Biceps femoris long head muscle and aponeurosis geometry in males with and without a history of hamstring strain injury.

OBJECTIVES: Hamstring strain injuries (HSIs) commonly affect the proximal biceps femoris long head (BFlh) musculotendinous junction. Biomechanical modeling suggests narrow proximal BFlh aponeuroses and large muscle-to-aponeurosis width ratios increase localized tissue strains and presumably risk of HSI. This study aimed to determine if BFlh muscle and proximal aponeurosis geometry differed between limbs with and without a history of HSI. METHODS: Twenty-six recreationally active males with (n = 13) and without (n = 13) a history of unilateral HSI in the last 24 months underwent magnetic resonance imaging of both thighs. BFlh muscle and proximal aponeurosis cross-sectional areas, length, volume, and interface area between muscle and aponeurosis were extracted. Previously injured limbs were compared to uninjured contralateral and control limbs for discrete variables and ratios, and along the relative length of tissues using statistical parametric mapping. RESULTS: Previously injured limbs displayed significantly smaller muscle-to-aponeurosis volume ratios (p = 0.029, Wilcoxon effect size (ES) = 0.43) and larger proximal BFlh aponeurosis volumes (p = 0.019, ES = 0.46) than control limbs with no history of HSI. No significant differences were found between previously injured and uninjured contralateral limbs for any outcome measure (p = 0.216-1.000, ES = 0.01-0.36). CONCLUSIONS: Aponeurosis geometry differed between limbs with and without a history of HSI. The significantly larger BFlh proximal aponeuroses and smaller muscle-to-aponeurosis volume ratios in previously injured limbs could alter the strain experienced in muscle adjacent to the musculotendinous junction during active lengthening. Future research is required to determine if geometric differences influence the risk of re-injury and whether they can be altered via targeted training.

Quantifying demands on the hamstrings during high-speed running: A systematic review and meta-analysis.

INTRODUCTION: Hamstring strain injury (HSI) remains a performance, economic, and player availability burden in sport. High-speed running (HSR) is cited as a common mechanism for HSI. While evidence exists regarding the high physical demands on the hamstring muscles in HSR, meta-analytical synthesis of related activation and kinetic variables is lacking. METHODS: A systematic search of Medline, Embase, Scopus, CINAHL, SportDiscus, and Cochrane library databases was conducted in accordance with the PRISMA 2020 guidelines. Studies reporting hamstring activation (electromyographic [EMG]) or hamstring muscle/related joint kinetics were included where healthy adult participants ran at or beyond 60% of maximum speed (activation studies) or 4 m per second (m/s) (kinetic studies). RESULTS: A total of 96 studies met the inclusion criteria. Run intensities were categorized as "slow," "moderate," or "fast" in both activation and kinetic based studies with appropriate relative, and raw measures, respectively. Meta-analysis revealed pooled mean lateral hamstring muscle activation levels of 108.1% (95% CI: 84.4%-131.7%) of maximal voluntary isometric contraction (MVIC) during "fast" running. Meta-analysis found swing phase peak knee flexion internal moment and power at 2.2 Newton meters/kilogram (Nm/kg) (95% CI: 1.9-2.5) and 40.3 Watts/kilogram (W/kg) (95% CI: 31.4-49.2), respectively. Hip extension peak moment and power was estimated as 4.8 Nm/kg (95% CI: 3.9-5.7) and 33.1 W/kg (95% CI: 17.4-48.9), respectively. CONCLUSIONS: As run intensity/speed increases, so do the activation and kinetic demands on the hamstrings. The presented data will enable clinicians to incorporate more objective measures into the design of injury prevention and return-to-play decision-making strategies.

Variations in Concurrent Validity of Two Independent Inertial Measurement Units Compared to Gold Standard for Upper Body Posture during Computerised Device Use.

