Shoulder and elbow symptoms in talented Dutch baseball pitchers: results of a two-season prospective study.

CONTEXT: Baseball pitching requires fast and coordinated motions of the whole body to reach high ball speeds, putting considerable strain on the musculoskeletal system, particularly the shoulder and elbow. DESIGN: Descriptive epidemiology study. OBJECTIVE: To describe musculoskeletal symptoms and the functional status of the shoulder and elbow in male high school baseball pitchers. SETTING: Dutch baseball talent academies. PATIENTS OR OTHER PARTICIPANTS: 125 male high school baseball pitchers aged 12 to 18 years, who participated in one of the six Dutch baseball talent academies and the Dutch National U-18 team were recruited and enrolled. MAIN OUTCOME MEASURE(S): Musculoskeletal symptoms, functional status of the shoulder and elbow were registered for each player every six months over two consecutive baseball seasons through self-assessment questionnaires, including the Kerlan-Jobe Orthopaedic Clinic (KJOC) and the Western Ontario Shoulder Instability Index (WOSI) questionnaires. RESULTS: 570 musculoskeletal (MSS) symptoms in 93 of the 125 players were reported. The average six-month prevalence for symptoms of the throwing shoulder was 37% (95% CI: 33% - 41%), and for the elbow 37% (95% CI: 31% - 42%), followed by the lower back with 36% (95% CI: 26% - 45%). The baseball pitchers who experienced only shoulder symptoms had an average KJOC score of 80.0 (95% CI: 75.3-84.7) points, while those with only elbow symptoms reported a score of 90.2 (95% CI: 89.2-95.3). On the WOSI questionnaire, baseball pitchers scored an average of 421.2 (95% CI: 200.1 - 642.4) points. CONCLUSION: In a cohort of Dutch high school baseball pitchers, one-third reported shoulder and elbow symptoms on the throwing side, with reduced functional status and lower back symptoms. Future efforts should focus on developing preventive strategies through early symptom detection, aiming to prevent symptom progression and, ultimately, the development of severe injuries.

Cavity Quantum Optomechanical Nonlinearities and Position Measurement beyond the Breakdown of the Linearized Approximation.

Several optomechanics experiments are now entering the highly sought nonlinear regime where optomechanical interactions are large even for low light levels. Within this regime, new quantum phenomena and improved performance may be achieved; however, a corresponding theoretical formalism of cavity quantum optomechanics that captures the nonlinearities of both the radiation-pressure interaction and the cavity response is needed to unlock these capabilities. Here, we develop such a nonlinear cavity quantum optomechanical framework, which we then utilize to propose how position measurement can be performed beyond the breakdown of the linearized approximation. Our proposal utilizes optical general-dyne detection, ranging from single to dual homodyne, to obtain mechanical position information imprinted onto both the optical amplitude and phase quadratures and enables both pulsed and continuous modes of operation. These cavity optomechanical nonlinearities are now being confronted in a growing number of experiments, and our framework will allow a range of advances to be made in, e.g., quantum metrology, explorations of the standard quantum limit, and quantum measurement and control.

Hybrid electronic-photonic sensors on a fibre tip.

Most sensors rely on a change in an electrical parameter to the measurand of interest. Their direct readout via an electrical wire and an electronic circuit is, in principle, technically simple, but it is subject to electromagnetic interference, preventing its application in several industrial environments. Fibre-optic sensors can overcome these limitations because the sensing region and readout region can be spaced apart, sometimes by kilometres. However, fibre-optic sensing typically requires complex interrogation equipment due to the extremely high wavelength accuracy that is required. Here we combine the sensitivity and flexibility of electronic sensors with the advantages of optical readout, by demonstrating a hybrid electronic-photonic sensor integrated on the tip of a fibre. The sensor is based on an electro-optical nanophotonic structure that uses the strong co-localization of static and electromagnetic fields to simultaneously achieve a voltage-to-wavelength transduction and a modulation of reflectance. We demonstrate the possibility of reading the current-voltage characteristics of the electro-optic diode through the fibre and therefore its changes due to the environment. As a proof of concept, we show the application of this method to cryogenic temperature sensing. This approach allows fibre-optic sensing to take advantage of the vast toolbox of electrical sensing modalities for many different measurands.

