Search

The aim of this study was to investigate the differences between sitting volleyball (SV) skills and para-athletes’ sport classes. Twelve games involving 151 athletes from 11 countries from the Rio ...

Concussions are becoming an increasingly important issue in sports, especially in an area like volleyball that, until recently, seemed less prone to such injuries. The purpose of this study was to determine the coefficient of restitution and basic mechanical properties of standardized volleyballs, including stiffness and hysteresis, dependent on different influencing factors. A drop test was performed to calculate the coefficient of restitution based on the time of flight of the ball between the first and second bounce. This was detected using a microphone with a sampling frequency of 44.1 kHz. To determine the mechanical properties, a materials testing machine applied a compression force until a deformation of 50 mm was achieved. These data were sampled with a frequency of 12.5 kHz. The results showed that the three analysed factors in this study, including the ball model, gauge pressure, and incident velocity, had a significant influence on the coefficient of restitution. Therefore, the amount of energy dissipation during an impact situation at low velocities was significantly different within the tested sample of official standardized volleyballs. The stiffness and hysteresis of the volleyballs also varied significantly. These basic mechanical findings raise an interesting question as to whether the investigated factors are appropriate to predict forces acting on the head during a high velocity collision (25–30 m/s), ultimately resulting in a risk of concussion.

The current technological age has created exponential growth in the availability of technology and data in every industry, including sport. It is tempting to get caught up in the excitement of purchasing and implementing technology, but technology has a potential dark side that warrants consideration. Before investing in technology, it is imperative to consider the potential roadblocks, including its limitations and the contextual challenges that compromise implementation in a specific environment. A thoughtful approach is therefore necessary when deciding whether to implement any given technology into practice. In this article, we review the vision and pitfalls behind technology's potential in sport science and medicine applications and then present a critical decision-making framework of 4 simple questions to help practitioners decide whether to purchase and implement a given technology.

A high incidence of overuse knee injuries among youth basketball players may be attributed to number of jumps. Wearable technology may be an effective tool for measuring jump load compared to traditional counting methods. The purpose of this study was to validate a commercially available jump counter (VERT® Classic) in youth basketball practices and games, and to identify the characteristics (i.e., height, direction, takeoff) of jumps recorded by the VERT® Classic. 46 (19F, 27M) youth basketball players wore a VERT® Classic and were recorded on video during games and practices. The number of jumps recorded by the VERT® Classic and evaluated by video raters were compared for each jump characteristic using intraclass correlation coefficient (ICC(3

A time-loss injury definition continues to be the most widely used injury definition despite evidence that it fails to accurately capture overuse injuries. An overuse injury questionnaire, using an “all complaints” definition has been created to address the limitation of a time-loss definition. The main aim of this work was to determine the effect that injury definition and registration methodology has on the collection of knee injuries among elite level volleyball players. To reach this goal, seventy-two volleyball players were prospectively followed over 32-weeks. Time-loss injuries were captured using an individual injury report form (IIRF). Study participants completed an overuse injury questionnaire (mOIQ) via a weekly short message service (SMS). The IIRF captured 15 time-loss knee injuries in 72 study participants (20%). Based on the mOIQ, 84.7% of participants reported having a knee problem and 66.7% sustained a substantial knee problem. All IIRF knee injuries captured were also registered by the mOIQ. Agreement on the specific diagnosis occurred for 66.7% of injuries resulting in a moderate Kappa score of 0.51. In conclusion, an overuse injury questionnaire provided a greater understanding of the magnitude and burden of knee injuries in this population.

Objectives To validate the use of an inertial measurement unit (IMU) for the collection of total jump count and assess the validity of an IMU for the measurement of jump height against 3-D motion analysis. Design Cross sectional validation study. Setting 3D motion-capture laboratory and field based settings. Participants Thirteen elite adolescent volleyball players. Independent variables Participants performed structured drills, played a 4 set volleyball match and performed twelve counter movement jumps. Main outcome measures Jump counts from structured drills and match play were validated against visual count from recorded video. Jump height during the counter movement jumps was validated against concurrent 3-D motion-capture data. Results The IMU device captured more total jumps (1032) than visual inspection (977) during match play. During structured practice, device jump count sensitivity was strong (96.8%) while specificity was perfect (100%). The IMU underestimated jump height compared to 3D motion-capture with mean differences for maximal and submaximal jumps of 2.5 cm (95%CI: 1.3 to 3.8) and 4.1 cm (3.1–5.1), respectively. Conclusion The IMU offers a valid measuring tool for jump count. Although the IMU underestimates maximal and submaximal jump height, our findings demonstrate its practical utility for field-based measurement of jump load.

