Maturity-related developmental inequalities in age-group swimming: The testing of ‘Mat-CAPs’ for their removal

ObjectivesTo (1) examine the association between maturity timing and performance-based selection levels in (N = 708) Australian male 100-m Freestyle swimmers (12–17 years); (2) identify the relationship between maturation status and 100-m Freestyle performance; and (3) determine whether Maturation-based Corrective Adjustment Procedures (Mat-CAPs) could remove maturation-related differences in swimming performance.MethodsIn Part 1, maturity timing category distributions (‘Early’, ‘Early Normative’, ‘Late Normative’ and ‘Late’) for ‘All’, ‘Top 50%’ and ‘25%’ of raw swimming times were examined within and across age-groups. In Part 2, multiple regression analyses quantified the relationship between maturity offset (YPHV) and swimming performance. In Part 3, sample-based maturity timing category distributions were examined based on raw and correctively adjusted swim times for 12–17 year old age-groups.ResultsBased on raw swim times, a high prevalence of ‘Early-maturing’ swimmers, with large effect sizes was identified (e.g., 14 years ‘All’ — χ² (3, 151 = 111.98, p < 0.001; ‘Early’ v ‘Late’ OR = 82.0 95%CI = 4.77, 1409.9); while a complete absence of ‘Late-maturers’ was apparent in the sample (N = 708). When maturity categories were re-defined based on sample mean ± standard deviation, and when using the expected curvilinear trendline identified in Part 2, Mat-CAPs mitigated maturity timing biases across all age-groups and selection levels, and removed the Freestyle performance advantage afforded by advanced maturity timing and status.ConclusionsRemoving the influence of maturation-related developmental differences could help improve youth swimmer participation experiences and improve the accuracy of identifying genuinely skilled age-group swimmers.     

Accident and emergency radiography: A comparison of radiographer commenting and ‘red dotting’

PurposeThe College of Radiographers has called for ‘Red Dot’ schemes to evolve and has recommended the development of radiographer commenting. The implementation of a radiographer comment scheme assumes that radiographers previously participating in ‘red dot’ schemes have been accurately recognising radiographic abnormalities and are, therefore, able to comment upon, and describe, such radiographic appearances. Research evidence to support such an assumption is sparse. This study compares the ability of radiographers attending a short course on musculoskeletal trauma to ‘red dot’ and comment on A&E radiographic appearances.MethodsThis study adopted a pre-test, post-test approach. One hundred and twenty one radiographers attending a short course on musculoskeletal trauma (Bradford Red Dot Course) were invited to undertake an assessment of their ability to recognise (‘red dot’) and describe (comment upon) radiographic abnormalities at the start and end of the short course.ResultsOne hundred and fifteen radiographers (n = 115/121; 95.0%) completed both the pre- and post-training assessments. Post-training mean scores per case improved on average by 9.8% [p = 0.012; 95% CI: 2.4, 17.1] for ‘red dots’ and 12.7% [p = 0.007; 95% CI: 3.8, 21.5] for commenting. However, the difference between mean ‘red dot’ and commenting scores remained similar with mean radiographer comment scores being 13.7% less than mean ‘red dot’ scores pre-training and 10.8% less post-training.ConclusionsThe results of this study indicate that the accuracy of radiographer comments was significantly reduced when compared to the accuracy of ‘red dots’ for the same radiographic images. The clinical significance of these findings for departments wanting to move from a ‘red dot’ system to a radiographer commenting scheme is that without appropriate training and audit, the quality of service and assistance to the A&E department could be significantly reduced.     

Uncertainty in the number of contributors for the European Standard Set of loci

The effect of masking on the assignment of the number of contributors is assessed for the European Standard Set of loci by simulation. The risk that a two person mixture presents as single source is assessed as 2.6 × 10⁻¹³, a three person mixture presents as a two person 6.7 × 10⁻⁴ and a four person mixture presents as a three person 0.165.     

