A 6-year surveillance study of “Stingers” in NCAA American Football

This study describes the epidemiology of “stinger” injuries in National Collegiate Athletic Association (NCAA) Men’s Football. About 57 NCAA Men’s Football programmes provided 153 team-seasons of injury data to the NCAA Injury Surveillance Programme (NCAA-ISP) during the 2009/2010–2014/2015 academic years. In the study period, 229 “stingers” were reported for an injury rate of 2.04/10,000 athlete-exposures (AE). Most “stingers” were reported during competitions (55.5%) and the preseason (80.3%) and resulted in time loss less than 24 hours (63.8%). One in five (18.8%) were recurrent. Most “stingers” were due to player contact (93.0%), particularly while tackling (36.7%) and blocking (25.8%) and occurred to defensive ends/linebackers (25.8%) and offensive linemen (23.6%). Although previous research reports a large prevalence of “stingers” among football players, the NCAA-ISP reported a relatively low injury rate. The transient nature of pain associated with “stingers” may have contributed to under-reporting, highlighting the need to deduce manners to increase reporting.     

Association between Cardiac Dimensions and Athlete Lineup Position: Analysis Using Echocardiography in NCAA Football Team Players

Abstract

In determining what is “abnormal”-in terms of cardiac electrical and morphologic remodeling in athletes-it is important to identify what is “normal” or expected. With specialization for each position in a football team lineup, we attempted to describe the association between the position played and the physiologic cardiac changes of designated players. We evaluated data from 85 National College Athletic Association football players from a single team. The participants were assigned to 1 of 3 groups based on position and training regimen: lineman (n = 34), mobility/power players (n = 13), and skill players (n = 38). Players underwent assessment with electrocardiography and echocardiography (ECHO), with results interpreted by reviewers blinded to players' positions. Linemen were found to have greater body mass index and body surface area (BSA), as well as longer QRS duration (102 ± 10 ms vs 101 ± 7 ms in mobility/power players, and 96 ± 7 ms in skill players; P < 0.007). Left ventricular (LV) voltage values were lower in linemen (27.7 ± 6.5 mV vs 28.8 ± 7 mV in mobility/power players, and 31.8 ± 7.6 mV in skill players; both, P < 0.05). No differences in ejection fraction between groups were revealed on ECHO, but ECHO did show greater calculated LV mass, LV end-diastolic diameter, aortic root diameter, and LV outflow tract diameter in linemen, whether adjusted for BSA or not, and the differences were statistically different. Multivariate analysis showed that position (P < 0.0004 and QRS duration (P = 0.03) predicted LV mass. Echocardiographic variables found to be associated with player position included LV mass adjusted for BSA (P < 0.0001), LV end-diastolic diameter adjusted for BSA (P < 0.0003), and QTc interval (P = 0.007). On multivariate analysis, racial identity did not demonstrate significant differences; however, differences existed on univariate analysis of electrocardiography and ECHO variables, mostly in skill players. In skill players, QRS duration was shorter in the African American (AA) subgroup compared with that in the white/other subgroup. Lateral ST elevation and LV end-systolic volume were greater in AA players after adjustment for BSA, and AA linemen had greater LV posterior wall thickness after adjustment for BSA. In summary, we found that football players who are linemen had greater heart mass than did other players, despite adjustments for body size.     

A 2.5 min cold water immersion improves prolonged intermittent sprint performance