Prospective evaluation of cardiac effects of first-time marathon training, running, and recovery in middle-aged men: cohort study rationale and design.

BACKGROUND: Several phenomena may point to potentially detrimental cardiac effects of endurance exercise, such as elevated circulating cardiac troponin levels and reductions in systolic and diastolic function directly after marathon completion. Furthermore, while myocardial abnormalities have been reported in patients who recovered from COVID-19, the cardiac impact of extensive endurance exercise in individuals who recovered from COVID-19 remains unknown. We therefore aim to investigate (potentially detrimental) cardiac effects of first-time marathon training and participation, including a subset of participants who recovered from COVID-19, in apparently healthy middle-aged men. STUDY DESIGN: This exploratory prospective cohort study investigates cardiac effects of first-time marathon running in 24 middle-aged (35-50 years) healthy men. Primary outcomes are cardiac morphological changes from pre-training up to 1 month after marathon completion, measured with magnetic resonance imaging (MRI) at 4 time points: 1) baseline (4 months before the marathon), 2) pre-marathon (2 weeks before the marathon), 3) post-marathon (< 24 h post-marathon), and 4) recovery (4 weeks after the marathon). Secondary parameters include other cardiac or non-cardiac changes: 1) quantitative MRI myocardial mapping, including mean diffusivity and extracellular volume fraction, 2) echocardiographic morphology and function changes, 3) VO2max, 4) electrocardiogram changes, and 5) levels of cardiac biomarkers. DISCUSSION: This study will contribute to our understanding of cardiac adaptations and maladaptations to first-time marathon running in middle-aged men, and the interaction between extreme endurance exercise and potential detrimental cardiac effects, also in the context of COVID-19. Results will inform on future research directions while providing new clinical insights for health professionals involved in athlete care.

The effectiveness of a golf injury prevention program (GRIPP intervention) compared to the usual warm-up in Dutch golfers: protocol design of a randomized controlled trial.

BACKGROUND: Sixty million golfers around the world play golf. Golf injuries are most frequently located in the spine, elbow, wrist, hand and shoulder. Those injuries are often seen in golfers with more playing hours and suboptimal swing biomechanics, resulting in overuse injuries. Golfers who do not perform a warm-up or do not warm-up appropriately are more likely to report an injury than those who do. There are several ways to warm-up. It is unclear, which warm-up is most useful for a golfer to perform. Moreover, there is currently no evidence for the effectiveness of a warm-up program for golf injury prevention. We previously have developed the Golf Related Injury Prevention Program (GRIPP) intervention using the Knowledge Transfer Scheme (KTS). We aim to evaluate the effect of the GRIPP intervention on golf-related injuries. The hypothesis is that the GRIPP intervention program will reduce the number of golf-related injuries. METHODS AND DESIGN: The GRIPP study is a two-armed randomized controlled trial. Twenty-eight golf clubs with 11 golfers per club will be randomly allocated to the intervention or control group. The intervention group will perform the GRIPP intervention program, and the control group will perform their warm-up as usual. The GRIPP intervention is conducted with the Knowledge Transfer Scheme framework, which is a systematic process to develop an intervention. The intervention consists of 6 exercises with a maximum total of 10 min. The primary outcome is the overall prevalence (%) of golf injuries measured with the Oslo Sports Trauma Research Center (OSTRC-H) questions on health problems every fortnight. The secondary outcome measures will be exposure to golf and compliance to the intervention program. DISCUSSION: In other sports warm-up prevention programs are effective in reducing the risk of injuries. There are no randomized trials on golf injury prevention. Therefore, an individual unsupervised golf athlete intervention program is conducted which reflects the daily practice of predominantly unsupervised exposure of amateur golfers. TRIAL REGISTRATION: The trial is retrospectively (28 October 2021) registered at the Dutch Trial Register: NL9847 ( https://trialsearch.who.int ).

Breakdown of Spin-to-Helicity Locking at the Nanoscale in Topological Photonic Crystal Edge States.

