Effects of plyometric-based structured game active breaks on fundamental movement skills, muscular fitness, self-perception, and actual behaviour in primary school students.

This study examined the effects of plyometric-based structured game active breaks on fundamental movement skills (FMS), muscular fitness, student self-perception, and teacher's rating of actual behaviour in Grade 3 and 4 students. Primary school children aged 8-10 years old, from four classes, were cluster-randomly assigned to an intervention group (IG) (n = 54) or a control group (CG) (n = 48). The IG participated in structured plyometric-based game active breaks for 7-10 minutes daily, for six consecutive weeks. The CG resumed their regular daily school routine. FMS were assessed with the Canadian Agility Movement Skills Assessment test, and muscular fitness with the standing long jump (SLJ), countermovement jump (CMJ), and seated medicine ball chest throw tests. The Self-Perception Profile for Children and the Teacher's Rating Scale of Child's Actual Behaviour assessed student self-perception and teacher's perception of student actual behaviour, respectively. A significant (p < 0.01) interaction group by time was observed, with greater improvements in the IG compared to the CG in FMS (%diff = 13.11, ƞp2 = 0.12), SLJ (%diff = 6.67, ƞp2 = 0.02), seated medicine ball chest throw (%diff = 4.69, ƞp2 = 0.08), student social self-perception (%diff = 9.31, ƞp2 = 0.10), student scholastic self-perception (%diff = 7.27, ƞp2 = 0.10), and teacher perception of student social competence (%diff = 8.31, ƞp2 = 0.05). No difference (p > 0.05) was found in other variables. Integrating plyometric-based structured game active breaks into primary school settings evidenced improvement in FMS, muscular fitness, student self-perception, and teacher's rating of student actual behaviour.

Need a break? The locomotor and tackle pacing profile and loads of women's rugby league match-play following various between-match turnaround durations.

OBJECTIVES: The study investigated the locomotor and tackle pacing profile and loads of female rugby league players following various between-match turnaround durations. Specifically, the study examined the (1) pacing of locomotor and tackle loads across the time-course of a match and; (2) whole-match and peak locomotor and tackle loads of match-play. METHODS: Microtechnology data were collected from elite female rugby league players (n = 172) representing all National Rugby League Women's teams (n = 6 teams) across two seasons. Players were categorised into backs, adjustables, forwards or interchange players. Data was calculated for the whole-match (m), per minute (m.min-1) and peak (running: m.min-1; acceleration: m.s-2) locomotor and tackle loads (number and efficiency (%)) of match-play. The pacing as well as the locomotor and tackle loads of match-play were examined following short (≤6 days), normal (7 days) or long (≥8 days) turnarounds. RESULTS: The pacing profile of playing positions varied across short, normal and long match turnarounds. Trivial to moderate differences existed in the whole-match, per minute and peak locomotor loads across match turnaround durations (effect size ≤ 1.2). CONCLUSIONS: Following various between-match turnaround durations (i.e., short, normal and long match turnarounds), there were variations in the locomotor and tackle pacing profile and loads whereby, the pacing profile of positional groups was more affected than the load profile. The findings can be used in applied settings to guide the recovery strategies and training plans of female rugby league players to optimise performance and wellbeing across various match turnaround durations.

Investigating the Emergence of Collective States Within Rugby Sevens Gameplay.

Rugby sevens is a small-sided variant of rugby union characterised by fast-moving, high-intensity gameplay and is an example of a team invasion sport, where players work together to achieve a shared goal of attacking and defending as a cohesive unit. The dynamics of such sports can be viewed as self-organizing systems, where individual players form collective patterns without a centralized mechanism of control. Inspired by the analysis of collective movement in animals, this novel study investigates the emergent patterns of order and disorder in sub-elite female rugby sevens using order parameters (typically used to analyse particle systems) to characterize the team's collective state during different phases of play. The findings demonstrate that defensive gameplay is more ordered, with more compact formations, compared to attacking play, and there is a correlation between alignment/order in player motion and group speed. The work further suggests that the collective states formed differ between sequences of play with different levels of ground gained by the attacking team. These observations provide a sound justification for player training with a focus on cohesive defensive movements to resist disruptions from opposing attackers, while employing attacking tactics that disrupt the cohesion and order of opposing teams.

