Toxic tau: The TAU gene polymorphisms associate with concussion history in rugby union players

Objectives

Concussion is a brain injury that occurs when biomechanical forces are transmitted to the head region resulting in neurological deficits. The accumulation of tau protein in autopsies of athletes with multiple concussions implicates tau in concussion-associated neurodegeneration. The TAU rs2435211 (C > T) and rs2435200 (G > A) polymorphisms are involved in pathological tau expression and neurodegenerative disease risk. The aims of this study were to investigate the associations of TAU (rs2435211, rs2435200) polymorphisms with concussion history and sustaining multiple concussions in rugby.

Entropy measures detect increased movement variability in resistance training when elite rugby players use the ball

Objectives

This study described the variability in acceleration during a resistance training task, performed in horizontal inertial flywheels without (NOBALL) or with the constraint of catching and throwing a rugby ball (BALL).

The validity of the sphygmomanometer for shoulder strength assessment in amateur rugby union players

ObjectivesTo determine the concurrent validity of a sphygmomanometer for assessing shoulder strength in the I, Y and T positions during the athletic shoulder test (ASH test). Force platforms were used as the gold standard measurement tool for this purpose.DesignShoulder strength was assessed using force platforms and a sphygmomanometer, both placed on the floor and the participant positioned prone. One rater assessed strength, taking three measurements in each of the I, Y and T positions, using the sphygmomanometer and force platforms. Concurrent validity was calculated using the force platforms as the gold standard device.SettingData was collected within the treatment room of an amateur rugby club.ParticipantsTwenty male amateur rugby players (25.15 years old ± 3.27 years) were recruited for this study.Main outcome measuresPeak force across the shoulder girdle was assessed using the force platforms and sphygmomanometer which provided values in Newtons (N) and millimetres of mercury (mmHg) respectively.ResultsResults showed high concurrent validity (Pearsons r = 0.76–0.81) between the sphygmomanometer and the force platform. Coefficient of determination (r² = 0.59–0.67) showed the sphygmomanometer to have a valid predictive model in the I, Y and T positions.ConclusionsThe sphygmomanometer is suitable for monitoring force transfer across the shoulder during the ASH test, and is able to quantify peak force in mmHg. The sphygmomanometer enables coaches and clinicians to accurately quantify force production across the shoulder girdle in order to screen and monitor players at a low cost.     

The clinical assessment of hip muscle strength in professional rugby union players

Groin/hip injuries are prevalent in rugby union (RU). Assessment of hip muscle strength is important when designing bespoke injury prevention and rehabilitation programmes.ObjectiveThe primary aim of this study was to determine normative values of hip muscle strength in elite-level RU players. A secondary aim of this study was to compare the Copenhagen Hip and Groin Outcome Score (HAGOS) between players with and without a history of groin/hip injury.DesignCross-sectional cohort study.SettingProfessional RU club.Participants58 male professional RU players competing in the PRO14 league elite club level competition.Main outcome measuresHandheld dynamometry eccentric strength values of hip abduction (ABD), adduction (ADD), internal rotation (IR) and external rotation (ER), HAGOS.ResultsPlayers' dominant (DOM) and non-dominant (NDOM) hip strength values were, 2.38 and 2.34 N m/kg for ABD, 2.79 and 2.71 N m/kg for ADD, 2.69 and 2.55 N m/kg for IR, and 2.65 and 2.54 N m/kg for ER. ADD:ABD strength ratio was 1.17 ± 0.26 for the DOM limb and 1.16 ± 0.24 for the NDOM limb. There was no clinically significant difference in strength between players’ DOM and NDOM limbs. Players with a history of groin/hip injury scored lower on four of the HAGOS subscales (pain; symptoms; sport; quality of life) compared to those without a history of groin/hip injury.ConclusionsThis study may help establish normative hip strength and HAGOS values for elite-level RU players. The results presented have important implications for the assessment of hip muscle strength and could provide clinical markers for return-to-play following injury.     

The association between harm avoidance personality traits and self-reported concussion history in South African rugby union players

Objectives

Personality traits have been proposed to affect the risk of sports concussion, but evidence is limited. Cloninger’s Tridimensional Personality Questionnaire (TPQ) measures novelty seeking, harm avoidance (HA), and reward dependence traits. The aim of this study was to investigate the relationship between TPQ scores and concussion history in rugby union players.

