With a validated mathematical model of the head-neck consisting of nine rigid bodies (skull, seven cervical vertebrae, and torso), we simulated head impacts to estimate the injury risk associated with soccer heading. Experimental data from head-linear accelerations during soccer heading were used to validate the nine-body head-neck model for short duration impact loading of the head. In the computer simulations, the mass ratios between head mass and impacting body mass, the velocity of the impacting body, and the impact elasticity were varied. Head-linear and angular accelerations were compared to standard head-injury tolerance levels, and the injury risk specifically related to soccer heading was estimated. Based on our choice of tolerance levels in general, our simulations showed that injury risk from angular head accelerations was greater than from linear head accelerations, and compared to frontal impacts, lateral impacts had greater angular and less linear head accelerations. During soccer heading, our simulations indicated an unacceptable injury risk caused by angular head accelerations for frontal and lateral impacts at relatively low impact velocities for children, and at medium range impact velocities for adults. For linear head accelerations, injury risk existed for frontal and lateral impacts at medium range to relatively larger impact velocities for children, while no injury risk was shown for adults throughout the entire velocity range. For injury prevention, we suggest that head-injury risk can be reduced most substantially by increasing the mass ratio between head and impacting body. In soccer with children, the mass of the impacting body has to be adjusted to the reduced head mass of a child, that is, it must be clearly communicated to parents, coaches, and youngsters to only use smaller soccer balls.
Klaus Schneider and Ronald F. Zernicke
Christopher A. DiCesare, Scott Bonnette, Gregory D. Myer and Adam W. Kiefer
performance, quality of movement, or injury risk. To that end, dynamic unilateral and bilateral tasks, such as the single-limb drop landing ( Ali, Rouhi, & Robertson, 2013 ; Ford et al., 2006 ) and the drop vertical jump ( Hewett et al., 2005 ; Myer et al., 2010 ), respectively, have been used to identify
Matthew J. Cross, Sean Williams, Grant Trewartha, Simon P.T. Kemp and Keith A. Stokes
To explore the association between in-season training-load (TL) measures and injury risk in professional rugby union players.
This was a 1-season prospective cohort study of 173 professional rugby union players from 4 English Premiership teams. TL (duration × session-RPE) and time-loss injuries were recorded for all players for all pitch- and gym-based sessions. Generalized estimating equations were used to model the association between in-season TL measures and injury in the subsequent week.
Injury risk increased linearly with 1-wk loads and week-to-week changes in loads, with a 2-SD increase in these variables (1245 AU and 1069 AU, respectively) associated with odds ratios of 1.68 (95% CI 1.05–2.68) and 1.58 (95% CI 0.98–2.54). When compared with the reference group (<3684 AU), a significant nonlinear effect was evident for 4-wk cumulative loads, with a likely beneficial reduction in injury risk associated with intermediate loads of 5932–8651 AU (OR 0.55, 95% CI 0.22–1.38) (this range equates to around 4 wk of average in-season TL) and a likely harmful effect evident for higher loads of >8651 AU (OR 1.39, 95% CI 0.98–1.98).
Players had an increased risk of injury if they had high 1-wk cumulative loads (1245 AU) or large week-to-week changes in TL (1069 AU). In addition, a U-shaped relationship was observed for 4-wk cumulative loads, with an apparent increase in risk associated with higher loads (>8651 AU). These measures should therefore be monitored to inform injury-risk-reduction strategies.
Katherine Lee, James Onate, Samar McCann, Tamerah Hunt, Wilbert Turner and Mark Merrick
In wrestling, athletes often support a large amount of weight on their heads or are forced into extreme ranges of motion. These suboptimal movement conditions lead to a high prevalence of neck injuries in wrestlers. A large portion of the work done by the cervical musculature in wrestling is theorized to be eccentric or isometric types of contractions. Strengthening of these cervical muscles is clinically considered to play a vital role in being competitive on the wrestling mat. The cervical stability provided by strengthening these muscles may also play a part in injury prevention among wrestlers.
Focused Clinical Question:
Does increased cervical strength lead to a decreased risk of injury in wrestling?
Summary of Search, “Best Evidence” Appraised, and Key Findings:
The literature was searched for studies of level 4 evidence or higher using the Oxford Centre for Evidence-Based Medicine level of evidence system that investigated the relationship between cervical strength and injury risk in wrestling. No studies were found comparing cervical strength to injury risk in wrestling, but 2 related studies were found and have been included in this critically appraised topic.
Clinical Bottom Line:
There is poor evidence to support a relationship between cervical strength and injury risk in wrestling.
Strength of Recommendation:
There is grade C evidence to indicate that increased cervical strength decreases the risk of injury in wrestling.