Background: Chronic kidney disease (CKD) is common in patients with type 2 diabetes mellitus (T2DM) and limits therapeutic options. Dipeptidyl peptidase-4 (DPP-4) inhibitors represent a novel class of oral glucose-lowering agents and are known to be safe and effective in the general population. Methods: We searched Cochrane, EMBASE, and PubMed from the time of their inception until March 2015. We included randomized controlled trials analyzing the efficacy (change in hemoglobin A1C [HbA1C]) and safety of DPP-4 agents in individuals with reduced kidney function (estimated glomerular filtration rate 2). We extracted study characteristics, participants' baseline characteristics, and safety outcomes from eligible studies. We performed a random effects meta-analysis to summarize the change in HbA1C and the relative risk of cardiovascular events in patients with T2DM and CKD. We also collected data on hypoglycemia, other serious adverse events, and mortality. Results: We reviewed 12 studies with 4,403 patients with CKD and 239 on dialysis, finding a mean weighted decline in HbA1C of -0.48 (95% CI -0.61 to -0.35) with DPP-4 inhibitor therapy compared to placebo. DPP-4 inhibitors did not result in any additional adverse events, hypoglycemic episodes, or increased mortality. Restricting to studies with low risk of bias did not alter these findings. Conclusions: DPP-4 inhibitors can lower HbA1C without increasing the risk of cardiovascular or other major adverse events in patients with CKD. Few studies reported critical adverse events such as heart failure and hypersensitivity. If compared with other oral antiglycemic drugs, the effect of DPP-4 inhibitors is limited; however, their low risk of hypoglycemia may favor their use in patients with CKD. Summary: This systematic review of DPP-4 inhibitors in CKD suggests that they reduce HbA1C by about 0.5%. Furthermore, there was not any increase in the risk for significant adverse events. More research is needed to determine the safety and efficacy of DPP-4 inhibitors in CKD.

Sport is becoming increasingly competitive and athletes are being exposed to greater physical demands, leaving them prone to injuries. Monitoring athletes with the use of wearable technology could provide a way to potentially manage training and competition loads and reduce injuries. One such technology is the VERT inertial measurement unit, a commercially available discrete wearable device containing a 3-axis accelerometer, 3-axis gyroscope and 3-axis magnetometer. Some of the main measurement outputs include jump count, jump height and landing impacts. While several studies have examined the accuracy of the VERT’s measures of jump height and jump count, landing impact force has not yet been investigated. The objective of this research study was to explore the validity of the VERT landing impact values. We hypothesized that the absolute peak VERT acceleration values during a jump-land cycle would fall within 10% of the peak acceleration values derived simultaneously from a research-grade accelerometer (Shimmer). Fourteen elite university-level volleyball players each performed 10 jumps while wearing both devices simultaneously. The results showed that VERT peak accelerations were variable (limits of agreement of -84.13% and 52.37%) and had a propensity to be lower (mean bias of -15.88%) when compared to the Shimmer. In conclusion, the validity of the VERT device’s landing impact values are generally poor, when compared to the Shimmer.

BackgroundEarly accurate detection of acute kidney injury (AKI) occurring after cardiac surgery may improve morbidity and mortality. Although several novel biomarkers have been developed for the early detection of AKI, their clinical utility in the critical intraoperative and immediate postoperative period remains unclear.Study DesignSystematic review and meta-analysis.Setting & PopulationAdult patients having cardiac surgery.Selection Criteria for StudiesEMBASE, CINAHL, Cochrane Library, Scopus, and PubMed from January 1990 until January 2015 were systematically searched for cohort studies reporting the utility of novel biomarkers for the early diagnosis of AKI after adult cardiac surgery. Reviewers extracted data for study design, population, timing of biomarker measurement and AKI occurrence, biomarker performance (area under the receiver operating characteristic curve [AUROC]), and risk of bias.Index TestsNovel urine, plasma, and serum AKI biomarkers, measured intraoperatively and in the early postoperative period (

