Modelling the potential spread of virus during soccer matches.

Objective: In the present study, we model the potential spread of virus during soccer matches. Methods: Tracking data from 14 elite soccer matches was used. One player in each match was designated as a virus carrier (called 'infected player') for the purpose of the study. The exposure score (measured in seconds) was calculated as time spent closer than 1.5 m from the infected player or time spent in an exponentially declining zone, where the infected player was positioned earlier. Results: The results revealed that, on average, each player was exposed for 87.8 s per match. Conclusion: Potential spread of virus during soccer matches was modelled and it revealed that the exposure to a virus during soccer matches is limited.

Differences in sport-related concussion for female and male athletes in comparable collegiate sports: a study from the NCAA-DoD Concussion Assessment, Research and Education (CARE) Consortium.

OBJECTIVES: To examine sex differences in sport-related concussion (SRC) across comparable sports. METHODS: Prospective cohort of collegiate athletes enrolled between 2014 and 2017 in the Concussion Assessment, Research and Education Consortium study. RESULTS: Among 1071 concussions (females=615; 57.4%), there was no difference in recovery (median days to full return to play) (females=13.5 (IQR 9.0, 23.1) vs males=11.8 (IQR 8.1, 19.0), p=0.96). In subgroup analyses, female recovery was longer in contact (females=12.7 days (IQR 8.8, 21.4) vs males=11.0 days (IQR 7.9, 16.2), p=0.0021), while male recovery was longer in limited contact sports (males=16.9 days (IQR 9.7, 101.7) vs females=13.8 days (IQR 9.1, 22.0), p<0.0001). There was no overall difference in recovery among Division I schools (females=13.7 (IQR 9.0, 23.1) vs males=12.2 (IQR 8.2 19.7), p=0.5), but females had longer recovery at the Division II/III levels (females=13.0 (IQR 9.2, 22.7) vs males=10.6 (IQR 8.1, 13.9), p=0.0048). CONCLUSION: Overall, no difference in recovery between sexes across comparable women's and men's sports in this collegiate cohort was found. However, females in contact and males in limited contact sports experienced longer recovery times, while females had longer recovery times at the Division II/III level. These disparate outcomes indicate that, while intrinsic biological sex differences in concussion recovery may exist, important, modifiable extrinsic factors may play a role in concussion outcomes.

Validation methods for global and local positioning-based athlete monitoring systems in team sports: a scoping review.

BACKGROUND/OBJECTIVE: Global navigation satellite systems (GNSS) and local positioning systems (LPS) are to date common tools to measure external training load in athletes. The aim of this scoping review was to map out and critically appraise the methods used to validate different GNSS and LPS used in team sports. METHOD: A total of 48 studies met the eligibility criteria and were included in the review. The reference systems applied in the validations, and the parameters investigated were extracted from the studies. RESULTS: The results show a substantial range of reference systems used to validate GNSS and LPS and a substantial number of investigated parameters. The majority of the validation studies have employed relatively simple field-based research designs, with use of measure tape/known distance as reference measure for distance. Timing gates and radar guns were frequently used as reference system for average and peak speed. Fewer studies have used reference system that allow for validation of instantaneous dynamic position, such as infrared camera-based motion capture systems. CONCLUSIONS: Because most validation studies use simple and cost-effective reference systems which do not allow to quantify the exact path athletes travel and hence misjudge the true path length and speed, caution should be taken when interpreting the results of validation studies, especially when comparing results between studies. Studies validating instantaneous dynamic position-based measures is warranted, since they may have a wider application and enable comparisons both between studies and over time.

International consensus definitions of video signs of concussion in professional sports.

BACKGROUND: The use of video to assist professional sporting bodies with the diagnosis of sport-related concussion (SRC) has been well established; however, there has been little consistency across sporting codes with regards to which video signs should be used, and the definitions of each of these signs. AIM: The aims of this study were to develop a consensus for the video signs considered to be most useful in the identification of a possible SRC and to develop a consensus definition for each of these video signs across the sporting codes. METHODS: A brief questionnaire was used to assess which video signs were considered to be most useful in the identification of a possible concussion. Consensus was defined as >90% agreement by respondents. Existing definitions of these video signs from individual sports were collated, and individual components of the definitions were assessed and ranked. A modified Delphi approach was then used to create a consensus definition for each of the video signs. RESULTS: Respondents representing seven sporting bodies (Australian Football League, Cricket Australia, Major League Baseball, NFL, NHL, National Rugby League, World Rugby) reached consensus on eight video signs of concussion. Thirteen representatives from the seven professional sports ranked the definition components. Consolidation and refinement of the video signs and their definitions resulted in consensus definitions for six video signs of possible concussion: lying motionless, motor incoordination, impact seizure, tonic posturing, no protective action-floppy and blank/vacant look. CONCLUSIONS: These video signs and definitions have reached international consensus, are indicated for use by professional sporting bodies and will form the basis for further collaborative research.