How fast is fast? Defining velocity zones in women's rugby league.

OBJECTIVES: The study aimed to: 1) apply a data-mining approach to identify velocity zone thresholds for female rugby league players and 2) apply these velocity zones to examine the locomotor demands of match-play. METHODS: Microtechnology data were collected from elite female rugby league players representing all National Rugby League Women's teams (n = 85 players; n = 224 files) over one season. Spectral clustering with a beta smoothing cut-off of 0.1 was applied to each player's instantaneous match-play velocity data for the identification of four zones. To account for outliers within repeated data-points, the velocity zones for each player were calculated as the median. The overarching velocity zones were determined through an incremental search to minimise the root mean square error. RESULTS: Through a data-mining approach, four velocity zones were determined. Rounded to the nearest 0.5 km.h-1 the velocity values across each zone were classified as low (<11.49 km.h-1), moderate (11.50 to 17.49 km.h-1), high (17.50 to 20.99 km.h-1) and very-high (>21.00 km.h-1). Practical application of the zones demonstrated positional group differences in the absolute (effect size (ES): 0.03 to 1.77) and relative (ES: 0.04 to 1.60) locomotor demands of match-play. The back positional group covered greater absolute and relative distances at a very-high velocity than all other positions. CONCLUSIONS: This work informs the velocity zones that could be applied consistently to women's rugby league data within practical (i.e., in the training and monitoring of players) and academic (i.e., as a model for future research to analyse locomotor demands) settings.

Changing gears: data-driven velocity zones to support monitoring and research in men's rugby league.

OBJECTIVES: The study aimed to (1) apply a data-mining approach to league-wide microtechnology data to identify absolute velocity zone thresholds and (2) apply the respective velocity zones to microtechnology data to examine the locomotor demands of elite match-play. METHODS: League-wide microtechnology data were collected from elite male rugby league players representing all National Rugby League (NRL) teams (n = 16 teams, one excluded due to a different microtechnology device; n = 4836 files) over one season. To identify four velocity zones, spectral clustering with a beta smoothing cut-off of 0.1 was applied to each players' instantaneous match-play velocity data. Velocity zones for each player were calculated as the median while the overarching velocity zones were determined through an incremental search to minimise root mean square error. RESULTS: The velocity zones identified through spectral clustering were 0-13.99 km · h-1 (i.e., low velocity), 14.00-20.99 km · h-1 (i.e., moderate velocity), 21.00-24.49 km · h-1 (i.e., high velocity) and >24.50 km · h-1 (i.e., very-high velocity). CONCLUSIONS: The application of spectral clustering (i.e., a data-mining method) to league-wide rugby league microtechnology data yielded insights into the distribution of velocity data, thereby informing the cut-off values which best place similar data points into the same velocity zones. As the identified zones are representative of the intensities of locomotion achieved by elite male rugby league players, it is suggested that when absolute zones are used, the consistent application of the identified zones would facilitate standardisation, longitudinal athlete monitoring as well as comparisons between teams, leagues and published literature.

The Validity of Automated Tackle Detection in Women's Rugby League.

ABSTRACT: Cummins, C, Charlton, G, Naughton, M, Jones, B, Minahan, C, and Murphy, A. The validity of automated tackle detection in women's rugby league. J Strength Cond Res 36(7): 1951-1955, 2022-This study assessed the validity of microtechnology devices to automatically detect and differentiate tackles in elite women's rugby league match-play. Elite female players (n = 17) wore a microtechnology device (OptimEye S5 device; Catapult Group International) during a representative match, which involved a total of 512 tackles of which 365 were defensive and 147 were attacking. Tackles automatically detected by Catapult's tackle detection algorithm and video-coded tackles were time synchronized. True positive, false negative and false positive events were utilized to calculate sensitivity (i.e., when a tackle occurred, did the algorithm correctly detect this event) and precision (i.e., when the algorithm reported a tackle, was this a true event based on video-coding). Of the 512 video-derived attacking and defensive tackle events, the algorithm was able to detect 389 tackles. The algorithm also produced 81 false positives and 123 false negatives. As such when a tackle occurred, the algorithm correctly identified 76.0% of these events. When the algorithm reported that a tackle occurred, this was an actual event in 82.8% of circumstances. Across all players, the algorithm was more sensitive to the detection of an attacking event (sensitivity: 78.2%) as opposed to a defensive event (sensitivity: 75.1%). The sensitivity and precision of the algorithm was higher for forwards (sensitivity: 81.8%; precision: 92.1%) when compared with backs (sensitivity: 64.5%; precision: 66.1%). Given that understanding the tackle demands of rugby league is imperative from both an injury-prevention and physical-conditioning perspective there is an opportunity to develop a specific algorithm for the detection of tackles within women's rugby league.