Inertial measurement units (IMUs) may provide an objective method for measuring posture during computer use, but research is needed to validate IMUs' accuracy. We examine the concurrent validity of two different IMU systems in measuring three-dimensional (3D) upper body posture relative to a motion capture system (Mocap) as a potential device to assess postures outside a laboratory environment. We used 3D Mocap and two IMU systems (Wi-Fi and Bluetooth) to capture the upper body posture of twenty-six individuals during three physical computer working conditions (monitor correct, monitor raised, and laptop). Coefficient of determination (R2) and root-mean-square error (RMSE) compared IMUs to Mocap. Head/neck segment [HN], upper trunk segment [UTS], and joint angle [HN-UTS] were the primary variables. Wi-Fi IMUs demonstrated high validity for HN and UTS (sagittal plane) and HN-UTS (frontal plane) for all conditions, and for HN rotation movements (both for the monitor correct and monitor raised conditions), others moderate to poor. Bluetooth IMUs for HN, and UTS (sagittal plane) for the monitor correct, laptop, and monitor raised conditions were moderate. Frontal plane movements except UTS (monitor correct and laptop) and all rotation had poor validity. Both IMU systems were affected by gyroscopic drift with sporadic data loss in Bluetooth IMUs. Wi-Fi IMUs had more acceptable accuracy when measuring upper body posture during computer use compared to Mocap, except for trunk rotations. Variation in IMU systems' performance suggests validation in the task-specific movement(s) is essential.

Evidence for the Effectiveness of Feedback from Wearable Inertial Sensors during Work-Related Activities: A Scoping Review.

Background: Wearable inertial sensor technology (WIST) systems provide feedback, aiming to modify aberrant postures and movements. The literature on the effects of feedback from WIST during work or work-related activities has not been previously summarised. This review examines the effectiveness of feedback on upper body kinematics during work or work-related activities, along with the wearability and a quantification of the kinematics of the related device. Methods: The Cinahl, Cochrane, Embase, Medline, Scopus, Sportdiscus and Google Scholar databases were searched, including reports from January 2005 to July 2021. The included studies were summarised descriptively and the evidence was assessed. Results: Fourteen included studies demonstrated a 'limited' level of evidence supporting posture and/or movement behaviour improvements using WIST feedback, with no improvements in pain. One study assessed wearability and another two investigated comfort. Studies used tri-axial accelerometers or IMU integration (n = 5 studies). Visual and/or vibrotactile feedback was mostly used. Most studies had a risk of bias, lacked detail for methodological reproducibility and displayed inconsistent reporting of sensor technology, with validation provided only in one study. Thus, we have proposed a minimum 'Technology and Design Checklist' for reporting. Conclusions: Our findings suggest that WIST may improve posture, though not pain; however, the quality of the studies limits the strength of this conclusion. Wearability evaluations are needed for the translation of WIST outcomes. Minimum reporting standards for WIST should be followed to ensure methodological reproducibility.

Jump-landing mechanics in patellar tendinopathy in elite youth basketballers.

Patellar tendinopathy (PT) is a leading cause of morbidity in jump-landing athletes. Landing mechanics are identified as a factor associated with PT and/or patellar tendon abnormality. This study aimed to identify key jump-landing variables associated with PT. Thirty-six junior elite basketball players (men n = 18, women n = 18) were recruited from a Basketball Australia development camp. Three-dimensional (3D) kinematic and ground reaction force (GRF) data during a stop-jump task were collected as well as ultrasound scans of the patellar tendons and recall history of training load data. Mixed-model factorial analyses of variance were used to determine any significant between-group differences. Of the 23 participants included for statistical analyses, 11 had normal bilateral patellar tendons (controls) and eight reported PT (currently symptomatic); however, the four participants categorized as asymptomatic with patellar tendon abnormality on diagnostic imaging were excluded from statistical analyses due to their small sample size. Athletes with PT displayed a similar knee flexion angle at initial foot-ground contact (IC) and hip extension strategy during a stop-jump horizontal landing. Despite a similar kinematic technique, athletes with PT utilized a strategy of a longer stance duration phase from IC to peak force. This strategy did not lead to those athletes with PT decreasing their peak vertical GRF nor patellar tendon force during landing but enabled these athletes to land with a lower rate of loading (control 59.2 ± 39.3 vs. PT 29.4 ± 33.7 BW.s-1). Athletes with PT still reported significantly reduced training volume (control 4.9 ± 1.8 vs PT 1.8 ± 1.1 sessions/wk; total training time/wk control 2.4 ± 1.0 vs PT 1.4 ± 1.1 h/wk).

A biomechanical comparison of conventional classifications of bowling action-types in junior fast bowlers.

Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase.

A Pilot Longitudinal Study of 3-Dimensional Head and Neck Kinematics During Functional Tasks in Individuals With Chronic Idiopathic Neck Pain Either Wait-Listed for or Receiving Chiropractic Spinal Manipulative Therapy With Exercise.