The concurrent validity and intrarater reliability of a hand-held dynamometer for the assessment of neck strength in semi-professional rugby union players

ObjectivesThe main objective of this study was to determine the concurrent validity between a hand-held (HHD) and mounted hand-held dynamometer (MHHD) for assessing isometric neck strength.DesignObservational design.SettingSemiprofessional rugby club.ParticipantsNineteen semi-professional rugby players (age = 26 ± 5 years, stature = 186.5 ± 6.5 cm, body mass = 98.7 ± 12.8 kg).Main outcome measuresConcurrent validity (limits of agreement, correlation) between HHD and MHHD, the intrarater reliability (intra-class correlation, ICC) and comparison between playing positions.ResultsAbsolute peak and mean peak force were systematically lower when using the HHD compared to MHHD, with the mean bias ranging from −1.8 to −3.8 kgf (P < 0.05). Differences were not evident for flexion when applying the correction equations (−0.5 to 2.1 kgf, P > 0.05) but remained for extension. Correlations between methods were large-to-very large; the ICCs for both methods were good (ICC = 0.72–0.89), with no difference between positions (P < 0.05).ConclusionThe concurrent validity of HHD was considered acceptable when compared to the MHHD and the correction equation applied. Both methods are reliable and useful for assessing neck strength in rugby players, though, caution is needed when determining strength during neck extension.     

The effect of tackling on shoulder joint positioning sense in semi-professional rugby players

ObjectiveTo assess the effect of a tackling task replicating the force magnitudes and directions seen in a competitive game or training session, on a players shoulder joint position sense.DesignRepeated measures design.SettingField based.ParticipantsNineteen, senior, male, semi-professional rugby union players.Main outcome measuresTwo criterion angles of 45° and 20° off maximal range of shoulder external rotation in the 90° angle of abduction, were assessed for reproduction accuracy prior to, and following a field based tackling task against an opponent. A comparison between dominant and non-dominant side accuracy was also obtained.ResultsPrior to the tackling task, joint positioning sense was poorer at the 45° criterion angle than for 20° off the athletes' maximal range angle. Following the tackling task, error scores were significantly increased from baseline measures at the outer-range criterion angle for both dominant and non-dominant sides. In contrast to previous research the detrimental effect of the task was also greater. In addition, there was a significant decrease in accuracy at the 45° criterion angle for the players' non-dominant side.ConclusionsThis study found a significant decrease in accuracy of joint position sense following the tackling task. It also found this decrease to be greater than previous research findings. In contrast to previous studies that found no effect at the 45° criterion angle, this study found significant changes for the players' non-dominant side occurred at this angle. A possible explanation for this is that the sensory motor system is negatively affected by fatigue and consequently shoulder dynamic stability is reduced. This fatigue element explains the trend for increased injury frequency in the third quarter of the game and would provide a rationale for the inclusion of conditioning programmes that address fatigue resistance and motor co-ordination in the region.     

Evaluation of foot support in rugby players: a baropodometric analysis

Abstract Intense sports practice has effects on normal locomotion which may predispose athletes to certain injuries. The aim of the study was to evaluate weather playing rugby can change the distribution of forces on the surface of the foot plantar region and if these possible changes are caused by the high loading and the postural stances that this sport involves. The evaluation was performed using a baropodometer in static and dynamic conditions. We studied a group of 23 professional rugby players (scrums and three-quarters) who regularly trained 4-times per week. A control group consisted of 17 non-athletic healthy subjects. Baropodometric analysis revealed significantly higher rear-foot surface area and pressure for both feet in static conditions in rugby players compared to controls. In dynamic conditions, rugby players exerted a significantly higher ground pressure with respect to controls. Within the group of rugby players, scrums had significantly higher pressure than three-quarters, as well as a pressure increase in the lateral foot area. We conclude that rugby players tend to adopt an unbalanced posture posteriorly. The higher ground pressure together with the prevalent load on the lateral foot area may be associated with a difficult control of foot stability, possibly due to the higher body weight and to the increased tone and trophism of the triceps surae subsequent to the various athletic gestures that the game demands. In agreement with the literature, the variations of foot support observed in rugby players may be associated with adaptations induced by this sport, thus favoring an increased risk of bone, joint and muscle traumas and pathologies.     

Epidemiology of injuries in Australian junior rugby league players

ObjectivesConduct a large-scale epidemiological study of injury characteristics (location, type, mechanism, severity, burden) and incidence in community junior rugby league.DesignProspective cohort epidemiology study.MethodsInjury surveillance was conducted in three district leagues (Penrith, Canberra, Melbourne) in under 6 (U6) to under 18 years (U18) age groups across the 2016 season. Club sports trainers recorded all match/training medical-attention injuries using a commercial electronic application which recorded injury circumstances and characteristics.ResultsA total of 13,169 players from 897 teams participated and 408 (89% male) players sustained 485 injuries, 94% of which were match related. The overall injury incidence was 5.9 injuries/1000 player hours and highest in U13–U18 female players (22.2 injuries/1000 player hours). The mean injury severity of 16 ± 31 days missed training/match-play caused an overall injury burden of 94.2 days missed/1000 player hours). Tackles accounted for 84% of injuries. Joint and contusion injuries were the most prevalent injury type and the head (35% total injuries, primarily bruising and bleeding) was the most injured body site.ConclusionsThis is the first study to report injuries across a large cohort of all-age Australian community junior rugby league players over one season. Injury prevalence was lower than previously reported in junior rugby league suggesting the sport has not become more dangerous for junior players. These findings provide an evidence-base to inform or revise policy, training and injury prevention programs and athlete development pathways in relation to game-wide safety and develop best-practice protocols in injury management for rugby league athlete support personnel.     