A new energetics model for the assessment of the power-duration relationship during over-ground running.

We evaluated the reliability of an over-ground running three-minute all-out test (3MT) and compared this to traditional multiple-visit testing to determine the critical speed (CS) and distance > CS (D´). Using a novel energetics model during the 3MT, critical power (CP) and work > CP (W´) were also evaluated for reliability and compared to the multiple-visit tests. Over-ground running speed was measured using Global Positioning Systems during fixed-speed trials on a 400 m track to exhaustion, at four intensities corresponding to: (i) maximal oxygen uptake (V˙O2max) (Vmax), (ii) 110% V˙O2max(110%Vmax), (iii) Δ70% (i.e. 70% of the difference between gas exchange threshold and Vmax) and (iv) Δ85%. The participants subsequently performed the 3MT across two days to determine its reliability. There were no differences between the multiple-visit testing and the 3MT for CS (P = 0.328) and D´ (P = 0.919); however, CP (P = 0.02) and W´ (P < 0.001) were higher in the 3MT. The reliability of the 3MT was stable (P > 0.05) between trials for all variables, with coefficient of variation ranging from 2.0-8.1%. The current over-ground energetics model can reliably estimate CP and W´ based on GPS speed data during the 3MT, which supports its use for most athletic training and monitoring purposes. The reliability of the over-ground running 3MT for power- and speed-related indices was sufficient to detect typical training adaptations; however, it may overestimate CP (∼ 25 W) and W´ (∼ 7 kJ) compared to multiple-visit tests.

Co-expression analysis identifies networks of miRNAs implicated in biological ageing and modulated by short-term interval training.

Exercise training seems to promote healthy biological ageing partly by inducing telomere maintenance, yet the molecular mechanisms are not fully understood. Recent studies have emphasised the importance of microRNAs (miRNAs) in ageing and their ability to mirror pathophysiological alterations associated with age-related diseases. We examined the association between aerobic fitness and leukocyte telomere length before determining the influence of vigorous exercise training on the regulation of leukocyte miRNA networks. Telomere length was positively correlated to aerobic fitness (r = 0.32, p = 0.02). 104 miRNAs were differentially expressed after six weeks of thrice-weekly sprint interval training (SIT) in healthy men (q < 0.05). Gene co-expression analysis (WGCNA) detected biologically meaningful miRNA networks, five of which were significantly correlated with pre-SIT and post-SIT expression profiles (p < 0.001) and telomere length. Enrichment analysis revealed that the immune response, T cell differentiation and lipid metabolism associated miRNAs clusters were significantly down-regulated after SIT. Using data acquired from the Gene Expression Omnibus (GEO), we also identified two co-expressed miRNAs families that were modulated by exercise training in previous investigations. Collectively, our findings highlight the miRNA networks implicated in exercise adaptations and telomere regulation, and suggest that SIT may attenuate biological ageing through the control of the let-7 and miR-320 miRNA families.

Women's Rugby League: Positional Groups and Peak Locomotor Demands.