Removing relative age effects from youth swimming: The development and testing of corrective adjustment procedures

Objectives(1) Generate accurate estimates of the relationship between decimal age (i.e., chronological and relative) with swimming performance based on longitudinal data. (2) Determine whether corrective adjustment procedures can remove Relative Age Effects (RAEs) from junior/youth swimming.DesignLongitudinal and repeated years of cross-sectional performance data were examined.Methods(1) Participants were 553 male 100 m Freestyle swimmers (10–18 years) who participated in ≥five annual events between 1999–2017. Growth curve modelling quantified the relationship between age and swimming performance, permitting corrective adjustment calculations. (2) Participants were N = 2141 male 100 m Freestyle swimmers (13–16 years) who swam at state/national events in 2015–2017. Relative age distributions for ‘All’, ‘Top 50%’, ‘25%’ and ‘10%’ of swimming times were examined based on raw and correctively adjusted swim times. Chi-square, Cramer’s V and Odds Ratios (OR) determined whether relative age (quartile) inequalities existed according to age-groups, selection level and correctively adjusted swim times.ResultsBased on raw swim times, for ‘All’ swimmers RAEs was evident at 13 and 14 years-old and dissipated thereafter. But, RAE effect sizes substantially increased with selection level, with large-medium effects between 13–15 years-old (e.g., 15 years — Top 50% Q1 v Q4 OR = 2.28; Top 10% = 6.02). However, when correctively adjusted swim times were examined, RAEs were predominantly absent across age-group and selection levels.ConclusionsWith accurate longitudinal reference data, corrective adjustment procedures effectively removed RAEs from 100 m Freestyle swimming performance, suggesting the potential to improve swimming participation experience and performance evaluation.     

Ethanol as a single toxin in non-traumatic deaths – A toxicology perspective

There were 285 autopsy cases in 2010 where ethanol was the only toxin. To try to ascertain the toxicity of ethanol alone, those cases where clinical details stated ‘sudden death’, ‘collapsed’, ‘brought in dead to hospital’, ‘found dead at home’, ‘fell down stairs and dead at end of stairs’, ‘sudden death in alcoholic’ and ‘brought in dead and seizures’ were extracted. There were 55 males aged from 23 to 76 years and 17 females aged from 41 to 71 years who fulfilled these criteria. Blood ethanol ranged from <50 to 556 mg/dl. The median band in males is 200–249 mg/dl and the 31% of male cases are in the 200s mg/dl range, levels conventionally considered benign. The levels found in females were spread relatively evenly across the range 150–600 mg/dl. The urine/blood ethanol ratios ranged from 0.13 to 2.02. The blood/vitreous ratios in 10 cases ranged from 0.76 to 1.24 with a median value of 1.16. Calculated blood ethanol from vitreous levels showed a negative bias when compared to the measured value but not in all cases. This limits the role of calculated values in legal cases. The threshold for lethal alcohol toxicity is indistinct and likely to be lower than conventionally acknowledged.     

The relationship between pre-season fitness testing and injury in elite junior Australian football players

ObjectivesAustralian Football (AF) is a collision sport containing high injury rates in junior competition. Successful performance at the elite junior level not only requires superior specific football knowledge and skills, but also well developed fitness qualities. However, no studies have examined the link between physical fitness qualities and injury in AF.DesignProspective cohort.MethodsInjury data were collected through the use of a Player Movement Record (PMR) and a standardized Injury Report Form (IRF). Fitness test data was collected during the pre-season of the 2010 and 2011 seasons.Results382 players consented to participate in the study. The cohort experienced an injury incidence rate of 24.29/standardized club (40 players/club). A faster 5-m sprint was associated with ‘injury status’ (p = 0.016) and a ‘knee’ region (p ≤ 0.001) injury. A faster planned agility score was associated with an increased risk of a ‘hip/groin/thigh’ region (p = 0.010) injury, and specifically a ‘quadriceps strain’ (p = 0.005). A lower 20-m shuttle run was associated with an increased risk of a ‘shin/ankle/foot’ (p = 0.045) injury. Increased injury severity was associated with a higher left foot running vertical jump (VJ) (p = 0.040), and faster 5-m sprint (p = 0.043).ConclusionsLower aerobic endurance, faster 5-m acceleration and greater planned agility were associated with an increased risk of various injury types in elite junior AF players. Furthermore, a higher left foot running VJ and faster 5-m acceleration were associated with injury severity. These results may largely relate to a greater work capacity placing a higher load upon the musculoskeletal system in contact and non-contact situations.     