We measure the local near-field spin in topological edge state waveguides that emulate the quantum spin Hall effect. We reveal a highly structured spin density distribution that is not linked to a unique pseudospin value. From experimental near-field real-space maps and numerical calculations, we confirm that this local structure is essential in understanding the properties of optical edge states and light-matter interactions. The global spin is reduced by a factor of 30 in the near field and, for certain frequencies, flipped compared to the pseudospin measured in the far field. We experimentally reveal the influence of higher-order Bloch harmonics in spin inhomogeneity, leading to a breakdown in the coupling between local helicity and global spin.

No association between rate of torque development and onset of muscle activity with increased risk of hamstring injury in elite football.

Hamstring injuries remain a significant burden in sports that involve high-speed running. In elite male football, hamstring injury has repeatedly been identified as the most common non-contact injury, representing 12% of all injuries. As the incidence remains high, investigations are aimed at better understanding how to improve prevention efforts. Intrinsic risk factors such as strength have been investigated extensively in a cohort of professional football players; however, other intrinsic measures of neuromuscular function have not been studied in this cohort. This study aims to investigate the association between timing of hamstring muscle activity onset and the rate of torque development during the early phase of isokinetic strength testing with risk of hamstring injury in professional football players in a prospective cohort study. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included rate of torque development and timing of muscle activity onset. A total of 367 unique players (60.6% of all QSL players) competed for 514 player seasons (103 players competed both seasons) and sustained 65 hamstring injuries. There was no difference in the onset of muscle activity between the biceps femoris and medial hamstrings comparing the injured to uninjured players. For both onset of muscle activity and rate of torque development, there were no significant differences between any of the variables (P > .05), with small effect sizes detected across all the different variables (d < 0.3). Rate of torque development and onset of muscle activity were not associated with a risk of future hamstring injury. The use of these measures as part of a periodic health evaluation to identify risk of hamstring injury is unsupported.

Trends in time-loss injuries during the 2011-2016 South African Rugby Youth Weeks.

Youth rugby is a popular sport in South Africa (SA) with a high injury incidence. The annual SA Rugby Youth Week tournaments attract the top age-group players in the country providing a sample of players for reliable injury surveillance. The aim of the study was to analyze the changes in time-loss injury rates at the SA Rugby Youth Week tournaments between 2011 and 2016, differences between age-groups, and to investigate associated injury risk factors. All confirmed time-loss injuries at the 4 age-group tournaments (under-13, under-16, and 2 under-18) from 2011 to 2016 were recorded. Injury incidence densities (IID) for years, tournaments, and injury risk factors were calculated and Poisson regression analyses were performed to determine differences. Time-loss injuries (n = 494) were reported over 24 240 exposure hours, with an overall IID of 20.4 (18.6-22.2) injuries per 1000 player hours. The year 2013 had a significantly lower IID compared to 2011. Injury risk decreased with increasing age; under-13 and under-16 had significantly higher IID compared to under-18 Craven Week. Tackling was the phase of play at highest risk, with an IID of 7.4 (6.3-8.5) injuries per 1000 player hours. Central/peripheral nervous system (CNS/PNS) and, therefore, the head/neck were the most commonly occurring injuries/location injured. In conclusion, within the SA Rugby tournament structure, the older players had a decreased rate of injury. The tackle event was still the phase of play with the highest injury incidence regardless of age. This increase in incidence is largely due to an increase in CNS/PNS injuries.

Injuries in Dutch elite field hockey players: A prospective cohort study.