The aims of this study were to (a) use a data-based approach to identify positional groups within National Rugby League Women's (NRLW) match-play and (b) quantify the peak locomotor demands of NRLW match-play by positional groups. Microtechnology (Global Navigational Satellite System [GNSS] and integrated inertial sensors; n = 142 files; n = 76 players) and match statistics (n = 238 files; n = 80 players) were collected from all NRLW teams across the 2019 season. Data-based clustering of match statistics was utilized to identify positional clusters through classifying individual playing positions into distinct positional groups. Moving averages (0.5, 1, 2, 3, 5, and 10 min) of peak running and average acceleration/deceleration demands were calculated via microtechnology data for each player per match. All analysis was undertaken in R (R Foundation for Statistical Computing) with positional differences determined via a linear mixed model and effect sizes (ES). Data-based clustering suggested that, when informed by match statistics, individual playing positions can be clustered into one of three positional groups. Based on the clustering of the individual positions, these groups could be broadly defined as backs (fullback, wing, and center), adjustables (halfback, five-eighth, and hooker), and forwards (prop, second-row, and lock). Backs and adjustables demonstrated greater running (backs: ES 0.51-1.00; p < 0.05; adjustables: ES 0.51-0.74, p < 0.05) and average acceleration/deceleration (backs: ES 0.48-0.87; p < 0.05; adjustables: ES 0.60-0.85, p < 0.05) demands than forwards across all durations. Smaller differences (small to trivial) were noted between backs and adjustables across peak running and average acceleration/deceleration demands. Such findings suggest an emerging need to delineate training programs in situations in which individual playing positions train in positional group based settings. Collectively, this work informs the positional groupings that could be applied when examining NRLW data and supports the development of a framework for specifically training female rugby league players for the demands of the NRLW competition.

Collective states and their transitions in football.

Movement, positioning and coordination of player formations is a key aspect for the performance of teams within field-based sports. The increased availability of player tracking data has given rise to numerous studies that focus on the relationship between simple descriptive statistics surrounding team formation and performance. While these existing approaches have provided a high-level a view of team-based spatial formations, there is limited research on the nature of collective movement across players within teams and the establishment of stable collective states within game play. This study draws inspiration from the analysis of collective movement in nature, such as that observed within schools of fish and flocking birds, to explore the existence of collective states within the phases of play in soccer. Order parameters and metrics describing group motion and shape are derived from player movement tracks to uncover the nature of the team's collective states and transitions. This represents a unique addition to the current body of work around the analysis of player movement in team sports. The results from this study demonstrate that sequences of ordered collective behaviours exist with relatively rapid transitions between highly aligned polar and un-ordered swarm behaviours (and vice-versa). Defensive phases of play have a higher proportion of ordered team movement than attacking phases, indicating that movements linked with attacking tactics, such as player dispersion to generate passing and shooting opportunities leads to lower overall collective order. Exploration within this study suggests that defensive tactics, such as reducing the depth or width to close passing opportunities, allows for higher team movement speeds and increased levels of collective order. This study provides a novel view of player movement by visualising the collective states present across the phases of play in football.

Correction to: Quantifying the Collision Dose in Rugby League: A Systematic Review, Meta-analysis, and Critical Analysis.

An amendment to this paper has been published and can be accessed via the original article.

Quantifying the Collision Dose in Rugby League: A Systematic Review, Meta-analysis, and Critical Analysis.