Objectives To examine potential intrinsic risk factors that may contribute to the onset of jumper's knee in elite level-male volleyball players. Design Prospective Cohort Study. Setting Varsity and National team volleyball gymnasiums. Participants Sixty elite adult male volleyball players from Canada. Assessment of risk factors Players completed a series of risk factor assessments at the commencement of their seasons, including vertical jump (cm), ankle dorsiflexion range (degrees), dynamic balance (normalized distance reached; cm), dynamic knee alignment (degrees), and landing mechanics (degrees). Main outcome measure Self-reported knee problems, captured via short message service. Results Knee problem prevalence was 75% [95% confidence intervals (CIs): 62.2-84.6] and the incidence rate for substantial injuries over the study period was 30 injuries/100 players/season (95% CI: 19.5-43.1). No risk factor was found to significantly predict the future occurrence of developing jumper's knee. The odds ratios were close to unity (range: 0.94-1.07) with narrow confidence intervals and P > 0.05. Conclusions A more sensitive capture of overuse knee problems did not result in the identification of distinct risk factors for the development of jumper's knee. These findings highlight a lack of available methodology to accurately assess risk factors for overuse injuries.

ObjectivesThe objective of this systematic review was to study the impact of preoperative physical activity levels on adult cardiac surgical patients’ postoperative: (1) major adverse cardiac and cerebrovascular events (MACCEs), (2) adverse events within 30 days, (3) hospital length of stay (HLOS), (4) intensive care unit length of stay (ICU LOS), (5) activities of daily living (ADLs), (6) quality of life, (7) cardiac rehabilitation attendance and (8) physical activity behaviour.MethodsA systematic search of MEDLINE, Embase, AgeLine and Cochrane library for cohort studies was conducted.ResultsEleven studies (n=5733 patients) met the inclusion criteria. Only self-reported physical activity tools were used. Few studies used multivariate analyses to compare active versus inactive patients prior to surgery. When comparing patients who were active versus inactive preoperatively, there were mixed findings for MACCE, 30 day adverse events, HLOS and ICU LOS. Of the studies that adjusted for confounding variables, five studies found a protective, independent association between physical activity and MACCE (n=1), 30-day postoperative events (n=2), HLOS (n=1) and ICU LOS (n=1), but two studies found no protective association for 30-day postoperative events (n=1) and postoperative ADLs (n=1). No studies investigated if activity status before surgery impacted quality of life or cardiac rehabilitation attendance postoperatively. Three studies found that active patients prior to surgery were more likely to be inactive postoperatively.ConclusionDue to the mixed findings, the literature does not presently support that self-reported preoperative physical activity behaviour is associated with postoperative cardiac surgical outcomes. Future studies should objectively measure physical activity, clearly define outcomes and adjust for clinically relevant variables.RegistrationTrial registration numberNCT02219815. PROSPERO number CRD42015023606.

Spikes in training and competition workloads, especially in undertrained athletes, increase injury risk.1 However, just as attributing athletic injuries to single risk factors is an oversimplification of the injury process,2 3 interpreting this workload-injury relationship should not be done in isolation. Instead, we must further unpack how (ie, through which mechanisms) workload spikes might result in injury, and what characteristics make athletes more robust or more susceptible to injury at any given workload. In other words, which factors mediate the workload-injury relationship, and which moderate the relationship. Like dominoes being knocked over, mediators can be viewed as the intermediary steps that explain the association between an observed variable and an outcome.4 In this context, mediating variables help to explain ‘why changes in workloads might cause injuries?’ For example, it is known that rugby league players exposed to spikes in running workloads, indicated by a high acute:chronic workload ratio, are at an increased risk for non-contact injuries.5 One potential explanation is that neuromuscular fatigue mediates this relationship, such that increased …

Delirium is an acute syndrome that involves fluctuating changes in attention and cognition. Although delirium is the most common neurologic complication after cardiac operation, data about its impact on long-term outcomes are lacking. The purpose of this systematic review was to examine the effect of postoperative delirium (PoD) on long-term outcomes, including morbidity, probability of death, cognitive decline, institutionalization, and health-related quality of life (HRQoL) in patients undergoing cardiac operation. After performing this systematic review we determined that PoD after cardiac operation is associated with an increased risk of probability of death and readmission to the hospital and a decrease in cognitive function, overall function, and HRQoL.