This study describes the prevalence, incidence density, severity, and nature of injuries in elite field hockey players over the Dutch 2015-2016 season. Eighty players answered a baseline questionnaire and were subsequently followed up every 2 weeks to report the hours spent on training/competition and experienced injuries, which were registered using the Oslo Sports Trauma Research Centre Questionnaire on Health Problems. Of the 74 players included in the analysis, 52 (70%) reported 112 injuries. Eighty-seven injuries (78%) received medical attention, and 56 (50%) led to training/competition time-loss. Thirty-four injuries (30%) hampered players' availability to train and compete. Most of the injuries (74%) were not caused by any contact. The mean prevalence of injury was 29% (95% confidence interval [CI] 3-55) for all, 9% (95% CI 0-20) for acute, and 14% (95% CI 0-36) for overuse injuries. Players sustained 3.5 (95% CI 2.5-4.5) new acute injuries per 1000 hours of training and 12.3 (95% CI 7.6-17.0) per 1000 hours of competition. The median of the severity score was 28 from 100 (25%-75% interquartile range [IQR] 16-42) for all, 35 (IQR 23-53) for acute, and 21 (IQR 16-31) for overuse injuries. On average, 1 in 4 elite field hockey players experiences an injury within a 2-week period during the season. Although acute injuries are common, overuse injuries pose a comparable problem in elite field hockey. As injuries are a burden on players' health and may hamper performance and availability to train and compete, prevention is of great importance.

Preventing recurrent ankle sprains: Is the use of an App more cost-effective than a printed Booklet? Results of a RCT.

Recurrent ankle sprains can be reduced by following a neuromuscular training (NMT) program via a printed Booklet or a mobile application. Regarding the high incidence of ankle sprains, cost-effectiveness regarding implementation can have a large effect on total societal costs. In this economic analysis, we evaluated whether the method of implementing a proven effective NMT program using an App or a Booklet resulted in differences in injury incidence rates leading to costs and hence to differences in cost-effectiveness. In total, 220 athletes with a previous ankle sprain were recruited for this randomized controlled trial with a follow-up of 12 months. Half of the athletes used the freely available "Strengthen your ankle" App and the other half received a printed Booklet. After the 8-week program, athletes were questioned monthly on their recurrent injuries. Primary outcome measures were incidence density of ankle injury and incremental cost-effectiveness ratio (ICER). During follow-up, 31 athletes suffered from a recurrent ankle sprain that led to costs resulting in a hazard ratio of 1.13 (95% CI: 0.56-2.27). The incremental cost-effectiveness ratio of the App group in comparison with the Booklet group was €361.52. The CE plane shows that there was neither a difference in effects nor in costs between both intervention methods. This study showed that the method of implementing the NMT program using an App or a Booklet led to similar cost-effectiveness ratios and the same occurrence of recurrent injuries leading to costs. Both the App and the Booklet can be used to prevent recurrent ankle injuries, showing no differences in (cost-) effectiveness at 12-month follow-up.

High prevalence of self-reported injuries and illnesses in talented female athletes.

BACKGROUND: A thorough knowledge of the epidemiology and severity of injuries and illness in youth female elite sports is lacking due to the methodological challenges involved in recording them. In this study, the prevalence and incidence of injuries and illness are assessed among youth female elite athletes. Instead of solely focusing on time-loss injuries, our study included all substantial and non-substantial health problems (ie, injuries, mental problems and illnesses). METHODS: Sixty young elite Dutch female athletes (age: 16.6 years (SD: 2.3), weight: 58.3 kg (SD: 15.1), height: 154.1 cm (SD: 44.2)) participating in soccer (n=23), basketball (n=22) and gymnastic (n=15) talent development programmes were prospectively followed during one season (September 2014 to April 2015). To collect health problem data, all athletes completed the Oslo Sports Trauma Research Center Questionnaire on Health Problems every other week. Main outcome measures were average prevalence of injury and incidence density of injury. RESULTS: At any given time, 47.9% of the athletes reported an injury (95% CI 43.6% to 52.6%) and 9.1% reported an illness (95% CI 5.1 to 19.0). The average injury incidence density was 8.6 per 1000 hours of athlete exposure. The average number of self-reported injuries per athlete per season was significantly higher in soccer athletes (4.3±2.7) than in basketball athletes (2.6±2.0) (p=0.03) and not significantly higher than in the gymnastic squad. The knee and the ankle were two of the most common injury locations for all squads. Knee injuries in basketball and soccer and heel injuries in the gymnastic squad had the highest impact on sports participation. CONCLUSION: High prevalence of self-reported injuries among talented female athletes suggests that future efforts towards their prevention are warranted.

Incidence, aetiology and prevention of musculoskeletal injuries in volleyball: A systematic review of the literature.

