Decision boundaries and receiver operating characteristic curves: New methods for determining accelerometer cutpoints

Abstract

We propose and evaluate the utility of an alternative method (decision boundaries) for establishing physical activity intensity-related accelerometer cutpoints. Accelerometer data collected from seventy-six 11- to 14-year-old boys during controlled bouts of moderate- and vigorous-intensity field physical activities were assessed. Mean values and standard deviations for moderate- and vigorous-intensity activities were obtained and normal equivalents generated. The decision boundary (the point of intersection of overlapping distributions) was used to create a lower-bound vigorous-intensity cutpoint. Receiver operating characteristic (ROC) curves compared the sensitivity and specificity of the new cutpoint and mean values with the actual activity. There was a 96.5% probability that participants performing vigorous-intensity physical activity were accurately classified when using the decision boundary of 6700 counts per minute, in contrast to the 50% accurately classified when the mean value was used. Inspection of the empirical ROC curve indicated that the decision boundary provided the optimal threshold to distinguish between moderate and vigorous physical activity for this dataset. In conclusion, decision boundaries reduced the error associated with determining accelerometer threshold values. Applying these methods to accelerometer data collected in specific populations will improve the precision with which accelerometer thresholds can be identified.     

Equivalence of accelerometer data for walking and running: Treadmill versus on land

This study examined temporal trends in home advantage in the top two English football divisions and used change point analysis to test the hypothesis that home advantage has not remained constant over time. Regression analysis was used to model the impact of substitutions (a proxy for “information transfer”) and the points system on home advantage. The results suggest that changing from two points for a win to three points for a win has led to a 0.39 reduction (95% confidence interval = 0.21 to 0.56) in the ratio of home wins to away wins. Increasing the number of substitutions is associated with a small increase in the ratio of home wins to away wins, although this is not statistically significant. The evidence indicates that, in this particular context, the extent of home advantage has diminished. This contradicts most other published work, which suggests that home advantage is stable over time. I argue that this reduction is more likely to be the result of the introduction of three points for a win, which has lessened the incentives for away teams to settle for a draw, than an increase in “information transfer”. Research into temporal trends in home advantage is interesting in its own right but might, in addition, shed light on determinants of the home advantage phenomenon.     

A new approach to determining net impulse and identification of its characteristics in countermovement jumping: reliability and validity

Examining a countermovement jump (CMJ) force-time curve related to net impulse might be useful in monitoring athletes' performance. This study aimed to investigate the reliability of alternative net impulse calculation and net impulse characteristics (height, width, rate of force development, shape factor, and proportion) and validate against the traditional calculation in the CMJ. Twelve participants performed the CMJ in two sessions (48 hours apart) for test–retest reliability. Twenty participants were involved for the validity assessment. Results indicated intra-class correlation coefficient (ICC) of ≥ 0.89 and coefficient of variation (CV) of ≤ 5.1% for all of the variables except for rate of force development (ICC = 0.78 and CV = 22.3%). The relationship between the criterion and alternative calculations was r = 1.00. While the difference between them was statistically significant (245.96 ± 63.83 vs. 247.14 ± 64.08 N s, p < 0.0001), the effect size was trivial and deemed practically minimal (d = 0.02). In conclusion, variability of rate of force development will pose a greater challenge in detecting performance changes. Also, the alternative calculation can be used practically in place of the traditional calculation to identify net impulse characteristics and monitor and study athletes' performance in greater depth.     

Perceptual Decision Making for Baseball Pitch Recognition: Using P300 Latency and Amplitude to Index Attentional Processing

Abstract

This study was designed to examine the perceptual and attentional processes associated with the effects of administering a cost-benefit precuing paradigm to intermediate and advance-level baseball batters. Psychophysiological and performance data obtained from 10 advanced and 10 intermediate-level players were compared. A total of 400 pitches (200 fastballs, 200 curveballs) was randomly presented via a large projection screen, and participants pressed one of two buttons to indicate the type of pitch thrown. Verbal precues were given for 300 of the pitches. Of those, 75% were valid, and 25% were invalid. Electroencephalographic data collected from the P_z location was used to assess the latency and amplitude of P300. Analysis of variance (Skill Level x Precue x Pitch) for P300 and reaction time (RT) indicated that intermediate batters produced shorter P300 latencies, larger P300 amplitudes, longer RTs, and less correct responses than the advanced batters; the effects were more pronounced for the curveballs. These results suggest that intermediate batters are less efficient in their perceptual decision-making processes due to greater limitations in attentional capacity when compared with advanced batters.     

