Profile of position movement demands in elite junior Australian rules footballers

This study investigated the positional movement patterns in elite junior Australian Football (AF). Thirty players (17.1 ± 0.9 years) participating in this study were tracked over seven home games of the regular 2006 Victorian junior (Under 18) league season. Using lapsed-time video analysis, each position for an entire match was videotaped on three separate occasions over the course of the season. Data analysed included the number of individual efforts, duration and frequency of efforts; distance and percentage time for the classifications of standing, walking jogging, running and sprinting. Results showed that the midfield position travelled the greatest distance (4173 ± 238 m per quarter; p < 0.05; ES = .94) whilst the full forward/full back travelled the least (2605 ± 348 m per quarter, p < 0.05, ES = 1.21). For all positions, walking or jogging accounted for the greatest number of efforts (45-55%), conversely running and sprinting accounted for 5-13% of match efforts. The majority of efforts across all classifications were between 0-3.99 s. The data from this study provides further evidence that AF is an intermittent sport characterised by high intensity movements separated by low intensity movements at a ratio of one high intensity effort every 12-40 s. However, careful interpretation of the data is required when training junior AF players for specific positions, given the specific group studied.

The Yo-Yo Intermittent Recovery Test (Level 1) to discriminate elite junior Australian football players

The Yo-Yo Intermittent Recovery (IR) Test is currently used to assess endurance performance in team sport athletes. However, to date, no data has been presented on its application to an elite junior Australian football (AF) playing group. Therefore, the aim of this study was to evaluate the Yo-Yo Intermittent Recovery Test Level 1 (IR1) ability to discriminate between junior AF players at two different playing standards and a group of non-athletic healthy males. Sixty age matched participants (16.6 ± 0.5 years) spread over three groups (20 per group): elite junior footballers; sub-elite junior footballers; and non-athletic healthy males participated in this study. Participants undertook a single Yo-Yo test performance on an indoor basketball court for each group. A one-way ANOVA with Scheffe's post hoc analysis revealed the elite junior footballers covered a significantly greater total distance (p < 0.001) and completed a significantly greater number of high-intensity efforts (p < 0.001) in comparison to their sub-elite counterparts, whilst both AF groups performed significantly better (p < 0.001) than the non-athletic healthy males. This study demonstrates the ability of the Yo-Yo IR1 to discriminate endurance performance between elite and sub-elite AF players, whilst further distinguishing AF players from a non-athletic healthy control group.

A comparison of two methods in acquiring stimulus-response curves with transcranial magnetic stimulation

Background
The stimulus–response (S–R) curve is a well accepted constituent in transcranial magnetic stimulation (TMS) studies. However, it has been suggested that parameters of the S–R curve differ when stimuli are provided in a “ramped” (measured steps from low to high intensity), or “random” fashion.

Hypothesis
We hypothesized that there would be no difference in the parameters of the S–R curve between either methodologies.

Methods
Using a randomised cross-over design, 10 healthy participants (29.6 ± 6.4 yrs, 3 f) completed “ramped” or “random” curves in biceps brachii (BB) and first dorsal interosseous (FDI) muscles of both limbs. Curves were compared using mixed-factor ANOVA and correlated between limbs and methodologies.

Results
No differences (P > 0.05) and high correlations (range 0.71–0.97; P < 0.001) were observed in BB and FDI data between curves.

Conclusions
This study demonstrated that either methodology provides similar parameters of the S–R curve in healthy participants.

Upward needleless electrospinning of nanofibers

Polyacrylonitrile (PAN) nanofibers were prepared by a needleless electrospinning method using three rotating fiber generators, cylinder, disc and coil. The effects of the spinneret shape on the electrospinning process and resultant fiber morphology were examined. The disc spinneret needed the lowest voltage to initiate fiber formation, followed by the coil and cylinder. Compared to cylinder, the disc and coil produced finer fibers with narrower diameter distribution. The productivity of a coil was 23 g/hr, which was much larger than that of the cylinder spinneret having the same length and diameter. Finite elementary method was used to analyze the electric field. Stronger electric field was found to be formed on disc and coil surface, which concentrated on the disc circumferential edge and coil wire surface, respectively. For cylinder, the high intensity electric field was mainly concentrated on the end area. Concentrated electric field on the fiber generating surface could be used to explain the better electrospinning performance of coil, which may form a new concept for designing needleless electrospinning spinnerets.