Currently, there is no overview of the incidence and (volleyball-specific) risk factors of musculoskeletal injuries among volleyball players, nor any insight into the effect of preventive measures on the incidence of injuries in volleyball. This study aimed to review systematically the scientific evidence on the incidence, prevalence, aetiology and preventive measures of volleyball injuries. To this end, a highly sensitive search strategy was built based on two groups of keywords (and their synonyms). Two electronic databases were searched, namely Medline (biomedical literature) via Pubmed, and SPORTDiscus (sports and sports medicine literature) via EBSCOhost. The results showed that ankle, knee and shoulder injuries are the most common injuries sustained while playing volleyball. Results are presented separately for acute and overuse injuries, as well as for contact and non-contact injuries. Measures to prevent musculoskeletal injuries, anterior knee injuries and ankle injuries were identified in the scientific literature. These preventive measures were found to have a significant effect on decreasing the occurrence of volleyball injuries (for instance on ankle injuries with a reduction from 0.9 to 0.5 injuries per 1000 player hours). Our systematic review showed that musculoskeletal injuries are common among volleyball players, while effective preventive measures remain scarce. Further epidemiological studies should focus on other specific injuries besides knee and ankle injuries, and should also report their prevalence and not only the incidence. Additionally, high-quality studies on the aetiology and prevention of shoulder injuries are lacking and should be a focus of future studies.

Head injuries in children's football-results from two prospective cohort studies in four European countries.

Head injuries are considered harmful in children. We analyzed head and neck injuries in organized football in 7- to 12-year-old children. Data for this analysis were obtained from a prospective cohort study over two consecutive football seasons in two European countries, and a randomized intervention trial over one season in four European countries. Football exposure and injuries were documented through an online database. Detailed information regarding injury characteristics and medical follow-up was retrieved from coaches, children and parents by phone. Thirty-nine head injuries and one neck injury (5% of all 791 injuries) were documented during 9933 player-seasons (total football exposure 688 045 hours). The incidence was 0.25 [95%CI 0.15, 0.35] head/neck injuries per 1000 match hours (N=23 match injuries) and 0.03 [95%CI 0.02, 0.03] per 1000 training hours. Eleven concussions (27.5%), nine head contusions (22.5%), eight lacerations or abrasions (20%), two nose fractures (2.5%), and two dental injuries (2.5%) occurred. The remaining eight injuries were nose bleeding or other minor injuries. Thirty injuries (75%) resulted from contact with another player, and ten injuries were due to collision with an object, falling or a hit by the ball. Whereas 70% of all head injuries (N=28) were due to frontal impacts, 73% of concussions (N=8) resulted from an impact to the occiput. The incidence and severity of head injuries in children's football are low. Coaches and parents, however, should be sensitized regarding the potential of concussions, particularly after an impact to the occiput.

The "Strengthen your ankle" program to prevent recurrent injuries: A randomized controlled trial aimed at long-term effectiveness.

OBJECTIVES: Recurrent ankle sprains can be reduced by a neuromuscular training program (NMT). The way NMT is delivered may influence the incidence of long term recurrent injuries, residual pain and disability. DESIGN: This RCT with a follow-up of twelve months, evaluated whether the implementation method of a proven effective NMT program delivered by a mobile application or a written instruction booklet, resulted in differences in injury incidence rates, functional ankle disability/pain in the long term, assuming equal compliance - as is shown in previous research - with the 8-week intervention. METHODS: 220 athletes with a history of ankle sprain were recruited for this RCT. 110 athletes were offered the freely available "Strengthen your ankle App" and the other 110 received a printed Booklet. Primary outcome measure was incidence density of ankle sprains. Secondary outcome measures were residual pain/disability and the individual cumulative number of ankle sprains during follow-up. RESULTS: The incidence densities of self-reported ankle sprain recurrences were not significantly different between both groups (HR 1.06; 95% CI 0.76-1.49). Median FADI (Functional Ankle and Disability Index) scores increased equally over time in both groups, indicating a lower rate of limitation and pain in both groups at follow-up. Neither FADI scores nor cumulative recurrent injuries were significantly different between groups. CONCLUSIONS: This study showed that the implementation method of a NMT program by using an App or a Booklet did neither lead to different injury incidence rates in the long term nor did it influence residual functional disability/pain. Assuming equal compliance during the 8-week intervention, both methods show similar effectiveness in twelve-month follow-up.

