A comparison of ratio and allometric scaling methods for normalizing power and strength in elite rugby union players

Abstract

In this study, we compared the effectiveness of ratio and allometric scaling for normalizing power and strength in elite male rugby union players. Rugby union forwards (n = 18) and backs (n = 20) were assessed for squat jump and bench throw peak power, and box squat and bench press one-repetition maximum strength. The performance data for the forwards and backs were compared using ratio (P/BM) and allometric scaling (P/BM^b ), where P represents performance, BM is body mass in kilograms, and b is a power exponent. A proposed allometric exponent (0.67) and exponents (±95% confidence intervals) derived for the box squat (0.33 ± 0.31), bench press (0.45 ± 0.30), bench throw (0.46 ± 0.36), and squat jump (0.64 ± 0.31) exercises were used. In general, the absolute expression of power and strength was superior for the heavier forwards, but after ratio scaling these performance measures then favoured the lighter backs. There were no performance differences between the forwards and backs after allometric scaling using either the proposed or the derived exponents. Thus, allometric scaling may provide a more effective method for normalizing power and strength in elite athletes when body size is a confounding variable.     

Obesity paradoxes

Abstract

In this review, we examine the original obesity paradox phenomenon (i.e. in cardiovascular disease populations, obese patients survive better), as well as three other related paradoxes (pre-obesity, “fat but fit” theory, and “healthy” obesity). An obesity paradox has been reported in a range of cardiovascular and non-cardiovascular conditions. Pre-obesity (defined as a body mass index of 25.0–29.9 kg · m^?2) presents another paradox. Whereas “overweight” implies increased risk, it is in fact associated with decreased mortality risk compared with normal weight. Another paradox concerns the observation than when fitness is taken into account, the mortality risk associated with obesity is offset. The final paradox under consideration is the presence of a sizeable subset of obese individuals who are otherwise healthy. Consequently, a large segment of the overweight and obese population is not at increased risk for premature death. It appears therefore that low cardiorespiratory fitness and inactivity are a greater health threat than obesity, suggesting that more emphasis should be placed on increasing leisure time physical activity and cardiorespiratory fitness as the main strategy for reducing mortality risk in the broad population of overweight and obese adults.     

The motivation to study: an analysis of undergraduate engineering students at a Caribbean university

The link between motivation and success is well documented; however, there is still room to problematise motivation in regards to the individual and contextual levels. This study looks at motivation in relation to students studying undergraduate engineering courses at a Caribbean university and seeks to discover the factors that motivate them to study and the factors that keep them motivated. An online questionnaire was constructed using 19 Likert-type questions and 5 questions that allowed for open-ended qualitative responses. The findings reveal that participants tended to be motivated by the increased possibility of desired future careers and tended to stay motivated by a combination of goal-orientation and family support. It is recommended that departments, faculties and institutions deliberate on shared and contextually constructed understandings of why students choose to enrol in particular university courses.     

能量平衡研究的10大问题

摘要：肥胖是较长时间段内热量摄入和消耗失衡导致的结果。两者关系可以用能量平衡方程描述,能量储存的速率等于能量摄入减去消耗的速率。尽管这种基于简单数学运算的关系可能容易理解,但在现实中,各种已知和未知的系统影响能量平衡的各个组成部分（能量储存,能量摄入,能量消耗）。显然,如果对于能量平衡有完整的理解,有效的预防和治疗策略就不会让肥胖在世界范围内大规模流行。目的是针对能量平衡的组成部分进行简要的概述,确定10个关键主题以及悬而未决的问题,如果这些问题得以解决,可以推动整个研究领域。这些主题涉及多个方面,从一般（方法学问题）到特定领域。这个列表并不是详尽无遗,但却为能量平衡领域的科学家制定了研究议程,为公共卫生专家制定肥胖干预的措施提供了建议。     

Early Parenting and the Development of Externalizing Behavior Problems: Longitudinal Mediation Through Children's Executive Function

Path analysis was used to investigate the longitudinal associations among parenting and children's executive function and externalizing behavior problems from 36 to 90 months of age in the Family Life Project (N = 1,115), a study of child development in the context of rural poverty. While controlling for stability in the constructs, semistructured observations of parenting prospectively predicted performance on a battery of executive function tasks and primary caregivers' reports of externalizing behavior. Furthermore, the association between early parenting and later externalizing behavior was longitudinally mediated by executive function, providing support for a process model in which sensitive parenting promotes children's self‐regulation, which in turn reduces children's externalizing behavior.     