Post-exercise muscle glycogen repletion in the extreme : effect of food absence and active recovery

Glycogen plays a major role in supporting the energy demands of skeletal muscles during high intensity exercise. Despite its importance, the amount of glycogen stored in skeletal muscles is so small that a large fraction of it can be depleted in response to a single bout of high intensity exercise. For this reason, it is generally recommended to ingest food after exercise to replenish rapidly muscle glycogen stores, otherwise one's ability to engage in high intensity activity might be compromised. But what if food is not available? It is now well established that, even in the absence of food intake, skeletal muscles have the capacity to replenish some of their glycogen at the expense of endogenous carbon sources such as lactate. This is facilitated, in part, by the transient dephosphorylation-mediated activation of glycogen synthase and inhibition of glycogen phosphorylase. There is also evidence that muscle glycogen synthesis occurs even under conditions conducive to an increased oxidation of lactate post-exercise, such as during active recovery from high intensity exercise. Indeed, although during active recovery glycogen resynthesis is impaired in skeletal muscle as a whole because of increased lactate oxidation, muscle glycogen stores are replenished in Type IIa and IIb fibers while being broken down in Type I fibers of active muscles. This unique ability of Type II fibers to replenish their glycogen stores during exercise should not come as a surprise given the advantages in maintaining adequate muscle glycogen stores in those fibers that play a major role in fight or flight responses.

Wikis as individual student learning tools : the limitations of technology

This paper presents research into the attitudes and behaviours of students using wikis for individual writing tasks. The wiki-based assignment differs from the use of wikis normally researched because it was an individual task, not involving collaborative writing. This activity provides an excellent opportunity to learn more about how wikis are actually used by students in higher education. The research finds there is no compelling evidence that the wiki on its own improves performance over and above the general aptitude of students. It also finds that students generally did not utilise the wikis for high-intensity editing and revision. However, students did report that the wiki was valuable as a way of aiding them to review and develop their ideas. We conclude that using wikis for individual writing tasks can, where appropriate active instructions are given to support development of cognitive abilities, lead to improved outcomes for students.

Insulin sensitivity in response to a single resistance exercise session in apparently healthy individuals

BACKGROUND: Regular resistance exercise completed for a number of weeks has been shown to increase insulin sensitivity and reduce the risk of diabetes-related complications. However, the acute responses to resistance exercise have not been adequately investigated in relation to training frequency.
AIM: To investigate the changes to insulin sensitivity in apparently healthy individuals following a single session of unaccustomed resistance exercise.
SUBJECTS AND METHODS: Ten sedentary, apparently healthy individuals performed a baseline oral glucose tolerance test and maximal strength testing. Participants then performed a single session of moderate-high intensity resistance exercise which was followed by 4 consecutive days of oral glucose tolerance testing, for which participants replicated their initial diet. Mean estimated insulin sensitivity change scores from baseline values and their 95% confidence intervals were compared to the previously determined values for a clinically meaningful change.
RESULTS: Two participants were identified as having hyperinsulinemia and their data were therefore removed from the main analysis. There was a clinically meaningful increase in insulin response (mean >7237 pmol·l⁻¹·120 min⁻¹) on all days following the exercise session and a clinically meaningful increase in glucose response (mean >81 mmol·l⁻¹·120 min⁻¹) on only the 3rd day following exercise. These changes suggest a potentially adverse short-term effect. Additionally, the 2 individuals with hyperinsulinemia displayed more extreme results.
CONCLUSION: These results suggest that insulin sensitivity may be impaired following a single session of unaccustomed resistance exercise for approximately 4 days in healthy untrained, older individuals. Further research is required for individuals with hyperinsulinemia

Quantification of tackling demands in professional Australian football using integrated wearable athlete tracking technology

Objectives
To describe and quantify the frequency, velocity and acceleration at impact during tackling in Australian football using a combination of video and athlete tracking technology.