OBJECTIVE: The purpose of this study was to determine if there is a relationship between pain and movement kinematics during functional tasks, evaluated over time, in individuals with chronic idiopathic neck pain. METHODS: Ten participants with chronic idiopathic neck pain performed 2 functional tasks (overhead reach to the right and putting on a seatbelt) while evaluated using 8 Oqus 300+ cameras. Kinematic variables included joint angles and range of motion (ROM) (°), head segment relative to neck segment (head-neck [HN]); and head/neck segment relative to upper thoracic segment (head/neck-trunk), velocity (m/s), and time (% of movement phase). Pain was quantified using a 100-mm visual analog scale. Linear mixed effects regression models were used to analyze associations between pain and kinematic variables adjusting for treatment group. RESULTS: For overhead reach, higher pain was associated with less HN peak rotation at baseline (ß = -0.33; 95% CI -0.52 to -0.14, P = .003) and less HN total rotation ROM at 6 months (ß = -0.19; 95% CI -0.38 to -0.003, P = .048). For the seatbelt task, higher pain was associated with less HN peak rotation (ß = -0.52; 95% CI -0.74 to -0.30 to -0.74, P < .001) and less HN total rotation ROM at baseline (ß = -0.32; 95% CI -0.53 to -0.10, P = .006). No other movement variables demonstrated meaningful relationships with pain for the reach or seatbelt tasks. CONCLUSION: Higher pain is associated with less HN peak and total rotation during functional reaching tasks requiring head rotation. Recognizing altered functional kinematics in individuals with chronic neck pain may assist patient management.

Development of a deep neural network for automated electromyographic pattern classification.

Determining the signal quality of surface electromyography (sEMG) recordings is time consuming and requires the judgement of trained observers. An automated procedure to evaluate sEMG quality would streamline data processing and reduce time demands. This paper compares the performance of two supervised and three unsupervised artificial neural networks (ANNs) in the evaluation of sEMG quality. Manually classified sEMG recordings from various lower-limb muscles during motor tasks were used to train (n=28,000), test performance (n=12,000) and evaluate accuracy (n=47,000) of the five ANNs in classifying signals into four categories. Unsupervised ANNs demonstrated a 30-40% increase in classification accuracy (>98%) compared with supervised ANNs. AlexNet demonstrated the highest accuracy (99.55%) with negligible false classifications. The results indicate that sEMG quality evaluation can be automated via an ANN without compromising human-like classification accuracy. This classifier will be publicly available and will be a valuable tool for researchers and clinicians using electromyography.

Caution using data from triaxial accelerometers housed in player tracking units during running.

Usage of accelerometers within player tracking devices in sport to quantify load, vertical ground reaction force (vGRF) or energy expenditure is contrary to placement guidelines. This study aimed to determine whether trunk-mounted accelerometers were a valid and reliable method to estimate thoracic segment or centre of gravity (COG) acceleration or vGRF, and the whether the elasticised harness contributes to the overestimation of acceleration. Ten male amateur rugby players performed five linear running tasks per lower limb at three speeds, twice, each with a different player tracking unit. Three-dimensional data were recorded and triaxial accelerometers were attached lateral to the device on the harness and skin and both shanks. Accelerometers demonstrated poor reliability (ICC:0.0-0.67), high variability (CV%:14-33%) and change in mean (41-160%), and were not valid to estimate vertical acceleration of the COG and thoracic segment nor vGRF. Caution is advised when utilising trunk-mounted triaxial accelerometer data as it is not a valid or reliable means to estimate peak vertical acceleration for its thoracic location nor whole-body COG acceleration or vGRF during running. To improve player tracking instrument validity and reliability, a new attachment method and/or harness material(s), that reduce or eliminate extraneous acceleration during running, are urgently required.

Consistency of kinematic and kinetic patterns during a prolonged spell of cricket fast bowling: an exploratory laboratory study.

Due to the high incidence of lumbar spine injury in fast bowlers, international cricket organisations advocate limits on workload for bowlers under 19 years of age in training/matches. The purpose of this study was to determine whether significant changes in either fast bowling technique or movement variability could be detected throughout a 10-over bowling spell that exceeded the recommended limit. Twenty-five junior male fast bowlers bowled at competition pace while three-dimensional kinematic and kinetic data were collected for the leading leg, trunk and bowling arm. Separate analyses for the mean and within-participant standard deviation of each variable were performed using repeated measures factorial analyses of variance and computation of effect sizes. No substantial changes were observed in mean values or variability of any kinematic, kinetic or performance variables, which instead revealed a high degree of consistency in kinematic and kinetic patterns. Therefore, the suggestion that exceeding the workload limit per spell causes technique- and loading-related changes associated with lumbar injury risk is not valid and cannot be used to justify the restriction of bowling workload. For injury prevention, the focus instead should be on the long-term effect of repeated spells and on the fast bowling technique itself.