The estimation of body density in rugby union football players.

The general regression equation of Durnin and Womersley for estimating body density from skinfold thicknesses in young men, was examined by comparing the estimated density from this equation, with the measured density of a group of 45 rugby union players of similar age. Body density was measured by hydrostatic weighing with simultaneous measurement of residual volume. Additional measurements included stature, body mass and skinfold thicknesses at the biceps, triceps, subscapular and suprailiac sites. The estimated density was significantly different from the measured density (P < 0.001), equivalent to a mean overestimation of relative fat of approximately 4%. A new set of prediction equations for estimating density was formulated from linear regression using the logarithm of single and sums of skinfold thicknesses. Equations were derived from a validation sample (n = 22) and tested on a crossvalidation sample (n = 23). The standard error of the estimate (s.e.e.) of the equations ranged from 0.0058 to 0.0062 g ml-1. The derived equations were successfully crossvalidated. Differences between measured and estimated densities were not significant (P > 0.05), total errors ranging from 0.0067 to 0.0092 g ml-1. An exploratory assessment was also made of the effect of fatness and aerobic fitness on the prediction equations. The equations should be applied to players of similar age and playing ability, and for the purpose of identifying group characteristics. Application of the equations to individuals may give rise to errors of between -3.9% to +2.5% total body fat in two-thirds of cases.     

Playing through the pain: The prevalence of perceived shoulder dysfunction in uninjured rugby players using the Rugby Shoulder Score

ObjectiveThis study aimed to investigate the prevalence of self-reported shoulder dysfunction using the Rugby Shoulder Score (RSS) reported in arbitrary units (AU) of rugby players available for match selection (uninjured).DesignCross-sectional survey.MethodsPaper survey at the mid-point of the season of uninjured players (n = 86 males (mean age (±SD): 26 ± 6.9y) from 8 squads (professional n = 34; amateur; n = 52)), using the RSS, subjective impact on rugby performance and previous shoulder injury, analysed using a Mann-Whitney U test.Results55% of players reported a level of RSS dysfunction despite being uninjured. Players who also reported their shoulder was impacting on performance had significantly higher median RSS (61, IQR 28AU, p = 0.02) than those who reported no impact on performance (40, IQR 22AU). Conclusions: Findings from this study show that over half of players were playing with a level of self-reported shoulder dysfunction. This figure is higher in the professional game, for those with a history of previous injury and for forwards.     

Shoulder functional status in rugby union players with and without history of shoulder problems

ObjectivesTo assess the effects of (1) rugby union practice, (2) history of injury managed nonoperatively, and (3) history of injury managed operatively on shoulder functional status in male rugby union players.DesignCross sectional study.SettingClinical.Participants86 male athletes were assigned into four groups: multisport athletes, rugby union players without shoulder problems, with history of shoulder injury managed nonoperatively and with history of shoulder injury managed operatively.Main outcome measuresSI-RSI questionnaire, maximal isometric glenohumeral internal and external rotator strength, unilateral seated shot put test, upper quarter Y balance test.ResultsHealthy players presented higher internal (p = 0.03) and external (p = 0.04) rotator strength than multisport athletes. History of shoulder injury managed nonoperatively did not impair physical abilities but limited player’s psychological readiness (p < 0.001). After 4.5-months, shoulder stabilization surgery impaired maximal muscle strength and upper quarter body stability and mobility (p < 0.001 for all).ConclusionsThe shoulder functional status in rugby union player presented increased glenohumeral rotator strength when compared to non-collision sport athletes. In rugby union players, psychological concerns remained in the long-term after a shoulder injury managed nonoperatively, and psychological and physical readiness seemed not be reached at 4.5 months postoperatively to respond to rugby union practice demand.     

The influence of match exposure on injury risk in elite men's rugby union

ObjectivesTo investigate the influence of previous season match exposure on injury incidence and burden in elite men's rugby union.DesignA three-season (2016–17 to 2018–19) retrospective cohort design was used to collect and analyse injury and exposure data across English Premiership rugby union teams.MethodsGeneralised linear mixed-effects models were used to model the influence of match exposure (all match involvements, match involvements of ≥20 mins, and full-game equivalents) upon match and training injury incidence and burden in the following season.ResultsInvolvement in ≥31 matches within a season was associated with substantially increased match and training injury burden in the following season. Match exposure was not clearly associated with injury incidence in the following season. The increased match injury burden associated with higher match involvements appeared to be driven by an increased risk for older (>26 y) Forwards, whilst the increased training injury burden associated with higher match involvements appeared to be driven by an increased risk for older (>26 y) Backs.ConclusionsThe present study demonstrates that all match involvements, regardless of duration, should be considered when exploring associations between match exposure and injury risk. High match involvements (≥ 31 matches) are associated with elevated injury burden, in both matches and training, in the following season. The physical and psychological load of players with high previous-season match exposure should be carefully managed.     