Beighton scoring of joint laxity and injury incidence in Middle Eastern male youth athletes: a cohort study.

OBJECTIVES: To examine the association between generalised joint laxity (GJL) and injury rates in Middle Eastern male youth athletes. DESIGN: Prospective observational study consisting of GJL screen and injury audit (season 2009/2010). SETTING: Aspire Sports Academy Doha, Qatar. PARTICIPANTS: A total of 226 adolescent male athletes (mean age: 14.2 years; SD: 1.7; range: 10-18) involved in 15 sporting activities were grouped into contact and non-contact sports. All available athletes were included in this study. OUTCOME MEASURES: A seasonal injury audit, athletes' anthropometric characteristics, for example, weight, height and body mass index and screen for GJL to determine Beighton Score (BS). RESULTS: The 226 athletes sustained 596 injuries and 75% reported at least one injury over a seasonal injury audit. Players in contact sports were injured more often than players in non-contact sports (more frequent injuries than injury-free time in contact sports; 127 days (95% CI 93 to 160) vs 176 days in non-contact sports (95% CI 118 to 234) (p<0.001). Survival analysis showed that gradient BS was not associated with injury HR=1.004 (95% CI 0.95 to 1.06) in the overall cohort. However, BS was associated with a greater injury risk in contact sports (HR: 1.29; 95% CI 1.05 to 1.59; p=0.015). CONCLUSION: Greater GJL, defined by gradient BS, plus involvement in contact sports together influence injury risk in youth athletes. Preseason documentation of GJL scoring should be considered specifically for contact sports as injury pre-emptive measure.

Evaluation of spine MRIs in athletes participating in the Rio de Janeiro 2016 Summer Olympic Games.

BACKGROUND/AIM: In high-level Olympic athletes, many spinal pathologies arise from overuse, while others are the result of acute injury. Our aim is to analyse the epidemiology of spinal pathologies detected on MRI in athletes participating in the 2016 Rio de Janeiro Summer Olympics. METHODS: In this retrospective study, all spine MRIs performed during the 2016 Rio Games were analysed. Descriptive data from the MRIs were tabulated and analysed for disc degeneration, spinal canal and/or neural foraminal narrowing, and acute/chronic fractures. Data were analysed by sport, continent of origin, age and sex. RESULTS: Of 11 274 athletes participating in the Olympic games, 100 received spine MRI. Fifty-two of the 100 (52%) athletes who received cervical, thoracic and/or lumbar spine MRI showed moderate to severe spinal disease. The highest sport-specific incidence of moderate to severe spine disease was seen in aquatic diving athletes (67%, 3 per 100 divers). Weightlifting had the second highest sport-specific incidence of spine disease (67%, 1.5 per 100 weightlifters). Athletics used the most spine MRIs (31 of 107 MRIs, 29%). European athletes had more spine MRIs than all other continents combined (55 of 107 MRIs, 51%). Athletes over 30 years old had the highest rate of moderate to severe spine disease on MRI (24 of 37 athletes >30 years old, 65%). CONCLUSIONS: A high number of the world's premier athletes demonstrated moderate to severe spine disease on MRI during the 2016 Summer Olympics, including moderate/severe degenerative disc changes with varying degrees of disc bulges and herniations.

Spatiotemporal characteristics of motor actions by blind long jump athletes.

BACKGROUND: Blind people depend on spatial and temporal representations to perform activities of daily living and compete in sport. OBJECTIVE: The aim of this study is to determine the spatiotemporal characteristics of long jumps performed by blind athletes and compare findings with those reported for sighted athletes. METHODS: We analysed a sample of 12 male athletes competing in the F11 Long Jump Finals at the Paralympic Games in London 2012. Performances were recorded using four high-speed cameras, and speeds were measured using a radar speed gun. The images were processed using validated image analysis software. RESULTS: The long jump run-up is shorter in blind athletes than in sighted athletes. We observed statistically significant differences for body centre of mass velocity and an increase in speed over the last three strides prior to take-off, contrasting with reports for sighted athletes and athletes with less severe visual impairment, who maintain or reduce their speed during the last stride. Stride length for the last three strides was the only spatial characteristic that was not significantly associated with effective jump distance. Blind long jumpers extend rather than shorten their last stride. Contact time with the take-off board is longer than that reported for sighted athletes. CONCLUSION: The actions of blind long jumpers, unlike those without disabilities, do not vary their leg actions during the final runway approach for optimal placement on the take-off board.

