Fluid and electrolyte balance in elite male football (soccer) players training in a cool environment

There are few data in the published literature on sweat loss and drinking behaviour in athletes training in a cool environment. Sweat loss and fluid intake were measured in 17 first-team members of an elite soccer team training for 90 min in a cool (5°C, 81% relative humidity) environment. Sweat loss was assessed from the change in body mass after correction for the volume of fluid consumed. Sweat electrolyte content was measured from absorbent patches applied at four skin sites. Mean (?± s) sweat loss during training was 1.69?±?0.45 l (range 1.06?-?2.65 l). Mean fluid intake during training was 423?±?215 ml (44?-?951 ml). There was no apparent relationship between the amount of sweat lost and the volume of fluid consumed during training (r ² = 0.013, P = 0.665). Mean sweat sodium concentration was 42.5?±?13.0 mmol?·?l^?1 and mean sweat potassium concentration was 4.2?±?1.0 mmol?·?l^?1. Total salt (NaCl) loss during training was 4.3?±?1.8 g. The sweat loss data are similar to those recorded in elite players undergoing a similar training session in warm environments, but the volume of fluid ingested is less.     

The impact of 100 hours of exercise and sleep deprivation on cognitive function and physical capacities

Abstract

In this study, we examined the effect of 96–125 h of competitive exercise on cognitive and physical performance. Cognitive performance was assessed using the Stroop test (n = 9) before, during, and after the 2003 Southern Traverse adventure race. Strength (MVC) and strength endurance (time to failure at 70% current MVC) of the knee extensor and elbow flexor muscles were assessed before and after racing. Changes in vertical jump (n = 24) and 30-s Wingate performance (n = 27) were assessed in a different group of athletes. Complex response times were affected by the race (16% slower), although not significantly so (P = 0.18), and were dependent on exercise intensity (less so at 50% peak power output after racing). Reduction of strength (P < 0.05) of the legs (17%) and arms (11%) was equivalent (P = 0.17). Reductions in strength endurance were inconsistent (legs 18%, P = 0.09; arms 13%, P = 0.40), but were equivalent between limbs (P = 0.80). Similar reductions were observed in jump height (?8 ± 9%, P < 0.01) and Wingate peak power (?7 ± 15%, P = 0.04), mean power (?7 ± 11%, P < 0.01), and end power (?10 ± 11%, P < 0.01). We concluded that: moderate-intensity exercise may help complex decision making during sustained stress; functional performance was modestly impacted, and the upper and lower limbs were affected similarly despite being used disproportionately.     

Change-of-direction,speed and jump performance in soccer players: a comparison across different age-categories

ABSTRACT

This study examined the age-specific development of vertical jump height, straight and change-of-direction (COD) speed, and COD deficit in one-hundred and eighty-two elite soccer players from different age-categories (U15, U17, U20, and Senior). All participants were players of two distinct clubs and were undertaking different training routines, as planned by their technical staff members. For this purpose, the soccer players performed: (1) squat and countermovement jumps; (2) a maximal 20-m linear sprint speed test, and (3) the Zigzag COD test. The magnitude-based inference approach and standardized differences were used to compare the age-groups. Sprint speed at longer distances (20-m) increased progressively across the age-ranges. In contrast, speed and acceleration performances at shorter distances (5-m) were better in U15 than in the other age-categories. The COD speed did not change throughout the younger categories but presented a meaningful decrease in the Senior category. Surprisingly, despite the progressive increase in volume and intensity of neuromuscular training from younger to older categories, the COD deficit presented a gradual increase across the age-groups. It is possible that simple modulation of the strength-power training program during the maturation process is not sufficient to produce faster adult players with enhanced ability to change direction. Therefore, coaches are strongly encouraged to implement specific COD training practices to tolerate braking at increasing running speeds and appropriate volume and intensity of soccer specific training throughout the players’ specialization process.     

Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy

The present study investigated the effects of different intensities of resistance training (RT) on elbow flexion and leg press one-repetition maximum (1RM) and muscle cross-sectional area (CSA). Thirty men volunteered to participate in an RT programme, performed twice a week for 12 weeks. The study employed a within-subject design, in which one leg and arm trained at 20% 1RM (G20) and the contralateral limb was randomly assigned to one of the three conditions: 40% (G40); 60% (G60), and 80% 1RM (G80). The G20 started RT session with three sets to failure. After G20 training, the number of sets was adjusted for the other contralateral limb conditions with volume-matched. CSA and 1RM were assessed at pre, post-6 weeks, and post-12 weeks. There was time effect for CSA for the vastus lateralis (VL) (8.9%, 20.5%, 20.4%, and 19.5%) and elbow flexors (EF) (11.4%, 25.3%, 25.1%, and 25%) in G20, G40, G60, and G80, respectively (p?>?.05). G80 showed higher CSA than G20 for VL (19.5% vs. 8.9%) and EF (25% vs. 11.4%) at post-12 weeks (p?p?相似文献   

Truth and Provability

The views of Redhead ([2004]) are defended against the argumentby Panu Raatikainen ([2005]). The importance of informal rigouris canvassed, and the argument for the a priori nature of inductionis explained. The significance of Gödel's theorem is againrehearsed.     

