Hydration,sweat and thermoregulatory responses to professional football training in the heat

Abstract

This study examined the relationship between intensity of training and changes in hydration status, core temperature, sweat rate and composition and fluid balance in professional football players training in the heat. Thirteen professional football players completed three training sessions; “higher-intensity” (140 min; HI₁₄₀), “lower-intensity” (120 min; LI₁₂₀) and “game-simulation” (100 min; GS₁₀₀). Movement demands were measured by Global Positioning System, sweat rate and concentration were determined from dermal patches and body mass change. Despite similar environmental conditions (26.9 ± 0.1°C and 65.0 ± 7.0% relative humidity [Rh]), higher relative speeds (m · min^?1) and increased perceptions of effort and thermal strain were observed in HI₁₄₀ and GS₁₀₀ compared with LI₁₂₀ (P < 0.05). Significantly (P < 0.05) greater sweat rate (L · h^?1) and electrolyte losses (g) were observed in HI₁₄₀ and GS₁₀₀ compared with LI₁₂₀. Rate of rise in core temperature was correlated with mean speed (r = 0.85), session rating of perceived exertion (sRPE) (r = 0.61), loss of potassium (K⁺) (r = 0.51) sweat rate (r = 0.49), and total sweat loss (r = 0.53), with mean speed the strongest predictor. Sodium (Na⁺) (r = 0.39) and K⁺ (r = 0.50) losses were associated with total distance covered. In hot conditions, individualised rehydration practices should be adopted following football training to account for differences in sweat rate and electrolyte losses in response to intensity and overall activity within a session.     

Activity profiles of the Australian female netball team players during international competition: Implications for training practice

Abstract

In elite sport, to remain competitive at the international level, it is critical to understand the game demands on players to ensure sport specific training programmes are designed for optimal athlete preparation and conditioning. In netball, recent research examining the activity patterns of players at the elite level is lacking, with only one study undertaken on this level of competition in the past 30 years. Therefore, the aim of this study was to provide coaches with up to date knowledge of player activity patterns as a basis for the design of optimal sport specific training programmes. The Australian female netball team were analysed using video footage of three international test matches. Player activity was categorised into five movement and eight game-based activities; and further classified as work or rest. Results suggest that differences in the current game exist when compared to the previous analysis. Positional differences were also found with regard to player activity confirming the need for an individualised component of training based on player position.     

Relative age effects in Australian Football League National Draftees

Abstract

This study examined the birth distribution for adolescent (i.e. <20 years) and mature age players (i.e. ≥20 years) selected in the Australian Football League (AFL) National Draft between 2001 and 2012. Birth-date information was accessed for all first time AFL national draftees and players were then classified as either adolescent (N = 736) or mature age (N = 70) draftees. Chi-squared analysis showed a clear bias in the birth distribution of adolescent draftees towards players born in the first part of the classification period for both quartile (P < 0.001) and half-year (P < 0.001) compared to the Australian national population. There was a reverse relative age effect (RAE) for mature age draftees, with a significant bias towards players born in the latter part of the selection period for both quartile (P = 0.047) and half-year (P = 0.028) compared to the Australian national population. The selection bias towards relatively older players in adolescent AFL draftees may be related to advanced physical and psychological maturity, and exposure to higher-level coaching compared to their younger counterparts. The reverse RAE in mature age draftees is a novel finding and supports the need for strategies to encourage continued participation pathways for talented Australian football players born later in the selection year.     

The influence of 2 weeks of low-volume high-intensity interval training on health outcomes in adolescent boys

Abstract

The present study aimed to establish whether 2 weeks of high-intensity interval training would have a beneficial effect on aerobic fitness, fat oxidation, blood pressure and body mass index (BMI) in healthy adolescent boys. Ten adolescent boys (15.1 ± 0.3 years, 1.3 ± 0.2 years post-estimated peak height velocity) completed six sessions of Wingate-style high-intensity interval training over a 2-week period. The first session consisted of four sprints with training progressed to seven sprints in the final session. High-intensity interval training had a beneficial effect on maximal O₂ uptake (mean change, ±90% confidence intervals: 0.19 L · min^?1, ±0.19, respectively), on the O₂ uptake at the gas exchange threshold (0.09 L · min^?1, ±0.13) and on the O₂ cost of sub-maximal exercise (–0.04 L · min^?1, ±0.04). A beneficial effect on the contribution of lipid (0.06 g · min^?1, ±0.06) and carbohydrate (–0.23 g · min^?1, ±0.14) oxidation was observed during sub-maximal exercise, but not for the maximal rate of fat oxidation (0.04 g · min^?1, ±0.08). Systolic blood pressure (1 mmHg, ±4) and BMI (0.1 kg · m², ±0.1) were not altered following training. These data demonstrate that meaningful changes in health outcomes are possible in healthy adolescent boys after just six sessions of high-intensity interval training over a 2-week period.     