TPH1 A218 allele is associated with suicidal behavior in Turkish population

BackgroundSerotonergic dysfunction is implicated in depression, psychiatric disorders and suicidal behaviors. The first and rate-limiting step in the synthesis of serotonin is catalyzed by tryptophan hydroxylase (TPH) which is encoded by TPH1 and THP2 genes. Genetic association studies have revealed contradictory results about the effect of the TPH1 A218C (rs1800532) polymorphism on suicidal behavior in different populations.Material and methodIn this study, we investigated A218C polymorphism in 109 suicide attempters and 98 healthy controls. Socio-demographic characteristics of participants were obtained through questionnaire. DNA was extracted from peripheral blood and genotyping was performed by Real Time PCR. Fisher’s exact test was used to evaluate the significance of the difference among the independent variables. Hardy-Weinberg equilibrium was tested using Pearson’s goodness-of-fit chi-squared test.ResultsThe frequency of A allele was significantly higher in suicide attempters than controls (46.33% vs. 35.71%, p = 0.0357). However, there were no differences in genotype frequencies of this locus between participants having attempted suicide and controls (p > 0.05). Among males, frequencies of CC genotype and C allele were found to be significantly higher in controls (p = 0.0125, p = 0.0298). With regard to the female subjects and female controls, no significant association was detected between suicidal behavior and genotype/allele frequencies (p > 0.05).ConclusionOur results provide evidence that A allele of TPH1 A218C polymorphism may be associated with suicidal behavior in Turkish population.     

Exploring associations between neuromuscular performance,hypermobility, and children’s motor competence

ObjectivesTo evaluate if neuromuscular performance and hypermobility are factors associated with children’s motor competence.DesignCross-sectional observation study.MethodsData was collected on 60 children aged 6–12 years; motor competence was determined using the Movement Assessment Battery for Children-2 test, with children classified into 3 groups (Typically Developing n = 30; ‘At Risk’ of low motor competence (LMC) n = 9; LMC n = 21). Neuromuscular performance was determined utilising the Resistance Training Skills Battery for Children (RTSBc), 5-repetition maximum (5RM) leg press and Biodex dynamometry to assess isometric and isokinetic peak torque of the knee flexors and extensors. Hypermobility was measured using the Beighton and Lower Limb Assessment Score.ResultsBetween-groups MANCOVA revealed typically developing children scored significantly higher on the RTSBc than those ‘at risk’ of LMC (p = 0.021) and those in the LMC group (p < 0.001). 5RM scores also differed between groups, with typically developing children achieving significantly higher scores than the LMC group. No differences were found between groups for isometric or isokinetic measures of strength. Sequential regression analysis revealed neuromuscular performance variables explained 44.7% of the variance in motor competence, with RTSBc (p < 0.001) and 5RM (p = 0.019) emerging as positive significant predictors. Hypermobility failed to explain significant variance in motor competence beyond that explained by neuromuscular performance.ConclusionsNeuromuscular performance of children varies according to levels of motor competence, with those with LMC performing poorly on tasks requiring multi-joint movement. Furthermore, neuromuscular performance predicted almost half the variance observed in motor competence and highlights a novel intervention strategy.     