Reliability of a Squat Movement Competency Screen in Individuals With a Previous Knee Injury.

CONTEXT: Movement screens are a common method of assessing movement efficiency either against a specific criterion of segments/joint(s) motion (segmental method) or a summary label of general quality of the whole movement (overall method). While not as commonly utilized within clinical practice as the segmental method, the overall method is less time consuming to perform and more reliable. OBJECTIVES: The aim of this study was to assess the reliability of the "overall" method approach during a squat in individuals with a previous knee joint injury. DESIGN: Cross-sectional, clinical measurement. PARTICIPANTS: Two-dimensional video recordings of 5 squat trials were recorded for 16 participants with a history of a major knee joint injury(s) and were visually rated by 3 novice and 3 expert raters. MAIN OUTCOME MEASURES: Weighted quadratic Kappa was used to determine the intra- and inter-rater reliability of the squat movement competency screen. RESULTS: Good inter-rater reliability for the expert and novice groups was observed. Intra-rater reliability was very good between analysis sessions for 1 expert rater. CONCLUSIONS: The overall method is a reliable method that enables allied health professionals of different levels of clinical experience to utilize a framework to assess movement quality during a squat in patients with a previous knee joint injury.

Asymptomatic players with a patellar tendon abnormality do not adapt their landing mechanics when fatigued.

This study aimed to explore how asymptomatic athletes with a patellar tendon abnormality (PTA), who are at high risk of developing patellar tendinopathy, alter their landing technique and net patellar tendon loads generated in response to fatigue. Seven asymptomatic players with a PTA performed five successful vertical stop-jump trials before and after a fatigue protocol. Fatigue protocol involved participants repeatedly performing sets of 30 submaximal jump exercises on a sledge apparatus followed by 30 s rest until the task failure criteria were reached. Three-dimensional ground reaction forces, lower limb kinematics and net peak patellar tendon force were recorded during the stop-jump task. No significant between-fatigue condition differences in net patellar tendon loading, or most secondary outcome variables were observed. Only some fatigue changes were seen during the vertical landing phase. Asymptomatic PTA participants did not modify their landing technique or net patellar tendon loading during a stop-jump task in response to fatigue. The lack of between-fatigue condition differences displayed by the asymptomatic PTA participants during both landing phases suggest that these individuals may not be capable of sufficient movement variability in their landing strategies to adapt to fatigue.

The Role of the Trunk Control in Athletic Performance of a Reactive Change-of-Direction Task.

Edwards, S, Austin, AP, and Bird, SP. The role of the trunk control in athletic performance of a reactive change-of-direction task. J Strength Cond Res 31(1): 126-139, 2017-Agility is vital to success in team sport competition with the trunk argued to play a key role in sport performance. This study explored the role of trunk control during a reactive change-of-direction task (R-COD) and field-based measures of athletic performance. Twenty male players completed field-based athletic performance assessments (modified Illinois agility test [mIAT], 3 repetition maximum back squat, and 5 countermovement jumps [CMJ]) and R-CODs, during which 3-dimensional ground reaction forces and kinematics were recorded. Trunk control was assessed as the sum of the trunk relative to the pelvis range of motion (ROM) in all 3 planes during the R-COD. Participants with the highest (HIGH, n = 7) and lowest (LOW, n = 7) trunk ROM values were grouped. The HIGH group achieved significantly shorter mIAT time duration, higher CMJ height, and lower knee flexion angles, greater trunk lateral flexion and rotation relative to pelvis, and greater angular momentum during the R-COD compared with the LOW group. Superior athletic performance was associated with decreased trunk control (high trunk ROM) during the R-COD. Although this study suggested that trunk control is a vital component of performance, it is unknown whether this trunk control is inherent or an effect of training history, nor does not support current optimal athletic performance recommendation of decreased trunk motion during R-COD.

Tacklers' shoulder abduction and flexion at contact alter when engaging in different front-on, one-on-one tackle instructions from an expert coach.