ObjectivesWe investigated if cold water immersion (CWI) affects exercise performance during a prolonged intermittent sprint test (IST), designed to mimic activity patterns of team-sports.DesignRandomized-crossover design.MethodsTen male team-sport players completed 3 IST protocols (two 40-min “halves” of repeated 2-min blocks consisting of a 8-s “all-out” sprint, 100-s active recovery and 12-s rest) on a cycle ergometer at normothermic conditions. Each “half” was separated by a 15 min recovery period of either: (i) passive rest, (ii) 5-min CWI at 8 °C (CWI-5) or (iii) 2.5-min CWI at 8 °C (CWI-2.5), in a random counterbalanced order.ResultsPhysical performance, core temperature (T_core) and heart rate were not different among conditions in the first half. In the passive rest trial, total work (TW) and peak power (PP) were lower during the second half (TW: 5.04 ± 1.11 kJ; PP: 929 ± 286 W) than the first half (TW: 5.66 ± 1.02 kJ; PP: 1009 ± 266 W); while TW and PP were not different between halves following CWI-5 (first half, TW: 5.34 ± 1.02 kJ, PP: 1016 ± 283 W; second half, TW: 5.19 ± 1.38 kJ; PP: 996 ± 318 W) and CWI-2.5 (first half, TW: 5.47 ± 1.19 kJ, PP: 966 ± 261 W; second half, TW: 5.25 ± 1.17 kJ; PP: 952 ± 231 W). T_core was lower until the 20^th minute of the second half after CWI-5 and CWI-2.5 compared with passive rest.ConclusionsA post-exercise 2.5–5-min CWI attenuates the reductions in prolonged sprint performance that occur in the second half of team sports, due, at least partly, to reductions in core temperature and associated increase in heat storage.     

Effect of Computerized Physician Order Entry on Imaging Study Indication

PurposeThe effect of computerized physician order entry (CPOE) on imaging indication quality had only been measured in one institution’s emergency department using a homegrown electronic health record with faculty physicians, and only with one instrument. To better understand how many US hospitals’ recent CPOE implementations had affected indication quality, we measured its effect in a generalizable inpatient setting, using one existing and one novel instrument.MethodsWe retrospectively analyzed the indications for 100 randomly selected inpatient abdominal CT studies during 2 calendar months immediately prior to a 3/3/2012 CPOE implementation (1/1/2012-2/29/2012) and during 2 subsequent calendar months (5/1/2012-6/30/2012). We excluded 2 intervening months to avoid behaviors associated with adoption. We measured indication quality using a published 8-point explicit scoring scale and our own, novel, implicit 7-point Likert scale.ResultsExplicit scores increased 93% from a pre-CPOE mean ± 95% confidence interval of 1.4 ± 0.2 to a CPOE mean of 2.7 ± 0.3 (P < .01). Implicit scores increased 26% from a pre-CPOE mean of 4.3 ± 0.3 to a CPOE mean of 5.4 ± 0.2 (P < .05). When presented with a statement that an indication was “extremely helpful,” and choices ranging from “strongly disagree” = 1 to “strongly agree” = 7, implicit scores of 4 and 5 signified “undecided” and “somewhat agree,” respectively.ConclusionsIn an inpatient setting with strong external validity to other US hospitals, CPOE implementation increased indication quality, as measured by 2 independent scoring systems (one pre-existing explicit system and one novel, intuitive implicit system). CPOE thus appears to enhance communication from ordering clinicians to radiologists.     

Acoustic radiation force impulse tissue characterization of the anterior talofibular ligament: a promising noninvasive approach in ankle imaging

Objectives: The anterior talofibular ligament (ATFL) is the most frequently injured ligament during inversion strains of the ankle. The purpose of this study was to evaluate the feasibility of acoustic radiation force impulse (ARFI) elastography and to determine the in vivo mechanical properties of the ATFL in healthy athletes.

Methods: Sixty healthy athletes (32 female, 28 male; 28.9 ± 2.1 years) were recruited from the medical and sports faculty. ARFI values, represented as shear wave velocities (SWVs) as well as conventional ultrasound were obtained for the ATFL in neutral ankle position. A clinical assessment was performed in which the American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Score and the functional ankle ability measure (FAAM) were collected. Interobserver and intraobserver reliability (repeated sessions and repeated days) were assessed using an intra class correlation coefficient (ICC) and typical error (TE) calculation in absolute (TE) and relative units as coefficient of the variation (CV).

Results: SWV values of the ATFL had an average velocity of 1.79 ± 0.20 m/s for all participants, with an average of 1.72 ± 0.36 m/s for females and 1.85 ± 0.31 m/s for males. The interobserver and intraobserver reliability revealed an ICC of 0.902 and 0.933 (TE of 0.67 (CV: 5.2%) and 0.52 (CV: 3.84%)), respectively. FAAM and AOFAS revealed the best possible scores.