Objective To assess the incidence of concussions among adolescent volleyball players in Canada. Design Cross sectional survey. Setting Online survey. Participants In total, 663 registered Volleyball Canada members completed a national survey, with a response rate of 13.0%; web-based survey response rates rarely exceed 5%. The 452 (68.2%) female and 211 (31.8%) male responders had a mean age of 16.2 (95% CI: 16.1to 16.4) years with a range from 14 to 19 years. Assessment of risk factors The type of environment: controlled non-competitive environment (practice or warm-up) versus competitive game play environment. Outcome measures Whether the athletes sustained a concussion as defined by the 2012 Zurich Consensus. Main results A total of 86 concussions were reported, of which 52 were in the previous 12 months, yielding a one-year cumulative incidence per 100 athletes of 7.1 (95% CI: 4.3 to 11.4) and 7.5 (95% CI: 5.4 to 10.3) for males and females, respectively. In total, 57.1% (95% CI: 46.2 to 67.5) of all concussions involved ball-to-head contact. Player-to-player contact and head-to-floor contact were less prevalent at 20.2% (95% CI: 12.8 to 30.4) and 15.5% (95% CI: 9.1 to 25.1) respectively. Practice environment accounted for 46.5% of all concussions while 38.4% occurred in game play. The remaining 15.1% occurred in warm-up. In total, 61.6% (95% CI: 50.2 to 71.7) of concussions occurred outside of free-flow competitive game play, in a more structured environment. Conclusions There is a significant margin for injury prevention as a substantial proportion (61.6%) of concussions happening in a noncompetitive, controlled environment that may be amenable to change that would reduce the potential for such injury. Competing interests The authors have no competing interest to state.

Background There is a growing body of evidence illustrating the contribution of training load to musculoskeletal injury risk. There is a gap in the literature, however, regarding the impact of training on concussion risk. Objective To evaluate the association between sport-specific participation volume and concussion risk in male youth ice hockey players. Design Cohort study. Setting Community ice rinks and sport medicine clinics (2011–15 hockey seasons). Patients (or Participants) Male Pee Wee (11–12 years old), Bantam (13–14 years old) and Midget (15–17 years old) ice hockey players were eligible. Players were excluded if they reported unhealed injuries at study entry, had missing/systematically incomplete hockey participation exposure data, or if they sustained a concussion but participation volume could not be estimated from the day of injury. Interventions (or Assessment of Risk Factors) Cumulative hockey participation volume (CPHV) was estimated based on participation exposure data reported by team designate. The association between concussion risk and total 7-day and 28-day CHPV was evaluated using multivariable logistic regression [OR (95%CI)]. Models were adjusted for concussion history and cluster by player (α Main Outcome Measurements Medically diagnosed concussion. Results Participants who met the inclusion criteria (n=1235/1990) sustained 34 medically diagnosed concussions. Increased concussion risk was associated with hourly increases in 7-day CHPV [OR=1.16 (95%CI: 1.08–1.25), p Conclusions Increased hockey participation volume was associated with increased concussion risk in male youth ice hockey players. This is the first study to explore the association between training volume and concussion risk. Future research utilizing objective volume measurements and training response tools will be critical to the development of primary concussion prevention strategies that optimize the role of training load.

Background The efficacy of erythropoietin-stimulating agents (ESAs) for improving health-related quality of life (HRQOL) in anemia of chronic kidney disease (CKD) is unclear. Purpose To determine the effect of ESAs on HRQOL at different hemoglobin targets in adults with CKD who were receiving or not receiving dialysis. Data sources Searches of PubMed, EMBASE, the Cochrane Library, and ClinicalTrials.gov from inception to 1 November 2015, supplemented with manual screening. Study selection Randomized, controlled trials that evaluated the treatment of anemia with ESAs, including erythropoietin and darbepoetin, targeted higher versus lower hemoglobin levels, and used validated HRQOL metrics. Data extraction Study characteristics, quality, and data were assessed independently by 2 reviewers. Outcome measures were scores on the Short Form-36 Health Survey (SF-36), Kidney Dialysis Questionnaire (KDQ), and other tools. Data synthesis Of 17 eligible studies, 13 reported SF-36 outcomes and 4 reported KDQ outcomes. Study populations consisted of patients not undergoing dialysis (n = 12), those undergoing dialysis (n = 4), or a mixed sample (n = 1). Only 4 studies had low risk of bias. Pooled analyses showed that higher hemoglobin targets resulted in no statistically or clinically significant differences in SF-36 or KDQ domains. Differences in HRQOL were further attenuated in studies at low risk of bias and in subgroups of dialysis recipients. Limitation Statistically significant heterogeneity among studies, few good-quality studies, and possible publication bias. Conclusion ESA treatment of anemia to obtain higher hemoglobin targets does not result in important differences in HRQOL in patients with CKD. Primary funding source KRESCENT and Manitoba Health Research Council Establishment.