilsson  Lars Karlöf  Vidar Jakobsen 《Sports Engineering》2013,16(1):55-59

The pressure/force acting between the running surface of a ski and the snow may indirectly change glide friction. Thus, measuring the pressure/force distribution may be important for a deeper understanding of glide in skiing. The present aim was to construct a device that allowed the pressure/force underneath the ski running surface (SRS) to be recorded. Pressure sensors were attached on top of a platform. Sheets of different materials were used to improve the interaction between the SRS and the sensors. Possible functions of the device are demonstrated in three applications that emphasized comparison of force distribution underneath skis selected for similarity, force distribution under both skis and a single ski as well as backward weight distribution. The results show that the device with the pressure sensors mapped pressure/force distribution underneath the skis in the applications presented, and the system can thus be a useful tool for further optimizing e.g., ski designs.  相似文献   

When Teaching Makes a Difference: Developing science teachers’ pedagogical content knowledge through learning study     

Pernilla Nilsson 《International Journal of Science Education》2013,35(11):1794-1814

It is a common view that developing teachers’ competence to restructure or reframe their knowledge and beliefs is inevitably a complex challenge. This paper reports on a research project with the aim to develop science teachers’ pedagogical content knowledge (PCK) through their participation in a learning study. A learning study is a collegial process in which teachers work together with a researcher to explore their own teaching activities in order to identify what is critical for their students’ learning. During one semester, three secondary science teachers worked in a learning study together with a researcher in a cyclical process in order to create prerequisites and further identify conditions for students’ learning. During the learning study, data were collected from video-recorded lessons and stimulated recall sessions in which the teachers and the researcher reflected on the lessons to analyze their development of PCK, their students’ learning and the impact of that knowledge on their own teaching. The results provide an insight into how the teachers developed their self-understanding in which they questioned their own epistemological beliefs, aims and objectives of teaching and taken-for-granted assumptions about science teaching and learning. As such, the study provides an understanding of teacher professional learning through a careful investigation of how teachers’ PCK is enhanced through their participation in the learning study, and further, how students’ learning might be developed as a consequence.  相似文献