Retrospective comparison of three-dimensional imaging sequences in the visualization of posterior fossa cranial nerves

PurposeTo compare efficancy of three-dimentional SPACE (sampling perfection with application-optimized contrasts using different flip-angle evolutions) and CISS (constructive interference in steady state) sequences in the imaging of the cisternal segments of cranial nerves V–XII.MethodsTemporal MRI scans from 50 patients (F:M ratio, 27:23; mean age, 44.5 ± 15.9 years) admitted to our hospital with vertigo, tinnitus, and hearing loss were retrospectively analyzed. All patients had both CISS and SPACE sequences. Quantitative analysis of SPACE and CISS sequences was performed by measuring the ventricle-to-parenchyma contrast-to-noise ratio (CNR). Qualitative analysis of differences in visualization capability, image quality, and severity of artifacts was also conducted. A score ranging ‘no artefact’ to ‘severe artefacts and unreadable’ was used for the assessment of artifacts and from ‘not visualized’ to ‘completely visualized’ for the assesment of image quality, respectively. The distribution of variables was controlled by the Kolmogorov–Smirnov test. Samples t-test and McNemar’s test were used to determine statistical significance.ResultsRates of visualization of posterior fossa cranial nerves in cases of complete visualization were as follows: nerve V (100% for both sequences), nerve VI (94% in SPACE, 86% in CISS sequences), nerves VII–VIII (100% for both sequences), IX–XI nerve complex (96%, 88%); nerve XII (58%, 46%) (p < 0.05). SPACE sequences showed fewer artifacts than CISS sequences (p < 0.002).     

Effect of dual-task-induced uncertainty on gait biomechanics in patients with multiple sclerosis with 2–6.5 EDSS grade

The goal of this study was to assess the effect that uncertainty induced by dual task conditions has on reaction-response time parameters and gait patterns of patients with multiple sclerosis (MS) with a 2–6.5 EDSS grade. The study involved eleven patients – nine women and two men – diagnosed with multiple sclerosis (age, 48 ± 10 years; height, 1.65 ± 0.1 m; weight, 72 ± 22 kg) with capacity to walk five meters without any aid or assistance. We employed an intra-group repeated measures design. Each participant was asked to walk with and without task-related uncertainty. Reaction-response and gait cycle times, as well as center of mass (CM) dynamics were measured using three force plates synchronized with a video camera through an electronic device that also controlled the system of uncertainty. The results obtained reveal that uncertainty induced by dual tasking is related to a reduction in the mean stride length and mean displacement and horizontal velocity of the CM in patients with MS. The values obtained for CM parameters indicate that uncertainty affects balance, as compared to no-uncertainty situations. These results confirm the necessity of including controlled dual-task-induced uncertainty in physical training programs for MS patients.     

Trunk muscle action compensates for reduced quadriceps force during walking after total knee arthroplasty

Patients with total knee arthroplasty (TKA) frequently exhibit changes in gait biomechanics post-surgery, including decreased ranges of joint motion and changes in joint loading; however, the actions of the lower-limb muscles in generating joint moments and accelerating the center of mass (COM) during walking are yet to be described. The aim of the present study was to evaluate differences in lower-limb joint kinematics, muscle-generated joint moments, and muscle contributions to COM accelerations in TKA patients and healthy age-matched controls when both groups walk at the same speed. Each TKA patient was fitted with a posterior-stabilized total knee replacement and underwent patellar resurfacing. Three-dimensional gait analysis and subject-specific musculoskeletal modeling were used to determine lower-limb and trunk muscle forces and muscle contributions to COM accelerations during the stance phase of gait. The TKA patients exhibited a ‘quadriceps avoidance’ gait pattern, with the vasti contributing significantly less to the extension moment developed about the knee during early stance (p = 0.036). There was a significant decrease in the contribution of the vasti to the vertical acceleration (support) (p = 0.022) and forward deceleration of the COM (braking) (p = 0.049) during early stance; however, the TKA patients compensated for this deficiency by leaning their trunks forward. This significantly increased the contribution of the contralateral back extensor muscle (erector spinae) to support (p = 0.030), and that of the contralateral back rotators (internal and external obliques) to braking (p = 0.004). These findings provide insight into the biomechanical causes of post-operative gait adaptations such as ‘quadriceps avoidance’ observed in TKA patients.     