OBJECTIVES: To ascertain how the three-dimensional shoulder kinematics of tacklers alter when performing four legal types of front-on, one-on-one, rugby-style torso tackles. DESIGN: Controlled laboratory study. METHODS: Three-dimensional motion capture measured 15 male amateur-level rugby code players (24.3 ±â€¯6.1 years) who were instructed by an expert coach to perform four sets of 10 front-on, one-on-one tackles. Four sets comprised two smother and two dominant tackles: two based on the Australian National Rugby League coaching manual (Dominant NRL, Smother NRL); and two modifications via increasing the contact height from the lower- to mid-torso (Dominant, Torso Stick) or from the upper- to mid-upper torso with a vertical 'pop action' that changes the way the tackler contacted the ball carrier's upper torso (Smother, Pop, Lock). Mixed general linear models were applied. RESULTS: Greater shoulder abduction, flexion and internal rotation were displayed by the DNRL tackle technique than in any other technique (p < 0.001). At contact, the Smother and Dominant NRL (p < 0.03) showed greater head-uptrunk contralateral rotation away from the tackle than the Smother, Pop, Lock. CONCLUSIONS: Tacklers modified the way they positioned their shoulder joint when engaging in legal front-on, one-on-one tackles with different tackle instructions. More prominent positions of shoulder abduction and flexion, and head-uptrunk contralateral rotation were observed when executing the traditional tackle techniques (Smother NRL, Dominant NRL) as opposed to two variants of these (Smother, Pop, Lock, Dominant, Torso Stick). Inclusion of tackle specific coaching instructions provides emerging scientific evidence to support revised coaching tackling technique interventions that might enhance player safety.

Tackle Risk Factors for Head Injury Assessments (HIAs) in Sub-Elite Rugby League and Recommendations for Prevention: Head Contacts from Upright Tackles Increase the HIA Risk to Both Ball Carrier and Tackler.

BACKGROUND: The rugby league tackle has been identified as the game event with the greatest propensity for a clinically diagnosed concussion. This study aims to replicate the work conducted in professional rugby league and rugby union by examining Head Injury Assessment (HIA) events to determine the associated tackle characteristics that increase concussion risk in sub-elite rugby league players. This comparison between competition levels is important due to the less developed physiological and tackle proficiency characteristics of sub-elite rugby league players and the fewer resources available for an on-field diagnosis, compared to the elite level of the sport. RESULTS: Tackles resulting in Head Injury Assessments (HIAs, n = 131) and 2,088 tackles that did not result in a head injury were identified and coded from one season of the 2019 Queensland Cup. The body position of both ball carrier and tackler, tackle height, and body contact areas were evaluated. The propensity for tacklers to undergo a head injury assessment was 1.49 HIAs per 1,000 tackles, equating to a 2.5-fold higher risk than that of the ball carrier (0.59 HIAs per 1,000 tackles). The risk for an HIA was 2.75-fold greater when the tackler was upright (2.89 HIAs per 1,000 tackles) compared to a bent-at-the-waist tackler (1.05 HIAs per 1,000 tackles). The greatest risk for the tackler and ball carrier sustaining an HIA occurred when the tackle height was high, with head-to-head contact having the greatest propensity for an HIA (44.37 HIAs per 1,000 tackles). HIA risk was also greater for both players when the ball carrier did not employ an evasion strategy (3.73 HIAs per 1,000 tackles). CONCLUSIONS: The study replicates results from research in elite rugby league and rugby union. A combination of higher head contact/proximity and upright body position significantly increase an HIA risk. Tackler head position and ball carrier evasion behaviours also affect risk, suggesting that injury prevention strategies designed to reduce tackle height and improve tackle technique by focusing on head position, body position, and in a novel finding, ball carrier evasion, may reduce head injury risk in sub-elite rugby league players.

Injury-Reduction Programs Containing Neuromuscular Neck Exercises and the Incidence of Soccer-Related Head and Neck Injuries.

