Data should be made as simple as possible but not simpler: The method chosen for dimensionality reduction and its parameters can affect the clustering of runners based on their kinematics.

Dimensionality reduction is a critical step for the efficacy and efficiency of clustering analysis. Despite the multiple available methods, biomechanists have often defaulted to Principal Component Analysis (PCA). We evaluated two PCA- and one autoencoder-based dimensionality reduction methods for their data compression and reconstruction capability, assessed their effect on the output of clustering runners' based on kinematics, and discussed their implications for the biomechanical assessment of running technique.

Consumer-priced wearable sensors combined with deep learning can be used to accurately predict ground reaction forces during various treadmill running conditions.

Ground reaction force (GRF) data is often collected for the biomechanical analysis of running, due to the performance and injury risk insights that GRF analysis can provide. Traditional methods typically limit GRF collection to controlled lab environments, recent studies have looked to combine the ease of use of wearable sensors with the statistical power of machine learning to estimate continuous GRF data outside of these restrictions. Before such systems can be deployed with confidence outside of the lab they must be shown to be a valid and accurate tool for a wide range of users.

Clustering analysis across different speeds reveals two distinct running techniques with no differences in running economy.

Establishing the links between running technique and economy remains elusive due to high inter-individual variability. Clustering runners by technique may enable tailored training recommendations, yet it is unclear if different techniques are equally economical and whether clusters are speed-dependent. This study aimed to identify clusters of runners based on technique and to compare cluster kinematics and running economy.

Tackle direction and preferred side affect upper body loads and movements in rugby union tackling.

Tackling in Rugby Union is associated with most match injuries. New tackle regulations have been explored to reduce injuries, but limited quantitative evidence is available to inform any law changes. Using a novel tackle simulator, we investigated upper body loading under different tackling conditions: direction of approach (0° - frontal, 45° and 90° to the ball carrier direction) and side of body (dominant vs.

The approach towards the ball, rather than the physical characteristics of the kicker, limits accurate rugby place kicking range.

The aim of this study was to understand how a place kicker's range is limited by their approach to the ball and their physical characteristics. Thirty-three kickers performed maximal place kicks and vertical jumps in a laboratory. Whole-body motion and ground reaction forces during the approach phase of the kicks, jump performance and anthropometric measurements of those whose predicted was limited by range (n = 17) rather than accuracy were analysed.

Development and validation of FootNet; a new kinematic algorithm to improve foot-strike and toe-off detection in treadmill running.

The accurate detection of foot-strike and toe-off is often critical in the assessment of running biomechanics. The gold standard method for step event detection requires force data which are not always available. Although kinematics-based algorithms can also be used, their accuracy and generalisability are limited, often requiring corrections for speed or foot-strike pattern.

A joint kinetic analysis of rugby place kicking technique to understand why kickers achieve different performance outcomes.

We aimed to identify differences in kicking leg and torso mechanics between groups of rugby place kickers who achieve different performance outcomes, and to understand why these features are associated with varying levels of success. Thirty-three experienced place kickers performed maximum effort place kicks, whilst three-dimensional kinematic (240 Hz) and ground reaction force (960 Hz) data were recorded. Kicking leg and torso mechanics were compared between the more successful ('long') kickers and two sub groups of less successful kickers ('short' and 'wide-left') using magnitude-based inferences and statistical parametric mapping.

Kicking foot swing planes and support leg kinematics in rugby place kicking: Differences between accurate and inaccurate kickers.

Place kicking is a complex whole-body movement that contributes 45% of the points scored in international Rugby Union. This study compared the kicking foot swing plane characteristics of accurate and inaccurate kickers, underpinned by differences in their support leg and pelvis kinematics at support foot contact, to identify key technique characteristics. Motion capture data (240 Hz) were collected from 33 experienced kickers, and distinct groups of accurate (n = 18) and inaccurate (n = 8) kickers were identified based on their performance characteristics.

Assessing rugby place kick performance from initial ball flight kinematics: development, validation and application of a new measure.

The appropriate determination of performance outcome is critical when appraising a performer's technique. Previous studies of rugby place kicking technique have typically assessed performance based on ball velocity, but this is not the sole requirement. Therefore, a mathematical model of rugby place kick ball flight was developed to yield a single measure more representative of true performance.

Does the Reliability of Reporting in Injury Surveillance Studies Depend on Injury Definition?

Background: Choosing an appropriate definition for injury in injury surveillance studies is essential to ensure a balance among reporting reliability, providing an accurate representation of injury risk, and describing the nature of the clinical demand.

Purpose: To provide guidance on the choice of injury definition for injury surveillance studies by comparing within- and between-team variability in injury incidence with >24-hour and >7-day time-loss injury definitions in a large multiteam injury surveillance study.

Study Design: Cohort study (diagnosis); Level of evidence, 2.

Bend sprinting performance: new insights into the effect of running lane.

Athletes in inner lanes may be disadvantaged during athletic sprint races containing a bend portion because of the tightness of the bend. We empirically investigated the veracity of modelled estimates of this disadvantage and the effect of running lane on selected kinematic variables. Three-dimensional video analysis was conducted on nine male athletes in lanes 8, 5 and 2 of the bend of an outdoor track (radii: 45.

Validity of an Isometric Midthigh Pull Dynamometer in Male Youth Athletes.

Till, K, Morris, R, Stokes, K, Trewartha, G, Twist, C, Dobbin, N, Hunwicks, R, and Jones, B. Validity of an isometric midthigh pull dynamometer in male youth athletes. J Strength Cond Res 32(2): 490-493, 2018-The purpose of this study was to investigate the validity of an isometric midthigh pull dynamometer against a criterion measure (i.

Efficacy of a movement control injury prevention programme in adult men's community rugby union: a cluster randomised controlled trial.