The DREAMS Team: Creating community partnerships through research advocacy training for diverse older adults

The DREAMS Team research advocacy training program helps clinical faculty and health students introduce basic clinical research concepts to diverse older adults to galvanize their active involvement in the research process. Older adults are frequently underrepresented in clinical research, due to barriers to participation including distrust, historical mistreatment, and their lack of health literacy. The DREAMS Team program aims to involve diverse older adults throughout all phases of research and increase research participation, thereby contributing to the growth of quality patient-centered, evidence-based health care. This course was developed for clinical faculty to deliver to diverse adults aged 55+ in eight 50-minute lectures, followed by half-hour small group discussions moderated by health students. A pilot cohort of 24 individuals was assessed for satisfaction post-program, and self-efficacy before and after the program. Older adult participants improved on a survey measure of self-efficacy, and indicated satisfaction on a post-program questionnaire. All agreed or strongly agreed that they enjoyed participating, and that classes enhanced knowledge/skills about the topics, were high quality, and provided useful information. Twenty-two out of 24 individuals who completed the program indicated they planned to get involved as research advocates. The DREAMS Team program can be offered either on its own, or as a follow-up program to a general health education course led by health students and/or professional researchers or clinicians. Educating older adults about the research process and advocacy through interactive seminars led by congenial and respectful researchers and health students may remove some barriers to research participation and involvement among diverse older adults.     

Invoking politics and ethics in the design of information technology: undesigning the design

It is a truism that the design and deployment of information and communication technologies is vital to everyday life, the conduct of work and to social order. But how are individual, organisational and societal choices made? What might it mean to invoke a politics and an ethics of information technology design and use? This editorial paper situates these questions within the trajectory of preoccupations and approaches to the design and deployment of information technology since computerisation began in the 1940s. Focusing upon the dominant concerns over the last three decades, the paper delineates an interest in design and use in relation to socio-technical theories, situated practices and actor-network theory. It is argued that each of these approaches is concerned with a particular form of politics that does not explicitly engage with ethics. In order to introduce ethics into contemporary debates about information technology, and to frame the papers in the special issue, it is argued that Levinas’ ethics is particularly valuable in problematising the relationship between politics and ethics. Levinas provides a critique of modernity’s emphasis on politics and the egocentric self. It is from a Levinasian concern with the Other and the primacy of the ethical that a general rethinking of the relationship between politics, ethics and justice in relation to information and communication technologies can be invoked.     

The Role of the Microcomputer-Based Laboratory Display in Supporting the Construction of New Understandings in Kinematics

Teachers' failure to utilise MBL activities more widely may be due to not recognising their capacity to transform the nature of laboratory activities to be more consistent with contemporary constructivist theories of learning. This research aimed to increase understanding of how MBL activities specifically designed to be consistent with a constructivist theory of learning support or constrain student construction of understanding. The first author conducted the research with his Year 11 physics class of 29 students. Dyads completed nine tasks relating to kinematics using a Predict-Observe-Explain format. Data sources included video and audio recordings of students and teacher during four 70-minute sessions, students' display graphs and written notes, semi-structured student interviews, and the teacher's journal. The study identifies the actors and describes the patterns of interactions in the MBL. Analysis of students' discourse and actions identified many instances where students' initial understanding of kinematics were mediated in multiple ways. Students invented numerous techniques for manipulating data in the service of their emerging understanding. The findings are presented as eight assertions. Recommendations are made for developing pedagogical strategies incorporating MBL activities which will likely catalyse student construction of understanding.     

Digital literacy,fake news and education / Alfabetización digital,fake news y educación

Abstract

The role of digital literacy in strengthening citizens’ resilience to misinformation and ‘fake news’ has been the subject of research projects and networking and academic and policy discourses in recent years, given prominence by an escalation of the perceived crisis following election and referendum results in the US and UK respectively. This special issue sets out to take forward critical dialogue in the field of media and digital literacy education by publishing rigorous research on the subject. The research disseminated in this collection speaks to the political and economic contexts for ‘fake news’, the complex issue of trust and the risks of educational solutionism; questions of definition and policy implementation; teaching about specific subgenres such as YouTube and clickbait; international comparisons of pedagogic approaches and challenges for teachers in this changing ecosystem.