Conclusion: ARFI seems to be a valuable diagnostic modality and represents a promising imaging marker for the assessment and monitoring of ankle ligaments in the context of acute and chronic ankle instabilities; ARFI could also be used to investigate loading or sport dependent adaptions.     

Are acceleration and cardiovascular capacities related to perceived load in professional soccer players?

ABSTRACT

This study aims at assessing physical fitness performance and its relationship with the differential ratings of perceived exertion of training load (dRPE TL) and match load (dRPE ML) in a Spanish professional soccer team at the beginning of several in-season periods: 1–4 weeks, 5–8 weeks and 1–8 weeks. Performance and mechanical variables over the acceleration phase, as well as cardiovascular performance variables were evaluated in 20 male professional soccer players of a team competing in the Spanish Second Division League. Moreover, dRPE TL and dRPE ML were quantified. The dRPE TL showed negative and large associations between both maximal aerobic speed (MAS) and maximal oxygen consumption (VO_2max) (from r = ?0.53; ± 0.06 to r = ?0.53; ± 0.05 95% CL, p = 0.035 to 0.036) and RPEres TL values throughout the 5–8 and 1–8 week periods. Furthermore, dRPE ML positive and large associations were found between players initial MAS or VO_2max (from r = 0.50; ± 0.17 to r = 0.56; ± 0.11 95% CL, p = 0.026 to 0.049) and RPEmus ML in 1–4 and 1–8 week periods. The current study suggests that a better cardiovascular capacity could be connected with a lower RPEres TL and higher RPEmus ML.     

Lifetime prevalence of injuries in incoming division I collegiate football players

Objectives: The purpose of this study is to determine the lifetime prevalence of past injuries in incoming first year football players in a Division 1 college football team.

Methods: Pre-participation questionnaires from 605 first-year football players over 20 years (1996–2015) were examined to determine the prevalence of concussions, stingers, fractures, and musculoskeletal surgeries sustained before playing at the collegiate level. Players were grouped by position: wide receiver and defensive back (WR/DB), offensive and defensive linemen (OL/DL), all other positions (OP), and unknown (UKN). Prevalence of injuries by year and position was compared using Pearson’s χ² Test (p < 0.05).

Results: The reported lifetime prevalence is as follows: concussion (21%), stinger (23%), musculoskeletal surgery (23%), and fracture (44%). There were no significant differences in lifetime prevalence of concussions (p = 0.49), stingers (p = 0.31), fractures (p = 0.60), or musculoskeletal surgeries (p = 0.97) based on position. There were also no significant differences in the lifetime prevalence of concussions (p = 0.14), musculoskeletal surgeries (p = 0.50), or fractures (p = 0.59) based on year. However, there was a significant difference in the lifetime prevalence of stingers based on year (p < 0.001).

Conclusions: There was an expectation to observe an increase in injury prevalence by entering year, but this was not seen. A decrease in stingers was actually observed, but there was no significant difference among any other injury recorded. These results do not support the perception that football injuries are on the rise. Under reporting is a significant concern as players may fear disqualification or that they are evaluated by the coaching staff based on their medical history. More research is needed to confirm lifetime injury prevalence and evaluate differences over time among football players.     

Physical and physiological demands and hormonal responses in basketball small-sided games with different tactical tasks and training regimes

Objectives

To evaluate external and internal training load (TL) and hormonal responses in basketball 3-versus-3 small-sided games (SSGs).