Time Needed to Change the Isometric Force Production of a Response

Abstract

This study investigated the time needed to change a motor program that specified the elbow flexor muscles to gradually increase the isometric force production from 15% to 75% of one's maximum voluntary contraction (MVC). A double-stimulation paradigm was used with the restriction that subjects (N = 12) be at 15% of their MVC before the presentation of the first stimulus. Subjects reacted to the first stimulus (randomly presented) by gradually increasing their isometric force from 15% to 75% of their MVC and then reacted to the second stimulus by altering the force production in one of four ways: (a) increasing the force to the 75% level rapidly instead of gradually, (b) discontinuing the increase and maintaining the level of force attained, (c) discontinuing all force production, or (d) reversing the direction of force so that it is produced by the elbow extensors. The data revealed that more time was needed to increase the force rapidly than to perform any of the other three conditions.     

Young people, citizenship and citizenship education in Zimbabwe

Citizenship education in Zimbabwe is based on the claim that young people lack citizenship virtues. This study set out to investigate these assumptions by assessing high school students’ knowledge of, attitudes towards and participation levels in citizenship issues. Findings show that while students are knowledgeable about citizenship issues they are however, hesitant about involvement in political activities. The study concludes that the reported claims are partly not valid. In a politically sensitive environment students are unwilling to engage in political activities. They accurately assess the situation and adopt a position which other citizens in similar circumstances might take.     

Cultivating Practical Wisdom as Education

This article argues, from a critical realist perspective, that it would be beneficial to extend thinking on how personal and social education could become more central to students’ learning. We explore how constructive-informed arrangements which emphasize cognitive skills and affective qualities could be realized through experiential approaches to learning. Our theorizing is informed by neo-Aristotelian thinking on the importance of identifying mutually acceptable value commitments which can cultivate practical wisdom as well as generally benefit society. Thereafter, we outline how the recent writings of Tiberius could inform thinking on how, epistemologically and ethically, a first person perspective on learning and personal growth could connect with normative decision making on how to make good life choices. We conclude by briefly highlighting the methodological potential of using outdoor learning environments to help students make informed and wise judgements which show evidence of discernment, deliberation and effective decision making.     

Legislating Character: Moral Education in North Carolina's Public Schools

This article analyzes the epistemological aims and justification of character education legislation passed by the North Carolina General Assembly. I take this specific state law as representative of the broader national trends in the character education movement. I primarily use the work of Richard Rorty as the theoretical lens for the analysis and critique. I conclude by commending aspects of the legislative effort, but I suggest that greater emphasis must be placed on strengthening students' ethics through democratic action inside and outside schools and not on a right-leaning, conservative, and didactic curriculum. Further, as social foundations educators, it is imperative to make strides in our classrooms to expose preservice teachers to the apparent and hidden contradictions of using character education as a tool of educational reform.     

Educational governance,school autonomy,and curriculum implementation: A comparative study of Arab and Jewish schools in Israel

In recent years, the predominance of the nation-state as the sole arbiter of curricular matters has eroded. New actors and organizations, especially local schools, have acquired greater discretion over the definition of school subjects and curricular emphases. This study investigates whether and how different patterns of educational governance influence the actual curriculum that local schools put into place. It is argued that uniformity/diversity in the implemented curriculum reflects macro-level factors (i.e. structural and institutional characteristics of national educational systems), and meso-level factors (i.e. community and local school characteristics). Specifically, it investigates between-school variation in curricular implementation in two major sectors of the Israeli public educational system: Jewish (secular), and Arab. School-based differences are reported in course offerings and time-allocations to subject areas in each sector. In addition, it compares actual curricular implementation in relation to official guidelines established by central authorities. Implementation patterns between and within sectors are discussed in light of educational governance differences and key macro- and local-level factors.