Repulsive interaction between coplanar cracks in the double–cantilever geometry

Experiments on thin mica sheets are used to demonstrate that coplanar cracks in double-cantilever beam specimens do not universally attract each other, as conventionally portrayed, but, at long range, actually repel. An elasticity analysis explains the repulsion in terms of a compression zone, 0.35 times the beam half-thickness ahead of the crack tip, generated by bending moments from the cantilever arms on the remaining specimen section.

The dynamic role of elite coach : player and coach perspectives

As part of a larger study on talent development, ten top ranked players and ten coaches (nominated by the player) responded to open-ended questionnaires. Players and coaches were asked them to recall their background in tennis, describe the role of the coach and any changes in this role, and offer suggestions to coaches for nurturing talent. A series of inductive content analyses was conduct to analyze the data. These analyses revealed significant, and changing, roles of the coach during a player’s development to professional status. Recommendations to coaches highlighted the importance of coach philosophy, communication, and planning. Implications for coach education programs are discussed.

Warming up and stretching for athletes : A meta-analysis of the research literature from 2000 to 2006 in light of current athletic practice

This review presents the methods used to investigate the effects of various stretching protocols on muscular force and performance, in light of current individual and elite athlete stretching practices in their warm-up routines. A meta-analysis of peer-reviewed articles between the years of 2000 and 2007 revealed the majority of studies support the notion that static stretching is detrimental to muscular force and performance. However, the meta-analysis also revealed that the protocols used do not necessarily match current practice with many elite athletes. This article proposes, based on the mismatch between research and practice, that further studies must address this issue in further exploring the role of stretching in pre-training and competition warm-up routines.

Energy deficiency, menstrual disturbances, and low bone mass : what do exercising Australian women know about the female athlete triad?

Purpose: Prevention of the female athlete triad is essential to protect female athletes’ health. The aim of this study was to investigate the knowledge, attitudes, and behaviors of regularly exercising adult women in Australia toward eating patterns, menstrual cycles, and bone health.
Methods: A total of 191 female exercisers, age 18–40 yr, engaging in ≥2 hr/wk of strenuous activity, completed a survey. After 11 surveys were excluded (due to incomplete answers), the 180 participants were categorized into lean-build sports (n = 82; running/ athletics, triathlon, swimming, cycling, dancing, rowing), non-lean-build sports (n = 94; basketball, netball, soccer, hockey, volleyball, tennis, trampoline, squash, Australian football), or gym/fitness activities (n = 4).
Results: Mean (± SD) training volume was 9.0 ± 5.5 hr/wk, with participants competing from local up to international level. Only 10% of respondents could name the 3 components of the female athlete triad. Regardless of reported history of stress fracture, 45% of the respondents did not think that amenorrhea (absence of menses for ≥3 months) could affect bone health, and 22% of those involved in lean-build sports would do nothing if experiencing amenorrhea (vs. 3.2% in non-lean-build sports, p = .005). Lean-build sports, history of amenorrhea, and history of stress fracture were all significantly associated with not taking action in the presence of amenorrhea (all p < .005). Conclusions: Few active Australian women are aware of the detrimental effects of menstrual dysfunction on bone health. Education programs are needed to prevent the female athlete triad and ensure that appropriate actions are taken by athletes when experiencing amenorrhea.

Exploring the utility of collaborative governance in a National Sport Organization running head: Collaborative sport governance

This paper presents the outcomes of an 18-month developmental action research study to enhance the governance capability of a national sport organization. Bowls Australia, the national governing body for lawn bowls
in Australia, includes nine independent state and territory member-associations. An intervention was designed and implemented with the Bowls Australia Board. The purpose of the intervention was to enact collaborative governance to overcome a perceived cultural malaise in the governance of the sport. This study is one of the first to examine collaborative governance in a federal sport structure. Results demonstrate the utility of collaborative governance to overcome adversarial national, member-state relations for the purpose of establishing a common and unifying vision for bowls, while also enhancing governance capability. This study identified the importance of collective board leadership in governance decision-making throughout the sport. It also highlights future research directions in relation to collective board leadership in federal governance structures.

Validity and reliability of field-based measures for assessing movement skill competency in lifelong physical activities: a systematic review

Background: It has been suggested that young people should develop competence in a variety of ‘lifelong physical activities’ to ensure that they can be active across the lifespan. Objective: The primary aim of this systematic review is to report the methodological properties, validity, reliability, and test duration of field-based measures that assess movement skill competency in lifelong physical activities. A secondary aim was to clearly define those characteristics unique to lifelong physical activities. Data Sources: A search of four electronic databases (Scopus, SPORTDiscus, ProQuest, and PubMed) was conducted between June 2014 and April 2015 with no date restrictions. Study Selection: Studies addressing the validity and/or reliability of lifelong physical activity tests were reviewed. Included articles were required to assess lifelong physical activities using process-oriented measures, as well as report either one type of validity or reliability. Study Appraisal and Synthesis Methods: Assessment criteria for methodological quality were adapted from a checklist used in a previous review of sport skill outcome assessments. Results: Movement skill assessments for eight different lifelong physical activities (badminton, cycling, dance, golf, racquetball, resistance training, swimming, and tennis) in 17 studies were identified for inclusion. Methodological quality, validity, reliability, and test duration (time to assess a single participant), for each article were assessed. Moderate to excellent reliability results were found in 16 of 17 studies, with 71 % reporting inter-rater reliability and 41 % reporting intra-rater reliability. Only four studies in this review reported test–retest reliability. Ten studies reported validity results; content validity was cited in 41 % of these studies. Construct validity was reported in 24 % of studies, while criterion validity was only reported in 12 % of studies. Limitations: Numerous assessments for lifelong physical activities may exist, yet only assessments for eight lifelong physical activities were included in this review. Generalizability of results may be more applicable if more heterogeneous samples are used in future research. Conclusion: Moderate to excellent levels of inter- and intra-rater reliability were reported in the majority of studies. However, future work should look to establish test–retest reliability. Validity was less commonly reported than reliability, and further types of validity other than content validity need to be established in future research. Specifically, predictive validity of ‘lifelong physical activity’ movement skill competency is needed to support the assertion that such activities provide the foundation for a lifetime of activity.