Perception of whole-body motion during balance perturbations is impaired in Parkinson's disease and is associated with balance impairment

BackgroundIn addition to motor deficits, Parkinson's disease (PD) may cause perceptual impairments. The role of perceptual impairments in sensorimotor function is unclear, and has typically been studied in single-joint motions.Research questionWe hypothesized that perception of whole-body motion is impaired in PD and contributes to balance impairments. We tested (1) whether directional acuity to whole body perturbations during standing was worse in people with PD compared to neurotypical older adults (NOA), and (2) whether balance ability, as assessed by the MiniBESTest, was associated with poor directional acuity in either group.MethodsParticipants were exposed to pairs of support-surface translation perturbations in a two-alternative forced choice testing paradigm developed previously in a young healthy population. The first perturbation of each pair that was to be judged by participants was directly backward, and the second perturbation deviated from the left or right from the backward direction by 1°–44°. Participants reported whether the perturbations in each pair were in the “same” or “different” direction. Judgements from 24 to 67 perturbation pairs were used to calculate directional acuity thresholds corresponding to “just-noticeable differences” in perturbation direction. Linear mixed models determined associations between directional thresholds and clinical variables including MDS-UPDRS-III score, age, and MiniBESTest score.Results20 PD (64 ± 7 y, 12 male, ≥12 h since last intake of antiparkinsonian medications) and 12 NOA (64 ± 8, 6 male) were assessed. Directional thresholds were higher (worse) among PD participants (17.6 ± 5.9° vs. 12.8 ± 3.3°, P < 0.01). Linear mixed models further showed that higher thresholds were associated with MDS-UPDRS-III score (P < 0.01), and were associated with poorer balance ability among PD participants (P < 0.01), but not among NOA participants (P = 0.40).SignificancePerception of whole-body motion is impaired in PD and may contribute to impaired balance and falls.     

Retinal endothelial function in cardiovascular risk patients: A randomized controlled exercise trial

The aim of this study was to investigate, for the first time, the effects of high-intensity interval training (HIIT) on retinal microvascular endothelial function in cardiovascular (CV) risk patients. In the randomized controlled trial, middle-aged and previously sedentary patients with increased CV risk (aged 58 ± 6 years) with ≥ two CV risk factors were randomized into a 12-week HIIT (n = 33) or control group (CG, n = 36) with standard physical activity recommendations. A blinded examiner measured retinal endothelial function by flicker light-induced maximal arteriolar (ADmax) and venular (VDmax) dilatation as well as the area under the arteriolar (AFarea) and venular (VFarea) flicker curve using a retinal vessel analyzer. Standardized assessments of CV risk factors, cardiorespiratory fitness, and retinal endothelial function were performed before and after HIIT. HIIT reduced body mass index, fat mass, and low-density lipoprotein and increased muscle mass and peak oxygen uptake (VO2peak). Both ADmax (pre: 2.7 ± 2.1%, post: 3.0 ± 2.2%, P = .018) and AFarea (pre: 32.6 ± 28.4%*s, post: 37.7 ± 30.6%*s, P = .016) increased after HIIT compared with CG (ADmax, pre: 3.2 ± 1.8%, post: 2.9 ± 1.8%, P = .254; AFarea, pre: 41.6 ± 28.5%*s, post: 37.8 ± 27.0%*s, P = .186). Venular function remained unchanged after HIIT. There was a significant association between ∆-change VO2peak and ∆-changes ADmax and AFarea (P = .026, R² = 0.073; P = .019, R² = 0.081, respectively). 12-weeks of HIIT improved retinal endothelial function in middle-aged patients with increased CV risk independent of the reduction in classical CV risk factors. Exercise has the potential to reverse or at least postpone progression of small vessel disease in older adults with increased CV risk under standard medication. Dynamic retinal vessel analysis seems to be a sensitive tool to detect treatment effects of exercise interventions on retinal microvascular endothelial function in middle-aged individuals with increased CV risk.     