Is risk-taking in talented junior tennis players related to overuse injuries?

Overuse injuries are a serious problem in junior tennis. Gaining insight in age-specific risk factors can contribute to prevention. The developmental cognitive processes that take place during adolescence make talented players more inclined to take risks. This may be even more pronounced in the high performance culture in which they move. Therefore, this study focuses on the relationship between risk-taking and overuse injuries in talented tennis players. Seventy-three talented tennis players (45 boys and 28 girls, age 11-14 years) were monitored for 32 weeks, using the Oslo Sports Trauma Research Centre Questionnaire on Health Problems. Risk-taking was measured at the start of the season with the Iowa Gambling Task. Linear regression analyses were executed to predict (a) overuse injuries, (b) time loss overuse injuries and (c) overuse severity, by risk-taking, exposure time, and injury history. In boys, risk-taking contributed significantly to time loss overuse injuries [F(1,39) = 7.764, P = 0.008, R2  = 0.15] and to overuse severity [F(1,39) = 5.683, P = 0.022, with an R2 of 0.13] In girls, time loss overuse injuries [F(1,23) = 6.889, P = 0.018, R2  = 0.20] and overuse severity [F(1,23) = 7.287, P = 0.013, R2  = 0.24] were predicted by exposure time. Coaches and trainers should be aware that talented male tennis players who are inclined to take risks, are more likely to maintain risky behavioral patterns related to overuse injuries.

Upper extremity injuries in Danish children aged 6-12, mechanisms, and risk factors.

Although injuries to the upper extremity are most costly, the picture of the upper extremity injury problem remains incomplete. This study is the first to describe the etiology and mechanisms of upper extremity injuries in Danish children. A 2.5-year observational prospective cohort study was conducted to record upper extremity injuries in 1048 children. Data were weekly collected by sending a text message. A total of 176 upper extremity injuries were reported (128 acute injuries). Of the acute upper extremity injuries, 55% were sprains, 47% occurred in the hand/wrist, and 53% of cases were caused by a fall. When corrected for exposure to physical activity, this resulted in an acute upper extremity injury incidence density of 0.18 per 1000 h of physical activity. The odds of sustaining an upper extremity injury was higher in the older children (HR: 1.84, 95% CI: 1.10-3.09), a tendency was found suggesting that girls are at increased acute upper extremity risk compared to boys (HR: 1.40 95% CI: 0.97-2.04). The findings that most injuries occur after a fall, that injury risk increases over age and that girls seem to be at increased injury risk provides essential information to guide future childhood injury prevention.

Increasing compliance with neuromuscular training to prevent ankle sprain in sport: does the 'Strengthen your ankle' mobile App make a difference? A randomised controlled trial.

BACKGROUND: E-health has the potential to facilitate implementation of effective measures to prevent sports injuries. AIM: We evaluated whether an interactive mobile application containing a proven effective exercise programme to prevent recurrent ankle sprains resulted in higher compliance as compared with regular written exercise materials. METHODS: 220 athletes participated in this randomised controlled trial with a follow-up of 8 weeks; 110 athletes received a booklet explaining an 8-week neuromuscular training programme; 110 athletes participated in the same programme in an interactive mobile App (Strengthen your ankle). The primary outcome was compliance with the exercise programme. Secondary outcome measure was the incidence density of self-reported recurrent ankle sprains. RESULTS: The mean compliance to the exercise scheme was 73.3% (95% CI 67.7% to 78.1%) in the App group, compared with 76.7% (95% CI 71.9% to 82.3%) in the Booklet group. No significant difference in compliance was found between groups. The incidence densities of self-reported time-loss recurrences were not significantly different between both groups (HR 3.07; 95% CI 0.62 to 15.20). SUMMARY: This study shows that the method of implementing the exercises by using an App or a Booklet does not lead to different compliance rates. NEW FINDINGS: The use of a mobile App or a Booklet lead to similar compliance and injury rates in the short term. TRIAL REGISTRATION NUMBER: The Netherlands National Trial Register NTR 4027. The NTR is part of the WHO Primary Registries.