Assessment of the test–retest reliability of a foot placement accuracy protocol in assisted-living older adults

IntroductionThis study assessed the test–retest reliability of a foot placement accuracy protocol in a population of assisted-living elderly. The goal was to evaluate the execution of foot placement performance with increasing complexity of the walking condition.MethodsTwenty-five elderly participants (5 males, 20 females, 80.4 ± 8.6 years) were assessed by one observer in two sessions with 48 h between the measurements. Participants walked at self-selected pace along a pathway with three different walking conditions composed of two rectangular foam target locations and an obstacle on the walking surface. The main outcome measures were foot placement distance error, intra-class correlation coefficients (ICC), and the smallest detectable difference (SDD).ResultsMean absolute values of the foot placement distance errors were 14.0 ± 4.5 mm for medio-lateral deviation and 27.2 ± 2.1 mm for anterior–posterior deviation, respectively. ICC values for test–retest reliability showed ‘fair to good’ to ‘excellent’ reliability across all conditions with values ranging from 0.63 to 0.94. SDD values were between 3.6 and 37.3 mm.ConclusionThe protocol showed good reliability for test–retest measurements of foot placement accuracy, thus making this protocol a reliable and location-independent tool to assess performance of foot placement in elderly in assisted-living settings. In the future, measurements with elderly fallers and non-fallers should be conducted to assess validity of the protocol.     

Are children with higher self-reported wellbeing and perceived motor competence more physically active? A longitudinal study

ObjectivesSelf-perceptions such as perceived motor competence and psychosocial wellbeing have been identified as important to children’s physical activity. The study’s purpose was to explore whether perceived motor competence and psychosocial wellbeing were determinants of physical activity, one year after a baseline assessment.DesignLongitudinal study.MethodsA total of 134 children (65.7% boys, 34.3% girls) aged 6–7 years at baseline (2016), and 7–8 years at follow-up (2017) were included in this study. Pearson’s correlations assessed associations at baseline and follow-up between moderate- to vigorous-intensity physical activity (MVPA) (accelerometers) and (i) total perceived motor competence and subdomains (the pictorial scale of Perceived Movement Skill Competence) and (ii) psychosocial wellbeing and sub-domains — KidKINDL KINDer Lebensqualitätsfragebogen: Children Quality of Life Questionnaire (KINDL^R). Variables identified as significant in Pearson’s correlations were included in mixed model analyses, adjusting for accelerometer wear time, sex and age.ResultsBaseline perceived object control skills was associated with MVPA at follow-up (r = 0.38, p < 0.001), but perceived locomotor skills were not. Self-esteem was the only subdomain of psychosocial wellbeing that demonstrated significant association with MVPA at baseline (r = 0.21, p < 0.05). Perceived object control (B = 1.36, p = 0.019, 95% CI [0.23, 2.50]) and self-esteem (B = 0.32, p = 0.001, 95% CI [0.13, 0.50]) positively predicted MVPA; albeit with small effects.ConclusionsFocusing on improving children’s perceived object control and self-reported self-esteem may contribute to children’s physical activity participation.     

Options for radiation dose optimisation in pelvic digital radiography: A phantom study

PurposeTo investigate the effects of phantom orientation and AEC chamber selection on radiation dose and image quality (IQ) for digital radiography (DR) examinations of the pelvis.MethodsA phantom study was conducted using a DR detector, utilising all AEC chamber combinations. Current recommended orientation (Cr-AEC) was with the outer AEC chambers cranially orientated. mAs (given), source-to-skin distance and kV_p data facilitated entrance surface dose and effective dose calculations. Six anatomical areas were blindly graded by two observers (3-point scale) for IQ. Statistical differences in radiation dose were determined using the paired Student’s t-test. IQ data was analysed for inter-observer variability (ICC) and statistical differences (Wilcoxon test).ResultsSwitching phantom orientation (caudally orientated outer AEC chambers: Ca-AEC) reduced mean radiation dose by 36.8%, (p < 0.001). A minor reduction in median IQ (15.5 vs. 15) was seen (p < 0.001). One Ca-AEC orientated image (1.6%) had all anatomical areas graded ‘inadequate’ by at least one observer; all other images were considered ‘adequate’ for all areas. In the Ca-AEC orientation, at least a 44% dose reduction was achievable (p < 0.001) when only the outer AEC chambers were used. In the Cr-AEC orientation, at least 11% dose reduction was achieved (p < 0.001); here the central chamber was used alone, or in combination. IQ scores fell, but remained ‘adequate’.ConclusionSwitching pelvic orientation relative to AEC chamber position can optimise radiation dose during pelvic radiography. AEC chamber position should be clearly marked on equipment to facilitate this. AEC selection should be an active process.     