Upper body accelerations as a biomarker of gait impairment in the early stages of Parkinson’s disease

BackgroundChanges in upper body (UB) motion during gait may be a marker of incipient pathology, intervention response and disease progression in Parkinson’s disease (PD), which if independent from the lower body motion, might provide an improved assessment of gait.Research questionThis study aimed to test this hypothesis and establish whether variables calculated from accelerations measured on the UB are unique from spatiotemporal characteristics and can contribute to an improved classification of PD gait.MethodsData was obtained from 70 people with PD (69.2 ± 9.9 y.o., UPDRS III: 36.9 ± 12.3) and 64 age-matched controls (71.6 ± 6.8 y.o.). Spatiotemporal characteristics were measured using a pressure sensitive mat (GAITRite). Head and pelvis accelerations were synchronously measured with wearable inertial sensors (Opal, APDM). Pearson’s product-moment correlations were calculated between 49 selected variables from UB accelerations (representing magnitude, smoothness, regularity, symmetry and attenuation) and 16 traditional spatiotemporal characteristics (representing pace, variability, rhythm, asymmetry and postural control). Univariate and multivariate regression analysis was used to test the variables ability to classify PD gait.ResultsThe variables were mostly unique from each other (67% of variables recorded an r < 0.3). Univariate and multivariate analysis showed that UB variables were moderately better at classifying PD gait than the spatiotemporal characteristics (Univariate: 0.70 to 0.81, Multivariate: 0.88 to 0.91 AUC).SignificanceThis study showed for the first time that, if aiming at objective and optimal sensitive biomarkers for PD, UB variables should be measured in conjunction with spatiotemporal characteristics to obtain a more holistic assessment of PD gait for use in a clinical or free-living environment.     

The Primary Gait Screen in Parkinson’s disease: Comparison to standardized measures

BackgroundPersons with Parkinson’s disease exhibit gait deficits during comfortable-pace overground walking and data from pressure sensitive mats have been used to quantify gait performance. The Primary Gait Screen is a new assessment which includes gait initiation, overground walking, turning, and gait termination. Although overground assessments are useful, the Primary Gait Screen offers a more complex evaluation than traditional gait assessments.Research questionIs the overground walking portion of the Primary Gait Screen comparable to traditional gait assessments?MethodsPersons with Parkinson’s disease (N = 175; 47 F, 128 M; 67 ± 9 yrs) prospectively completed 4 passes at a self-selected speed and two trials of the Primary Gait Screen on an 8 m long pressure-sensing mat. Spatiotemporal gait variables were computed and a repeated-measures MANOVA with a Bonferroni correction compared the spatiotemporal variables from the Primary Gait Screen to the self-selected trials: gait velocity, cadence, step length, step time, and stride length.ResultsThe analyses failed to detect differences between the Primary Gait Screen and self-selected trials for gait velocity, step length, or stride length (p > .01). Post-hoc tests revealed decreased cadence and increased step time were the only differences between the Primary Gait Screen trials and the self-selected trial (p < .001).SignificanceDifferences seen in cadence and step time during the Primary Gait Screen may be attributed to patients’ strategy, but are likely not clinically meaningful. The Primary Gait Screen appears to be a comparable assessment of overground walking in persons with Parkinson’s disease, and may be a useful and accurate clinical assessment of walking.     

Asymmetry in multi-directional jumping tasks

ObjectivesQuantify and compare average symmetry indexes (ASI) across jumping directions (vertical, lateral and horizontal) and variables (jump distance and height, peak force and peak power) in a non-injured population of netball players.MethodsNineteen sub-elite netball players (age: 19.5 ± 1.1 years, body mass: 75.1 ± 11.8 kg, height: 177.6 ± 5.2 cm) performed three single-leg countermovement jumps from a force plate in the vertical, horizontal and lateral directions. Force, power and jump height ASI’s were calculated from force plate data. Jump distance ASI was calculated as the distance jumped.ResultsIndividual ASI’s ranged from 0.0 to 48.6% while averaged ASI’s ranged from 3.1% (peak force) to 11.4% (peak power). Significant (p ≤ 0.05) ASI differences were observed between vertical force (3.0%) and power (9.2%) (p = 0.02), horizontal power (11.4%) and jump distance (4.6%) (p < 0.001), horizontal force (8.0%) and distance (4.6%) (p < 0.001) and lateral power (10.0%) and jump distance (6.2%) (p = 0.05). The greatest ASI was found for the lateral direction (8.4 ± 1.2% averaged across the three variables).ConclusionsThere appears to be some variation in the magnitude of the ASI depending on the variable and direction used to quantify the asymmetry. Decisions need to be made by the strength and conditioning practitioner as to which variables and directions are specific to the requirements of their sport, position or activity.     