Design
Quasi-experimental.

Methods
Data was collected from twenty professional Australian Football League players during four in-season matches. All tackles made by the player and those against the player were video-coded and time stamped at the point of contact and then subjectively categorised into low, medium and high intensity impact groups. Peak GPS and acceleration data were identified at the point of contact. Two-way analysis of variance was used to assess differences (p < 0.05) between tackle type (made and against) and tackle intensity.

Results
A total of 173 tackles made and 179 tackles against were recorded. Significant differences were found between all tackle intensity groups. Peak velocity was significantly greater in high (19.5 ± 6.1 km h−1) compared to medium (13.4 ± 5.8 km h−1) and low intensity (11.3 ± 5.0 km h−1) tackles. Peak Player Load™, a modified vector magnitude of tri-axial acceleration, was significantly greater in high (7.5 ± 1.7 a.u.) compared to medium (4.9 ± 1.5 a.u.) and low intensity (4.0 ± 1.3 a.u.) tackles.

Conclusions
High intensity tackles, although less frequent, are significantly greater in speed of movement immediately prior to contact and in the resultant impact acceleration compared to tackles of lower intensity. Differences in accelerometer data between tackles observed to be progressively greater in intensity suggest a level of ecological validity and provide preliminary support for the use of accelerometers to assess impact forces in contact invasion sports.

Cambodian migrant women's postpartum experiences in Victoria, Australia

Objective: to explore the postpartum experiences of Cambodian born migrant women who gave birth for the first time in Victoria, Australia between 2000 and 2010. Design: an ethnographic study with 35 women using semi-structured and unstructured interviews and participant observation; this paper draws on interviews with 20 women who fit the criteria of first time mothers who gave birth in an Australian public hospital. Setting: the City of Greater Dandenong, Victoria Australia. Participants: twenty Cambodian born migrant women aged 23-30 years who gave birth for the first time in a public hospital in Victoria, Australia. Findings: after one or two home visits by midwives in the first 10 day postpartum women did not see a health professional until 4-6 weeks postpartum when they presented to the MCH centre. Women were home alone, experienced loneliness and anxiety and struggled with breast feeding and infant care while they attempted to follow traditional Khmer postpartum practices. Implications for practice: results of this study indicate that Cambodian migrant women who are first time mothers in a new country with no female kin support in the postpartum period experience significant emotional stress, loneliness and social isolation and are at risk of developing postnatal depression. These women would benefit from the introduction of a midwife-led model of care, from antenatal through to postpartum, where midwives provide high-intensity home visits, supported by interpreters, and when required refer women to professionals and community services such as Healthy Mothers Healthy Babies (Victoria Department of Health, 2011) for up to 6 weeks postpartum

Short-term intensified cycle training alters acute and chronic responses of PGC1α and cytochrome C oxidase IV to exercise in human skeletal muscle

Reduced activation of exercise responsive signalling pathways have been reported in response to acute exercise after training; however little is known about the adaptive responses of the mitochondria. Accordingly, we investigated changes in mitochondrial gene expression and protein abundance in response to the same acute exercise before and after 10-d of intensive cycle training.

Nine untrained, healthy participants (mean±SD; VO2peak 44.1±17.6 ml/kg/min) performed a 60 min bout of cycling exercise at 164±18 W (72% of pre-training VO2peak). Muscle biopsies were obtained from the vastus lateralis muscle at rest, immediately and 3 h after exercise. The participants then underwent 10-d of cycle training which included four high-intensity interval training sessions (6×5 min; 90–100% VO2peak) and six prolonged moderate-intensity sessions (45–90 min; 75% VO2peak). Participants repeated the pre-training exercise trial at the same absolute work load (64% of pre-training VO2peak). Muscle PGC1-α mRNA expression was attenuated as it increased by 11- and 4- fold (P<0.001) after exercise pre- and post-training, respectively. PGC1-α protein expression increased 1.5 fold (P<0.05) in response to exercise pre-training with no further increases after the post-training exercise bout. RIP140 protein abundance was responsive to acute exercise only (P<0.01). COXIV mRNA (1.6 fold; P<0.01) and COXIV protein expression (1.5 fold; P<0.05) were increased by training but COXIV protein expression was decreased (20%; P<0.01) by acute exercise pre- and post-training.