Male basketball players who report hip and groin pain perceive its negative impact both on- and off-court: A cross-sectional study

ObjectivesTo identify if basketball players aged <20 years (U20) self-report hip and/or groin pain and if they perceive this as a problem. To determine potential differences in self-reported playing (training and match play) loads and Copenhagen Hip and Groin Outcome Score (HAGOS) between those with and without hip/groin pain.DesignCross-sectional.MethodsFifty-one pre-elite (state/national representative level) male U20 basketball players (Australian n = 38; Italian n = 13) self-reported current/historical hip/groin ‘discomfort/pain’ and ‘problems’, and playing loads. A two-factor regression model was fitted including main effects for hip/groin pain and Cohort and their interaction, with outcome variables playing loads and HAGOS subscale scores and dependent variable hip/groin pain.ResultsTwenty-one players (41%) self-reported hip/groin ‘discomfort/pain’, of which nine perceived no ‘problems’. Two of these nine players reported training/playing time loss due to pain. Those self-reporting hip/groin discomfort/pain scored lower than those without in HAGOS subscales Symptoms (mean difference in score 8.94; 95%CI ?25.24, ?5.97), Pain (5.00; ?16.42, ?2.81), Function in daily living (0.00; ?26.72 to ?5.59), Function in sport and recreation (6.25; ?21.24, ?5.33), and hip and/or groin Quality of Life (5.00; ?28.63, ?8.10), indicating worse hip/groin problems. Participation subscale scores were different only for Italian players (36.25; ?51.25, ?20.00), with players self-reporting hip/groin discomfort/pain scoring lower.ConclusionMost players who perceive both hip/groin ‘discomfort/pain’ and ‘problems’ also report training/playing time loss, suggesting players’ perceptions of problematic symptoms and time-loss are associated. Adolescent basketball players perceive hip/groin pain to negatively impact their daily lives and sporting function.     

Prevalence and application of priming exercise in high performance sport

ObjectivesRecent research has revealed that low volume resistance ‘priming’ exercise may improve neuromuscular performance when completed within 48 h before competition. The aim of this study was to investigate the current prevalence and application of this strategy by practitioners in sport.DesignThis study surveyed practitioners who were currently programming and/or prescribing resistance training programs for high performance athletes.MethodsSixty-nine practitioners completed the online survey relating to their perceptions of resistance priming exercise strategies and the training methods prescribed in the days prior to competition.ResultsFifty-one percent of respondents currently prescribed priming exercise. Of the practitioners who prescribed this strategy, most respondents (59%) prescribed this session within 8 h of competition. Sessions typically included 2–3 upper body and lower body exercises (mean = 2.5 ± 0.7 and 2.1 ± 0.6 respectively), usually involving both loaded and unloaded activities. Large variations in exercise selection were reported, however, unloaded jumps (87%), loaded jumps (60%) and bench press (56%) were commonly prescribed. A low volume of sets (mean = 2.8 ± 0.9) and repetitions (mean = 3.8 ± 1.3) were used during these sessions. Lastly, various resistance loading strategies were prescribed, ranging from unloaded activities to heavy loaded exercises performed at ≥85% 1RM.ConclusionsPriming exercise is currently prescribed by many practitioners to prepare athletes for competition. A wide range of priming exercise methods are used, despite limited evidence supporting these methods. Future research should examine the effects of the various priming methods which are currently applied in practice.     