International online collaboration as a boundary crossing activity for vocational educators

Vocational educators cross boundaries between practices in schools, colleges and workplaces, renegotiating their identities as professionals in a particular vocation and as educators. In order to support learners to enter the global workforce, they also require opportunities to cross boundaries through international practices. However, opportunities for international and intercultural learning are often limited, particularly for trainee vocational educators. This paper highlights an online collaborative process (COLIGE) designed to develop competencies for global education. The COLIGE process has been evaluated through the lens of boundary crossing. Participants were trainee vocational educators undergoing their professional teaching qualification in Scotland and Finland. Action research was undertaken during this three-year project to explore participants’ experiences and evaluate the learning mechanisms observed during the activities. Findings suggest activity though all four learning mechanisms (identification, coordination, reflection, transformation), although they were not universally experienced. Difficulties faced by learners are discussed and point to the potential for transformation of practice without sequential engagement with all learning mechanisms.     

Improving Practice through Reflective Enquiry: confessions of a first‐time action researcher

A number of key constructs underpin educational action research. This paper focuses on the concept of ‘truth’ and by doing so hopes to highlight some debate in this area. In reflecting upon what ‘truth’ might mean to those involved in action research, I shall critically evaluate Thorndike's ‘Law of Effect’ and Bruner's ‘Three Forms of Representation’, and explain how these perspectives might help us find ‘the truth’ of an area under study and how they might inform the methodology of research. I shall close by suggesting that teacher‐researchers should allow for a constructivist approach in their action research methodology in order to help them in their sense‐making process.     

Right–left digit ratio (2D:4D) predicts free testosterone levels associated with a physical challenge

Abstract

There is evidence that the digit ratio (2D:4D) is a negative correlate of prenatal levels of testosterone, but there is no association between 2D:4D and the circulating levels of both total and free testosterone. Sports provide a physical challenge and participants often show increased levels of free testosterone immediately preceding and during competition. We tested this hypothesis of a link between 2D:4D and testosterone under challenge in 79 professional rugby players using the following procedures; (i) 25 players were physically challenged using a repeated sprint agility test, and saliva samples were assayed for testosterone immediately preceding the repeated sprint agility test (time 1) and 5 minutes (time 2) and 20 minutes after completion of the repeated sprint ability (time 3); (ii) 54 players were also tested for salivary testosterone in an unchallenged condition. We found that right-left 2D:4D was significantly and negatively related to testosterone concentrations at times 1, 2 and 3 following the repeated sprint agility test (P < 0.05) and there was no association between the 2D:4D and basal testosterone levels in the unchallenged group. We suggest that low right–left 2D:4D is a predictive marker of free testosterone responsiveness when trained men are physically challenged, and that this association is programmed by the action of prenatal testosterone.     

Leisure Time Physical Activity and Job Performance

In this study, the dual-task paradigm was used to determine peak attentional demand during the free-throw process. Thirty participants completed 40 free-throw trials. The free throw was the primary task, but participants also verbally responded to a tone administered at one of four probe positions (PP). Repeated measures analysis of variance showed no significant difference in free-throw performance across PPs, indicating participants were able to keep the free throw as the primary task. Repeated measures analysis of response time (RT) showed significant differences, with RT at PP1 (preshot routine) and PP2 (first upward motion of the ball) significantly higher than baseline RT. These results suggest that PP1 requires the greatest attentional demand, followed by PP2.     

Extending the Theory of Planned Behavior in the Exercise Domain: A Comparison of Social Support and Subjective Norm

Abstract

A sedentary and unfit way of life leads to increased risk for several chronic diseases and premature mortality. Sedentary and unfit individuals are also more likely to develop functional limitations as they age. The precise type, amount, and intensity of physical activity required for protection needs further investigation. Traditional exercise recommendations suggest a threshold of activity that necessary for protection, although current evidence does not support a dichotomous view of this issue. Clinical and epidemiological studies show a continuous dose-response gradient of outcome variables across a wide range of activity or fitness levels. Moderate amounts and intensities of physical activity are associated with improved health and reduced risk of morbidity and mortality when compared with low activity or fitness. The major public health emphasis for physical activity recommendations and programming should be to encourage the most sedentary and unfit 20 to 25 % of the population to become at least moderately active, and this can yield substantial benefits for the population.