BACKGROUND: Collisions (i.e. tackles, ball carries, and collisions) in the rugby league have the potential to increase injury risk, delay recovery, and influence individual and team performance. Understanding the collision demands of the rugby league may enable practitioners to optimise player health, recovery, and performance. OBJECTIVE: The aim of this review was to (1) characterise the dose of collisions experienced within senior male rugby league match-play and training, (2) systematically and critically evaluate the methods used to describe the relative and absolute frequency and intensity of collisions, and (3) provide recommendations on collision monitoring. METHODS: A systematic search of electronic databases (PubMed, SPORTDiscus, Scopus, and Web of Science) using keywords was undertaken. A meta-analysis provided a pooled mean of collision frequency or intensity metrics on comparable data sets from at least two studies. RESULTS: Forty-three articles addressing the absolute (n) or relative collision frequency (n min-1) or intensity of senior male rugby league collisions were included. Meta-analysis of video-based studies identified that forwards completed approximately twice the number of tackles per game than backs (n = 24.6 vs 12.8), whilst ball carry frequency remained similar between backs and forwards (n = 11.4 vs 11.2). Variable findings were observed at the subgroup level with a limited number of studies suggesting wide-running forwards, outside backs, and hit-up forwards complete similar ball carries whilst tackling frequency differed. For microtechnology, at the team level, players complete an average of 32.7 collisions per match. Limited data suggested hit-up and wide-running forwards complete the most collisions per match, when compared to adjustables and outside backs. Relative to playing time, forwards (n min-1 = 0.44) complete a far greater frequency of collision than backs (n min-1 = 0.16), with data suggesting hit-up forwards undertake more than adjustables, and outside backs. Studies investigating g force intensity zones utilised five unique intensity schemes with zones ranging from 2-3 g to 13-16 g. Given the disparity between device setups and zone classification systems between studies, further analyses were inappropriate. It is recommended that practitioners independently validate microtechnology against video to establish criterion validity. CONCLUSIONS: Video- and microtechnology-based methods have been utilised to quantify collisions in the rugby league with differential collision profiles observed between forward and back positional groups, and their distinct subgroups. The ball carry demands of forwards and backs were similar, whilst tackle demands were greater for forwards than backs. Microtechnology has been used inconsistently to quantify collision frequency and intensity. Despite widespread popularity, a number of the microtechnology devices have yet to be appropriately validated. Limitations exist in using microtechnology to quantify collision intensity, including the lack of consistency and limited validation. Future directions include application of machine learning approaches to differentiate types of collisions in microtechnology datasets.

Exercise tolerance during flat over-ground intermittent running: modelling the expenditure and reconstitution kinetics of work done above critical power.

PURPOSE: We compared a new locomotor-specific model to track the expenditure and reconstitution of work done above critical power (W´) and balance of W´ (W´BAL) by modelling flat over-ground power during exhaustive intermittent running. METHOD: Nine male participants completed a ramp test, 3-min all-out test and the 30-15 intermittent fitness test (30-15 IFT), and performed a severe-intensity constant work-rate trial (SCWR) at the maximum oxygen uptake velocity (vV̇O2max). Four intermittent trials followed: 60-s at vV̇O2max + 50% Δ1 (Δ1 = vV̇O2max - critical velocity [VCrit]) interspersed by 30-s in light (SL; 40% vV̇O2max), moderate (SM; 90% gas-exchange threshold velocity [VGET]), heavy (SH; VGET + 50% Δ2 [Δ2 = VCrit - VGET]), or severe (SS; vV̇O2max - 50% Δ1) domains. Data from Global Positioning Systems were derived to model over-ground power. The difference between critical and recovery power (DCP), time constant for reconstitution of W´ ([Formula: see text]), time to limit of tolerance (TLIM), and W´BAL from the integral (W´BALint), differential (W´BALdiff), and locomotor-specific (OG-W´BAL) methods were compared. RESULTS: The relationship between [Formula: see text] and DCP was exponential (r2 = 0.52). The [Formula: see text] for SL, SM, and SH trials were 119 ± 32-s, 190 ± 45-s, and 336 ± 77-s, respectively. Actual TLIM in the 30-15 IFT (968 ± 117-s) compared closely to TLIM predicted by OG-W´BAL (929 ± 94-s, P > 0.100) and W´BALdiff (938 ± 84-s, P > 0.100) but not to W´BALint (848 ± 91-s, P = 0.001). CONCLUSION: The OG-W´BAL accurately tracked W´ kinetics during intermittent running to exhaustion on flat surfaces.

Storage and handling of human faecal samples affect the gut microbiome composition: A feasibility study.