Graduate radiographers' expectations for role development – The potential impact of misalignment of expectation and valence on staff retention and service provision

PurposeThe purpose of this study was to investigate the role development expectations of graduate radiographers with a view to predicting the potential impact of a misalignment of these expectations and valence on service delivery and staff retention. A final year cohort of radiography students completed a questionnaire designed to explore topics associated with role development opportunities.MethodStructured questionnaires, in the Likert scale format, utilised 20 attitude questions constructed to elicit information in relation to 3 main themes of investigation; expectation, valence and knowledge.ResultsAll participants (n = 37) stated an expectation for role development opportunities with 97.3% (n = 36) indicating that these expectations would be realised within 5 years of graduation and 75.7% (n = 28) within 2 years of graduation. A significant correlation between expectation for role development and job satisfaction was seen (p < 0.05). 81.1% (n = 30) of participants stated turnover intentions in order to meet their expectations.ConclusionThere is an expectation for role development opportunities for new graduates with a valence noted of the intrinsic reward of meeting these expectations. Expectation and valence are seen to be intrinsically linked with job satisfaction suggesting that misalignment of these would have a potentially negative impact on motivation and retention of the future radiography workforce demonstrating a positive correlation with withdrawal behaviours, including turnover intentions. In a relatively small professional group such as radiography the phenomenon of group cohesion may be strong suggesting that withdrawal behaviours may manifest as ‘resignation in post’, impacting on the quality of care and service provision for patients.     

Patterns of head impact exposure in men’s and women’s collegiate club water polo

ObjectivesRecent reports have demonstrated a risk of concussion and subconcussive head impacts in collegiate varsity and international elite water polo. We sought to characterize patterns of head impact exposure at the collegiate club level of water polo.DesignProspective cohort study.MethodsHead impact sensors (SIM-G, Triax Technologies) were worn by men’s (n = 16) and women’s (n = 15) collegiate club water polo players during 11 games. Peak linear acceleration (PLA) and peak rotational acceleration (PRA) of head impacts were recorded by the sensors. Two streams of competition video were used to verify and describe the nature of head impacts.ResultsMen’s players sustained 52 verified head impacts of magnitude 39.7 ± 16.3 g PLA and 5.2 ± 3.2 krad/s² PRA, and women’s players sustained 43 verified head impacts of magnitude 33.7 ± 12.6 g PLA and 4.0 ± 2.8 krad/s² PRA. Impacts sustained by men had greater PLA than those sustained by women (p = .045). Athletes were impacted most frequently at the offensive center position, to the back of the head, and by an opponent’s torso or limb.ConclusionsOur cohort of male and female athletes sustained relatively infrequent head impacts during water polo competitions played at the collegiate club level. The amount of head impact exposure in our cohort was dependent on player position, with offensive centers prone to sustaining the most impacts. Head impact sensors are subject to large amounts of false positives and should be used in conjunction with video recordings to verify the validity of impact data.     

Interpersonal interactions for haptic guidance during maximum forward reaching

Caregiver–patient interactions rely on interpersonal coordination (IPC) involving the haptic and visual modalities. We investigated in healthy individuals spontaneous IPC during joint maximum forward reaching. A ‘contact-provider’ (CP; n = 2) kept light interpersonal touch (IPT) laterally with the wrist of the extended arm of a forward reaching, blind-folded ‘contact-receiver’ (CR; n = 22). Due to the stance configuration, CP was intrinsically more stable. CR received haptic feedback during forward reaching in two ways: (1) presence of a light object (OBT) at the fingertips, (2) provision of IPT. CP delivered IPT with or without vision or tracked manually with vision but without IPT. CR’s variabilities of Centre-of-Pressure velocity (CoP) and wrist velocity, interpersonal cross-correlations and time lags served as outcome variables. OBT presence increased CR’s reaching amplitude and reduced postural variability in the reach end-state. CR’s variability was lowest when CP applied IPT without vision. OBT decreased the strength of IPC. Correlation time lags indicated that CP retained a predominantly reactive mode with CR taking the lead. When CP had no vision, presumably preventing an effect of visual dominance, OBT presence made a qualitative difference: with OBT absent, CP was leading CR. This observation might indicate a switch in CR’s coordinative strategy by attending mainly to CP’s haptic ‘anchor’. Our paradigm implies that in clinical settings the sensorimotor states of both interacting partners need to be considered. We speculate that haptic guidance by a caregiver is more effective when IPT resembles the only link between both partners.