Children's movement skills when playing active video games

Active video games (AVGs) may be useful for movement skill practice. This study examined children's skill execution while playing Xbox Kinect™ and during movement skill assessment. Nineteen children (10 boys, 9 girls; M age = 7.9 yr., SD = 1.4) had their skills assessed before AVG play and then were observed once a week for 6 wk. while playing AVGs for 50 min. While AVG play showed evidence of correct skill performance (at least 30-50% of the time when playing table tennis, tennis, and baseball), nearly all skills were more correctly performed during skill assessment (generally more than 50% of the time). This study may help researchers to better understand the role AVGs could play in enhancing real life movement skills.

A behavioural therapy approach to self-management: the Flinders Program

Chronic diseases, including diabetes, represent the most prevalent problem in healthcare today. They are the most common cause of disability and consume the largest part of health expenditures internationally. Most diabetes care is provided by people with diabetes and their family or supporters. Therefore, understanding how to enhance diabetes self-management is of primary importance in addressing this growing burden. The effective self-management of type 2 diabetes is closely linked to environmental factors and a person’s lifestyle. In this article, the authors describe the Flinders Chronic Condition Self-Management Program, which highlights the person’s perspective, and provide an example of its practical application in an Aboriginal population in South Australia.

Adolescents' ratings of features of parks that encourage park visitation and physical activity

BACKGROUND: The neighbourhood environment such as the availability of parks are a key, but under-researched, influence on adolescents' physical activity. In addition to overall physical activity levels, park-based physical activity and park visitation is low in this age group. Thus, it is critical to identify park features that may encourage or discourage adolescents from visiting parks. This study used a novel methodology to identify key physical characteristics of parks that are perceived to be important for park visitation and park-based physical activity among adolescents.

METHODS: Four secondary schools located in low, mid and high socio-economic status areas of Victoria, Australia were recruited. Using a purpose-built computer application, students in years 8-10 were presented with 44 original photographic images of park features. Participants rated each image (range 1-10) on how likely the feature would be to encourage them to visit a park and to engage in park-based physical activity, and placed symbols ('thumbs up'/'thumbs down') on aspects of the image that had a positive or negative influence on their ratings.

RESULTS: Participants (n = 99) had a mean age of 13.3 years (SD = 0.87) and 53% were female. Overall, the top three rated images prompting park visitation by adolescents were: a long steep slide, a flying fox and a table tennis table. These first two features were also reported as being likely to promote physical activity in the park. Differences in ratings were observed for boys and girls. The images that received the greatest number of "thumbs-up" symbols included large swings and slides, table tennis tables, no-smoking signs, flying foxes and BMX tracks. The images that received the greatest number of "thumbs-down" symbols included signage about rules, graffiti, toilets, concrete steps, and skate bowls.

CONCLUSION: Physically challenging play equipment is likely to encourage adolescents to visit and be active in parks. Rules, graffiti, toilets and skate bowls may discourage visitation. It is important for park designers, planners and policy makers to consider adolescents' views of what park design features are important so that parks are created that support and encourage visitation and optimise levels of physical activity when in the park.

Measuring chronic condition self-management in an Australian community: factor structure of the revised Partners in Health (PIH) scale

Purpose To evaluate the factor structure of the revised Partners in Health (PIH) scale for measuring chronic condition self-management in a representative sample from the Australian community.

Methods A series of consultations between clinical groups underpinned the revision of the PIH. The factors in the revised instrument were proposed to be: knowledge of illness and treatment, patient–health professional partnership, recognition and management of symptoms and coping with chronic illness. Participants (N = 904) reporting having a chronic illness completed the revised 12-item scale. Two a priori models, the 4-factor and bi-factor models were then evaluated using Bayesian confirmatory factor analysis (BCFA). Final model selection was established on model complexity, posterior predictive p values and deviance information criterion.

Results Both 4-factor and bi-factor BCFA models with small informative priors for cross-loadings provided an acceptable fit with the data. The 4-factor model was shown to provide a better and more parsimonious fit with the observed data in terms of substantive theory. McDonald’s omega coefficients indicated that the reliability of subscale raw scores was mostly in the acceptable range.

Conclusion The findings showed that the PIH scale is a relevant and structurally valid instrument for measuring chronic condition self-management in an Australian community. The PIH scale may help health professionals to introduce the concept of self-management to their patients and provide assessment of areas of self-management. A limitation is the narrow range of validated PIH measurement properties to date. Further research is needed to evaluate other important properties such as test–retest reliability, responsiveness over time and content validity.