CONTEXT: Concern is growing among soccer players, coaches, and parents regarding head and neck injuries, including concussion, particularly from heading a ball. Thus, we need to explore soccer-specific head injury risk-reduction initiatives. One such initiative is to condition the neck musculature of young players by adding neuromuscular neck exercises to existing injury-reduction exercise programs. OBJECTIVE: To investigate the effect of neuromuscular neck exercises completed as part of an injury risk-reduction exercise program on the incidence of soccer-related head and neck injuries in adolescent soccer players. DESIGN: Prospective cohort study. SETTING: Two sports high schools and 6 soccer clubs during the 2021 soccer season. PATIENTS OR OTHER PARTICIPANTS: A total of 364 male and female soccer players, aged 12 to 18 years. INTERVENTION(S): Members of 1 sports high school and 2 soccer clubs performed neuromuscular neck exercises as part of an injury-reduction program during training (neck training group). Members of another sports high school and 4 soccer clubs performed an injury-reduction program but without neck exercises (comparison group). MAIN OUTCOME MEASURE(S): Self-reported injury data were collected from each player at the end of the season and used to calculate incidence rate ratios (IRRs) with 95% CIs. RESULTS: In total, 364 players completed the study, including 146 players in the neck training group and 218 players in the comparison group. Despite players in the neck training group being less likely to self-report a concussion (IRR = 0.23; 95% CI = 0.03, 1.04) and pain on heading a ball (IRR = 0.62; 95% CI = 0.34, 1.07), only a lower incidence of possible concussive events (IRR = 0.38; 95% CI = 0.14, 0.90; P < .05) was significant. CONCLUSIONS: Integrating neuromuscular neck exercises into injury-reduction exercise programs has the potential to reduce the risk of adolescent soccer players sustaining a possible concussive event, concussion, or pain on heading a ball.

The impact of previous musculoskeletal injury on running gait variability: A systematic review.

BACKGROUND: Growing evidence suggests that identifying movement variability alterations in pathological vs. healthy gait may further understanding of injury mechanisms related to gait biomechanics; however, in the context of running and musculoskeletal injuries the role of movement variability remains unclear. RESEARCH QUESTION: What is the impact of a previous musculoskeletal injury on running gait variability? METHODS: Medline, CINAHL, Embase, Cochrane library and SPORTDiscus were searched from inception until February 2022. Eligibility criteria were (a) included a musculoskeletal injury group, (b) compared running biomechanics data to a control group, (c) measured movement variability for at least one dependent variable, (d) provided a statistical between-group comparison of variability outcomes. Exclusion criteria were neurological conditions impacting gait, upper body musculoskeletal injuries and age < 18 years old. A summative synthesis was performed instead of a meta-analysis due to methodological heterogeneity. RESULTS: Seventeen case-control studies were included. The most common deviations in variability observed among the injured groups were: (1) high and low knee-ankle/foot coupling variability and (2) low trunk-pelvis coupling variability. Significant (p < 0.05) between-group differences in movement variability were identified in 8 of 11; 73% of studies of runners with injury-related symptoms, and 3 of 7; 43% of studies of recovered or asymptomatic populations. SIGNIFICANCE: This review identified limited to strong evidence that running variability is altered in adults with a recent history of injury for specific joint couplings only. Individuals with ankle instability or pain employed altered running strategies more often than those who have recovered from injury. Altered variability strategies have been proposed to contribute to future running-related injuries, therefore these findings are relevant to clinicians managing active populations.

A case-control study of tackle based head impact event (HIE) risk factors from the first three seasons of the National Rugby League Women's competition.

Objective: The tackle is the most injurious event in rugby league and carries the greatest risk of concussion. This study aims to replicate previous research conducted in professional men's rugby league by examining the association between selected tackle characteristics and head impact events (HIEs) in women's professional rugby league. Methods: We reviewed and coded 83 tackles resulting in an HIE and every tackle (6,318 tackles) that did not result in an HIE for three seasons (2018-2020) of the National Rugby League Women's (NRLW) competition. Tackle height, body position of the tackler and ball carrier, as well as the location of head contact with the other player's body were evaluated. Propensity of each situation that caused an HIE was calculated as HIEs per 1,000 tackles. Results: The propensity for tacklers to sustain an HIE was 6.60 per 1,000 tackles (95% CI: 4.87-8.92), similar to that of the ball carrier (6.13 per 1,000 tackles, 95% CI: 4.48-8.38). The greatest risk of an HIE to either the tackler or ball carrier occurred when head proximity was above the sternum (21.66 per 1,000 tackles, 95% CI: 16.55-28.35). HIEs were most common following impacts between two heads (287.23 HIEs per 1,000 tackles, 95% CI: 196.98-418.84). The lowest propensity for both tackler (2.65 per 1,000 tackles, 95% CI: 0.85-8.20) and ball carrier HIEs (1.77 per 1,000 tackles, 95% CI: 0.44-7.06) occurred when the head was in proximity to the opponent's shoulder and arm. No body position (upright, bent or unbalanced/off feet) was associated with an increased propensity of HIE to either tackler or ball carrier. Conclusions: In the NRLW competition, tacklers and ball carriers have a similar risk of sustaining an HIE during a tackle, differing from men's NRL players, where tacklers have a higher risk of HIEs. Further studies involving larger samples need to validate these findings. However, our results indicate that injury prevention initiatives in women's rugby league should focus on how the ball carrier engages in contact during the tackle as well as how the tackler executes the tackle.