Clustering of screen time behaviours in adolescents and its association with waist circumference and cardiorespiratory fitness

ObjectivesTo identify the association of clusters of screen time (ST) behaviours with waist circumference (WC) and cardiorespiratory fitness (CRF) among adolescents.DesignCross-sectional study of 574 adolescents (53% girls, 13 years), conducted in 2017.MethodsWaist circumference was measured, a shuttle run was performed to assess CRF, and a questionnaire was applied. Sex, age, socioeconomic status was reported, and daily duration of ST indicators for television viewing, computer use, videogame playing, and cellphone use, in weekdays and weekend days. Latent class analysis was performed to identify typologies of ST behaviours. Mixed-effects linear regressions were used to test the association of ST clusters with WC and CRF.ResultsParticipants’ WC was 66.9 ± 8 cm and CRF was 39.5 ± 4 ml O₂/kg/min. Four clusters were identified: “Low ST” (25%); “High ST” (20%); “Gamers” (17%); and “High cellphone” (39%). No significant associations were found between ST clusters and WC. Maximum oxygen uptake was higher in those in the “Low ST” cluster compared to the other clusters. No significant interactions for sex were observed.ConclusionsTypologies of ST behaviours do not seem to be related to WC; however, those in the Low ST cluster had higher CRF compared to their peers in the other clusters, suggesting that total ST may be more important for CRF than specific indicators.     

Testosterone,cortisol and alpha-amylase levels during a handball match; analysis of dynamics and associations

ABSTRACT

This study evaluated dynamics of testosterone, cortisol and alpha-amylase during a handball match in high-level male players. Ten male professional players (24.1 ± 3.1 years, 188.2 ± 6.4 cm, 94.6 ± 9.6 kg) were tested on salivary-testosterone, -cortisol and -alpha-amylase levels before (prematch), at halftime, and immediately after the game. Analysis of variance for repeated measurements (ANOVA) with consecutive post-hoc analyses and effect-size differences were calculated to identify differences between measurements. The associations among biomarkers were determined by Pearson’s product moment correlation (Pearson’s r). The ANOVA indicated significant differences in testosterone (F: 14.31, p < 0.01; significant post-hoc differences between prematch and remaining two measurements), and alpha-amylase (F: 9.78, p < 0.01; significant post-hoc differences between all measurements). Significant correlations were evidenced between: (i) alpha-amylase- and testosterone-changes during 1st halftime (Pearson’s r: 0.81, p < 0.01), and (ii) alpha-amylase- and cortisol-changes during 2nd halftime (Pearson’s r: 0.76, p < 0.05). The results indicated specific dynamics of biomarkers during the handball match, with significant increase in alpha-amylase during the entire match and significant increase in the testosterone level during the first half of the match. Further studies are needed to evaluate the associations between real-game performance and changes in hormonal responses.     

The effect of blood pressure on non-invasive fractional flow reserve derived from coronary computed tomography angiography

Objectives

The aim of this study is to assess the effect of blood pressure (BP) on coronary computed tomography angiography (CTA) derived computational fractional flow reserve (CTA-FFR).

Materials and methods

Twenty-one patients who underwent coronary CTA and invasive FFR were retrospectively identified. Ischemia was defined as invasive FFR ≤0.80. Using a work-in-progress computational fluid dynamics algorithm, CTA-FFR was computed with BP measured before CTA, and simulated BPs of 60/50, 90/60, 110/70, 130/80, 150/90, and 180/100 mmHg respectively. Correlation between CTA-FFR and invasive FFR was assessed using Pearson test. The repeated measuring test was used for multiple comparisons of CTA-FFR values by simulated BP inputs.