Background: Exercise programmes aimed at reducing injury have been shown to be efficacious for some non-collision sports, but evidence in adult men's collision sports such as rugby union is lacking.

Objective: To evaluate the efficacy of a movement control injury prevention exercise programme for reducing match injuries in adult men's community rugby union players.

Methods: 856 clubs were invited to participate in this prospective cluster randomised (single-blind) controlled trial where clubs were the unit of randomisation.

Subsequent Injuries and Early Recurrent Diagnoses in elite Rugby Union Players.

An eight-season (2005/06-2012/13) prospective cohort design was used to record time-loss injuries in 15 English Premiership teams. Data pertaining to a total of 1 556 players and 9 597 injuries (8 180 subsequent) were included in the analysis. Injuries subsequent to an index injury were classified as (1) New: different site; (2) Local: same site (and different type); or (3) Recurrent: same site and type.

Reducing musculoskeletal injury and concussion risk in schoolboy rugby players with a pre-activity movement control exercise programme: a cluster randomised controlled trial.

Background: Injury risk in youth rugby has received much attention, highlighting the importance of establishing evidence-based injury reduction strategies.

Aim: To determine the efficacy of a movement control exercise programme in reducing injuries in youth rugby players and to investigate the effect of programme dose on injury measures.

Methods: In a cluster-randomised controlled trial, 40 independent schools (118 teams, 3188 players aged 14-18 years) were allocated to receive either the intervention or a reference programme, both of which were to be delivered by school coaches.

How Much Rugby is Too Much? A Seven-Season Prospective Cohort Study of Match Exposure and Injury Risk in Professional Rugby Union Players.

Introduction: Numerous studies have documented the incidence and nature of injuries in professional rugby union, but few have identified specific risk factors for injury in this population using appropriate statistical methods. In particular, little is known about the role of previous short-term or longer-term match exposures in current injury risk in this setting.

Objectives: Our objective was to investigate the influence that match exposure has upon injury risk in rugby union.

Concussions and Head Injuries in English Community Rugby Union Match Play.

Background: Previous research has described general injury patterns in community-level rugby union, but specific information on time-loss head injuries has not been reported.

Purpose: To establish the incidence and nature of significant time-loss head injuries in English community rugby match play, and to identify the injury risk for specific contact events.

Study Design: Descriptive epidemiology study.

Cervical Spine Injuries: A Whole-Body Musculoskeletal Model for the Analysis of Spinal Loading.

Cervical spine trauma from sport or traffic collisions can have devastating consequences for individuals and a high societal cost. The precise mechanisms of such injuries are still unknown as investigation is hampered by the difficulty in experimentally replicating the conditions under which these injuries occur. We harness the benefits of computer simulation to report on the creation and validation of i) a generic musculoskeletal model (MASI) for the analyses of cervical spine loading in healthy subjects, and ii) a population-specific version of the model (Rugby Model), for investigating cervical spine injury mechanisms during rugby activities.

Monitoring What Matters: A Systematic Process for Selecting Training-Load Measures.

Purpose: Numerous derivative measures can be calculated from the simple session rating of perceived exertion (sRPE), a tool for monitoring training loads (eg, acute:chronic workload and cumulative loads). The challenge from a practitioner's perspective is to decide which measures to calculate and monitor in athletes for injury-prevention purposes. The aim of the current study was to outline a systematic process of data reduction and variable selection for such training-load measures.

Specific tackling situations affect the biomechanical demands experienced by rugby union players.

Tackling in Rugby Union is an open skill which can involve high-speed collisions and is the match event associated with the greatest proportion of injuries. This study aimed to analyse the biomechanics of rugby tackling under three conditions: from a stationary position, with dominant and non-dominant shoulder, and moving forward, with dominant shoulder. A specially devised contact simulator, a 50-kg punch bag instrumented with pressure sensors, was translated towards the tackler (n = 15) to evaluate the effect of laterality and tackling approach on the external loads absorbed by the tackler, on head and trunk motion, and on trunk muscle activities.

Hip joint contact loads in older adults during recovery from forward loss of balance by stepping.

Hip joint contact loads during activities of daily living are not generally considered high enough to cause acute bone or joint injury. However there is some evidence that hip joint loads may be higher in stumble recovery from loss of balance. A common laboratory method used to evaluate balance recovery performance involves suddenly releasing participants from various static forward lean magnitudes (perturbation intensities).

Professional Rugby Union players have a 60% greater risk of time loss injury after concussion: a 2-season prospective study of clinical outcomes.

Aim: To investigate incidence of concussion, clinical outcomes and subsequent injury risk following concussion.

Methods: In a two-season (2012/2013, 2013/2014) prospective cohort study, incidence of diagnosed match concussions (injuries/1000 h), median time interval to subsequent injury of any type (survival time) and time spent at each stage of the graduated return to play pathway were determined in 810 professional Rugby Union players (1176 player seasons).

Results: Match concussion incidence was 8.

Time loss injuries compromise team success in Elite Rugby Union: a 7-year prospective study.

Background: A negative association between injuries and team success has been demonstrated in professional football, but the nature of this association in elite Rugby Union teams is currently unclear.

Aim: To assess the association between injury burden measures and team success outcomes within professional Rugby Union teams.

Methods: A seven-season prospective cohort design was used to record all time-loss injuries incurred by English Premiership players.

Incidence and Nature of Medical Attendance Injuries in English Community Rugby Union.

Background: Previous research has identified injury patterns during community-level rugby union match play, but none have investigated the frequency and reasons for on-field injury management.

Purpose: To establish the frequency, reasons, and patterns of on-field injury management in English community rugby, including differences between different levels of play.

Study Design: Descriptive epidemiology study.