Human genetic variation: new challenges and opportunities for doping control

Sport celebrates differences in competitors that lead to the often razor-thin margins between victory and defeat. The source of this variation is the interaction between the environment in which the athletes develop and compete and their genetic make-up. However, a darker side of sports may also be genetically influenced: some anti-doping tests are affected by the athlete's genotype. Genetic variation is an issue that anti-doping authorities must address as more is learned about the interaction between genotype and the responses to prohibited practices. To differentiate between naturally occurring deviations in indirect blood and urine markers from those potentially caused by doping, the "biological-passport" program uses intra-individual variability rather than population values to establish an athlete's expected physiological range. The next step in "personalized" doping control may be the inclusion of genetic data, both for the purposes of documenting an athlete's responses to doping agents and doping-control assays as well facilitating athlete and sample identification. Such applications could benefit "clean" athletes but will come at the expense of risks to privacy. This article reviews the instances where genetics has intersected with doping control, and briefly discusses the potential role, and ethical implications, of genotyping in the struggle to eliminate illicit ergogenic practices.     

Capoeira for beginners: self-benefit for,and community action by,new Capoeiristas

Capoeira could be defined as a Brazilian martial art and game to be played. This research explored how capoeira play might be considered to facilitate connectedness amongst newly-recruited persons, plus any other ramifications of capoeira involvement. A beginners’ course of capoeira was provided to participants, free of charge, in an English city in the West Midlands—new capoeiristas in a new venue for capoeira. Researchers attended classes to collect/construct overt non-participant observation data. In addition, semi-structured interviews were undertaken with the new capoeiristas post-course. This article explores researchers’ observation fieldnotes and interviewees’ narratives. These qualitative data-driven debates include the concepts: self, identity, escapism, multiparty endeavour, community, temporality, enjoyment, and transcending boundaries. Capoeira is theorised in a fresh manner that highlights social benefits of capoeira—for example as an enjoyable and supportive group endeavour which includes elements of social play and community-building—plus benefits for self that can transcend the boundaries of the class. Findings highlight how capoeira can be considered an inherently multiparty endeavour whereby social actors form, and experience, a community in order to embrace capoeira play. Data suggest capoeira can facilitate group playfulness, joviality, and laughter. Further, capoeiristas can enact and experience—some mode of—escapism via capoeira, whereby new place and pursuit can facilitate hedonistic diversion from the mundane. Capoeira appears to provide adventure and liberation into a relatively unburdened part of, or place in, social life. Corporeal and discursive boundary-empowerment can also be experienced by capoeiristas, fostering positive identity work in the wider world. Capoeira can be argued to facilitate mutuality (e.g. community experience and group work) and egoism (e.g. an individual's identity work) concurrently. This research suggests that modified capoeira for beginners can be beneficial for both the new capoeiristas themselves and for positive community action during and beyond class.     

Imploding the boundaries of transformative/critical pedagogy and research in physical education and sport pedagogy: looking inward for (self-)consciousness/knowledge and transformation

The purpose of this paper is to analyze the concept of ‘transformative pedagogy’ (TP) in physical education and sport pedagogy (PESP) and research in order to provide an alternative perspective on freedom, justice and the limits of transformation. Although some of the limits of TP have already been pointed out in the literature, such limits have been presented as though originating and having to be resolved out there, in socio-cultural–political contexts. In an attempt to redirect the attention from the social to the personal, this paper points out the possibility of TP's limits being also within critical pedagogues and researchers ourselves. After analyzing three barriers to (self-)consciousness/knowledge (SC/K), two viable methods for developing SC/K and transformation are provided.     