These findings demonstrate that short-term intensified training promotes increased mitochondrial gene expression and protein abundance. Furthermore, acute indicators of exercise-induced mitochondrial adaptation appear to be blunted in response to exercise at the same absolute intensity following short-term training.

Stressors, Recovery Processes, and Manifestations of Training Distress in Dance

Abstract
Dancers are expected to maintain consistently high levels of performance capability and to perform on demand. To meet these expectations, they subject their bodies to long hours of intensive physical training. Such training regimens are often combined with tight rehearsal and performance schedules, which over time, can lead to persistent fatigue, psychological distress, performance decrements, and injury. A similar process has been observed as a consequence of high-intensity training in many different sports, and considerable sport-related research has been devoted to identifying the antecedents, the symptoms that are experienced, and the most cost-effective ways of monitoring symptom development. This paper presents a general heuristic framework for understanding this “training distress process” and discusses the framework with specific reference to dance.

Global positioning system data analysis: velocity ranges and a new definition of sprinting for field sport athletes

Global positioning system (GPS) technology has improved the speed, accuracy, and ease of time-motion analyses of field sport athletes. The large volume of numerical data generated by GPS technology is usually summarized by reporting the distance traveled and time spent in various locomotor categories (e.g., walking, jogging, and running). There are a variety of definitions used in the literature to represent these categories, which makes it nearly impossible to compare findings among studies.

The purpose of this work was to propose standard definitions (velocity ranges) that were determined by an objective analysis of time-motion data. In addition, we discuss the limitations of the existing definition of a sprint and present a new definition of sprinting for field sport athletes.

Twenty-five GPS data files collected from 5 different sports (men’s and women’s field hockey, men’s and women’s soccer, and Australian Rules Football) were analyzed to identify the average velocity distribution. A curve fitting process was then used to determine the optimal placement of 4 Gaussian curves representing the typical locomotor categories. 

Using recovery modalities between training sessions in elite athletes: does it help?

Achieving an appropriate balance between training and competition stresses and recovery is important in maximising the performance of athletes. A wide range of recovery modalities are now used as integral parts of the training programmes of elite athletes to help attain this balance. This review examined the evidence available as to the efficacy of these recovery modalities in enhancing between-training session recovery in elite athletes. Recovery modalities have largely been investigated with regard to their ability to enhance the rate of blood lactate removal following high-intensity exercise or to reduce the severity and duration of exercise-induced muscle injury and delayed onset muscle soreness (DOMS). Neither of these reflects the circumstances of between-training session recovery in elite athletes. After high-intensity exercise, rest alone will return blood lactate to baseline levels well within the normal time period between the training sessions of athletes. The majority of studies examining exercise-induced muscle injury and DOMS have used untrained subjects undertaking large amounts of unfamiliar eccentric exercise. This model is unlikely to closely reflect the circumstances of elite athletes. Even without considering the above limitations, there is no substantial scientific evidence to support the use of the recovery modalities reviewed to enhance the between-training session recovery of elite athletes. Modalities reviewed were massage, active recovery, cryotherapy, contrast temperature water immersion therapy, hyperbaric oxygen therapy, nonsteroidal anti-inflammatory drugs, compression garments, stretching, electromyostimulation and combination modalities. Experimental models designed to reflect the circumstances of elite athletes are needed to further investigate the efficacy of various recovery modalities for elite athletes. Other potentially important factors associated with recovery, such as the rate of post-exercise glycogen synthesis and the role of inflammation in the recovery and adaptation process, also need to be considered in this future assessment.