Differences in upper body posture between individuals with and without chronic idiopathic neck pain during computerised device use: A 3D motion analysis study.

BACKGROUND: Computer use is associated with poor postures and increased risk of developing neck pain. Evaluating differences in working posture of individuals with and without chronic neck pain may assist the development of strategies to lessen or prevent pain. OBJECTIVE: To identify if upper body kinematics differs between individuals with and without chronic idiopathic neck pain during four conditions (tablet, laptop, and desktop computer sitting and standing). METHODS: Three-dimensional (3D) motion capture measured upper body kinematics in 44 individuals with chronic idiopathic neck pain > 90 days (Cases n = 22) and without pain (Control n = 22), during a typing task under four conditions: tablet, laptop, desktop computer (sitting and standing). Differences between groups were evaluated using generalised linear mixed models. RESULTS: Across all conditions and compared to controls, cases had significantly less flexion between their head-neck and upper trunk segments (between group mean difference 7.15°, 2.1, 12.2, p = .006), greater upper trunk flexion relative to the laboratory (-6.15°, -10.9, -1.3, p = .012), greater shoulder flexion bilaterally (left 12.35°, 6.7, 17.9, p < .001; right 13.49°, 7.9, 19.1, p < .001) and less right elbow flexion (-6.87°, -12.1, -1.7, p = .010). Approaching significance, the case group had less left elbow flexion (between group mean difference -5.36°, -10.9, 0.1, p = .056) and a smaller mean craniocervical angle for the seated desktop condition (group x condition interaction -6.37°; 95% CI -12.7, -0.1, p = .052). SIGNIFICANCE: Individuals with neck pain consistently used different upper body postures compared to individuals without pain when working on computerised devices under varying workstation conditions. This finding suggests that people with neck pain work in potentially aggravating postures that may be associated with their pain.

Comparisons of cervical and thoracic spine kinematic joint and body segment angles, timing, and velocity between individuals with and without chronic idiopathic neck pain during functional tasks.

BACKGROUND: Few studies comprehensively analyse 3D neck kinematics in individuals with chronic idiopathic neck pain during functional tasks considered challenging. This critical knowledge is needed to assist clinicians to recognise and address how altered movement strategies might contribute to pain. RESEARCH QUESTION: Are there differences in 3D neck kinematics (angles, timing, velocity) during functional tasks in people with chronic neck pain compared to matched asymptomatic control participants? METHODS: Participants with chronic idiopathic neck pain (n = 33) and matched asymptomatic controls (n = 30) performed four functional tasks (overhead reach forward, right and left, and putting on a seatbelt) while evaluated using 3D motion capture. Kinematic variables included joint angles, range of motion (ROM,°), velocity (m s-1) and timing (% of movement phase) for joint angles (head-neck [HN joint], head+neck-upper trunk [HNT], and thoracolumbar) and segments (head, neck, head+neck [HN segment], upper trunk, and trunk. Generalised linear mixed models examined between-group differences. RESULTS: There were few between-group differences. The neck pain group had less HN segment extension that controls (mean difference [MD] left -2.06°; 95% CI -3.82, -0.29; p = .023; and right reach -2.52°; -4.67, -0.37; P = .022), and had less total sagittal HNT ROM across all tasks (-1.28; 95% CI -2.25, -0.31; p = .010). Approaching significance was the pain group having less thoracolumbar left rotation than controls (MD -2.14, 95% CI -4.41 to 0.13, p = .064). The pain group had higher neck segment peak flexion velocity than controls across all tasks (MD -3.09; 95% CI -5.21 to -0.10; P = .004). Timing of joint angle peaks did not differ between groups. SIGNIFICANCE: When performing an overhead reach task to the left and right and putting on a seatbelt, people with neck pain maintain a more flexed HN segment, use less sagittal ROM and have higher velocity peaks. These findings can assist clinicians in their assessment of patients by identifying possible underlying contributors to neck pain.