Motor schema theory after 27 years: reflections and implications for a new theory

The schema theory for discrete motor skill learning (Schmidt, 1975), originally published in 1975, has generated considerable interest and received strong challenges over its lifetime. In this paper, I focus on the findings generated since 1975 that bear on the theory and highlight those that produce difficulties for it and will be motivators for differing theoretical viewpoints in the future. At the same time, I examine other lines of evidence that seem to bolster the original lines of thinking. Finally, I provide some suggestions for a much needed new generation of motor learning theory, pointing out particular features from the schema theory that could be included and suggesting gaps and omissions that will need additional data and theorizing in future attempts.     

线粒体融合分裂与自噬：运动生理研究的新视角

自噬是广泛存在于真核细胞内的一种溶酶体依赖性的降解途径,它与泛素-蛋白酶体系统共同维持蛋白质及细胞器更新,对于维持细胞的稳态具有重要意义.线粒体作为真核生物最主要的细胞器之一,其代谢更新对于细胞状态有意义深远.作为线粒体更新的主要机制,线粒体自噬的发生逐渐引起关注.关于损伤的线粒体是如何通过自噬途径被移除的,其相关机制仍旧不明了.有研究认为线粒体融合分裂与线粒体自噬的发生关系密切,可能是其调控的关键部分.本文就线粒体自噬与线粒体融合分裂关系的相关研究进展进行了综述.     

运动和营养素的细胞内作用靶点——线粒体：阿尔茨海默病防治的新思路

阿尔茨海默病（Alzheimer Disease,AD）是一种与年龄相关的神经退行性疾病,目前缺乏有效的防治方法.研究表明,适量的运动和营养素,可以通过改善脑内线粒体的功能,延缓认知功能衰退和阿尔茨海默病的发生和发展.我们将这类靶向于线粒体的营养素或天然产物定义为线粒体营养素.本文从线粒体角度,综述了运动和线粒体营养素对阿尔茨海默病中神经元的作用机制,为阿尔茨海默病的防治提供新的思路.     

The new sporting Cold War: implications of the Russian doping allegations for international relations and sport

Abstract

This article examines current state of the new sporting cold war in the world of sports. It provides an examination of the 2014–2018 Russian doping scandal. Political and ideological prerequisites that triggered this scandal are considered, and based on obtained observations, an analysis of possible scenarios in the development of events is made as are recommendations for future progress in ending this unnecessary neo-cold war.     

Schema theory: critical review and implications for the role of cognition in a new theory of motor learning

This paper is based on a symposium celebrating the 26th anniversary of the publication of "A Schema Theory of Discrete Motor Skill Learning" (Schmidt, 1975) held at the annual conference of the North American Society for the Psychology of Sport and Physical Activity in June 2001. We provide a brief historical context for schema theory and a review of the development of the mechanistic approach to motor learning in general. We explore recent findings in mental practice, observational learning, augmented feedback presentation, and the variability of practice that are inconsistent with schema theory and provide a rationale for the importance of cognitive activity in motor learning.     

IGF1–PI3K-induced physiological cardiac hypertrophy: Implications for new heart failure therapies,biomarkers, and predicting cardiotoxicity

Heart failure represents the end point of a variety of cardiovascular diseases. It is a growing health burden and a leading cause of death worldwide. To date, limited treatment options exist for the treatment of heart failure, but exercise has been well-established as one of the few safe and effective interventions, leading to improved outcomes in patients. However, a lack of patient adherence remains a significant barrier in the implementation of exercise-based therapy for the treatment of heart failure. The insulin-like growth factor 1 (IGF1)–phosphoinositide 3-kinase (PI3K) pathway has been recognized as perhaps the most critical pathway for mediating exercised-induced heart growth and protection. Here, we discuss how modulating activity of the IGF1–PI3K pathway may be a valuable approach for the development of therapies that mimic the protective effects of exercise on the heart. We outline some of the promising approaches being investigated that utilize PI3K-based therapy for the treatment of heart failure. We discuss the implications for cardiac pathology and cardiotoxicity that arise in a setting of reduced PI3K activity. Finally, we discuss the use of animal models of cardiac health and disease, and genetic mice with increased or decreased cardiac PI3K activity for the discovery of novel drug targets and biomarkers of cardiovascular disease.