Human gut microbiome analysis through faecal sampling typically involves five stages: sample collection, storage, DNA extraction, next generation sequencing and bioinformatics analysis. Of these, the first three are considered irreversible. This feasibility study describes an assessment of methodologies used for faecal DNA extraction and sample handling, using the parameters DNA yield, purity and resultant microbial profile. Six DNA extraction techniques, including commercially available kits and manual protocols were compared on human faecal samples (n = 3). Different extraction techniques produced significant variance in DNA yield (range 2.7-164 ng/mg faeces) and microbial diversity profiles, with considerable variation in phyla dominance (Firmicutes (P < 0.001), Bacteroidetes (P = 0.003), Actinobacteria (P = 0.003), One-way ANOVA). The most effective method, with the highest DNA yield, was a simple and inexpensive extraction technique named MetaHIT. Using this method, DNA was extracted from separate faecal samples (n = 3) and had been aliquoted to seven storage conditions including three stabilizing buffers and three temperature conditions, for a period of 120-h, with storage at -80 °C as a control treatment. DNA yield and purity was not statistically different between the control and remaining treatments. 16S rDNA-based diversity profile was largely comparable across the treatments with only minor differences in genera between samples stored at room temperature in air and - 80 °C control. Overall these results suggest that the choice of DNA extraction method has a greater influence on the resultant microbial diversity profile than the short-term storage method.

Modelling the relationships between volume, intensity and injury-risk in professional rugby league players.

OBJECTIVE: This study aimed to: (a) identify the association between external-workloads and injury-risk in the subsequent week; and (b) understand the effectiveness of workload variables in establishing injury-risk. DESIGN: Retrospective cohort study. METHODS: Workload and injury data (soft-tissue) were collected from forty-eight professional male rugby league players. Load variables included duration (min), total distance (m), relative distance (mmin-1), high speed distance ([m]>20kmh-1), very-high speed distance ([m]>25kmh-1), acceleration and deceleration efforts (count) and PlayerLoad (Arbitrary Unit: AU). Cumulative two-, three- and four-weekly loads; Acute:Chronic Workload Ratio (ACWR); Mean-Standard Deviation Workload Ratio (MSWR) and strain values were calculated and divided into three equally-sized bins (low, moderate and high). Generalised Estimating Equations analysed relationships between workload variables and injury probability in the subsequent week. RESULTS: Injury-risk increased alongside increases in the ACWR for duration, total distance and PlayerLoad. Conversely, injury-risk decreased (Area Under Curve: 0.569-0.585) with increases in the four-weekly duration, total distance, accelerations, decelerations and PlayerLoad. For relative distance, high four-weekly workloads (high: >60mmin-1) demonstrated a positive association with injury-risk, whilst high two-weekly loads (high: >82 mmin-1) were negatively associated. CONCLUSIONS: A range of external workload metrics and summary statistics demonstrate either positive or negative associations with injury-risk status. Such findings provide the framework for the development of decision-support systems in which external workload metrics (e.g. total or high speed distance) can be uniquely and routinely monitored across a range of summary statistics (i.e. cumulative weekly loads and ACWR) in order to optimise player performance and welfare.

Small non-coding RNAs are altered by short-term sprint interval training in men.

Small non-coding RNAs (ncRNAs) are emerging as important molecules for normal biological processes and are deregulated in disease. Exercise training is a powerful therapeutic strategy that prevents cardiometabolic disease and improves cardiorespiratory fitness and performance. Despite the known systemic health benefits of exercise training, the underlying molecular mechanisms are incompletely understood. Recent evidence suggests a role for epigenetic mechanisms, such as microRNAs, but whether other small ncRNAs are modulated by chronic exercise training is unknown. Here, we used small RNA sequencing to explore whether sprint interval training (SIT) controls the abundance of circulating small ncRNAs in human whole blood samples. Ten healthy men performed SIT three times a week for 6 weeks. After training, subjects showed marked improvements in maximal oxygen consumption and cycling performance with concurrent changes to the abundance of diverse species of circulating small ncRNAs (n = 1266 small ncRNAs, n = 13 microRNAs, q < 0.05). Twelve microRNAs altered by 6 weeks of SIT were ubiquitously expressed microRNAs and two regulated important signaling pathways, including p53, thyroid hormone and cell cycle signaling. MicroRNAs altered by 6 weeks of SIT were unchanged after a single session of SIT (n = 24, all P > 0.05). Relative to older individuals, younger subjects exhibited an increased acute SIT-induced fold change in miR-1301-3p (P = 0.02) - a microRNA predicted to target mRNAs involved in alternative splicing, phosphoprotein and chromosomal rearrangement processes (all P < 0.001). Our findings indicate many species of circulating small ncRNAs are modulated by exercise training and that they could control signaling pathways responsible for health benefits achieved from exercise.