The prevalence of hand and wrist osteoarthritis in elite former cricket and rugby union players

ObjectivesThis study aimed to determine the prevalence of hand and wrist osteoarthritis in former elite cricket and rugby union players, by sport and playing position, and to define the prevalence of severe hand injury, and its association with hand osteoarthritis.DesignCross-sectional.MethodsData from cross-sectional studies of former elite male cricket and rugby players were used to determine the prevalence of hand pain, physician-diagnosed osteoarthritis, and previous severe injury. Multivariable logistic regression was used to determine the association of previous injury with pain and osteoarthritis.ResultsData from 200 cricketers and 229 rugby players were available. Complete case analysis resulted in 127 cricketers and 140 rugby players. Hand pain was more prevalent amongst cricketers (19.7%) than rugby players (10.0%). The prevalence did not differ between cricket and rugby players for hand osteoarthritis (2.4% and 3.6%), wrist osteoarthritis (1.6% and 2.1%), or previous severe hand injury (36.2% and 31.4%). No significant association between previous hand injury and pain or osteoarthritis was identified in either sport.ConclusionsFormer elite cricketers reported more hand pain than rugby players. No significant association was found between self-reported severe injury and hand osteoarthritis in either cohort, potentially indicating that risk factors aside from injury may be more prominent in the development of hand osteoarthritis.     

Changes in performance markers and wellbeing in elite senior professional rugby union players during a pre-season period: Analysis of the differences across training phases

ObjectivesTo assess the magnitude of change and association with variation in training load of two performance markers and wellbeing, over three pre-season training blocks, in elite rugby union athletes.DesignObservational.MethodsTwenty-two professional players (age 25 ± 5 years; training age 6 ± 5 years; body mass, 99 ± 13 kg; stature 186 ± 6 cm) participated in this study, with changes in lower (CMJ height) and upper body (bench press mean speed) neuromuscular function and self-reported wellbeing (WB) assessed during an 11-week period.ResultsThere was a small increase in CMJ height (0.27, ±0.17 – likely substantial; standardised effect size, ±95% confidence limits – magnitude-based inference) (p = 0.003), bench press speed (0.26, ±0.15 – likely substantial) (p = 0.001) and WB (0.26, ±0.12 – possibly substantial) (p < 0.0001) across the pre-season period. There was a substantial interaction in the effect of training load on these three variables across the three training phases. A two-standard deviation (2SD) change in training load was associated with: a small decrease in CMJ height during the power phase (−0.32, ±0.19 – likely substantial) (p = 0.001); a small reduction in bench press speed during the hypertrophy phase (−0.40, ±0.32 – likely substantial) (p = 0.02); and a small reduction in WB during the strength phase (−0.40, ±0.24 – very likely substantial) (p < 0.0001). The effects of changes in training load across other phases were either likely trivial, only possibly substantial, or unclear.ConclusionsThe effect of training load on performance can vary both according to the type of training stimulus being administered and based on whether upper- or lower-body outcomes are being measured.     

The influence of playing level on the biomechanical demands experienced by rugby union forwards during machine scrummaging

This study investigated machine scrummaging at different playing levels in rugby union and analysed kinetic factors that might influence performance and injury risk. Thirty‐four forward packs from six different playing levels scrummaged against an instrumented scrum machine under real environmental conditions. Applied forces were measured in three orthogonal directions. The peak (SD) of the overall compression forces during engagement ranged between 16.5 (1.4) kN (International‐Elite) and 8.7 (0.1) kN (Women), while sustained compression forces spanned between 8.3 (1.0) kN (International) and 4.8 (0.5) kN (Women). The peak of the overall vertical force during the initial engagement phase was between ?3.9 (0.7) kN (Elite) and ?2.0 (1.0) kN (School), and the range of lateral forces was between 1.8 (0.3) kN (International) and 1.1 (0.3) kN (School). Forces measured across all playing levels, particularly during initial engagement, were generally higher than those measured in the most commonly cited previous studies. This increase may be due to a combination of changes in modern scrummaging technique, changes in players' anthropometrics, and experimental conditions that better respect ecological validity. The magnitude of the measured forces is in the range of values that studies on cadaveric specimens have indicated as potentially hazardous for (chronic) spine injuries.