Health benefits of different sport disciplines for adults: systematic review of observational and intervention studies with meta-analysis.

The aim was to assess the quality and strength of evidence for the health benefits of specific sport disciplines. Electronic search yielded 2194 records and the selection resulted in 69 eligible studies (47 cross-sectional, 9 cohort, 13 intervention studies). 105 comparisons between participation and non-participation groups in 26 different sport disciplines were reported. Moderately strong evidence showed that both running and football improve aerobic fitness and cardiovascular function at rest, and football reduces adiposity. Conditional evidence showed that running benefits metabolic fitness, adiposity and postural balance, and football improves metabolic fitness, muscular performance, postural balance, and cardiac function. Evidence for health benefits of other sport disciplines was either inconclusive or tenuous. The evidence base for the health benefits of specific sports disciplines is generally compromised by weak study design and quality. Future research should address the health effects of different sport disciplines using rigorous research designs.

Legal responsibilities of physicians when making participation decisions in athletes with cardiac disorders: Do guidelines provide a solid legal footing?

Safe sports participation involves protecting athletes from injury and life-threatening situations. Preparticipation cardiovascular screening (PPS) in athletes is intended to prevent exercise-related sudden cardiac death by medical management of athletes at risk, which may include disqualification from sports participation. The screening physician relies on current guidelines and expert recommendations for management and decision-making. There is concern about false-positive screening results and wrongly grounding an athlete. Similarly, there is a concern about false-negative screening results and athletes participating with potentially lethal disorders. Who is legally responsible if an athlete suddenly dies after a proper PPS resulting in low risk? Several consensus documents based on expert opinion describe only a few lines on legal responsibilities in eligibility screening and disqualification decision-making in athletes. This article discusses legal responsibilities and concerns in eligibility decision-making for physicians.

The development of fatigue during match-play tennis.

Data describing the activity profile and physiological characteristics of tennis match-play are extensive. However, these data have generally provided descriptive accounts of the one-off match-play of amateur or lowly ranked professional players lasting <3 h. Accordingly, these research efforts have likely failed to fully capture the demands of Grand Slam tennis match-play, particularly in the men's game where matches can last >5 h. Furthermore, there is a distinct lack of evidence-based insight regarding the manifestation of fatigue within and between tennis matches, notwithstanding that skeletal muscle function has been reported to reduce following prolonged match-play. Moreover, it is evident that match-play evokes pronounced and prolonged physiological, neuromuscular and psychological perturbations that may be exacerbated with consecutive days of match-play. Separate to these internal load responses, a collection of non-uniform movement and technical performance changes are reported, though rarely from match-play data. Consequently, direct or causal links between altered physiological or muscle contractile function and subsequent match-play outcomes are lacking. Indeed, emerging evidence seems to infer that players adjust their game strategy, and the resultant execution of stroke play, to accommodate any such deterioration in physiological function. The purpose of this review was to discuss the available literature in terms of the physiological, mechanical and psychological responses that occur during prolonged match-play in the context of their likely effect on match-play performance.

London 2012 Paralympic swimming: passive drag and the classification system.

BACKGROUND: The key difference between the Olympic and Paralympic Games is the use of classification systems within Paralympic sports to provide a fair competition for athletes with a range of physical disabilities. In 2009, the International Paralympic Committee mandated the development of new, evidence-based classification systems. This study aims to assess objectively the swimming classification system by determining the relationship between passive drag and level of swimming-specific impairment, as defined by the current swimming class. METHODS: Data were collected on participants at the London 2012 Paralympic Games. The passive drag force of 113 swimmers (classes 3-14) was measured using an electro-mechanical towing device and load cell. Swimmers were towed on the surface of a swimming pool at 1.5 m/s while holding their most streamlined position. RESULTS: Passive drag ranged from 24.9 to 82.8 N; the normalised drag (drag/mass) ranged from 0.45 to 1.86 N/kg. Significant negative associations were found between drag and the swimming class (τ = -0.41, p < 0.01) and normalised drag and the swimming class (τ = -0.60, p < 0.01). The mean difference in drag between adjacent classes was inconsistent, ranging from 0 N (6 vs 7) to 11.9 N (5 vs 6). Reciprocal Ponderal Index (a measure of slenderness) correlated moderately with normalised drag (r(P) = -0.40, p < 0.01). CONCLUSIONS: Although swimmers with the lowest swimming class experienced the highest passive drag and vice versa, the inconsistent difference in mean passive drag between adjacent classes indicates that the current classification system does not always differentiate clearly between swimming groups.