Modelling Movement Energetics Using Global Positioning System Devices in Contact Team Sports: Limitations and Solutions.

Quantifying the training and competition loads of players in contact team sports can be performed in a variety of ways, including kinematic, perceptual, heart rate or biochemical monitoring methods. Whilst these approaches provide data relevant for team sports practitioners and athletes, their application to a contact team sport setting can sometimes be challenging or illogical. Furthermore, these methods can generate large fragmented datasets, do not provide a single global measure of training load and cannot adequately quantify all key elements of performance in contact team sports. A previous attempt to address these limitations via the estimation of metabolic energy demand (global energy measurement) has been criticised for its inability to fully quantify the energetic costs of team sports, particularly during collisions. This is despite the seemingly unintentional misapplication of the model's principles to settings outside of its intended use. There are other hindrances to the application of such models, which are discussed herein, such as the data-handling procedures of Global Position System manufacturers and the unrealistic expectations of end users. Nevertheless, we propose an alternative energetic approach, based on Global Positioning System-derived data, to improve the assessment of mechanical load in contact team sports. We present a framework for the estimation of mechanical work performed during locomotor and contact events with the capacity to globally quantify the work done during training and matches.

The relationship between lower body stiffness and injury incidence in female netballers.

The aim of this study was to provide contemporary information on injury rates in an elite and sub-elite netball population and to explore the relationship between lower body stiffness and lower body injuries. One elite and two sub-elite teams of female netballers (n = 29) performed the vertical hop test to assess active lower body stiffness (Kvert) and myometry to assess quasi-static stiffness. Lower body injuries were monitored via self-reporting and liaison with physiotherapists. Twelve lower body non-contact injuries were sustained by 10 players, equating to 11.29 lower body injuries per 1,000 exposure hours. The most commonly injured sites were the calf (33%) and ankle (25%). No significant differences between Kvert of injured and non-injured players were reported, however, injured elite players recorded significantly higher season mean quasi-static stiffness in the soleus (p = 0.037) and Achilles (p = 0.004) than non-injured elite players. Elite and sub-elite netball players recorded a higher injury incidence than previous reports of injuries in recreational netballers. Within the constraints of the study, relatively high stiffness of the soleus and Achilles appears to be related to lower body non-contact injury incidence in female netballers, particularly at the elite level. These results provide a basis for development of injury prevention strategies.

The effect of low- vs high-cadence interval training on the freely chosen cadence and performance in endurance-trained cyclists.

The aim of this study was to determine the effects of high- and low-cadence interval training on the freely chosen cadence (FCC) and performance in endurance-trained cyclists. Sixteen male endurance-trained cyclists completed a series of submaximal rides at 60% maximal power (Wmax) at cadences of 50, 70, 90, and 110 r·min(-1), and their FCC to determine their preferred cadence, gross efficiency (GE), rating of perceived exertion, and crank torque profile. Performance was measured via a 15-min time trial, which was preloaded with a cycle at 60% Wmax. Following the testing, the participants were randomly assigned to a high-cadence (HC) (20% above FCC) or a low-cadence (LC) (20% below FCC) group for 18 interval-based training sessions over 6 weeks. The HC group increased their FCC from 92 to 101 r·min(-1) after the intervention (p = 0.01), whereas the LC group remained unchanged (93 r·min(-1)). GE increased from 22.7% to 23.6% in the HC group at 90 r·min(-1) (p = 0.05), from 20.0% to 20.9% at 110 r·min(-1) (p = 0.05), and from 22.8% to 23.2% at their FCC. Both groups significantly increased their total distance and average power output following training, with the LC group recording a superior performance measure. There were minimal changes to the crank torque profile in both groups following training. This study demonstrated that the FCC can be altered with HC interval training and that the determinants of the optimal cycling cadence are multifactorial and not completely understood. Furthermore, LC interval training may significantly improve time-trial results of short duration as a result of an increase in strength development or possible neuromuscular adaptations.