Christopher A. DiCesare, Adam W. Kiefer, Scott Bonnette and Gregory D. Myer
Biomechanical analyses of sport movements have classically been used to quantify kinematic (ie, joint angular motion) and kinetic (ie, joint moments of force) factors in the context of task performance, injury risk, or pathology. Traditional biomechanical assessments include indices of walking and
Kristian M. O’Connor, Sarika K. Monteiro and Ian A. Hoelker
The purpose of this study was to compare the knee joint dynamics for males and females performing constrained cutting tasks to an unanticipated running and cutting maneuver. Sixteen male and 17 female recreational athletes were recruited to perform four cutting tasks; unanticipated run and cut (CUT), stride land and cut (SLC), far box-land and cut (FLC), and close box-land and cut (CLC). Three-dimensional knee joint kinematics and kinetics were recorded. Data were compared across gender and task with a 2 × 4 ANOVA (p < .05), and a factor analysis was performed to examine task relationships. There were significant group mean differences between the tasks and across genders. The factor analysis revealed high correlations between the three constrained tasks, but for variables typically associated with ACL injury risk there was a poor relationship to the CUT task. This was particularly true for the frontal plane variables. The constrained tasks were only moderately useful in predicting cutting mechanics.
Sandra J. Shultz
Despite extensive research, we still do not fully understand the biological mechanisms that underlie a female's increased susceptibility for suffering a noncontact ACL injury. While sex differences in neuromuscular control are often implicated, prevention efforts addressing these differences have not resulted in a profound or sustainable reduction in injury rates. This paper will explore two likely scenarios that explain this greater susceptibility in females: (1) females have a structurally weaker ligament that is more prone or susceptible to failure at a given load (scenario #1), or (2) females develop less knee protection and experiences higher relative loads on the ACL (scenario #2). While we have learned much over the last two decades about ACL injury risk in females, much remains unknown. Continued research is of paramount importance if we are to effectively identify those females who are at greatest risk for injury and effectively reduce their susceptibility through appropriate interventions.
Paul B. Gastin, Denny Meyer, Emy Huntsman and Jill Cook
To assess the relationships between player characteristics (including age, playing experience, ethnicity, and physical fitness) and in-season injury in elite Australian football.
Single-cohort, prospective, longitudinal study.
Player characteristics (height, body mass, age, experience, ethnicity, playing position), preseason fitness (6-min run, 40-m sprint, 6 × 40-m sprint, vertical jump), and in-season injury data were collected over 4 seasons from 1 professional Australian football club. Data were analyzed for 69 players, for a total of 3879 player rounds and 174 seasons. Injury risk (odds ratio [OR]) and injury severity (matches missed; rate ratio [RR]) were assessed using a series of multilevel univariate and multivariate hierarchical linear models.
A total of 177 injuries were recorded with 494 matches missed (2.8 ± 3.3 matches/injury). The majority (87%) of injuries affected the lower body, with hamstring (20%) and groin/hip (14%) most prevalent. Nineteen players (28%) suffered recurrent injuries. Injury incidence was increased in players with low body mass (OR = 0.887, P = .005), with poor 6-min-run performance (OR = 0.994, P = .051), and playing as forwards (OR = 2.216, P = .036). Injury severity was increased in players with low body mass (RR = 0.892, P = .008), tall stature (RR = 1.131, P = .002), poor 6-min-run (RR = 0.990, P = .006), and slow 40-m-sprint (RR = 3.963, P = .082) performance.
The potential to modify intrinsic risk factors is greatest in the preseason period, and improvements in aerobic-running fitness and increased body mass may protect against in-season injury in elite Australian football.
Paul J. Read, Jon L. Oliver, Gregory D. Myer, Mark B.A. De Ste Croix and Rhodri S. Lloyd
disruptions in motor control strategies underlie these periods of increased injury risk ( 2 , 30 , 38 ). Between-limb asymmetry in functional performance is a potential risk factor for male youth soccer players where preferred lower limb dominance is evident ( 11 ). This may be further confounded by
Eva Martin-Diener, Simon Foster, Meichun Mohler-Kuo and Brian W. Martin
This study investigates the relationships between physical activity (PA), sports participation and sensation seeking or aggression and injury risk in young men.
A representative cohort study was conducted with 4686 conscripts for the Swiss army. Risk factors assessed at baseline were PA, the frequency of sports participation, sensation seeking, and aggression. The number of injuries during the past 12 months was reported 16 months after baseline. Exposure to moderate-tovigorous physical activity (MVPA) was estimated based on baseline PA.
Among conscripts, 48.5% reported at least 1 injury for the past 12 months. After accounting for exposure to MVPA, the most inactive individuals (reference group) had the highest injury risk and those with high levels of PA and weekly sports participation the lowest (Poisson regression analysis: incidence rate ratio = 0.14 [0.12–0.16]). Independent of activity level, sensation seeking increased cumulative injury incidence significantly (Logistic regression analysis [injured vs. not injured]: odds ratio = 1.29 [1.02–1.63]) and incidence rates marginally. Aggression was marginally associated only with cumulative injury incidence and only in those participating in daily sports.
When accounting for exposure to PA, being inactive is a strong injury risk factor in young men, whereas the roles of the personality variables are less clear.