Results

Twenty-nine vessels (14 with invasive FFR?≤0.80) were assessed. The average CTA-FFR for measured BP (134?±?20/73?±?12 mmHg) was 0.77?±?0.12. Correlation between CTA-FFR by measured BP and invasive FFR was good (r?=?0.735, P?<?0.001). For simulated BPs of 60/50, 90/60, 110/70, 130/80, 150/90, and 180/100 mmHg, the CTA-FFR increased: 0.69?±?0.13, 0.73?±?0.12, 0.75?±?0.12, 0.77?±?0.11, 0.79?±?0.11, and 0.81?±?0.10 respectively (P?<?0.05).

Conclusion

Measurement of the BP just before CTA is preferred for accurate CTA-FFR simulation. BP variations in the common range slightly affect CTA-FFR. However, inaccurate BP assumptions differing from the patient-specific BP could cause misinterpretation of borderline significant lesions.

Key Points

? The blood pressure (BP) affects the CTA-FFR computation. ? Measured BP before CT examination is preferable for accurate CTA-FFR simulation. ? Inaccurate BP assumptions can cause misinterpretation of borderline significant lesions.

     

Weekly screening of youth male football players: a 14-week longitudinal investigation of interactions between groin pain and long lever adductor squeeze strength

ObjectivesTo explore relationships between groin pain and adductor squeeze strength in male academy football players over a 14-week period.DesignLongitudinal cohort study.MethodsWeekly monitoring of youth male football players consisted of reporting groin pain and testing long lever adductor squeeze strength. Players who reported groin pain at any time during the study period were stratified into the “groin pain” group while players who did not report pain remained in the “no groin pain” group. Baseline squeeze strength was retrospectively compared between groups. Players that developed groin pain were examined via repeated measures ANOVA at four timepoints: baseline, last squeeze before pain, pain onset, and return to pain-free.Results53 players were included (age 14.4 ± 1.6 years). Baseline squeeze strength was not different between players in the “groin pain” (n = 29, 4.35 ± 0.89 N/kg) versus “no groin pain” group (n = 24, 4.33 ± 0.90 N/kg, p = 0.83). At a group level, players with no groin pain maintained similar adductor squeeze strength throughout 14 weeks (p > 0.05). Compared to baseline (4.33 ± 0.90 N/kg), players with groin pain had decreased adductor squeeze strength at the last squeeze before pain (3.91 ± 0.85 N/kg, p = 0.003) and at pain onset (3.58 ± 0.78 N/kg, p < 0.001). Adductor squeeze strength at the point where pain subsided (4.06 ± 0.95 N/kg) was not different from baseline (p = 0.14).ConclusionsDecreases in adductor squeeze strength manifest one-week prior to groin pain onset and further decrease at pain onset. Weekly adductor squeeze strength may be an early detector for groin pain in youth male football players.     

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.     

Analysis of styles of play according to season and end of season rank in the National Rugby League

ObjectivesThis study aimed to identify styles of play in the National Rugby League (NRL) relative to season and end of season rank (position on the NRL ladder) across the 2015–2019 seasons.DesignRetrospective, longitudinal analysis of performance indicators.MethodsForty-eight performance indicators (e.g. runs, tackles) from all NRL teams and matches during the 2015–2019 seasons (n = 2010) were quantified. Principal component analysis (PCA) was then used to identify styles of play based on dimensions (Factors) of performance indicators. Multivariate analysis of covariance (MANCOVA) was then used to explain these emergent styles of play relative to ‘season’ and ‘end of season rank’.ResultsThe PCA revealed nine Factors (six attacking, two defensive and one contested style) accounting for ～51% of seasonal team performance variance. These nine Factors differed across ‘seasons’, with four showing an effect against ‘end of season rank’. From these four, two Factors (ball possession and player efforts) impacted upon the combined effects of ‘season’ and ‘end of season rank’.ConclusionsThe PCA identified nine Factors reflecting a spread of attacking, defensive and contested styles of play within the NRL. These styles differed relative to season and a team’s end of season ranking. These results may assist practitioners with the recognition of more contemporary styles of play in the NRL, enabling the development of strategies to exploit competition trends.