Health and economic burden of running-related injuries in runners training for an event: A prospective cohort study.

Prospective running-related injury (RRI) data from runners training for an event are scarce, especially with regard to RRI-associated costs. Therefore, the aim of this study was to investigate the prevalence and economic burden of RRIs in runners participating in an organized training program preparing them for an event. This was a prospective cohort study with 18 weeks of follow-up. Individuals aged 18 or older and registered to participate in an organized running program were eligible. Follow-up surveys were sent every 2 weeks to collect data about running exposure, RRIs, and costs. Of the 161 potential participants, 53 (32.9%) were included in this study. A total of 32 participants reported 41 RRIs. The mean prevalence during follow-up was 30.8% [95% confidence interval (CI) 25.6-36.0%]. Overuse was the main mechanism of RRI (85.4%, n = 35). An RRI was estimated to have an economic burden of €57.97 (95% CI €26.17-94.00) due to healthcare utilization (direct costs) and €115.75 (95% CI €10.37-253.73) due to absenteeism from paid work (indirect costs). These results indicate that the health and economic burden of RRIs may be considered significant for public health. Therefore, prevention programs are needed for runners participating in organized training programs.

The effectiveness of the nationwide BokSmart rugby injury prevention program on catastrophic injury rates.

Rugby Union ("rugby") participants have a higher than average risk of injury compared with participants of other popular team sports. BokSmart, a nationwide injury prevention program was launched in South Africa in mid-2009, with the goal of reducing catastrophic head/neck (serious) injuries in players. The program provides injury prevention information to coaches and referees. This study investigated if BokSmart has been associated with a reduction in these injuries. The BokSmart program collected data on all South African rugby-related serious injuries since 2008. Using a Poisson regression, injury numbers were compared pre-BokSmart (2008-2009) to the years post-implementation (2010-2013). Player numbers were assumed to be constant throughout this evaluation: junior = 529,483; senior = 121,663. In junior players, the "post-BokSmart" period had 2.5 less annual serious injuries than "pre-BokSmart" (incidence rate ratio: 0.6, 95% confidence interval: 0.5-0.7, P < 0.000). In contrast, there was no significant difference in these periods in seniors. The absence of effect in seniors may be a result of fewer players or of differences in effectiveness of BokSmart in this group--future studies should investigate these questions.

Positional OSA part 2: retrospective cohort analysis with a new classification system (APOC).

BACKGROUND: In Part 1 of this two-part article, the Amsterdam Positional Obstructive Sleep Apnoea Classification (APOC) was recently introduced, a classification system aimed at facilitating the identification of suitable candidates for positional therapy (PT): patients who will benefit from a clinically significant improvement of their obstructive sleep apnoea (OSA) with PT. APOC was developed with new generation PT devices in mind rather than conventional PT (tennis ball technique). New generation PT can be defined as a well-tolerated device which prevents a patient from adopting the worst sleeping position (WSP) without negatively influencing sleep efficiency, as objectified by a full night polysomnography (PSG). PT is rapidly gaining momentum in the scope of OSA treatment. The objective of this manuscript is to measure the prevalence of position-dependent obstructive sleep apnoea (POSA) according to the APOC, in a consecutive series of patients referred for PSG as well as an investigation of associations between POSA and certain patient characteristics. METHODS: We performed a retrospective, single-centre cohort study including a consecutive series of patients who underwent a PSG during the period of April 2010 until October 2010. RESULTS: Within this OSA-cohort (n = 253), a prevalence of POSA of 69 % when applying APOC is measured, compared to 64 % when applying Cartwright's classification. An inverse relation between POSA and BMI was observed, likewise between POSA and apnoea hypopnoea index (AHI). CONCLUSION: We are of opinion that APOC is a suitable tool to identify patients who will or will not benefit from PT, thus resulting in more cost-efficient treatment.